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  • An Evaluation of Chicken Litter Ash, Wood

    Ash and Slag for Use as Lime and Phosphate

    Soil Amendments

    Baiq Emielda Yusiharni SP (B.Sc-Hon) in Soil Science

    University of Mataram, Indonesia 2001

    This thesis is presented for the degree of

    Master of Science of

    The University of Western Australia

    School of Earth and Geographical Sciences

    Faculty of Natural and Agricultural Sciences 2007

  • ABSTRACT

    Standard AOAC methods of chemical analysis have been used to characterize and

    evaluate the industrial byproducts; partly burnt chicken litter ash (CLA), totally burnt

    chicken litter ash (CLAT), wood ash (WA) and iron smelting slag for use as a

    combined liming agent and phosphate fertilizer. Rock phosphate has this function and

    was included for comparison purposes. All the byproducts had pH values above 9 and

    a liming capacity above 90% of pure lime, as a result, these materials will be effective

    as liming agents. Total P concentrations for CLA, CLAT, slag, and WA were 3.6%,

    4.75%, 0.26%, and 0.44% respectively indicating that they could be used as P

    fertilizers when applied at the high rates required for liming soils. For all the

    byproducts, citric acid (CA) dissolved phosphorus at faster rate than did neutral

    ammonium citrate (NAC) and alkaline ammonium citrate (AAC). For long extraction

    times total P dissolved mostly increased in the sequence CA>NAC>AAC. For no

    extraction time was the P soluble in the three extractants a reliable predictor of the

    effectiveness of these materials as P fertilizers which was established by plant growth

    measurements. XRD and SEM analyses identified the P containing compounds and

    provided explanations for the chemical analyses and dissolution behaviour. CLA,

    CLAT and WA consist mostly of mixtures of apatite, calcite, and quartz although

    CLA also contains much carbonised litter, which contains a low concentration of P.

    Calcium magnesium silicate (akermanite) and calcium aluminium silicate (gehlenite)

    were the main constituents of slag. For all apatitic materials little apatite persisted in

    CA residues after 120 hours extraction but considerable apatite remained in NAC and

    AAC residues.

    A glasshouse experiment was carried out to identify the effectiveness of the wastes as

    phosphate fertilizers for a highly P-deficient acid lateritic soil. Treatments included

    various types and rates of industrial byproducts and included monocalcium phosphate,

    dicalcium phosphate and rock phosphate as reference materials. Various levels of

    phosphate were applied, ryegrass was planted and harvested after 8 weeks and at 4

    week intervals thereafter. Dry matter yield ranged from 0.025 g to 2.3 g/pot for the

    first harvest, from 0.03 g to 2.3 g/pot for the second harvest and many plants died of P

    deficiency before the third harvest. The agronomic effectiveness of the materials as

    phosphate fertilizers was calculated by comparing the various amounts of phosphate

    i

  • required to produce the same yield for the various materials and relating these values

    to the performance of monocalcium phosphate. This is the horizontal comparison or

    substitution value procedure that gives values of Relative Effectiveness (RE) that

    are independent of the rate of application of the fertilizers. The RE values for all the

    materials relative to monocalcium phosphate (100%) for the first harvest are as

    follows, 50% for dicalcium phosphate, 31% for rock phosphate, 7% for partly burnt

    chicken litter ash, 7% for totally burnt chicken litter ash and 1% for wood ash and

    slag. The RE values for the second harvest were 100% for monocalcium phosphate,

    80% for dicalcium phosphate, 40% for rock phosphate, 10% for partly burnt chicken

    litter ash, 8% for totally burnt chicken litter ash and 2% for wood ash and slag. Data

    for subsequent harvests are not reported due to the death of many plants. Clearly

    chicken litter ash has appreciable value as a phosphate fertilizer whereas wood ash

    and slag are ineffective. Explanations for these differences in effectiveness are

    discussed in the text.

    An evaluation of the liming effect of the byproducts indicates that they may be used

    as a soil amendment on acid soils and are nearly as effective as standard lime

    (CaCO3). Byproducts are also sources of other plant nutrients so they may be regarded

    as a form of compound fertilizer and liming agent.

    ii

  • ACKNOWLEDGEMENTS

    I would like to give my deepest thanks and appreciation to my supervisor Prof.

    Bob Gilkes for his help, encouragement, and great attention during supervising my

    study. I also thank Dr. Andrew Rate as my cosupervisor.

    I acknowledged Australian Government (AusAID) for providing financial

    support for my postgraduate research. Special thanks to Rhonda Haskell and Cathy

    Tang (AusAID Liaison Officers) for being friendly and helpful in many things.

    I would like to express my great appreciation to my husband, Husnan Ziadi for

    helping me with laboratory and glasshouse work and especially for all his support so

    that I can finish my study. Special thank to my lovely daughters, Lula and Fadila.

    I also thank Michael Smirk for his assistance in solving chemical analysis

    problems. Special thanks to Gary Cass and Elizabeth Halladin for lending me

    laboratory equipment. Thanks to Rick Roberts and family, Cameron Duggin, Than

    Hai Ngo, Geoff Kew, Georgie Holbeche, Matt Landers, Yamin Ma and Rina Barus

    for being friendly and helpful.

    Finally, thanks to all mineralogy group members for your friendship and for

    sharing knowledge, experiences, thoughts, and laboratory equipment.

    iii

  • LISTS OF CONTENTS

    ABSTRACT i AKNOWLEDGEMENTS iii LISTS OF CONTENTS iv LIST OF TABLES vi LIST OF FIGURES vii LIST OF APPENDICES ix Chapter 1. INTRODUCTION

    1.1. General Introduction 1 1.2. Objectives of the Study 2 1.3. Structure of the Thesis 2

    Chapter 2. LITERATURE REVIEW 2.1. Acid Soils 3 2.2. Effect of Soil Acidity on Plants 4 2.3. Acid Soils in Australia 5 2.4. Liming Resources and Lime Requirement 7 2.5. Industrial Byproducts as Liming agents

    2.5.1 Slag 9 2.5.1.1 The Nature of Industrial slag 9 2.5.1.2 Application of Slag in Agriculture 12

    2.5.2 Wood Ash 13 2.5.2.1 The Nature of Industrial Wood Ash 13 2.5.2.2 Application of Wood Ash in Agriculture 16

    2.5.3 Chicken Litter Ash 16 2.5.3.1 The Nature of Industrial Chicken Litter Ash 16 2.5.3.2 The Use of Chicken Litter Ash in

    Agriculture 18

    Chapter 3. A Laboratory Evaluation Of The Industrial Byproducts: Chicken Litter Ash, Wood Ash And Iron Smelting Slag For Use As Combined Liming Agent And Phosphorus Fertilizer

    3.1. Introduction 20 3.2. Materials and Methods

    3.2.1. Calcination of Chicken Litter 21 3.2.2. Industrial Byproducts 22 3.2.3. Characterisation of the Materials 22 3.2.4. Chemical Extraction of the Materials (AOAC Method) 23 3.2.5. Chemical Analysis of the Extracts 23 3.2.6. Glasshouse Experiment 24

    3.3. Results and Discussion 24 3.3.1 Calcination of Chicken Litter 24

    3.3.2 Dissolution of Industrial Byproducts 31 3.3.3 Relationship of Relative Agronomic Effectiveness (RE) of

    CLA and CLAT with P Availability Determined by Chemical Extraction 39

    3.4. Conclusions 41

    iv

  • Chapter 4. Plant response to the byproducts: Chicken Litter Ash, Iron Smelting Slag and Wood Ash as Phosphorus Fertilizers 4.1. Introduction 42 4.2. Materials and Methods 42 4.2.1. Soil 42

    4.2.2. Industrial Byproducts and Reference Fertilizers 42 4.2.3. Analysis of Industrial Byproducts and Soil 43 4.2.4. Glasshouse Experiment 43 4.2.5. Relative Agronomic Effectiveness 44

    4.3. Results and Discussion 45 4.3.1. Byproduct Characterization 45 4.3.2. Soil pH, EC and Bicarbonate P 45

    4.3.3. Plant Composition and Yield Response Data 47 4.3.4. Relative Effectiveness (RE) 51 4.4. Conclusions 52 Chapter 5. General Summaries, Limitation and Future Work 54 5.1. General Summary 54

    5.2. Limitations and Future Works 55 Chapter 6. Publications from this thesis: 57 REFERENCES 58 APPENDICES 65

    v

  • LIST OF TABLES

    Table Page2.1.

    2.2.

    2.3.

    2.4.

    2.5.

    2.6.

    2.7.

    2.8.

    2.9.

    2.10

    3.1.

    3.2.

    3.3.

    4.1. 4.2.

    National and State areas (million hectares) of surface soil (0 - 10 cm) pH (measured in calcium chloride) based on information fromAustralian Soil Resources Information System (first number) andcommercial laboratories (second number).

    Calcium carbonate equivalence values of some liming materials Chemical constituents of blast furnace slag (Lee 1974). Major element composition of slags (Li and Gilkes 2002). Chemical compositions of slag products used in New Zealand (Bolan2004). Mineralogical compositions of slags (Li and Gilkes 2002) Concentration of total and water-soluble plant nutrients in wood ash The chemical composition of plant ash derived from diverse species Characterisation of the chemical properties of chicken litter ash Nutrients present in Fibrophos based on the grades for Southern andCentral England/Wales The nomenclature for calcined chicken litter samples produced bycalcination at various temperatures and their pH measured in water Properties of industrial byproducts. Percentages of total phosphorus, calcium, magnesium, potassium and sodium dissolved after 1hour extraction in citrate solutions for chicken litter ash calcined at various temperatures and for Sechura rock phosphate (RP), wood ash (WA) and slag. Chemical properties of industrial byproducts and rock phosphate. Levels of P added to soil for the plant growth experiment Basal fertilizer and dose per pot used in the glasshouse experiment

    6 8

    10

    11

    11

    12

    14

    15

    17

    18

    21

    27

    32

    43

    44

    vi

  • LIST OF FIGURES

    Figure Page2.1.

    2.2.

    3.1.

    3.2.

    3.3.

    3.4.

    3.5.

    3.6.

    3.7.

    3.8.

    3.9

    4.1

    4.2.

    4.3.

    Soil pH ranges Interpolated top soil pH (1990-1999) Percentages of total P extracted from chicken litter ash produced atvarious temperatures for various durations of extraction in citric acid (A), neutral ammonium citrate (B) and alkaline ammonium citrate (C) XRD patterns of chicken litter ash calcined at various temperaturesbefore (A) and after extraction for 120 hours in citric acid (B), neutralammonium citrate (C) and alkaline ammonium citrate (C). Q = quartz (d = 3.43), A = apatite (d = 2.84 ) Cu K radiation Scanning electron micrograph (SEM) and X-ray spectra of the indicated particles for 500oC calcined chicken litter (C500) before and after extraction for 120 hours in citrate solutions Percentage of P extracted from five phosphatic byproducts by threecitrate extractants for various durations of extraction XRD patterns of byproducts (A) and their residues after extraction for120 hours in citric acid (B), neutral ammonium citrate (C) and alkalineammonium citrate (D) Scanning electron micrographs (SEM) and X-ray spectra of indicated particles for original CLA and residues after extraction for 120 hours in three citrate solutions. X-ray spectrum of a carbon grain in partly burnt chicken litter ash showing that it contains minor amounts of Si, P, S, Cl, K, and Ca (A) and a silicate grain (feldspars) in totally burnt chicken litter ash containing much Si, Al, K and Ca (B). Scanning electron micrographs (SEM) and spectra of indicated grains for CLAT and residues after extraction for 120 hours in three citrate solutions. The relationship of relative agronomic effectiveness (RE) and thesolubility of P in CA for 6 hours extraction. Plots of log P applied (mg/kg) versus pH, EC, and Bic P for soil samples taken after the last harvest Yield (g/pot) versus log rate of P applied (mg/kg) for each harvest for the seven fertilizers Internal efficiency of P utilization curves for each harvest

    4 6

    25

    28

    30

    33

    35

    36

    37 38 40 46 48 49

    vii

  • 4.4. 4.5.

    P content versus log P applied for all harvests RE values for the byproducts based on yield and P content for the fourharvests

    50 52

    viii

  • LIST OF APPENDICES

    Appendix Page4.1.1

    XRF Analysis of Plant Dry Tops for Harvest I 65

    4.1.2

    XRF Analysis of Plant Dry Tops for Harvest II 66

    4.1.3

    XRF Analysis of Plant Dry Tops for Harvest III 67

    4.1.4

    XRF Analysis of Plant Dry Tops for Harvest IV 68

    4.2.1 Photograph showing the growth of ryegrass before the first harvest for the highest (a) and lowest (b) rates of all the fertilizers, including zero rate of application (control)

    69

    4.2.2 Photograph showing the growth of ryegrass before the second harvest for the highest (a) and lowest (b) rates of all the fertilizers, including zero rate of application (control).

    70

    4.2.3 Photograph showing the growth of ryegrass before the third harvest for the highest (a) and lowest (b) rates of all the fertilizers, including zero rate of application (control).

    71

    4.3

    Concentration of Phosphorus in Plants Tissue 72

    4.4.1

    RE Values Based on P Applied and Yield for Each Harvest 73

    4.4.2 RE Values Based on P Content and P Applied for Each Harvest

    74

    4.4.3

    RE Values Based on Soil Bic P and P Applied for Each Harvest 75

    ix

  • Chapter 1

    1.0 Introduction

    1.1. General Introduction

    Soil acidity is a major problem worldwide as it decreases plant growth by affecting

    the availability of nutrients and causes various toxicities. Acid soils may also suffer

    from phosphorus, nitrogen, calcium, magnesium, potassium and other deficiencies

    (Ritchie 1989; Samac and Tesfaye 2003). Acid conditions in soils cause aluminium

    (Al) and manganese (Mn) to become more soluble (Slattery et al. 1999) and these

    elements can be toxic to plants. Soil acidity also affects the activity of

    microorganisms in soil (Robson and Abbott 1989). Acid soils are commonly deficient

    in phosphate so that both conditions require correction, which can be carried out by

    application of a single mineral ameliorant, which is the focus of this thesis.

    Australia faces a serious problem with soil acidification. Acid soil has caused major

    land degradation and has decreased plant production over several million hectares of

    agricultural land in Australia (Evans, 1991). Approximately 35 million hectares of

    agriculturally productive land presently have strongly acid soils (pHCa < 4.8) and 55

    million hectares are fairly or slightly acid (pHCa 4.8-6.0) (Slattery et al. 1999).

    Liming is the most common way to ameliorate acid soils. At some locations sources

    of natural lime are inadequate or expensive. Alkaline industrial byproducts such as

    metal smelting slag, wood ash and chicken litter ash may be used as replacements for

    lime under these circumstances. Such byproduct materials are commonly dumped

    however they may be used to ameliorate soils with consequential environmental

    benefits. Some alkaline byproducts contain phosphate so that two adverse soil

    conditions can be overcome by a single application of byproduct.

    In contrast to the wealth of knowledge available on the nature and effectiveness of

    alternative liming agent in Europe and USA, little is known of their nature,

    effectiveness and availability in Australia. In particular the possibility of using lime

    from industrial byproducts and mineral processing activities as soil amendments has

    received little attention. Li and Gilkes (2002) mention that in 2001, almost 1 million

    1

  • tons of lime was applied to soils in Western Australia, most of which was supplied to

    farmers as natural lime, mostly as limesand and limestone from coastal areas. The

    sources of those limes are likely to be inadequate in the long term and lime is

    expensive in some locations. Therefore Western Australian agricultural soils might

    potentially receive lime from other sources that are available locally including iron-

    smelting slags, wood ash and chicken litter ash.

    1.2 Objectives of this study This study focused on the use of iron-smelting slags, wood ash and chicken litter ash,

    which might be used as liming agents and to increase soil fertility on agricultural land

    in Western Australia. These materials are readily available from present and planned

    industrial activities in Western Australia. The study has been conducted under

    laboratory, and glasshouse conditions to identify the properties of these industrial

    byproducts, the effects of the addition of industrial byproducts as liming agents and

    phosphate fertilizers to acid soils, together with effects on nutrient uptake, and growth

    of plants.

    1.3. Structure of the thesis

    The organisation of this thesis consists of 5 chapters in which each chapter specifies

    and discusses different aspects of the research and also discusses the related literature.

    Chapter 3 and 4 have been written in journal format and these manuscripts are

    currently under reviews. Justification and objectives of this research are introduced in

    Chapter 1. A general literature review is given in Chapter 2. An evaluation as

    phosphorus fertilizers of the byproducts: chicken litter ash, iron smelting slag and

    wood ash is presented in Chapter 3. Plant response to the byproducts: chicken litter

    ash, iron smelting slag and wood ash as phosphorus fertilizers is presented in Chapter

    4. General discussion and conclusions, limitations of this work and suggestions for

    further work are presented in Chapter 5. Tables and figures are placed within the text

    and all the references cited are listed at the end of the thesis followed by the

    appendices.

    2

  • Chapter 2

    2.0 Literature Review

    2.1 Acid Soils

    Soils become acid because of several factors. Many soils have become acid through

    slow, natural processes and agricultural development can accelerate these processes

    (Porter 1981; Whitney and Lamond 1993). Some soils are formed from parent

    materials that are intrinsically acid and have low abundances of the alkali elements;

    Ca, Mg, K and Na (Samac and Tesfaye 2003; Foy 1984). Soils containing sulphide

    become very acid when drained as H2SO4 is produced (Thomas and Hargrove, 1984).

    Whitney and Lamond (1993) point out that soil development processes under moist

    condition generally include leaching, which together with consequences of soil

    management cause soils to become acidic.

    Major mechanisms of acidification of soil according to Helyar and Porter (1989)

    relate to the carbon (C), and nitrogen (N) cycles. Carbonic acid results from

    dissolution in soil solution of CO2 in the soil air. As water percolates through the soil,

    acidification occurs as bicarbonates are leached and the hydrogen ion adsorbed and

    remains. Soil can become more acid as an effect of nitrogen movement into and out of

    the soil, depending on the nitrogen form that is added and on the form of nitrogen that

    is removed, or accumulates (Porter 1981). The application of nitrogen fertilizers to

    soils may cause a large acidifying effect. Nitrogen fertilizers contain ammonium and

    soil bacteria convert ammonium (NH4+) to nitrate (NO3+) through the nitrification

    process. Hydrogen (H+) is released in this process, and free hydrogen ions cause an

    increase in acidity. An important consequence of acidification is the replacement of

    calcium, magnesium, potassium, and sodium (basic cations) on the soil cation

    exchange complex by hydrogen, manganese, and aluminium (acidic cations) (Spies

    and Harms 2004).

    The acidity of a soil can be measured through its pH value, which may be taken to be

    the pH of water in equilibrium with the soil (i.e. the soil solution). Soil pH is a

    measure of the activity of the hydrogen ion (H+) in soil solution (Slattery et al. 1999).

    Soil pH is defined as the negative log 10 of the hydrogen-ion activity (pH = - log (H+)

    3

  • of soil solution (Evans 1991; Tan 1998). Soils can be separated into a several acidity

    and alkalinity categories (Slattery et al. 1999), as shown in Figure 2.1.

    NEUTRALITY

    3

    Slight

    Moderate Very strong

    Very strong

    Strong

    Very strong

    Moderate

    Slight

    Very strong

    Strong

    4 5 6 7 8 9 10

    Range in pH common for humid region mineral soils

    Range in pH common for most mineral soils

    Range in pH common for arid region mineral soils

    Extreme pH for acid peat soils

    11

    ACIDITY ALKALINITY

    Attained only by alkali mineral soils

    Figure 2.1. Soil pH ranges (Slattery et al. 1999)

    2.2 Effect of soil acidity on plants

    Soil acidity affects plant growth partially through direct effects of pH on root function

    and partly through its effects on soil properties (Russell 1988). Extreme subsoil

    acidity may be harmful for plant growth because it can cause shallow rooting, drought

    susceptibility, and poor use of nutrients in subsoil (Kauffman 1977). The cause of

    poor plant growth on acid soils may vary with soil pH, types and amounts of clay

    minerals, contents and types of organic matter, salts levels, and plant species or

    genotype (Clark 1982).

    In acid soils and mine spoils, the most important factor limiting plant growth is

    aluminium toxicity (Foy 1984; Samac and Tesfaye 2003). The problem mainly occurs

    below pH 5.0, but it may arise at values as high as pH 5.5 in kaolinite dominant soils.

    The poor root development, which occurs in acid soils at pH 5.0 and below, is

    probably due mostly to aluminium toxicity that limits both rooting depth and degree

    4

  • of root branching (Foy 1984). Aluminium in solution in acid soils occurs inter alia as

    Al3+, Al(OH2)2+, Al(OH)2+, and Al(H2O)3+ (Kinraide 1991). For most plants,

    aluminium ions rapidly reduce root growth at micromolar concentrations. The most

    toxic ion for the wheat plant is Al3+, while in dicotils the more toxic ions appear to be

    Al(OH)2+ and Al(OH)2+ (Samac and Tesfaye 2003).

    2.3 Acid Soils in Australia

    Like many regions of the world, Australia faces a serious problem with soil

    acidification. Acid soil has caused major land degradation and has decreased plant

    production over several million hectares of agricultural land in Australia (Evans,

    1991). Approximately 35 million hectares of agriculturally productive land presently

    have strongly acid soils (pHCa < 4.8) and 55 million hectares are fairly or slightly acid

    (pHCa 4.8-6.0) (AACM 1995). Coventry (1985) estimated that Western Australia has

    1.0 million hectares of severely acid soil in the eastern wheat belt, with a further 0.5-

    0.75 million hectares in the high rainfall southern region.

    Maps derived from commercial farm top soil testing data over the past decade (Figure

    2.2) show considerable spatial variation in surface soil pH within Australia's

    agricultural land and there are major areas of acidic soils (pH CaCl2 less than or equal

    to 5.5) in all States (Table 2.1) (The Australian Agriculture Assessment Report 2001).

    According to The Australian Agriculture Assessment Report (2001), the largest areas

    of strongly acidic soils (pH 4.3 - 4.8) exist in New South Wales (5 to 7 million

    hectares), Victoria (4 to 5 million hectares) and Western Australia (1 to 7 million

    hectares). The largest areas of moderately acidic soils (pH 4.8 - 5.5) are in Western

    Australia (7 to 19 million hectares) and New South Wales (11 to 13 million hectares)

    and to a lesser extent Victoria (2 to 3 million hectares). These estimations do not

    include all of the area where severe subsoil acidity occurs beneath a less acid topsoil.

    5

  • Table 2.1 National and State areas of surface soil (0 - 10 cm) in several pH (measured

    in calcium chloride solution) bands based on information from the

    Australian Soil Resources Information System (first number) and

    commercial laboratories (second number) (The Australian Agriculture

    Assessment Report 2001).

    < 4.3 4.3 - 4.8a a 4.8 - 5.5a 5.5 - 7.0a 7.0 - 8.5a > 8.5 Totalc

    (million hectares)

    New South Wales 0.2 - 1.1 4.8 - 7.1 12.7 - 10.6 18.5 - 10.9 1.5 - 7.9 0 - 0.0b 37.6 - 37.8

    Queensland ~ 0.3 0.6 - 1.0 1.5 - 1.8 7.4 - 3.7 0.8 - 4.3 0 10.5 - 11.1

    South Australia

  • Many Western Australian agricultural soils require lime applications to overcome soil

    acidity, which is widespread and which can affect both topsoils and subsoils (Penny

    2002). Two thirds of 10 million hectares of the Western Australian wheatbelt are

    affected by soil acidity (Leonard and Boland 1995). It is estimated that potential

    agricultural production worth $70 million is lost annually in Western Australia

    because of acid soil (Leonard and Boland 1995). Miller (2002) reported that 575,980

    tonnes of lime were used on agricultural land of Western Australia in 1999/2000 and

    in more recent years the amount is about 1M tonnes/year.

    2.4 Liming Resources and Lime Requirement

    Liming is one of the most common ways to ameliorate acid soils. Barber (1984)

    defined liming material as a material, which contains calcium and/or magnesium,

    which reduce the effects of soil acidity. Liming reduces the toxicity of aluminium

    (Ritchie 1989), the concentration of hydrogen ions and also adds base-forming cations

    to the soil (Thompson 2004). The solubility and plant availability of most of the

    nutrient ions in soil is affected by liming (Seatz and Peterson 1969). Furthermore,

    liming can improve soil structure, increase soil biological activity, and enhance the

    distribution of roots in soil.

    The mechanisms of CaCO3 reaction with acid soils are complex (Bear 1969). CaCO3

    dissolves and hydrolyses to form OH- ions, the reaction is as follows:

    CaCO3 + H2O Ca2+ + HCO3- +OH- (Seatz and Peterson 1969; Thomas and

    Hargrove 1984).

    In general, the reaction of lime and acid soils (Seatz and Peterson 1969) may be

    written as:

    2Al-soil + 3 CaCO3 + 3H2O 3Ca-soil + 2Al (OH)3 + 3 CO2 and

    2H-soil + CaCO3 Ca-soil + H2O + CO2

    Liming resources are valued for their capacity to ameliorate soil acidity and to

    maintain the availability of calcium and magnesium for crops. There are a number of

    liming materials and each liming material has a specific composition and capacity to

    neutralize acidity. The quality of the materials depends on their mineralogy, purity,

    and on the size of the particles (Heckman 2000).

    7

  • The standard for measuring purity is calcium carbonate equivalence (CCE) (Spies and

    Harms, 2004) so that the CCE value for pure calcium carbonate is 100 % (Whitney

    and Lamond 1993). The CCE values of some liming materials are shown in Table 2.2.

    Table 2.2. Calcium carbonate equivalence values of some liming materials (aHeckman

    2000; bThompson 2004).

    Liming Material a, b Source b Chemical Formula a, b

    CCE (%) a

    Calcium silicate Calcium carbonate Calcium magnesium carbonate Calcium hydroxide Calcium oxide

    Slags Limestone Dolomite Slaked lime Burned lime, quicklime

    CaSiO3 (and other) CaCO3CaCO3.MgCO3Ca(OH)2CaO

    60-90 100 109 136 179

    The fineness of liming materials is important because the surface area usually affects

    dissolution rate (Whitney and Lamond 1993). Small particles dissolve quickly and so

    decrease soil acidity quickly, whereas coarse particles may react very slowly and are

    of reduced value in managing soil acidity (Spies and Harms 2004).

    Seatz and Peterson (1969) defined the lime requirement of soils as the amount of

    liming material that should be supplied to increase the pH level of soil (depth not

    specified) to the desired value for a particular land use. Liming materials are applied

    commonly to raise soil pH to the desirable values for growth of particular plants

    (Cregan et al. 1989). There are several factors that need to be considered for

    determining the lime requirement of a soil, where both topsoil and subsoil need to be

    ameliorated. Under these circumstances the determination of lime requirement and the

    application of lime become complex (Adams, 1984). Thompson (2004) defines soil

    pH buffer capacity as the resistance capacity of the soil to change in pH. The pH

    buffering capacity is influenced by properties of soil components, including clay

    content and clay type, organic matter and hydrous oxides of Fe, Al or Mn, these are

    constituents that are capable of reacting with H+, Al3+ and OH-, and are the effective

    pH buffers in soil (Gilkes et al. 2003; Slattery et al. 1999).

    In agricultural practice, lime is mostly applied through surface application and may be

    mixed with soil by cultivation (Cregan et al. 1989). According to Barber (1984) lime

    is usually broadcast on the soil surface at rates of 2 to 12 t ha-1. Liming has also been

    8

  • placed as a band near the seed of legume crops where it is described to provide

    optimum condition for both root and rhizobia which can be particularly sensitive to

    soil acidity (Barber 1984).

    2.5 Industrial Byproducts as Liming Agents

    The quantity of industrial byproducts is increasing as global mining, manufacturing

    and energy production increase. Industrial byproducts are recycled, placed in landfills,

    incinerated, dumped in the sea, used as building material or used on farmland (Tan

    1994). According to Barker et al. (2000) a major concern over environmental and

    agricultural uses of industrial by-products on land is that some contain chemical

    constituents that might have hazardous effects on land, water and biota. Therefore, in

    most developed countries stringent environmental regulations specify the conditions

    under which industrial byproducts can be applied to soils.

    The beneficial use of industrial byproducts in agriculture may be to ameliorate land,

    reduce degradation of the environment, contribute to the preservation of resources and

    provide effective favourable solutions for the disposal of industrial byproducts

    (Francis and Youssef 2004). Much research has shown that byproducts from industrial

    processes have valuable uses in agriculture for example some byproducts may add

    nutrients and organic matter to soil and help recover soil structure (Barker et al.

    2000). Byproducts from some industrial processes using limestone or producing lime

    like byproducts can be used for neutralizing soil acidity (Cregan et al. 1989). Apart

    from organic byproducts, the most common industrial byproducts which are applied

    to agricultural land are coal combustion residues, gypsum containing by-products

    from chemical processes, residues from the mining and beneficiation of ores, wood

    ashes and various slags (Sims and Pierzynski 2000). This thesis investigated the

    nature and use of slag, wood ash and chicken litter ash, which are presently or will be

    readily available resources in southern Western Australia.

    2.5.1 Slag

    2.5.1.1 The nature of industrial slags

    Slags are non-metallic by-products of steel and other smelting industries (Kalyoncu

    1998; Bolan 2004). Some are a result of lime being added to furnaces in order to

    9

  • separate silicon and phosphate impurities from metals. Slags are commonly composed

    primarily of CaSiO3 and similar compounds (Miller et al. 2000). Slags are used in

    building and road construction, cement manufacture, concrete aggregate, agricultural

    fill and glass manufacture, as mineral supplements to stock, and also as liming agents

    in agriculture (Kalyoncu 1998; Lee 1974). In the early 20th century, slags produced by

    iron and steel-making industries were commonly used in agriculture as liming agents

    in Europe and North America (Miller et al. 2000). More recently, slags have been

    used as plant nutrient sources and soil amendments because most slags have high Ca

    and Mg contents, and in some instances contain significant amount of P and various

    micronutrients (Bolan 2004).

    Three forms of slag are commonly used as agricultural amendments (Barber 1984): (i)

    blast furnace slag, that is usually used as a liming agent for acid soils and which also

    provides Ca and Mg for plant nutrition and soil structure benefits; (ii) open-hearth

    slag, which is also rich in Ca and Mg, and can contain high amounts of Mn, this also

    has a good liming effect; (iii) basic slag, which has mostly been used as a P source

    rather than a liming agent although it does provide a liming benefit. Blast furnace

    slags consist mostly of silicates and alumino-silicates of lime (Lee, 1974) and contain

    smaller amounts of other alkali elements (Barber 1984; Francis and Youssef 2004).

    The chemical constituents of typical blast furnace slags (by mass) are shown in Table

    2.3. (Lee 1974). Open-hearth slag is from furnaces where pig iron is made into steel.

    This type of slag may be applied to soil as a source of Fe and Mn, because it contains

    approximately 200 g Fe and 100 g of Mn kg-1 (Barber 1984). Basic slag is a by-

    product of the refining of pig iron to steel where phosphatic iron ores have been used

    and the P in this type of slag may be readily accessible to plants growing on acid soils

    (Barber 1984).

    Table 2.3. Chemical constituents of blast furnace slag (Lee 1974).

    Constituent Chemical Formula Percentage Lime Silica Alumina Magnesia Total sulphur Total iron

    CaO SiO2Al2O3MgO S FeO, Fe2O3

    36 43 % 28 36 % 12 22 % 4 11 % 1 2 % 0.3 1.7 %

    10

  • A review of Australia and New Zealand slags was conducted by Li and Gilkes (2002).

    They summarised the typical major element chemical compositions of those slags

    including British Standards Institute reference slags (Table 2.4). Two slag products

    have been applied to New Zealand soils, European slag, and Glenbrook slag (Bolan

    2004). The chemical characteristics of the two slag materials from New Zealand are

    summarised in Table 2.5.

    Table 2.4. Major element composition of slags (Li and Gilkes 2002)

    Slags Al2O3

    (%)

    CaO

    (%)

    Fe2O3+

    (%)

    K2O

    (%)

    MgO

    (%)

    MnO

    (%)

    P2O5

    (%)

    SiO2

    (%)

    SO3

    (%)

    TiO2

    (%)

    HIsmelt 15.09 36.60 3.70 nd 8.72 0.57 0.62 27.37 0.27 0.75

    Whyalla 17.15 34.85 0.81 0.21 9.89 0.33 nd 29.76 1.18 0.76

    NZ slag 19.68 15.07 1.87 0.07 13.47 0.94 nd 8.44 0.34 36.08

    BCS-367

    measured

    20.65 30.15 0.82 1.07 6.72 1.01 0.095 31.47 2.23 0.81

    BCS-367

    expected

    20.00 32.40 1.00 1.17 7.10 1.16 na 34.40 2.34 0.75

    + All Fe expressed as Fe2O3

    Table 2.5. Chemical compositions of slag products used in New Zealand (Bolan 2004)

    Type of slag European slag Glenbrook slag Source Steel factory Steel factory Common name Belgian slag Kobmax Lime content* (%)

    44.9 52.2

    pH 9.7 12.6 Phosphorus (%) 3.9 0.7 Sulphur (%) - 0.2 Calcium (%) 32.2 37 Magnesium (%) 3.2 5.3 Boron (%) - 0.10 Fluoride (%) 0.8 -

    * Lime is presented as burnt lime (CaO) in European slag and Glenbrook slag .

    Li and Gilkes (2002) have conducted research on slag from the HIsmelt Iron

    Company in Western Australia. The typical mineralogical composition of HIsmelt

    slags has been described by Li and Gilkes (2002) as follows: merwinite

    (MgO.3CaO.2SiO2); gehlenite (2CaO.SiO2.Al2O3); akermanite (2CaO.MgO.2SiO2)

    11

  • Mg, Al-spinel (eg. Mg, Al2O4); magnesia-wustite (Fe2+Mg) O); and an unknown iron-

    sulphur phase. Li and Gilkes (2002) summarised the detailed mineralogical

    composition of three slags in Table 2.6.

    Table 2.6. Mineralogical compositions of slags (Li and Gilkes 2002)

    Type of slag Mineralogical composition HIsmelt slag Akermanite (2CaO.MgO.2SiO2)

    Gehlenite (2CaO.Al2O3.SiO2) Merwenite (3CaO.MgO.2SiO2) Monticellite (CaO.MgO.SiO2) Spinel (Mg Al2O4) Metallic Fe (little)

    Whyalla slag Akermanite (2CaO.MgO.2SiO2) Gehlenite (2CaO.Al2O3.SiO2) Monticellite (CaO.MgO.SiO2) Spinel (Mg Al2O4) Metallic Fe (little)

    New Zealand slag Perovskite (CaO.TiO2) MgTi2O5 CaMg(SiO3)2 Spinel (Mg Al2O4) Anatase Metallic Fe (little)

    2.5.1.2 Application of slags in agriculture

    Slags can be used as fertilizers and have been commonly used as sources of

    phosphorus, Ca, Mg and other nutrients (Bolan 2004). Slag fertilizers have been

    widely adopted in Europe, America, New Zealand, Egypt, and several other countries

    (Lee 1974; Kalyoncu 1998).

    Slags have been used on paddy soils in Japan as a source of silicon in order to

    increase rice production (Kato and Owa 1997a). The application of slags also

    increases pH and the calcium concentration in soil solution (Kato et al. 1997). The

    application of calcium silicate slags to rice increased yields by about 30% in each of 3

    years after application (Snyder et al. 1986). Calcium silicate slags, have also

    increased sugarcane yields in the USA as well as the silicon concentration in plant

    tissue (Anderson et al. 1991; Alvarez et al. 1988). Slags also provide a substrate for

    the growth of bacteria in soil including Thiobacillus ferrooxidans, Thiobacillus

    thiooxidants, and Thiobacillus thioparus (Male et al. 1997).

    12

  • Slags are used on agricultural soils as liming agents. Lintz-Donawit slag has been

    used as liming agent for pastureland in northern Spain (Rodriguez et al. 1994). Slag

    appeared to be a useful liming material, increased both yield and the concentrations of

    phosphorus, calcium, and magnesium in plants (Rodriguez et al. 1994). Khan et al.

    (1994) studied the application of basic slags from iron making industries to acid

    sulphate paddy soils. They determined that basic slags improved yield of rice, and

    increased uptake of calcium, magnesium and phosphorus.

    2.5.2 Wood Ash

    2.5.2.1 The Nature of Industrial Wood Ash

    Wood ash is a by-product from the forest and other industries, which produce wood

    fired-boiler ash and ash from combustion of waste wood, twigs and leaves (Nkana et

    al. 2002; Vance and Mitchell 2000). Several studies have shown that wood ash can be

    used as a liming agent and also as a nutrient source. The neutralizing value of wood

    ash is usually expressed as its calcium carbonate equivalent (CCE), which may range

    from 10-90 %. According to Nkana et al. (2002) the application of wood ash as a

    liming agent can increase soil pH, Ca, Mg, inorganic C, and SO4. Wood ash might

    also increase the availability of some soil nutrients to plants because of exchange

    with SO4 and OH ions (Nkana et al. 2002).

    Most of the inorganic nutrients including minor elements in wood are retained in the

    ash during combustion process with most N and some S being lost (Perkiomaki 2004).

    The composition of wood ash depends on boiler combustion efficiency and the tree

    species used (Clapham and Zibilske 1992; Vance and Mitchell 2000). The content of

    C in wood ash varies with combustion efficiency, with some C remaining as unburnt

    wood, charcoal and carbonate salts (Vance and Mitchell 2000). Demeyer et al. (2001)

    summarise the findings of several researchers concluding that the properties of wood

    ash depend on many factors: type of plant, part of plant combusted (bark, wood,

    leaves), type of waste (wood, pulp or paper residue), combination with other fuel

    sources, and conditions of combustion, collection and storage.

    Lerner and Utzinger (1986) reported that the calcium oxide (i.e. Ca expressed as CaO)

    content of wood ash ranges from 30% to 60% of the ash and various Ca compounds

    13

  • 14

    may be present including CaO, Ca(OH)2, CaCO3 and CaSO4. Wood ash contains most

    of the essential plant nutrient elements (Nkana et al. 2002) (Table 2.7). The chemical

    composition of wood ash from different plant species was determined by Lerner and

    Utzinger (1986) and is summarised in Table 2.8.

    Table 2.7. Concentrations of total and water-soluble plant nutrients in wood ash

    (Nkana et al. 2002)

    Parameter Concentration

    pH-H2O (1:5)

    CCE (%)

    10.2

    27.3

    Total content

    Ca

    Mg

    K

    Na

    P

    Fe

    Mn

    Zn

    Cu

    7.8 %

    0.8 %

    1.7 %

    416 ppm

    1360 ppm

    6066 ppm

    1253 ppm

    267 ppm

    52 ppm

    Water extractable

    Ca

    Mg

    K

    Na

    Cl-

    NO3-

    163 ppm

    984 ppm

    0.68 %

    57 ppm

    148 ppm

    58 ppm

  • Element composition

    P K Ca Mg Mn Fe B Cu Zn Al Na Pb Cr Ni Cd

    Species

    % % % % ppm ppm ppm ppm ppm ppm ppm ppm ppm ppm ppm

    Black Cherry *

    Hackberry *

    Red Oak *

    White oak *

    Mixture *

    Salix #

    Forest residue #

    Mischantus #

    Reed Canary Grass #

    Eucalyptus #

    Arundo Donax #

    Lucerne #

    1.0

    0.8

    0.8

    0.8

    1.0

    2.0

    2.5

    2.3

    0.5

    0.8

    1.7

    1.7

    5.7

    5.1

    12.9

    5.1

    4.4

    6.3

    9.9

    2.2

    1.3

    4.4

    8.5

    11.8

    27.1

    27.3

    24.2

    27.1

    20.3

    27.5

    20.4

    9.1

    3.9

    45.5

    5.5

    19.8

    1.5

    1.3

    2.0

    1.3

    1.6

    2.2

    4.0

    6.5

    0.6

    3.5

    6.1

    1.8

    669

    742

    615

    680

    595

    n.a

    n.a

    n.a

    n.a

    n.a

    n.a

    n.a

    1302

    989

    817

    1179

    1535

    1328

    1328

    4266

    898

    3287

    2514

    1049

    271

    254

    244

    260

    248

    n.a

    n.a

    n.a

    n.a

    n.a

    n.a

    n.a

    57

    54

    57

    62

    108

    n.a

    n.a

    n.a

    n.a

    n.a

    n.a

    n.a

    82

    66

    68

    87

    853

    n.a

    n.a

    n.a

    n.a

    n.a

    n.a

    n.a

    2932

    2121

    1150

    2826

    3561

    1667

    1799

    6430

    1129

    714

    2196

    793

    1125

    637

    340

    978

    1422

    3078

    3412

    4673

    148

    12611

    6216

    2596

    24

    26

    27

    19

    673

    n.a

    n.a

    n.a

    n.a

    n.a

    n.a

    n.a

    8

    9

    5

    7

    12

    n.a

    n.a

    n.a

    n.a

    n.a

    n.a

    n.a

    12

    14

    6

    18

    11

    n.a

    n.a

    n.a

    n.a

    n.a

    n.a

    n.a

    2

    1

    1

    1

    3

    n.a

    n.a

    n.a

    n.a

    n.a

    n.a

    n.a

    Average 1.3 6.5 21 2.7 660 1707 255 67 231 2276 3103 153 8.2 12.2 1.6

    Table 2. 8. The chemical composition of ash derived from diverse plant species (n.a. not analysed) (*Lerner and Utzinger 1986; #Onderwater et

    al. 2001).

    15

  • 2.5.2.2 Application of wood ash in agriculture

    The application of wood ash to agricultural land increases soil pH and may increase

    productivity (Etiegni et al. 1991). According to Rumf et al. (2001) the addition of

    wood ash increased pH and base saturation, improved biotic conditions of soils, and

    did not have any detrimental effects in the short term.

    Clapham and Zibilske (1992) have conducted glasshouse and laboratory experiments

    in order to determine the effectiveness of wood ash as a liming agent and found that

    soil EC, K, Ca, extractable soil P, Fe, Zn, Cu, and Mn increased linearly with

    increasing application rate of wood ash (0 to 20.17 g/kg soil). Mbahrekire et al.

    (2003) measured the nutrient element composition of bean (Phaseolus vulgaris) and

    soybean (Glycine max L.) grown on soils with wood ash amendment. They

    demonstrated that the application of wood ash to the soil at rates of up to 40 ton/ha

    increased the plant height by a factor of 1.5 for beans and 1.2 for soybeans with

    associated increases in biomass of 1.7 and 1.9 respectively. The increases in plant

    height and biomass are attributed mainly to the presence of P, K, Ca and Mg in wood

    ash.

    2.5.3 Chicken Litter Ash

    2.5.3.1 The Nature of Industrial Chicken Litter ash

    Chicken litter is a mixture of chicken manure, plant materials including wood

    shavings and sometimes mineral particles. For a number of physical and chemical

    properties (e. g. heating value, moisture content) it is comparable to wood chips

    (Power Plant Research Program 1998). Chicken litter provides a rich source of plant

    nutrients and is commonly used in agriculture (Pote et al. 2003). Chicken litter is

    commonly applied directly to agricultural land as a fertilizer, however, this has

    resulted in excessive levels of phosphorous and nitrogen leachate in some places and

    it may contribute to the appearance of flies and toxic micro- organisms (Power Plant

    Research Program 1998).

    16

  • One method to overcome these problems is by burning the chicken litter as a fuel

    source for power production (Power Plant Research Program 1998). Although all N

    and most S are lost during combustion, the ash resulting from the burning process has

    value as a multi-element fertilizer and is now recognised as a valuable source of plant

    nutrients. Codling et al. (2002) summarised the characteristics of chicken litter ash as

    a potential source of plant nutrients (Table 2.9).

    Table 2.9. Chemical properties of chicken litter ash (Codling et al. 2002)

    Analyte Chicken litter ashpH (1:2 H20) 12.2 EC (1:2 H20), mS/cm 27.5 Water soluble phosphorus, mg/kg

  • Table 2.10. Nutrients present in Fibrophos (a chicken litter ash) based on the grades in

    Southern and Central England/Wales (Fibrophos 2006).

    Analyte Concentration P (P2O5), % 22 K (K2O), % 12 Ca (CaO), % 25 S (SO3), % 7 Mg (MgO), % 5 Na (Na2O) 3 Fe, mg/kg 4000 Mn, mg/kg 2500 Zn, mg/kg 2000 Cu, mg/kg 500 B, mg/kg 150 Mo, mg/kg 30 Co, mg/kg 10 I, mg/kg 5 Se, mg/kg 5 Neutralising value, % 15

    2.5.3.2 The use of Chicken Litter Ash in Agriculture

    The application of chicken litter ash to agricultural land has not been widely adopted

    and no research has been carried out in Australia. Codling et al. (2002) in USA have

    conducted research into the effectiveness of poultry litter ash as a source of

    phosphorus to agricultural crops. They grew wheat in an acidic soil and compared the

    effectiveness of the ash as a P fertilizer with potassium phosphate. They found that

    the two source of phosphorus were not significantly different. The metal

    concentrations in wheat fertilised with poultry litter ash were lower, possibly due to

    the liming effect of the ash reducing the availability of metals. They concluded that

    poultry litter ash is an effective source of phosphorus.

    The John Hatcher Company in the UK has carried out plant growth experiments over

    the past 8 years to evaluate Fibrophos in relation to the yield and quality of various

    crops. They have included Triple Superphosphate (TSP) and Muriate of Potash

    (MOP) as standards (Fibrophos 2006). The results presented in sales literature show

    that the phosphate and potash in Fibrophos are as effective as Triple Superphosphate

    18

  • and Muriate of Potash and that Fibrophos also provides other major and minor

    nutrients. These data have not been published in peer-reviewed journals so await

    critical scrutiny. However the results are consistent with those published by Codling

    et al. (2002).

    19

  • Chapter 3

    3.0 A Laboratory Evaluation of the Industrial Byproducts: Chicken Litter Ash, Wood Ash and Iron Smelting Slag for use as a Combined Liming Agent and

    Phosphorus Fertilizer

    3.1 Introduction

    Soil acidity is a major problem worldwide as it decreases plant growth by affecting

    the availability of nutrients and causes various toxicities. Acid soils are commonly

    deficient in phosphate (P) so that both conditions require correction, which can be

    carried out by the application of a single mineral ameliorant with appropriate

    properties. Some alkaline industrial byproducts may be suitable as they contain P,

    which may be available to plants. These materials include iron smelting slag, wood

    ash and chicken litter ash but their fertilizer effectiveness is poorly defined.

    Byproducts are commonly dumped in landfill so that the use of byproducts to

    ameliorate land will contribute to the preservation of alternate resources and provide

    an effective solution for the disposal of byproducts (Francis and Youssef 2004).

    A laboratory assessment of the potential agronomic effectiveness of a material to be

    used as a P fertilizer has to be made to determine appropriate rates of application in

    the field. In order for a material to be an effective P fertilizer, substantial amounts of P

    should dissolve shortly after application to soils and all P should eventually dissolve

    (Hughes and Gilkes 1984). Conventional chemical P fertilizers (SP, DAP, MAP) are

    mostly soluble in water and are highly effective. Rock phosphate is almost insoluble

    in water as it relies on soil acidity and rhizosphere acidity to promote dissolution and

    is consequently much less effective than chemical fertilizers (Khasawneh and Doll

    1978). The solubility of the above-mentioned byproducts in soil is not known.

    The effectiveness of poorly soluble phosphate fertilizers such as rock phosphate and

    phosphatic byproducts may be assessed by standard analytical procedures (AOAC

    1975) that determine the solubility of phosphate in water, citric acid, neutral

    ammonium citrate and alkaline ammonium citrate. Depending on the composition of

    the fertilizer and its reactions in soil, a particular extractant may provide the best

    prediction of fertilizer performance as determined by field or glasshouse experiments

    20

  • and appropriate calibration is required (Colwell 1963). This chapter investigates the

    nature of byproducts (chicken litter ash, wood ash, iron-smelting slag) that may act as

    a combined liming agent and phosphate fertilizer and evaluates them using standard

    AOAC fertilizer analyses.

    Table 3.1. The nomenclature for calcined chicken litter samples produced by

    calcination at various temperatures and their pH measured in water

    Key Explanation pH H2O

    (1:5)

    C500 Chicken litter burnt at 500oC 10.18

    C550 Chicken litter burnt at 550oC 10.27

    C600 Chicken litter burnt at 600oC 10.29

    C650 Chicken litter burnt at 650oC 10.33

    C700 Chicken litter burnt at 700oC 10.37

    C750 Chicken litter burnt at 750oC 10.38

    C800 Chicken litter burnt at 800oC 10.52

    C850 Chicken litter burnt at 850oC 10.55

    C900 Chicken litter burnt at 900oC 10.56

    C950 Chicken litter burnt at 950oC 10.59

    C1000 Chicken litter burnt at 1000oC 10.62

    CLA Chicken litter partly burnt in incinerator at 700oC to 800oC 9.93

    CLAT CLA heated in furnace at 700oC 11.31

    RP Sechura rock phosphate 7.96

    WA Wood ash 12.77

    Slag Iron smelting slag 10.59

    3.2 Materials and Methods

    3.2.1. Calcination of chicken litter

    A bulk sample of chicken litter was supplied by Blair Fox Generation, which is

    developing a power station to be fired by this material. Combustion temperatures and

    conditions may vary substantially during this process, so that diverse combustion

    products may be produced. Subsamples of 1 kg of the chicken litter were burnt in a

    21

  • ventilated electric muffle furnace for 1 hour at 500o, 550o, 600o, 650o, 700o, 750o,

    800o, 850o, 900o, 950o, and 1000oC respectively. Large amounts (>100kg) of chicken

    litter were partially and totally burnt in a commercial incinerator. Chicken litter was

    partially burnt (CLA) for 36 hours at temperatures that varied between 700oC to

    800oC. Combustion was only partial as much carbonised litter (charcoal) remained.

    Totally burnt chicken litter (CLAT) was derived from CLA, by heating overnight in a

    fully oxidising environment at 700oC to remove residual charcoal from CLA. A key to

    the materials investigated, abbreviations used to identify these materials and the pH of

    these materials including Sechura rock phosphate are given in Table 3.1.

    3.2.2 Industrial Byproducts

    Iron smelting slag came from the HIsmelt Kwinana Demonstration Plant, Western

    Australia, which utilises iron ore, lime and coal. Wood ash was from eucalyptus

    (Mallee sp.) timber and litter, which is burnt in an experimental bioenergy Power

    Station at Narrogin Western Australia. The chemical compositions of the byproducts

    and Sechura rock phosphate, which as it acts as a combined P fertilizer and liming

    agent (Khasawneh et al. 1980) was included for comparative purposes, are given in

    Table 3.3.

    3.2.3 Characterisation of the materials

    The pH of the materials was determined in a 1:5 deionized water extract. Calcium

    carbonate equivalent (CCE) was determined as in the AOAC 1.005 procedure,

    (AOAC 1975). Major elements were determined by atomic absorption

    spectrophotometry (AAS) (Perkin-Elmer, Analyst 300, Norwalk, CT, USA) and trace

    elements with a model PE ELAN 600 inductively coupled plasma mass

    spectrometry (ICPMS) instrument (Perkin-Elmer, Norwalk, CT, USA) after

    perchloric acid digestion. Total phosphorous in these digest was determined

    colorimetrically using the molybdovanadophosphate (yellow) method (Rayment and

    Higginson 1992). The compounds in byproducts were identified by X-ray powder

    diffraction (XRD) using a Philips PW3020 diffractometer. Samples for scanning

    electron microscopy and energy dispersive X-ray spectrometry (EDS) using a JEOL

    3600 instrument were placed on metal stubs and carbon coated.

    22

  • 3.2.4 Chemical extraction of the materials (AOAC Method)

    Unlike many commercial P fertilizers little of the P in byproducts is soluble in water

    (Table 3.2). The byproducts were analysed for available P using Association of

    Official Analytical Chemistry (AOAC) standard methods (AOAC 1975) utilising

    citric acid (CA), neutral ammonium citrate (NAC) and alkaline ammonium citrate

    (AAC) extractions. Gilkes and Palmer (1979) have shown that the standard AOAC

    extraction procedures may not be optimum for the best prediction of the agronomic

    effectiveness of calcined phosphate minerals. They used various extraction times to

    evaluate the kinetic and congruency of dissolution of the phosphates to determine

    optimum extraction times. The same procedure has been followed here to determine

    an optimum procedure for byproducts and also for Sechura rock phosphate that was

    included as a comparison material. Citric acid 2% (CA) was prepared by dissolving

    100g of citric acid in five litres of deionised (DI) water. Neutral ammonium citrate

    (NAC) prepared as in the standard procedure, AOAC 2.036 (AOAC 1975). Alkaline

    ammonium citrate (AAC) solution was prepared by dissolving 865 g citric acid in two

    litres of water to which three litres of 5M NH4OH were added (Boxma 1977). The pH

    was adjusted to 9.35 and the specific gravity to 1.08 by small additions of these

    reagents. The solid: solution ratio for each extractant was 1:100 w/v and the

    temperature of extraction for NAC, AAC and CA was 65oC, 65oC and 25oC

    respectively.

    The extractants were shaken in a temperature controlled mechanical shaker with a

    vigorous action that kept particles in suspension. Aliquots of the suspension were

    removed for analysis after 7 times (0.5, 1, 2, 6, 24, 72, and 120 hours). Aliquots were

    quenched with pure ice (NAC and AAC) and cold water (CA) to slow the reaction

    during filtering. The suspension was immediately filtered through 0.22 m Millipore

    filters and the filtrate analysed for phosphorus, calcium, magnesium, sodium and

    potassium. The solid residue after 120-h extraction was washed three times with DI

    water and then analysed by XRD and SEM.

    3.2.5 Chemical analysis of the extracts

    Phosphate was determined in the extracts by spectrophotometry (molybdate blue

    method) (Rayment and Higginson 1992). The reagents were 0.02 M ammonium

    23

  • molybdate and 0.001 M hydrazine sulphate solution; equal volumes were freshly

    mixed for each batch of analyses. A 0.3 ml aliquot of the quenched citrate solution

    was added to 1 mL of hydrochloric acid and diluted with DI water to fill a 10 mL

    volumetric flask. Next 1 ml of the solution was mixed with 4 ml hydrazine solution

    and 5 ml of molybdate solution in a flask. The solution was shaken and placed in a

    boiling water bath for 10 minutes then cooled to room temperature in a water bath.

    The absorbance was read at 820nm on a Hitachi U-1100 spectrophotometer using a

    bandwidth of 2 nm and 1 cm path length cell. Calcium, magnesium, sodium and

    potassium were determined by AAS after dilution and addition of appropriate

    ionisation suppressants (Gilkes and Palmer 1979).

    3.2.6 Glasshouse experiment

    Details of a glasshouse experiment with an acid lateritic soil and ryegrass to evaluate

    the byproducts have been described in a paper by Yusiharni and Gilkes (2006), which

    occur in this thesis as Chapter 4. In this chapter values of agronomic relative

    effectiveness (RE) derived from these plant yield data with monocalcium phosphate

    (MCP) as the reference fertilizer have been related to the solubility (availability) of P

    determined using CA, NAC and AAC extractions following the procedure of Gilkes

    and Palmer (1979).

    3.3 Results and discussion 3.3.1. Calcination of chicken litter

    The calcined chicken litter samples had pH values that ranged from 10.18 (C500) to

    10.62 (C1000) (Table 3.1). For the calcined chicken litter ash samples, the solubility

    of phosphorus in AOAC citrate extractants varied with period of extraction and the

    type of extractant. The percentages of total P extracted from chicken litter ash

    calcined at various temperatures and for various extraction times are shown in Figure

    3.1. The major trend is that phosphorus solubility in all three extractants increased as

    calcination temperature increased up to the maximum calcination temperature of

    1000oC.

    24

  • Citric Acid

    0

    20

    40

    60

    80

    100

    120

    0.5 1 2 6 24 72 120

    Duration of Extraction (Hour)

    % P

    Ext

    ract

    ed

    A

    Neutral Ammonium Citrate

    01020304050607080

    0.5 1 2 6 24 72 120

    Duration of Extraction (Hour)

    % P

    Ext

    ract

    ed

    B

    Alkaline Ammonium Citrate

    010203040506070

    0.5 1 2 6 24 72 120

    Duration of Extraction (Hour)

    % P

    Ext

    ract

    ed

    C500 C550 C600 C650 C700 C750 C800C850 C900 C950 C1000

    C

    Figure 3.1. Percentages of total P extracted from chicken litter ash produced at

    various temperatures for various durations of extraction in citric acid (A), neutral

    ammonium citrate (B) and alkaline ammonium citrate (C).

    25

  • Most dissolution in CA occurred within 0.5 hour whereas dissolution continued for

    approximately 6 hours in NAC and 72 hours in AAC. For all three extractants

    considerable P had not dissolved after 120 hours of extraction and this is likely to be

    present in refractory inorganic or organic compounds. Doak et al. (1965) have

    demonstrated that the solubility of calcined Christmas Island Fe, Al containing rock

    phosphate in the same citrate extractants increased to a maximum solubility of nearly

    100% after calcination at temperatures between 500oC and 650oC and decreased for

    higher calcination temperatures. The proportion of total P that had dissolved after

    120-h was similar for all three extractants but increased in the sequence

    CA>NAC>AAC for short periods of extraction. In contrast Gilkes and Palmer (1979)

    observed that the dissolution of calcined iron-aluminium phosphate in CA and NAC

    was less than in AAC. The solubility of apatitic rock phosphate fertilizers in these

    reagents follows the same trend as for litter ash (CA>NAC>AAC) (Lehr 1980).

    The percentage dissolution of the major cations in calcined chicken litter in CA, NAC

    and AAC after a 1-h extraction is shown in Table 3.2. Dissolution was not congruent

    for any extractant or material as indicated by the different percentage dissolution

    values for each element. Dissolution of calcium in CA increased from C500 to C950

    and decreased at C1000. For NAC and AAC the percentages of calcium dissolved

    were less than for CA. Higher proportions of magnesium, potassium and sodium

    dissolved compared to calcium in all three extractants. CA, NAC and AAC dissolved

    most magnesium for calcination temperatures between 800oC to 1000oC. In contrast,

    there were no systematic trends with temperatures for potassium and sodium. These

    diverse behaviours for the four cations indicates that they do not coexist in the

    byproducts within a single compound.

    26

  • Table 3.2. Percentages of total phosphorus, calcium, magnesium, potassium and

    sodium dissolved after 1hour extraction in citrate solutions for chicken litter calcined

    at various temperatures and for Sechura rock phosphate (RP), wood ash (WA) and

    slag.

    Phosphorus (%) Calcium (%) Magnesium (%) Potassium (%) Sodium (%) Samples

    CA NACAAC CA NACAAC CA NAC AAC CA NAC AAC CA NAC AAC

    C500 37 37 23 21 21 11 47 46 39 47 52 51 28 34 30

    C550 39 37 26 21 21 11 48 47 40 47 53 52 29 35 32

    C600 43 40 27 23 21 12 50 49 41 50 54 52 31 38 32

    C650 44 41 29 23 22 13 53 51 42 54 58 53 34 43 33

    C700 54 42 30 24 22 13 54 52 43 58 64 63 38 45 37

    C750 48 44 30 25 22 13 55 52 45 62 67 65 40 46 37

    C800 53 45 32 28 22 14 67 62 52 68 74 71 48 51 46

    C850 64 46 32 33 22 15 78 70 60 75 82 79 54 57 51

    C900 71 47 32 88 62 11 82 71 56 68 33 30 66 31 22

    C950 71 48 36 92 40 8 23 94 78 90 32 30 90 39 34

    C1000 96 53 48 50 23 20 91 99 85 79 83 79 72 74 69

    CLA 75 46 34 88 62 58 82 71 56 95 46 43 80 38 26

    CLAT 81 49 39 92 40 39 86 72 60 90 32 30 90 39 34

    RP 38 2 1 77 16 3 30 10 6 4 4 3 74 47 32

    WA 57 78 69 85 85 88 79 75 82 87 55 51 2 78 79

    Slag 80 18 40 40 24 22 55 26 18 6 5 5 30 25 18

    The XRD patterns of chicken litter ash that had been calcined at various temperatures

    are shown in Figure 3.2.A. The major crystalline compounds present are apatite and

    quartz.

    27

  • 5 10 15 20 2 5 3 0 35 40 4 5

    2 ( d e g re e s )

    Calcined Chicken Lit ter Ash After CA Extract io n

    C100 0

    C950

    C90 0

    C850

    C80 0

    C750

    C700

    C6 50

    C6 00

    C550

    C500

    Q

    Citrate p recip itat ion

    B

    5 10 15 20 25 3 0 3 5 40 45

    2 (deg rees )

    Calcined Chicken Litter AshQ C10 00

    C950

    A

    C900

    C850

    C800

    C750

    C700

    C500

    C550

    C600

    C650

    A

    5 10 15 20 25 3 0 3 5 40 45

    2 ( d e g re e s )

    Calcined Chicken Lit ter Ash After NAC Extraction

    C1000

    C950C90 0

    C850C80 0

    C750

    C700

    C6 50

    C6 00

    C550

    C500

    Q

    A

    C

    5 10 15 2 0 2 5 30 3 5 4 0 4 5

    2 ( d e g re e s )

    Calcined Chicken Lit ter Ash After AAC Extract io n

    C10 0 0

    C9 50

    C9 0 0

    C8 50

    C8 0 0

    C750

    C70 0

    C6 50

    C6 0 0

    C550

    C50 0

    Q

    A

    D

    Figure 3.2. XRD patterns of chicken litter calcined at various temperatures before (A)

    and after extraction for 120 hours in citric acid (B), neutral ammonium citrate (C) and

    alkaline ammonium citrate (D). Q = quartz (d = 3.43 ), A = apatite (d = 2.84 ), Cu

    K radiation.

    28

  • Calcined chicken litter ash contains abundant amorphous material (mostly charcoal)

    as indicated by broad background scatter centred at 25o 2. As calcination temperature

    increased the intensity and sharpness of apatite peaks increased which is due to loss of

    charcoal, together with the increased abundance, greater structural order and larger

    crystal size of the apatite that formed during calcination (Klug and Alexander 1974).

    XRD patterns for the residues of calcined chicken litter ash samples after CA

    extraction (Figure 3.2.B) show stronger quartz peaks and a stronger amorphous

    carbon band than for CLA as these insoluble compounds have been concentrated by

    dissolution of apatite. All the apatite had dissolved in CA for each calcination

    temperature. Broad reflections due to precipitated citrate compounds are present for

    some CA residues and may be a consequence of the high alkalinity of the ash causing

    precipitation of calcium citrate salts.

    These XRD results may be compared with the dissolution data shown in Figure

    3.1.A., which indicate that for the higher calcination temperatures ( 850oC) most P

    had dissolved in CA after 120 hours of extraction. Much smaller amounts of P had

    dissolved for lower calcination temperatures and a similar trend occurred for Ca, Mg,

    K and Na (Table 3.2). It is suggested that CA completely dissolved the inorganic

    apatite that is the main form of P for high temperature calcines but did not dissolve

    organic forms of P associated with charcoal that persist in the lower temperature

    calcines. For NAC extraction, a comparison of Figures 3.1.B and 3.2.C shows that

    some apatite did not dissolve for the highest temperature ( 850oC) calcines, which is

    consistent with less P being extracted (maximum 70%) than for CA, the organic P

    once again being insoluble. For the AAC extraction (Figures 3.1.C and 3.2. D) even

    less apatite and P (maximum 58%) dissolved.

    SEM micrographs and EDS spectra of C500 and the residue of C500 after the three

    citrate extractions show the diverse particle sizes, shapes and compositions present in

    this material (Figure 3.3). Similar observation were made for the other calcined

    materials and their residues. Most grains seen in the micrographs consist mostly of

    carbon and contain only a little P and cations.

    29

  • C500 C500 after CA extraction

    C500 analysed grain C500 analysed grain after CA extraction

    C500 after NAC Extraction C500 after AAC Extraction

    C500 analysed grain after NAC extraction

    C500 analysed grain after AAC extraction

    050

    100150200250300350400

    0 5 10 15

    Energy (keV)

    P

    Si

    KCaMg

    0

    200

    400

    600

    800

    1000

    1200

    0 2 4 6 8 10

    Energy (keV)

    cps

    Na Mg

    P

    K

    Ca

    0

    100

    200

    300

    400

    500

    600

    0 2 4 6 8 10

    Energy (keV)

    cps

    Mg

    P

    Ca

    0

    100

    200

    300

    400

    500

    0 2 4 6 8 10

    Energy (keV)

    cps

    Mg

    P

    Ca

    Figure 3.3. Scanning electron micrograph (SEM) and spectra of the indicated particles

    for 500oC calcined chicken litter (C500) before and after extraction for 120 hours in

    citrate solutions. Most particles are charcoal.

    30

  • The P enriched grains in C500 have complex and diverse chemical compositions. The

    grain in C500 indicated in Figure 3.3 contains much Ca and P that could be present in

    apatite together with minor K, Mg, and Na that may also be present within apatite

    (Lindsay et al. 1989) or possibly in separate compounds such as carbonates or oxides

    as would be consistent with the dissolution data in Table 3.2 that indicate incongruent

    dissolution. After CA extraction of C500 few Ca, and P grains remained as they had

    mostly dissolved, but as only 40% of total P had dissolved much of the remaining P

    could be present in organic associated form in the charcoal grains. The rare P enriched

    grain indicated in Fig. 3.3 for CA residue is probably a mixture of apatite and a

    calcium silicate mineral. Figure 3.3 shows that some Ca and P rich apatite grains

    remain after NAC and AAC extraction, which is consistent with XRD and chemical

    extraction results. For all three types of citrate residue some of the P must be

    associated with the charcoal where it is present at the low concentrations (Codling et

    al. 2002) that were detected by EDS (less than 1%). The majority of the non-carbon

    grains were silicate minerals and represent sand (quartz, feldspar, etc) that had been

    incorporated into the litter.

    3.3.2 Dissolution of industrial byproducts

    The chemical compositions of the byproducts are given in Table 3.3 and indicate that

    these materials will provide several plant material elements in addition to P. Indeed at

    the rates of application of byproducts used to lime soils (tonnes/hectare) large amount

    of Ca, Mg, K and trace elements (Cu, Zn, Mn, etc) would be provided by the ash

    materials. Slag will provide much Ca and Mg, little K and some trace elements. The

    concentrations of the heavy metals Cd, Ni, As and Pb in the byproducts are

    insufficient to generate an environmental hazard at normal application rates for lime

    (Alloway and Ayres 1993). All of the byproducts are likely to be effective liming

    agents as they have calcium carbonate equivalent (CCE) values ranging from 93-98%

    whereas RP had much smaller CCE (48%) (Table 3.3).

    31

  • Table 3.3. Chemical properties of the industrial byproducts and rock phosphate.

    Properties CLA CLAT Slag WA RP

    pH (1:5 H2O) 9.93 11.31 10.59 12.77 7.66

    EC (1:5 H2O) (dS/m) 1.54 1.62 1.43 1.35 1.31

    CCE (%) 94 97 93 99 48

    Total phosphorus (%) 3.6 4.75 0.26 0.44 15.85

    P soluble in water + (%) 6 6 15 13 2

    Total calcium (%) 16.62 18.02 27.82 22.23 19.27

    Total magnesium (%) 1.48 1.94 6.07 3.75 0.48

    Total potassium (%) 2.93 4.11 0.12 3.65 0.78

    Total sodium (%) 1.53 1.86 0.22 2.62 0.98

    Total Cd (mg/kg) 5.75 6.62 0.27 0.59 47.2

    Total Ni (mg/kg) 15.9 19.3 14.9 52.6 26.1

    Total As (mg/kg) 20.8 30.4 3.1 2.1 25.5

    Total Pb (mg/kg) 7.4 8.5 0.6 15.4 8

    Total Cu (mg/kg) 47.9 52.4 18.2 41.3 11

    Total Mn (g/kg) 1.8 1.4 11.2 4.2 1.7

    Total Zn (g/kg) 7.4 9.5 0.1 0.2 0.1

    + Expressed as a percentage of total phosphorus

    The effects of extraction time and extractant type on dissolution of P from byproducts

    are illustrated in Figure 3.4. The solubility of the P in RP was small in NAC and

    AAC, and higher in CA reflecting the presence of well crystalline apatite. Apatite is

    almost insoluble in water so that when apatite RP is applied to soil, any dissolution

    that occurs is the result of a chemical reaction between soil acidity and RP, hence the

    use of an acidic extractant (CA) (Khasawneh and Doll 1978). Lim and Gilkes (2001)

    showed that the equilibrium solubility of various RPs in CA was reached after

    different durations of extraction but that it was generally attained within 24 hours,

    32

  • whereas minor additional dissolution of RP after 24 hours occurred in the present

    research.

    Citric Acid

    0

    20

    40

    60

    80

    100

    120

    0.5 1 2 6 24 72 120

    Duration of Extraction (Hour)

    % P

    Ext

    ract

    ed

    Neutral Ammonium Citrate

    0

    20

    40

    60

    80

    100

    120

    0.5 1 2 6 24 72 120

    Duration of Extraction (Hour)

    % P

    Ext

    ract

    ed

    Alkaline Ammonium Citrate

    0

    20

    40

    60

    80

    100

    120

    0.5 1 2 6 24 72 120

    Duration of Extraction (Hour)

    % P

    Ext

    ract

    ed

    Figure 3.4. Percentage of P extracted from five phosphatic byproducts by three citrate

    extractants for various durations of extraction: CLA, CLAT, RP, x WA,

    Slag

    33

  • CLAT and CLA showed similar and considerable amounts of dissolution in each

    extractant with amounts of soluble P being in the sequence CA>NAC>AAC for

    shorter extraction times. For all three extractants there was little or no additional

    dissolution after about 6 hours of extraction. Much of the P in WA rapidly dissolved

    in all three extractants, with little additional dissolution occurring for longer

    extraction periods. The P in slag dissolved more slowly in NAC and AAC than in CA

    but essentially all P had dissolved after 6 hours. Only a minor proportion of P in RP

    had dissolved in NAC and AAC after 120 hours. Much more of the P in RP dissolved

    in CA and most dissolution occurred within a short time.

    The diffraction patterns of CLA, CLAT, slag, WA and RP before and after the three

    extractions for 120 hours are shown in Figure 3.5. As for the laboratory calcined

    chicken litter, the major compounds present in CLA and CLAT are apatite and quartz

    with calcite being present in CLA. The broad background for CLA is higher

    compared to CLAT due to the carbon having been removed from CLAT by prolonged

    calcination. The sharp XRD reflections indicate that CLA and CLAT contain well-

    ordered apatite of large crystal size. Based on spacing data, the apatite in CLA and

    CLAT was carbonate apatite (Lehr 1980). Much apatite remained in CLA and CLAT

    after 120-h extraction in all three extractants, which is consistent with the P

    dissolution data (Figure 3.4). Oxalate precipitation occurred for CLA and CLAT

    extracted by CA.

    The minerals present in Sechura RP are carbonate apatite (francolite) and quartz

    (Figure 3.5) (Lim and Gilkes, 2001). Much apatite remains in the residues for all three

    extractants, which is consistent with the low extent of dissolution of RP in citrate

    extractants shown in Figure 3.4. Slag consists of calcium magnesium silicate

    (akermanite) and calcium aluminium silicate (gehlenite) (Li and Gilkes 2002). The

    residue of slag after CA extraction contains little akermanite and much gehlenite. The

    residues after NAC and AAC extraction contain abundant akermanite and gehlenite. It

    appears that there is no relationship between the extent of dissolution of these

    compounds and the dissolution of P, which was approximately 100% in all three

    extractants. We conclude that P is not contained within these silicates but is present in

    slag as a discrete, readily soluble compound.

    34

  • 5 10 15 2 0 2 5 3 0 3 5 4 0 45

    2 ( d e g re e s )

    Slag

    WA

    RP

    CLAT

    CLA

    Byprod ucts

    Q

    A

    Q

    C

    Ak

    G

    A

    A Q

    Ca

    A

    5 10 15 20 2 5 30 3 5 40 4 5

    2 ( d e g re e s )

    Slag

    WA

    RP

    CLAT

    CLA

    Byp ro ducts After CA Extract io n

    Q

    A

    A

    G

    A

    A A

    B

    5 10 15 2 0 2 5 30 3 5 40 4 5

    2 ( d e g re e s )

    Slag

    WA

    RP

    CLAT

    CLA

    Byprod ucts after NAC Extraction

    Q

    A

    A

    Ak

    G

    C

    A

    A

    A

    C

    5 10 15 20 2 5 3 0 35 4 0 4 5

    2 ( d e g re e s )

    Slag

    WA

    RP

    CLAT

    CLA

    Byp rod ucts After AAC Extractio n

    Q

    A

    A

    Ak

    G

    C

    D

    Figure 3.5. XRD patterns of byproducts (A) and their residues after extraction for 120

    hours in citric acid (B), neutral ammonium citrate (C) and alkaline ammonium citrate

    (D). Q = quartz (d = 3.43 ), A = apatite (d = 2.84 ), C = calcite (d = ), Ak =

    akermanite (d = 2.85) and G = gehlenite (d = 3.71 ), Cu K radiation.

    35

  • CLA CLA after CA extraction

    CLA analysed grain CLA analysed grain after CA extraction

    CLA after NAC Extraction CLA after AAC Extraction

    CLA analysed grain after NAC extraction

    CLA analysed grain after AAC extraction

    0

    200

    400

    600

    800

    1000

    1200

    0 2 4 6 8 10

    Energy (keV)

    cps

    Mg

    P Ca

    0

    500

    1000

    1500

    2000

    2500

    0 2 4 6 8 10

    Energy (keV)

    cps

    Si

    Mg

    Ca

    P

    0100200300400500600700800900

    0 2 4 6 8 10

    Energy (keV)

    cps

    Si

    P KCa

    Al

    0500

    10001500200025003000350040004500

    0 2 4 6 8 10

    Energy (keV)

    cps

    Na

    Mg

    P

    Ca

    Figure 3.6. Scanning electron micrographs (SEM) and spectra of indicated particles

    for original CLA and residues after extraction for 120 hours in three citrate solutions.

    36

  • WA consists mostly of calcite, quartz and several salts but apatite was not identified,

    although it has been observed in some plant ashes (Harper et al. 1982). Humpreys et

    al. (1987) also found that wood ash mainly consisted of calcite however Etiegni and

    Champbell (1991) observed that quicklime (CaO) and calcium silicate (Ca2SiO4)

    could be present. All of the calcite dissolved in CA but NAC and AAC residues of

    WA contain calcite together with minor amounts of unidentified compounds.

    0

    50

    100

    150

    200

    250

    300

    0 5 10 15

    Energy (keV)

    Ca

    PSi

    K

    A

    S Cl

    0200

    400600

    80010001200

    14001600

    18002000

    0 2 4 6 8 10 12 14

    Energy (keV)

    Si

    Al Ca

    K

    B

    Figure 3.7. X-ray spectrum of a carbon grain in partly burnt chicken litter ash showing

    that it contains minor amounts of Si, P, S, Cl, K, and Ca (A) and a silicate grain in

    totally burnt chicken litter ash containing much Si, Al, K and Ca (B).

    37

  • CLAT CLAT after CA extraction

    CLAT analysed grain CLAT analysed grain after CA extraction

    CLAT after NAC Extraction CLAT after AAC Extraction

    CLAT analysed grain after NAC extraction

    CLAT analysed grain after AAC extraction

    0

    1000

    2000

    3000

    4000

    5000

    6000

    7000

    0 2 4 6 8 10

    Energy (keV)

    cps

    Mg P

    Si

    K

    Ca

    0

    500

    10001500

    2000

    2500

    3000

    35004000

    4500

    5000

    0 5 10 15

    Energy (keV)

    cps

    Na

    Mg

    Si

    Cl

    K

    Ca

    0200400600

    800100012001400

    0 5 10 15

    Energy (keV)

    cps

    Mg

    P

    Cl

    Ca

    Si

    0100200300400500600700800900

    0 2 4 6 8 10

    Energy (keV)

    cps

    Na

    AlSi

    K

    Ca

    P

    Figure 3.8. Scanning electron micrographs (SEM) and X-ray spectra of indicated

    grains for CLAT and residues after extraction for 120 hours in three citrate solutions.

    38

  • The SEM image of CLA shows abundant charcoal particles and an apatite grain

    (Figure 3.6), consisting mostly of Ca and P with a little Mg, an element, which can

    substitute for Ca in the apatite structure (McClellan and Gremillion 1980). After CA,

    NAC and AAC extractions all calcite had been removed from CLA, some apatite

    grains persisted and these are often associated with silicate minerals as indicated by

    the EDS spectra of grains in Figure 3.6. The silicates include sand grain and

    compounds formed from silicon that was present in plant materials that were

    combusted. The ash of plant materials commonly contains organic compounds and

    particularly carbon resulting from incomplete combustion (Sander and Andren 1997).

    Many particles of carbon are present in CLA and although these contain only minor

    concentrations of P, Ca and other elements, they contain much of the total content of

    these elements in the materials (Figure 3.7.A). The SEM image for the completely

    combusted CLAT (Figure 3.8) is quite different from that of CLA as no carbon

    particles are present. Much Ca and P is present in compound particles, variously

    containing Si, Al, Mg and K. These compound particles persisted in all three

    extractant residues (Figure 3.7) so that the P (as apatite) in these particles may have

    been partly protected from dissolution by surrounding silicate compounds.

    3.3.3 Relationship of relative agronomic effectiveness (RE) of CLA and CLAT with P

    availability determined by chemical extraction.

    The solubility of P in bypoducts in AOAC extractants differs for the three extractants

    and the duration of extraction. Consequently there is uncertainty over which

    combination of extractant and extraction time will be most predictive of the

    agronomic effectiveness of byproducts. A comparison of these chemical results with

    values of agronomic relative effectiveness (RE) obtained in a glasshouse study

    (Chapter 4) (Yusiharni and Gilkes 2006) was done to determine the most suitable

    extraction procedure for these P fertilizers (Gilkes and Palmer 1979). Relative

    effectiveness is expressed as the substitution value of the fertilizer relative to the

    standard fertilizer monocalcium phosphate (MCP), which is the major P compound in

    superphosphate. All the byproducts together with Sechura RP were included in this

    comparison.

    39

  • r = - 0.90

    0

    5

    10

    15

    20

    25

    30

    0 20 40 60 80 100 120

    % P Soluble in CA for 6 Hours

    RE

    (%)

    WA

    CLATSlag

    CLA

    RP

    Figure 3.9. The relationship of relative agronomic effectiveness (RE) and the

    solubility of P in CA for 6 hours extraction.

    The values of relative effectiveness of the byproducts were less than 10% of the

    effectivenss of MCP (Yusiharni and Gilkes 2006) (Chapter 4). No measure of

    available P (no combination of extractant type and time) was systematically and

    positively related to RE values obtained from the plant experiment and in most

    instances there was a negative relationship between RE and the P soluble in

    extractants. This situation is illustrated by the relationship between agronomic

    effectiveness (RE) and the solubility of P in CA for a 6 hour extraction (Figure 3.9).

    The lack of a systematic positive relationship may be a consequence of the high pH of

    WA, CLA and CLAT raising soil pH, so that the dissolution of these P sources in soil

    and the consequent availability of P to plants is reduced and is not simply related to

    the solubility of P in citrate reagents. Where soil pH becomes elevated due to high

    rates of application of these alkaline materials as liming agents, apatite in the

    fertilizers will not dissolve to the same extent as in an acid soil (Anderson et al.

    1985). Furthermore the high concentration of Ca in soil solution due to the dissolution

    of Ca compounds in the byproducts will also reduce dissolution of apatite in the soil

    due to the common ion effect (Lindsay et al. 1989). Another consideration is that the

    high alkalinity of the byproducts (especially CLA, CLAT, WA) may have adversely

    affected the capacity of the citrate extractants to dissolve P and or retain dissolved P

    40

  • in solution. Due to these circumstances, CA, NAC and AAC extractions are unable to

    predict the agronomic effectiveness of this type of fertilizer.

    3.4 Conclusion

    This research has shown that the combustion of chicken litter such as occurs in a

    thermal power station produces a multi-element fertilizer where much of the

    phosphorus is soluble in citrate extractants. In general phosphorus solubility followed

    the sequence CA>NAC>AAC for short periods of extraction. Much of the P in CLA

    and CLAT was present as the mineral apatite, with the abundance, crystal order and

    crystal size of the apatite increasing with calcination temperature. The P in WA and

    slag is mostly soluble in citrate extractants whereas much of the P in rock phosphate

    is not.

    The high value of the correlation coefficient for the relationship between RE and CA

    soluble P (0.90) (Figure 3.9) might encourage the view that P soluble in citrate

    solution is highly predictive of RE but the relationship is negative and the data points

    are not sufficiently dispersed for the regression line to be reliable. This or similar

    situations exist for all extractants and extraction times. Thus it is not possible to

    predict the relative agronomic effectiveness (RE) of these materials using citrate

    extractants, which may be a consequence of the high pH of these materials. Chicken

    litter ash, wood ash and slag have important liming values and their application to

    acid soils at normal rates for liming will not increase soil pH to levels that prevent the

    apatite from eventually dissolving and providing substantial P to plants.

    41

  • Chapter 4

    4.0 Plant response to the byproducts: Chicken Litter Ash, Iron Smelting Slag

    and Wood Ash as Phosphorus Fertilizers

    4.1 Introduction

    The industrial byproducts iron smelting slag, wood ash and chicken litter ash contain

    phosphate (P) so that both acidity and P deficiency can be overcome by a single

    application of byproduct, however the agronomic effectiveness of the P in these

    materials is not known. Previous studies have used chemical tests to evaluate the

    byproducts as phosphorous fertilizers and demonstrated that they might be a

    significant asset to agriculture, however direct analysis of agronomic values of the

    byproducts needs to be undertaken using plant growth experiments. This chapter

    reports on an experiment where iron-smelting slag, wood ash and chicken litter ash

    were applied to an acid soil to evaluate their capacity to supply P to plants relative to

    a standard fertilizer.

    4.2 Materials and methods

    4.2.1 Soil

    The

  • in an experimental bioenergy Power Station at Narrogin Western Australia. Properties

    of these materials are given in Table 3.2.

    4.2.3 Analysis of industrial byproducts and soil

    The alkaline byproducts were chemically analysed for available P using Association

    of Official Analytical Chemistry (AOAC) standard methods (AOAC 1975). The

    major element content of industrial byproducts was determined by atomic absorption

    spectrometry (AAS) and trace element contents by inductively coupled plasma mass

    spectrometry (ICPMS) after perchloric acid digestion. Total P in solution was

    determined colorimetrically using the molybdovanadophosphate (yellow) method

    (Rayment and Higginson 1992). Analyses are reported in Table 3.3 (Chapter 3).

    4.2.4 Glasshouse Experiment

    The treatments consisted of various rates of application to the soil of the byproducts

    and the reference fertilizers; monocalcium phosphate (MCP), dicalcium phosphate

    (DCP) and rock phosphate from Sechura (RP). Levels of phosphate for all sources

    included a control (zero rate) and the rates listed in Table 4.1 differ for the different

    sources reflecting the various solubilities of these materials.

    Table 4.1. Levels of P added to soil for the plant growth experiment

    MCP

    (mg/kg)

    DCP

    (mg/kg)

    RP

    (mg/kg)

    CLA

    (mg/kg)

    CLAT

    (mg/kg)

    WA

    (mg/kg)

    Slag (mg/kg)

    4.2 8.3 20.8 33.3 18.8 10.4 12.5

    8.3 16.7 41.7 66.7 37.5 20.8 25

    16.7 33.3 83.3 133.3 75 41.7 50

    33.3 66.7 166.7 266.7 150 83.3 100

    66.7 133.3 333.3 533.3 300 166.7 200

    1.5 kg subsample of air dry

  • thinned to 20 uniform plants per pot after the plants had reached the two-leaf stage.

    The treatments were replicated two times and placed in a completely randomised

    block design. The pots were rerandomised each 7 days and maintained at constant

    weight with deionised water. Ryegrass was harvested after 8 weeks and at 4-week

    intervals thereafter. The plants were harvested by cutting the tops at about 1 cm above

    the soil surface to allow regrowth and dried at 60oC until constant weight occurred.

    Table 4.2 Basal fertilizer and dose per pot used in the glasshouse experiment

    Salt MWt Stock Soln (g/L) Aliquot (mL/1.5 kg soil)

    NH4NO3 80.04 57 5.01

    K2SO4 174.25 42 9.99

    CaCL2.2H2O 147.02 90 5.01

    MgSO4.7H2O 246.77 24 5.01

    MnSO4.H2O 169.01 6 5.01

    ZnSO4.7H2O 287.54 5.4 5.01

    CuSO4.5H2O 249.68 1.2 5.01

    H3BO3 61.83 0.42 5.01

    CoSO4.7H2O 281.11 0.16 5.01

    Na2Mo4.2H2O 241.95 0.12 5.01

    The harvested plant tops were then ground and analysed for P, Ca, Mg, K, Na, S and

    trace elements by X-ray fluorescence spectrometry of pressed powder (Rayment and

    Higginson 1992). Soil samples were analysed for pH and EC (1:5 H2O), and available

    P (Bic P-Colwell 1963) before planting and after the last harvest.

    4.2.5 Relative Agronomic Effectiveness

    The agronomic effectiveness (RE) of the materials as phosphate fertilizers was

    calculated for each of the four harvests, using the yield data. The ratio of the linear

    initial slope of the response curve for the fertilizer relative to the slope for

    monocalcium phosphate was calculated and it is the value of RE (Bolland and Gilkes

    1990). The same procedure was used to calculate RE values based on plant P content

    and soil Bic P values.

    44

  • 4.3 Results and discussion

    4.3.1 Byproduct Characterization

    Some characteristics of the industrial byproducts used in the study are provided in

    Table 3.2 in the previous chapter. The pH ranged from 9.9 to 12.8 indicating that

    these materials could be used to neutralize soil acidity (Cregan et al. 1989). Total P

    concentrations of CLA, CLAT, slag and WA were 3.6%, 4.75%, 0.26% and 0.44%

    respectively indicating their considerable value as P fertilizers especially as large rates

    of application are used for liming agents so that substantial amounts of P will be

    applied despite the quite low concentration of P in some byproducts. The water-

    soluble phosphorus concentration in the materials was very low to low due to the

    nature of the P compounds and to the alkaline pH of the water extracts of the

    byproducts (Lindsay 1979). The solubility of P in the byproducts was much higher in

    citric acid compare to neutral ammonium citrate and alkaline ammonium citrate. The

    higher concentration of phosphorus in CLAT relative to CLA is due to removal of

    charcoal from CLA so that recalcitrant and protected forms of P were no longer

    present (Chapter 3) (Codling et al. 2002). Other major plant nutrients present in these

    byproducts include calcium, magnesium, sodium and potassium. Concentrations of

    Cd, As and Cu in CLA and CLAT were moderately elevated, while concentrations of

    other trace elements in the byproducts were within the normal range for soils in

    Australia (ANZECC/NHMRC 1992) so that use of these materials is unlikely to

    contaminate soils.

    4.3.2 Soil pH, EC and Bicarbonate P

    The effects of the addition of industrial byproducts on pH, EC and Bic P values of the

    soil measured after the last harvest are presented in Figure 4.1. MCP, DCP and RP did

    not have a liming effect, whereas CLA, CLAT, WA and slag increased soil pH with

    each material producing a quite constant increase of pH for all rates of application

    rather than a progressive increase in pH with application rate indicating buffering

    effect for the compounds (Cregan et al. 1989). WA was the most effective liming

    agent and it increased soil pH by about 2.3 units. However for all the treatments soil

    pH was in the range of 5.5 to 7.0, which is suitable for ryegrass (Slattery et al. 1999).

    45

  • Soil pH

    4

    5

    6

    7

    8

    1 10 100 1000

    Log P Applied (mg/kg)

    pH S

    oil

    Soil pH

    Soil EC

    0.000.200.400.600.801.001.201.401.60

    1 10 100 1000

    Log P applied (mg/kg)

    EC S

    oil (

    dS/m

    )

    Soil EC

    Soil Bic P

    0

    2

    4

    6

    8

    10

    12

    1 10 100 1000

    Log P applied (mg/kg)

    Bic

    P S

    oil (

    mg/

    kg

    Soil Bic P

    Figure 4.1. Plots of log P applied (mg/kg) versus pH, EC, and Bic P for soil samples

    taken after the last harvest: MCP, DCP, RP, x Slag, WA, CLA, + CLAT

    The byproducts contain various amounts of water-soluble salts that could increase soil

    salinity at high rates of application. The EC values of the soil at the end of the

    46

  • experiment were low for all the soils with the highest EC value of 1.40 dS/m at the

    533 mg/kg rate of CLA being insufficient to affect the growth of ryegrass (Moore

    1998). The EC values decreased with the increasing application rate of MCP, DCP

    and RP, which may due to the greater uptake of natural and fertilizer salts by the

    larger plants that were produced by the higher levels of application of P fertilizers.

    The amount of Bic P increased systematically with the increasing rate of fertilizer for

    all P sources. The relative effectiveness of the byproducts was calculated from the

    linear slopes of the Bic P versus application rate graphs in Figure 4.1. Values of slope

    for each P fertilizer were derived by the slope for MCP, which is the reference

    fertilizer (RE = 100%). The RE values for DCP and RP were 59% and 40%, while the

    RE values for slag, WA, CLA and CLAT were 19%, 29%, 39%, and 45%

    respectively.

    4.3.3 Plant composition and yield response data

    Application of byproducts affected the concentrations of most nutrient elements (Na,

    Mg, K, Ca, Si, P, S, Cl, Mn, Cu and Zn) in the plants with both increases and

    decreases occurring due to fertilization depending on the nature of the fertilizers

    (Appendix 4.1). However nutrient concentrations were within the normal range for

    ryegrass so that it is unlikely that element toxicity or deficiency other than that of P

    occurred during the experiment (Reuter and Robinson 1997). The appearance of

    ryegrass for the highest and the lowest rates of fertilizer application before harvesting

    are presented in Appendix 4.2. It is clear from the foliar symptoms that ryegrass

    receiving the lowest rates of application experienced severe P deficiency.

    For each harvest dry matter yield generally increased with the amount of P applied

    indicating the P deficient nature of the soil and the influence of the P fertilizers (Fig.

    4.2). Dry matter yield of ryegrass ranged from 0.03 g to 2.37 g/pot, 0.06 g to 2.38

    g/pot, 0.12 g to 2.28 g/pot and 0.08 g to 2.81 g/pot respectively for the four harvests.

    For harvest III and IV some plants died due to P deficiency for the low P application

    rates.

    The P concentration (Appendix 4.3) in the plants ranged from 0.01% to 0.1% and

    according to the critical values of Reuter and Robinson (1997) this entire range

    47

  • represents deficiency, even for the highest rates of P application. However this

    particular ryegrass cultivar (Lolium rigidum Gaud), which is commonly grown on

    highly P deficient Western Australian soils, has a very low demand for P so that the

    published critical levels (for other ryegrass cultivars) are inappropriate. Snars et al.

    (2004) found that concentrations of P in this ryegrass cultivar at sufficiency were

    much lower than the published values of Reuter and Robinson (1997).

    Harvest 1

    0

    0.5

    1

    1.5

    2

    2.5

    1 10 100 1000

    Log P applied (mg/kg)

    Yie

    ld (g

    /pot

    )

    Harvest II

    0

    0.5

    1

    1.5

    2

    2.5

    1 10 100 1000

    Log P applied (mg/kg)

    Yie

    ld (g

    /pot

    )

    Harvest III

    0

    0.5

    1

    1.5

    2

    2.5

    1 10 100 1000

    Log P applied (mg/kg)

    Yie

    ld (g

    /pot

    )

    Harvest IV

    0

    0.5

    1

    1.5

    2

    2.5

    3

    1 10 100 1000

    Log P applied (mg/kg)

    Yie

    ld (g

    /pot

    )

    Figure 4.2. Yield (g/pot) versus log rate of P applied (mg/kg) for each harvest for the

    seven fertilizers: MCP, DCP, RP, x Slag, WA, CLA, + CLAT.

    The internal efficiency of P utilization by ryegrass is indicated by plots of plant dry

    matter versus the P content of plants (Palmer and Gilkes, 1982). For each harvest the

    48

  • existence of a single internal efficiency curve for all P sources (Figure 4.3) indicates

    that differences in yield were due predominantly to differences in plant P content as

    was also observed by Snars et al. (2004) in an experiment with the same ryegrass

    cultivar.

    Harvest I

    y = 1.25x + 0.090R2 = 0.9977

    0

    0.5

    1

    1.5

    2

    2.5

    0 0.5 1 1.5 2

    P Content (mg P/pot)

    Yiel

    d(g

    /pot

    )

    Harvest II

    y = 1.69x - 0.14R2 = 0.9964

    0

    0.5

    1

    1.5

    2

    2.5

    0 0.5 1 1.5 2

    P Content (mg P/pot)

    Yiel

    d(g

    /pot

    )

    Harvest III

    y = 1.39x + 0.03R2 = 0.9928

    0

    0.5

    1

    1.5

    2

    2.5

    0 0.5 1 1.5 2

    P Content (mg P/pot)

    Yie

    ld(g

    /pot

    )

    Harvest IV

    y = 1.61x + 0.02R2 = 0.9954

    0

    0.5

    1

    1.5

    2

    2.5

    3

    0 0.5 1 1.5 2

    P Content (mg P/pot)

    Yiel

    d(g

    /pot

    )

    Figure 4.3. Internal efficiency of P utilization curves for each harvest: MCP,

    DCP, RP, x Slag, WA, CLA, + CLAT

    49

  • Harvest I

    0

    0.5

    1

    1.5

    2

    1 10 100 1000

    Log P applied (mg/kg)

    PC

    onte

    nt(m

    g/po

    t)

    Harvest II

    0

    0.5

    1

    1.5

    2

    1 10 100 1000

    Log P applied (mg/kg)

    P C

    onte

    nt (m

    g/po

    t)

    Harvest III

    0

    0.5

    1

    1.5

    2

    1 10 100 1000

    Log P applied (mg/kg)

    P Co

    nten

    t (m

    g/po

    t)

    Harvest IV

    0

    0.5

    1

    1.5

    2

    1 10 100 1000

    Log P applied (mg/kg)

    P Co

    nten

    t (m

    g/po

    t)

    Figure 4.4. P content versus log P applied for all harvests: MCP, DCP, RP, x

    Slag, WA, CLA, + CLAT

    Figures 4.4. show the response curves for P content versus P applied for all the

    harvests. There was a large response in P content to MCP, DCP and RP application

    for all harvests. For the byproducts there was a much smaller response for harvest I

    and II; for harvest III and IV there was no systematic trend in response for the

    byproducts. Some plants died before the third harvest for slag, WA and CLAT. The

    growth and P content of ryegrass for soil amended with these byproducts may not

    simply reflect a response to applied P. For instance the liming effect of these materials

    increased soil pH (Turner 1993) and this may have affected the availability of

    nutrients, although this is not evident in the plant analyses. Similarly the presence of

    50

  • abundant Ca and other ions in soil solutions due to dissolution of the byproducts in

    the soil may have reduced the availability of P (Sample et al. 1980). Plants may have

    ceased to grow or died from a combination of P deficiency and the high level of pH in

    the soil (Barber, 1980).

    4.3.4 Relative Effectiveness (RE)

    The agronomic relative effectiveness (RE) of the phosphate fertilizers based on plant

    data was derived by comparing the initial slope of response curves for plant yield and

    P content for the various materials with the slope for MCP as the reference (Figure

    4.5). This is a reliable procedure providing that the yield values are well below the

    non P limiting yield plateau (Bolland and Gilkes 1990)

    Due to the death after the second harvest of some plants fertilised with WA and

    CLAT, no RE values could be calculated for these P sources for the later harvests. For

    the last two harvests, application of WA and CLAT as phosphorus fertilizers

    produced no systematic responses in yield and P content, so that response curves were

    poorly defined (low R2 values) (Appendix 4.4).

    The effectiveness of CLA, DCP, and RP relative to MCP showed an increasing trend

    with the harvest number. There was a systematic increase in RE values for the first

    three harvests of CLA, DCP and RP. It must be stressed that values of RE have been

    calculated relative to MCP for which the absolute effectiveness decreases with time

    since application (Bolland and Gilkes 1990). Thus despite the increase in RE values,

    the absolute effectiveness of the other P fertilizers may not have increased. However

    it is evident that chicken litter ash has appreciable rapid effect and a good residual

    value as a phosphate fertilizer (Codling et al. 2002) whereas wood ash and slag were

    relatively ineffective.

    51

  • Plant Yield

    0

    20

    40

    60

    80

    100

    120

    1 2 3 4

    Harvest

    RE (%

    )

    P Content

    0

    20

    40

    60

    80

    100

    120

    1 2 3 4

    Harvest

    RE

    (%)

    MCP DCP RP Slag WA CLA CLAT

    Figure 4.5. RE values for the byproducts based on yield and P content for the four

    harvests

    4.4 Conclusion

    The results of this study provide strong evidence that chicken litter ash is a

    moderately effective P fertilizer but that it is inferior to MCP, DCP and RP. Slag and

    WA were relatively poor sources of P probably due to the alkaline pH of the

    materials, which would have reduced the solubility of P in soil solution. However as

    52

  • CLA, CLAT, slag and WA have excellent liming value and as they would be applied

    at much higher rates as lime than are used for fertilizers it is likely that all four

    materials will provide substantial additional P to plants. They may be more suited for

    use on permanent pastures or for tree crops where a rapid response to P fertilizer

    application is less important than is the case for fast growing cereals or horticultural

    crops.

    53

  • Chapter 5

    5.0 General Summary, Limitations and Future Work 5.1 General Summary The main purposes of the research as discussed in the general introduction were to

    characterize iron-smelting slag, wood ash and chicken litter ash and evaluate the use

    of these materials as liming agents and sources of P for agricultural land in Western

    Australia. The main findings of the study were that the byproducts differ in

    mineralogy, morphology and chemistry. They provide P to plants and effectively

    ameliorate acid soils.

    The byproducts used in the study were chicken litter ash burnt at several temperatures,

    partly burnt chicken litter ash, totally burnt chicken litter ash, wood ash, and iron

    smelting slag. The pH of all the materials were above 9 and calcium carbonate

    equivalence values were above 90%, indicating that these materials will be effective

    liming agents. Chicken litter ash contains more than 3% total P while the values for

    slag and WA were above 0.25%. Other plant nutrients present in byproducts include

    calcium, magnesium, sodium, potassium and trace elements.

    For calcined chicken litter, the amount of P dissolved by citrate extractants varied

    with the extractant and calcination temperature. The P dissolved for short and long

    periods of extraction of the various calcines increased followed the sequence

    CA>NAC>AAC. The amounts of soluble P in CLA and CLAT also followed the

    sequence CA>NAC>AAC with little additional dissolution after 6 hours of extraction.

    Dissolution of P in WA was quite rapid for all the three extractants while P in slag

    dissolved slowly and at slower rate for NAC and AAC compared to CA.

    CLA, and CLAT were consisted of mixtures of apatite, calcite, and quartz together

    with much charcoal in CLA. The intensity and the sharpness of apatite XRD

    reflection for chicken litter ash increased with increased calcination temperature.

    Apatite persisted in the three extractant residues and followed the sequence

    CA

  • explanations for the chemical and XRD analysis. Some grains micrographs consist

    mostly of carbon but also contain P and cations.

    The minerals presents in RP were apatite and quartz and much apatite persisted in the

    residues for all three extractants. WA consisted mostly of calcite and quartz, with no

    apatite being observed. Calcite in WA dissolved in CA but remained in NAC and

    AAC residues. Calcium magnesium silicate (akermanite) and calcium aluminium

    silicate (gehlenite) were the main constituents of slag. CA dissolved much akermanite

    and lesser gehlenite in slag, while NAC and AAC dissolved less of both compounds.

    In the glasshouse experiment all P sources produced initial yield responses but for

    iron smelting slag and wood ash, many plants died of P deficiency before the third

    harvest. Based on plant yield data, the relative effectiveness (RE) of DCP compared

    to MCP was 57%, 72%, 73%, and 94 % respectively for four harvests, for RP was

    24%, 34%, 70% and 56%, for chicken litter ash was 13%, 16%, 33% and 39%, for

    slag was 8%, 9%, 16% and 10%, for WA was 6%, 9% and effectively zero for the

    final two harvests. Thus chicken litter ash could be used as a P fertilizer but it is less

    effective than MCP. Iron smelting slag and wood ash were much less effective

    fertilizers but may still provide significant amount of P to plant where large

    application of these materials are used as liming agents. Application of the byproducts

    increased the pH of the soil.

    Chicken litter ash is a moderately effective P fertilizer but inferior to DCP and RP.

    Slag and WA were relatively poor sources of P. However as CLA, CLAT, slag and

    WA have a liming action and would be applied at much higher rate than are used for

    fertilizers it is likely that all four materials will provide additional P to plants.

    5.2 Limitation and Future Works This research has several limitations and further research is needed. For example, the

    study was based on laboratory and glasshouse research and it is important that the

    assessment of industrial byproducts be carried out under field conditions. Importantly,

    an economic analysis including cost-benefit evaluation of the use of the byproducts

    needs to be carried out.

    55

  • Application of the industrial byproducts in large amounts to large areas of agricultural

    land has the potential to create unanticipated environmental problems. For example if

    the materials, especially in finely ground and ash form are used at a large scale there

    may be a dust problem that could be dangerous for human and animal respiratory

    systems. It may be possible to combine the byproducts with compost or other

    materials to reduce dust and possibly to increase the effectiveness of the byproducts.

    The glasshouse experiment to evaluate the agronomic effectiveness of the byproducts,

    was based on ryegrass which has a low P demand. A next step would be to study the

    effectiveness of the byproducts for cereals and other species with diverse P

    requirements (e.g. plantation forestry).

    This research has clearly demonstrated the value of byproducts as combined P

    fertilizers and liming agents. In view of the large amounts of these materials that will

    be produced in future years, there is a clear opportunity for integrating the materials

    into appropriate land management practices.

    56

  • Chapter 6 6.0 Publications from this thesis

    Conferences Publications

    Yusiharni, B. E., and Gilkes, B. 2006. The Use of Industrial Byproducts as Liming

    Agents And Phosphate Fertilizers. Proceedings The 18th World Congress of Soil

    Science, Philadelphia USA, 8-15 July 2006.

    Yusiharni, B. E., and Gilkes, B. 2006. Mineralogy of Chicken Poo. Proceedings

    AXAA/WASM 2006 Conference, Margaret River, Western Australia, 22-24

    September 2006.

    Yusiharni, B. E., and Gilkes, B. 2006. Chicken Litter Ash: An Evaluation of an

    Agronomic Resource. Reviewed Conference. Proceedings ASSSI - ASPAC National

    Soils Conference, Soil Science Solving Problems. The University of Adelaide

    North Terrace 3-7 December 2006.

    Journals Publications

    Chapter 3

    Yusiharni, B. E., Gilkes, R. J., and H. Ziadi., 2006. A laboratory evaluation of chicken

    litter ash, iron smelting slag and wood ash. In press. Aust. J. of Soil. Res.

    Chapter 4

    Yusiharni, B. E., Gilkes, R. J., 2006. An evaluation as phosphorus fertilizers of the

    byproducts: chicken litter ash, iron smelting slag and wood ash. Submitted to Aust. J.

    Agric. Res.

    57

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  • Appendix 4.1.1 XRF Analysis of Plant Dry Tops for Harvest 1

    Na Mg K Ca Si S Cl Mn Fe Cu Zn Rate of P Applied (mg/kg) (%) (%) (%) (%) (%) (%) (%) (ppm) (ppm) (ppm) (ppm)

    0 0.18 0.49 2.10 0.87 0.72 0.51 0.90 202 742 12 60

    MCP 4.17 0.16 0.47 1.89 0.82 0.79 0.33 1.00 146 693 9 50

    MCP 8.33 0.17 0.51 1.75 0.82 0.80 0.38 1.09 130 635 12 26

    MCP 16.67 0.16 0.43 2.30 0.74 0.75 0.32 0.87 132 926 9 28

    MCP 33.33 0.11 0.41 2.89 0.68 0.82 0.37 0.74 116 475 12 42

    MCP 66.67 0.07 0.28 2.74 0.48 0.46 0.27 1.11 70 524 5 30

    DCP 8.33 0.20 0.42 1.77 0.75 0.80 0.36 0.57 148 476 12 54

    DCP 16.67 0.17 0.52 2.28 0.90 0.84 0.39 1.23 163 543 16 61

    DCP 33.33 0.14 0.48 2.56 0.77 0.82 0.36 0.99 132 428 10 49

    DCP 66.67 0.09 0.30 3.01 0.53 0.61 0.28 0.49 84 232 8 34

    DCP 133.33 0.04 0.32 2.67 0.51 0.55 0.25 0.86 71 147 8 31

    RP 20.83 0.14 0.35 1.26 0.59 0.57 0.23 0.70 90 396 8 28

    RP 41.67 0.14 0.54 1.93 0.85 0.88 0.34 1.12 146 884 10 40

    RP 83.33 0.13 0.42 2.11 0.71 0.85 0.32 0.76 118 860 9 34

    RP 166.67 0.09 0.33 2.33 0.57 0.56 0.27 0.68 85 406 8 34

    RP 333.33 0.08 0.30 2.99 0.47 0.49 0.29 0.83 90 127 6 33

    Slag 12.50 0.21 0.53 1.75 0.88 0.89 0.35 1.16 160 694 13 52

    Slag 25 0.19 0.53 1.67 0.87 0.92 0.33 1.21 154 1470 16 44

    Slag 50 0.16 0.40 1.70 0.80 0.93 0.32 0.82 206 1356 28 46

    Slag 100 0.27 0.53 1.97 0.92 0.99 0.38 1.11 162 1824 25 37

    Slag 200 0.17 0.45 1.67 0.82 1.30 0.32 0.98 184 3056 20 40

    WA 10.42 0.29 0.49 1.91 0.78 0.80 0.35 1.03 162 647 8 40

    WA 20.83 0.23 0.54 2.04 0.94 0.90 0.39 1.06 215 615 20 50

    WA 41.67 0.15 0.42 1.58 0.73 0.88 0.33 0.78 128 595 12 52

    WA 83.33 0.21 0.46 1.80 0.79 1.04 0.38 0.89 134 434 8 42

    WA 166.67 0.31 0.57 1.91 0.89 0.92 0.35 1.10 151 1028 8 43

    CLA 33.33 0.22 0.49 1.68 0.79 0.70 0.35 1.08 128 848 16 34

    CLA 66.67 0.14 0.37 1.64 0.76 1.22 0.37 0.68 142 932 12 40

    CLA 133.33 0.15 0.41 2.00 0.74 1.00 0.33 0.77 122 912 16 42

    CLA 266.67 0.13 0.46 2.37 0.77 0.75 0.36 0.85 113 464 12 50

    CLA 533.33 0.10 0.36 2.88 0.67 0.74 0.35 0.64 91 229 10 53

    CLAT 18.75 0.25 0.55 1.61 0.86 1.30 0.39 1.04 170 2180 15 40

    CLAT 37.50 0.32 0.48 1.54 0.86 1.04 0.35 0.94 140 799 4 33

    CLAT 75 0.17 0.43 1.42 0.66 0.88 0.31 0.79 146 872 12 68

    CLAT 150 0.44 0.52 2.02 0.83 0.85 0.33 1.12 125 330 1 40

    CLAT 300 0.15 0.55 2.32 0.93 0.90 0.37 1.15 118 630 15 52

    65

  • Appendix 4.1.2 XRF Analysis of Plant Dry Tops for Harvest 2

    Na Mg K Ca Si S Cl Mn Fe Cu Zn Rate of P Applied (mg/kg) (%) (%) (%) (%) (%) (%) (%) (ppm) (ppm) (ppm) (ppm)

    0 0.26 0.58 2.59 1.07 0.77 0.60 1.34 248 716 18 70

    MCP 4.17 0.17 0.43 2.84 0.79 0.64 0.57 0.98 208 221 9 52

    MCP 8.33 0.23 0.51 2.58 0.82 0.71 0.58 1.24 197 338 15 66

    MCP 16.67 0.18 0.48 2.88 0.74 0.63 0.52 1.07 203 284 11 56

    MCP 33.33 0.16 0.40 3.35 0.56 0.53 0.49 1.09 194 89 9 44

    MCP 66.67 0.12 0.33 2.68 0.50 0.50 0.30 1.59 174 104 6 38

    DCP 8.33 0.23 0.46 2.93 0.81 0.78 0.63 0.75 211 516 16 73

    DCP 16.67 0.20 0.51 3.29 0.83 0.69 0.66 1.18 225 491 16 72

    DCP 33.33 0.15 0.45 3.03 0.73 0.54 0.52 1.08 221 128 11 66

    DCP 66.67 0.11 0.32 3.01 0.46 0.49 0.36 1.21 123 74 8 34

    DCP 133.33 0.08 0.32 2.50 0.50 0.52 0.26 1.52 157 110 7 30

    RP 20.83 0.17 0.52 2.70 0.93 0.66 0.56 1.22 208 540 12 72

    RP 41.67 0.20 0.52 2.89 0.81 0.65 0.61 1.14 223 279 14 79

    RP 83.33 0.14 0.41 2.86 0.68 0.64 0.52 0.85 202 171 9 56

    RP 166.67 0.17 0.35 3.02 0.55 0.56 0.49 1.05 190 121 6 48

    RP 333.33 0.09 0.31 2.70 0.44 0.41 0.31 1.29 168 96 7 39

    Slag 12.50 0.27 0.54 2.56 0.98 0.82 0.59 1.14 212 259 14 62

    Slag 25 0.27 0.57 2.40 0.96 0.75 0.49 1.41 232 1068 20 64

    Slag 50 0.31 0.50 2.33 0.93 0.79 0.51 1.13 242 750 22 66

    Slag 100 0.26 0.60 2.42 1.03 0.90 0.55 1.36 258 1412 20 66

    Slag 200 0.29 0.55 2.34 0.92 0.82 0.50 1.32 236 974 16 64

    WA 10.42 0.21 0.52 2.47 0.83 0.75 0.60 0.96 256 882 22 74

    WA 20.83 0.34 0.59 2.63 0.99 0.82 0.56 1.28 228 594 12 54

    WA 41.67 0.23 0.44 2.73 0.79 0.66 0.56 0.96 213 607 22 69

    WA 83.33 0.27 0.64 2.45 1.04 0.66 0.53 1.60 240 624 23 75

    WA 166.67 0.28 0.62 2.89 1.02 0.73 0.57 1.40 246 448 16 64

    CLA 33.33 0.20 0.48 2.80 0.85 0.73 0.64 1.04 218 231 12 76

    CLA 66.67 0.17 0.45 2.95 0.80 0.75 0.60 0.95 225 278 14 75

    CLA 133.33 0.15 0.44 2.97 0.38 0.78 0.55 1.03 224 180 13 83

    CLA 266.67 0.19 0.46 3.24 0.81 0.73 0.59 1.01 218 147 12 73

    CLA 533.33 0.12 0.36 3.23 0.58 0.66 0.63 0.83 192 128 13 63

    CLAT 18.75 0.30 0.59 2.58 1.07 0.82 0.59 1.60 260 758 18 74

    CLAT 37.50 0.20 0.50 2.50 0.87 0.91 0.56 1.13 252 1392 22 62

    CLAT 75 0.38 0.65 2.55 1.06 0.74 0.55 1.49 232 552 12 66

    CLAT 150 0.22 0.55 2.80 0.97 0.78 0.60 1.30 227 335 14 79

    CLAT 300 0.23 0.51 3.11 0.86 0.73 0.59 1.13 196 257 13 70

    66

  • Appendix 4.1.3 XRF Analysis of Plant Dry Tops for Harvest 3

    Na Mg K Ca Si S Cl Mn Fe Cu Zn Rate of P Applied (mg/kg) (%) (%) (%) (%) (%) (%) (%) (ppm) (ppm) (ppm) (ppm)

    0 0.68 1.30 2.84 2.15 0.45 0.42 4.29 467 187 11 98

    MCP 4.17 0.47 0.83 2.99 1.31 0.54 0.48 2.65 385 100 13 75

    MCP 8.33 0.40 0.70 2.63 1.05 0.64 0.49 2.36 356 97 15 92

    MCP 16.67 0.54 0.79 2.80 1.15 0.67 0.46 2.77 342 96 14 65

    MCP 33.33 0.45 0.72 3.37 0.90 0.51 0.45 2.84 342 113 11 59

    MCP 66.67 0.50 0.68 2.80 0.80 0.54 0.48 2.84 318 129 7 20

    DCP 8.33 0.44 0.80 2.81 1.28 0.68 0.58 1.73 410 119 12 78

    DCP 16.67 0.84 1.10 3.55 1.55 0.75 0.51 3.81 381 112 13 72

    DCP 33.33 0.46 0.74 3.13 1.04 0.52 0.43 2.64 381 98 14 77

    DCP 66.67 0.28 0.50 2.64 0.55 0.41 0.38 2.04 277 84 7 46

    DCP 133.33 0.20 0.48 2.81 0.56 0.50 0.47 1.97 298 94 10 61

    RP 20.83 0.37 0.76 2.88 1.19 0.65 0.54 2.15 360 134 10 64

    RP 41.67 0.55 0.85 2.85 1.24 0.56 0.49 2.64 360 106 14 74

    RP 83.33 0.25 0.72 2.98 0.95 0.53 0.54 2.33 347 152 10 68

    RP 166.67 0.64 0.71 2.93 0.77 0.46 0.33 3.06 305 112 15 69

    RP 333.33 0.27 0.50 2.94 0.55 0.43 0.45 2.19 300 77 10 63

    Slag 12.50 0.73 1.01 2.75 1.59 1.00 0.47 3.02 336 508 11 39

    Slag 25 0.99 1.49 3.35 2.45 0.84 0.60 4.59 475 190 10 70

    Slag 50 1.62 1.56 3.31 2.33 1.32 0.49 4.78 500 590 10 60

    Slag 100 1.05 1.20 3.23 1.99 0.66 0.42 3.94 385 295 15 70

    Slag 200 0.88 1.27 2.99 2.05 0.78 0.40 3.91 402 195 10 71

    WA 10.42 0.76 0.88 2.93 1.31 0.62 0.51 2.69 390 129 5 44

    WA 20.83 1.32 1.43 3.32 2.29 0.72 0.44 4.56 510 510 20 80

    WA 41.67 0.80 1.06 3.41 1.70 0.57 0.42 3.78 400 216 14 76

    WA 83.33 0.75 0.92 2.75 1.47 0.82 0.49 2.98 389 558 16 90

    WA 166.67 0.82 1.41 3.28 2.12 0.73 0.36 4.39 482 364 18 80

    CLA 33.33 0.44 0.81 2.78 1.27 0.65 0.49 2.28 301 114 10 83

    CLA 66.67 1.15 1.23 3.30 1.75 1.25 0.52 3.53 450 215 15 70

    CLA 133.33 0.73 0.74 2.82 1.20 0.66 0.57 2.29 245 115 10 50

    CLA 266.67 0.69 0.96 2.94 1.31 0.62 0.46 3.15 379 158 12 82

    CLA 533.33 0.65 0.72 2.93 1.36 0.54 0.50 2.58 326 82 14 80

    CLAT 18.75 1.54 1.53 3.48 2.21 0.85 0.54 4.87 440 230 10 30

    CLAT 37.50 0.99 1.00 3.14 1.46 0.73 0.44 3.44 402 120 6 60

    CLAT 75 0.95 1.22 2.97 1.92 0.80 0.51 3.34 408 484 16 90

    CLAT 150 0.58 1.17 2.67 1.73 0.80 0.45 3.37 390 183 16 104

    CLAT 300 1.24 1.26 3.40 1.92 0.66 0.35 5.19 374 271 13 77

    67

  • Appendix 4.1.4 XRF Analysis of Plant Dry Tops for Harvest 4

    Na Mg K Ca Si S Cl Mn Fe Cu Zn Rate of P Applied (mg/kg) (%) (%) (%) (%) (%) (%) (%) (ppm) (ppm) (ppm) (ppm)

    0 0.30 0.63 1.75 1.09 0.34 0.26 2.09 218 264 7 39

    MCP 4.17 0.49 1.29 3.56 2.03 0.53 0.52 4.02 495 253 15 84

    MCP 8.33 0.73 1.42 3.73 2.27 0.58 0.57 4.96 555 285 19 89

    MCP 16.67 0.79 1.30 4.07 2.06 0.60 0.70 4.89 537 380 13 79

    MCP 33.33 0.49 1.43 3.69 1.68 0.55 0.72 3.75 496 179 14 73

    MCP 66.67 0.58 1.14 2.69 1.25 0.46 0.59 6.27 486 133 14 49.5

    DCP 8.33 0.54 1.22 3.84 2.28 0.69 0.69 3.70 602 304 17 89

    DCP 16.67 0.59 1.48 4.18 2.57 0.48 0.66 4.75 459 214 13 76

    DCP 33.33 0.37 0.77 3.30 1.20 0.58 0.40 2.69 491 202.5 14 82

    DCP 66.67 0.57 1.20 3.82 1.15 0.46 0.68 5.36 315 95.5 16 79

    DCP 133.33 0.45 0.77 2.61 0.81 0.48 0.54 3.27 357 72 11 67

    RP 20.83 0.65 1.50 3.83 2.49 0.75 0.53 4.86 392 241.5 9 60

    RP 41.67 0.58 1.40 3.96 2.34 0.47 0.60 4.75 487 259 17 87

    RP 83.33 0.61 1.08 3.42 1.51 0.54 0.52 4.32 483 203 12 93

    RP 166.67 0.83 1.48 4.05 2.13 0.40 0.68 6.10 417 110 11 49

    RP 333.33 0.77 0.84 3.41 0.84 0.37 0.60 5.86 392 99 15 75

    Slag 12.50 0.39 0.86 2.03 1.68 0.47 0.38 2.55 310 372 12 38

    Slag 25 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0 0 0 0

    Slag 50 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0 0 0 0

    Slag 100 0.18 0.37 0.88 0.71 0.18 0.21 0.96 136 142 4 10

    Slag 200 0.58 1.01 3.36 1.77 0.70 0.38 3.30 415 315 5 45

    WA 10.42 0.69 1.03 3.89 1.74 0.56 0.47 3.72 449 288 6 76

    WA 20.83 0.74 1.61 4.53 2.93 0.86 0.77 4.99 631 629.5 16 105.5

    WA 41.67 0.27 0.45 1.56 0.79 0.38 0.23 1.50 252 99 7 50

    WA 83.33 0.55 1.15 3.57 1.95 0.71 0.47 3.89 539 448 15 83

    WA 166.67 0.27 0.61 1.80 0.90 0.37 0.28 1.55 185 155 5 35

    CLA 33.33 0.60 1.45 3.78 2.44 0.65 0.54 4.55 480 392 15 90

    CLA 66.67 0.55 1.05 3.67 1.90 0.71 0.63 3.37 540 289 13 96

    CLA 133.33 0.55 1.21 3.51 2.03 0.66 0.63 3.89 469 221 19 105

    CLA 266.67 0.66 1.56 4.32 2.81 0.52 0.68 3.90 602 309 16 90

    CLA 533.33 0.83 1.72 4.54 2.50 0.51 0.41 4.53 425 152 14 78

    CLAT 18.75 0.39 0.54 2.19 0.84 0.41 0.26 1.78 285 145 5 40

    CLAT 37.50 0.75 2.31 5.30 4.00 1.15 0.81 6.18 882 848 30 134

    CLAT 75 0.14 0.34 1.81 0.60 0.34 0.29 1.00 225 128 8 54

    CLAT 150 0.87 1.73 3.99 2.67 0.53 0.43 5.61 532 204 9.5 47.5

    CLAT 300 0.54 0.83 1.66 1.53 0.37 0.42 2.18 230 170 10 30

    68

  • A. The Highest Rates of P Application

    B. The Lowest Rates of P Application

    Appendix 4.2.1 The growth of ryegrass before the first harvest for the highest (a) and lowest (b) rates of all the fertilizers, including zero rate of application (control).

    69

  • A. The Highest Rates of P Application

    B. The Lowest Rates of P Application

    Appendix 4.2.2 The growth of ryegrass before the second harvest for the highest (a) and lowest (b) rates of all the fertilizers, including zero rate of application (control).

    70

  • A. The Highest Rates of P Application

    B. The Lowest Rates of P Application

    Appendix 4.2.3 The growth of ryegrass before the third harvest for the highest (a) and lowest (b) rates of all the fertilizers, including zero rate of application (control).

    71

  • Appendix 4.3 Concentration of Phosphorus in Plants Tissue

    P Concentration (%) Rate of P Applied mg/kg I Harvest II Harvest III Harvest IV Harvest

    0 0.051 0.086 0.066 0.035 MCP 4.17 0.054 0.076 0.06 0.066 MCP 8.33 0.059 0.075 0.055 0.058 MCP 16.67 0.062 0.071 0.061 0.066 MCP 33.33 0.066 0.07 0.059 0.061 MCP 66.67 0.078 0.057 0.065 0.048 DCP 8.33 0.062 0.085 0.062 0.06 DCP 16.67 0.0585 0.085 0.084 0.068 DCP 33.33 0.0645 0.073 0.062 0.055 DCP 66.67 0.073 0.059 0.054 0.061 DCP 133.33 0.071 0.06 0.078 0.063 RP 20.83 0.05 0.086 0.068 0.064 RP 41.67 0.066 0.084 0.07 0.07 RP 83.33 0.068 0.071 0.067 0.068 RP 166.67 0.0665 0.065 0.075 0.063 RP 333.33 0.079 0.062 0.069 0.063 Slag 12.50 0.058 0.088 0.08 0.034 Slag 25 0.056 0.078 0.08 0 Slag 50 0.054 0.076 0.13 0 Slag 100 0.063 0.078 0.08 0.012 Slag 200 0.058 0.084 0.082 0.085 WA 10.42 0.065 0.09 0.08 0.077 WA 20.83 0.08 0.086 0.1 0.088 WA 41.67 0.058 0.083 0.056 0.028 WA 83.33 0.056 0.077 0.08 0.058 WA 166.67 0.065 0.084 0.067 0.04 CLA 33.33 0.056 0.084 0.06 0.061 CLA 66.67 0.052 0.081 0.15 0.066 CLA 133.33 0.056 0.0625 0.085 0.06 CLA 266.67 0.063 0.078 0.073 0.05 CLA 533.33 0.074 0.074 0.062 0.059 CLAT 18.75 0.065 0.088 0.11 0.045 CLAT 37.50 0.067 0.082 0.082 0.084 CLAT 75 0.054 0.094 0.094 0.034 CLAT 150 0.075 0.103 0.08 0.07 CLAT 300 0.064 0.089 0.079 0.05

    72

  • Appendix 4.4.1 RE Values Based on P Applied and Yield for Each Harvest Harvest Fertilizer Equation RE (%) I MCP Y=0.033X+0.02 (R2= 0.96) 100 DCP Y=0.017X+0.10 (R2= 0.97) 57 RP Y=0.0057X+0.12 (R2= 0.97) 24 Slag Y=0.00033X+0.13 (R2= 0.71) 8 WA Y=0.00021X+0.09(R2= 0.12) 6 CMA Y=0.0014X+0.16 (R2= 0.98) 13 CMAT Y=0.0012X+0.06 (R2= 0.89) 7 II MCP Y=0.029X+0.22 (R2= 0.99) 100 DCP Y=0.018X+0.33 (R2= 0.83) 72 RP Y=0.0067X+0.23 (R2= 0.98) 34 Slag Y=0.00043X+0.12 (R2= 0.66) 9 WA Y=0.00081X+0.11 (R2= 0.66) 9 CMA Y=0.0018X+0.17 (R2= 0.99) 16 CMAT Y=0.0016X+0.12 (R2= 0.97) 12 III MCP Y=0.017X+0.57 (R2= 0.71) 100 DCP Y=0.011X+0.52 (R2= 0.82) 74 RP Y=0.0056X+0.72 (R2= 0.75) 70 Slag Y=0.0011X+0.18 (R2= 0.43) 16 WA Y=-0.00024X+0.27 (R2= 0.01) 18 CMA Y=0.0018X+0.38 (R2= 0.83) 33 CMAT Y=0.00062X+0.22 (R2= 0.33) 17 IV MCP Y=0.019X+0.55 (R2= 0.76) 100 DCP Y=0.019X+0.45 (R2= 0.94) 94 RP Y=0.0063X+0.53 (R2= 0.88) 56 Slag Y=0.0013X+0.08 (R2= 0.36) 10 WA Y=-0.00041X+0.35 (R2= 0.01) 22 CMA Y=0.0014X+0.52 (R2= 0.47) 39 CMAT Y=-0.00006X+0.27 (R2= 0.001) 18

    73

  • Appendix 4.4.2 RE Values Based on P Content and P Applied for Each Harvest Harvest Fertilizer Equation RE (%) I MCP Y=0.027X-0.053 (R2= 0.95) 100 DCP Y=0.012X+0.046 (R2= 0.97) 52 RP Y=0.0045X+0.030 (R2= 0.99) 20 Slag Y=0.00021X+0.069 (R2= 0.74) 6 WA Y=0.00022X+0.054 (R2= 0.27) 5 CMA Y=0.00083X+0.069 (R2= 0.99) 9 CMAT Y=0.00082X+0.035 (R2= 0.91) 6 II MCP Y=0.016X+0.22 (R2= 0.96) 100 DCP Y=0.0097X+0.29 (R2= 0.84) 77 RP Y=0.0043X+0.22 (R2= 0.97) 42 Slag Y=0.00032X+0.11 (R2= 0.53) 12 WA Y=0.00064X+0.096 (R2= 0.61) 12 CMA Y=0.0013X+0.13 (R2= 0.99) 20 CMAT Y=0.0015X+0.10 (R2= 0.97) 18 III MCP Y=0.012X+0.32 (R2= 0.79) 100 DCP Y=0.0083X+0.31 (R2= 0.91) 80 RP Y=0.0041X+0.49 (R2= 0.74) 78 Slag Y=0.00092X+0.16 (R2= 0.43) 23 WA Y=-0.00033X+0.19 (R2= 0.01) 24 CMA Y=0.00091X+0.38 (R2= 0.47) 48 CMAT Y=0.00043X+0.19 (R2= 0.18) 24 IV MCP Y=0.0081X+0.39 (R2= 0.51) 100 DCP Y=0.012X+0.26 (R2= 0.95) 107 RP Y=0.0039X+0.38 (R2= 0.84) 72 Slag Y=0.0012X+0.036 (R2= 0.39) 12 WA Y=-0.00043X+0.24 (R2= 0.03) 33 CMA Y=0.00072X+0.32 (R2= 0.37) 45 CMAT Y=-0.00006X+0.21 (R2= 0.003) 26

    74

  • Appendix 4.4.3 RE Values Based on Soil Bic P and P Applied for Each Harvest Fertilizer Equation RE (%) MCP Y=0.10X+2.81 (R2= 0.84) 100 DCP Y=0.028X+3.27 (R2= 0.64) 59 RP Y=0.029X+1.72 (R2= 0.98) 40 Slag Y=0.0093X+1.02 (R2= 0.72) 19 WA Y=0.010X+1.78 (R2= 0.84) 29 CMA Y=0.0091X+2.59 (R2= 0.88) 39 CMAT Y=0.015X+2.75 (R2= 0.82) 45

    75

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