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Differential effect of coal combustion products on the bioavailability of phosphorus between inorganic and organic nutrient sources
Accepted Manuscript Title: Differential effect of coal combustion products on the bioavailability of phosphorus between inorganic and organic nutrient sources Author: Balaji Seshadri Nanthi Bolan Girish Choppala Ravi Naidu PII: DOI: Reference:
S0304-3894(13)00317-8 http://dx.doi.org/doi:10.1016/j.jhazmat.2013.04.051 HAZMAT 15088
To appear in:
Journal of Hazardous Materials
Received date: Revised date: Accepted date:
15-8-2012 16-4-2013 21-4-2013
Please cite this article as: B. Seshadri, N. Bolan, G. Choppala, R. Naidu, Differential effect of coal combustion products on the bioavailability of phosphorus between inorganic and organic nutrient sources, Journal of Hazardous Materials (2013), http://dx.doi.org/10.1016/j.jhazmat.2013.04.051 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
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Differential effect of coal combustion products on the bioavailability of phosphorus between inorganic and organic nutrient sources Balaji SeshadriA,B,*, Nanthi BolanA,B , Girish ChoppalaA,B and Ravi NaiduA,B
Centre for Environmental Risk Assessment and Remediation, Building–X, University of South Australia, Mawson Lakes, South Australia 5095,
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A
Australia. B
Cooperative Research Centre for Contamination Assessment and Remediation of the Environment, PO Box 486, Salisbury, South Australia
5106, Australia.
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* Corresponding author at: Centre for Environmental Risk Assessment and Remediation (CERAR), University of South Australia, SA 5095, Australia.
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Tel.: +61-8-8302-6218, fax: +61-8-8302-3124 Email address: [email protected]
Highlights
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Examined effect of CCPs on increasing P bioavailability in P treated soils CCPs decreased soluble P from inorganic P; increased bioavailable P from organic P FBC emerged as the best CCP in enhancing the bioavailability of P in the soil FBC decreased leachate P by increasing bioavailable P and reducing water soluble P Plants utilised more P during second cropping because of increase in bioavailable P
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Abstract
In farming systems, all the applied phosphorus (P) is not available to plants because they are either adsorbed in soil or lost to the environment through leaching or runoff. The effect of coal combustion products (CCPs) for enhancing the bioavailability of applied phosphorus (P) in soil
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was examined separately for inorganic (KH2PO4 - PP) and organic (poultry manure - PM) P treatments, where fluidised bed combustion (FBC) ash emerged as the most effective amendment. Greenhouse study was conducted by growing mustard plants on FBC amended soils under
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leaching and non-leaching setups. The FBC increased the biomass yield for organic P treatments in the first crop and increased for both inorganic and organic P in the second cropping. The increase in cumulative yield was highest in leached PP and unleached PM treatments. Field experiment assessed the effectiveness of FBC on inorganic (single super phosphate – SSP) and organic P (biosolids – BS) uptake by mustard and sunflower plants. In the first cropping, the yield was higher in crops treated with SSP alone. In the second crop, yields were higher in the
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presence than absence of FBC, as reflected by the high relative agronomic effectiveness (RAE) exhibited by BS+FBC (462 %) combination. Overall, FBC used in these experiments enhanced bioavailability of P in soil through adsorption and mineralisation of inorganic and organic P, respectively as evident from phosphatase activity and Olsen P relationship. Hence the differential effect of CCPs has not only decreased the loss of applied P (from inorganic and organic sources) to the environment, but also enhanced the P bioavailability in the soil. Among the three CCPs
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environmental applications targeting P issues. coal
combustion
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bioavailability;
products;
residual
effect;
mineralisation.
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phosphorus;
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Keywords:
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used in the preliminary experiments, FBC proved to perform better than the other two and hence can be recommended for agricultural and
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1. Introduction
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The incessant growth in global population and consequent rise in the demand for food production have increased pressure on land and water resources [1]. As a result, soils are turning out to be the direct calamity of anthropological activities such as intensive cultivation and waste disposal. Firstly, the intensive use of agricultural inputs for maximising crop yields has not only provided nutrients to the growing crops, but also added undesirable nutrients and heavy metals into the soil [2, 3]. On the other hand, agricultural and industrial activities release toxic
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contaminants to soil, thereby impacting the environment [4, 5]. Selection of ideal agricultural amendments (including industrial byproducts) and
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optimal usage of these products are critical in terms of productivity [6]. The direct effect of intensive agriculture is loss of nutrients from soil, which is usually managed by the addition of fertilisers [7-9]. However, indiscriminate fertiliser application can be detrimental to the soil environment. Phosphorus (P) being one of the major plant nutrients, is an important growth limiting factor for plants [10]. Soil P loss through runoff/leaching results in land and water degradation [11, 12]. Generally, P
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is transported from soil in both particulate and dissolved forms. Although the former can be decreased through riparian buffers, the soluble inorganic P loss had been an issue in low P-retaining soils [13]. An understanding of P retention capacity (PRC) of soils is vital for fertiliser management [14] and safeguarding water quality [12]. Optimal pH and high concentration of P sorptive components such as calcium (Ca), iron (Fe) and aluminium (Al) in soil solution are good prerequisites for enhancing soil’s PRC [15]. Generally, at alkaline pH, Ca precipitates with P; in acidic conditions, P adsorbs to Al and Fe oxides. Traditionally, lime (CaCO3) has been widely used to alleviate soil acidity by increasing soil
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pH [16]. Several studies have investigated the positive impact of liming on P adsorption in soils through addition of Ca+ to the soil solution [1719].
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Several researchers explored the possibility of using coal combustion products (CCPs) for mitigating P loss in soil, mainly because of their liming value and Ca content [20-22]. There are different types of CCPs based on the combustion processes and the consequent end products; conventional byproducts include fly ash (FA) and bottom ash (BA) collected from electrostatic precipitators and boilers, respectively; and the clean coal technology products such as fluidised bed combustion (FBC) ash and flue gas desulphurisation (FGD) gypsum, collected from lime-
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based scrubbing systems [21, 23, 24]. Most studies were focussed towards the agronomic and environmental benefits of the CCPs such as increasing the soil pH and reducing P in the surface run off and subsurface drainage, sustaining bioavailability of P (i.e. Olsen P concentrations),
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and deducing optimal application rates [15, 25, 26]. Since CCPs have the potential to transform P in soils through (im)mobilisation (either immobilisation or mobilisation) of P compounds, they can be effective in improving P bioavailability when applied along with organic amendments [27-29]. The CCPs (FA, FBC and FGD) have proven capabilities on overall P transformation in soils [21, 22, 26]. Most of the
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studies on plant P availability in CCPs amended soils were conducted at laboratory scale and a very few research was conducted at the field level. For example, Ram et al. [30] used lignite FA for long term field trials on an experimental agricultural plot and observed increased Olsen P content in soil and a consequent increase in maize yields. Plants assimilate P only in their orthophosphate forms (HPO4-/HPO42-), but most soils contain P (organic and mineral P) in non-available forms. Generally, around 20 % of applied P becomes immediately available to crops and the remaining is unavailable because of
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adsorption/precipitation or conversion to organic forms [31, 32]. Hence, P pool needs to be replenished during successive crops to produce the desired yield [13, 33]. The use of organic P fertilisers will help reduce P through slow conversion to orthophosphates by phosphatase activity
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[34], which helps in the mineralisation process [34-36]. Although organic P mineralisation provide significant P source for plants [37], an adequate level of P in solution is the prerequisite for plant uptake, especially at early growth stage. Hence, there is a need for specific amendments which could mineralise organic P forms and immobilise the orthophosphate P forms. The CCPs can be an effective replacement for their natural counterparts (lime and gypsum) for mitigating P related issues in soil, if used
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judiciously. Therefore, development of strategies to minimise P loss from soils require detailed understanding of the CCPs-induced P transformation in soil under various P treatments. This paper addresses the effect of CCPs on bioavailability of both inorganic and organic P,
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explained using P fractionation experiment and plant studies (using greenhouse and field trials). The greenhouse study was set up under leaching and non-leaching conditions to study the immobilising effects of CCPs on applied P. The plant studies also focus on the effects of CCPs in P treated soils during the second cropping, which may help in understanding their long term (aging) effects.
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2. Materials and Methods
2.1. Characterisation of soils, CCPs and P sources The soils (0–10 cm depth) were collected around Adelaide, Australia – Adelaide hills (ADL) and Kapunda (KPD) (Table 1), air-dried and sieved to <2mm. The CCPs used were FA from Port Augusta Power Station, South Australia; FBC from Redbank Power Limited, Queensland, and
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FGD from Illinois, USA (Table 2). The P sources used in the experiment were laboratory KH2PO4 (PP), commercial poultry manure (PM) and phosphate rock (PR) from Nutri-Tech Solution, Queensland. The field study was conducted at Salisbury (location details in Section 2.3.2) by
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treating the soil (SLB) with an inorganic P source (single super phosphate–SSP), an organic amendment (biosolids–BS) and a CCP (FBC). The pH and EC for all samples were determined by end-over-end equilibration of soils with water at a ratio of 1:5 for an hour and measured with a pH/conductivity meter. For the total metal analysis, the samples were digested using aqua-regia (3:1 – HNO3:HCl) and the concentration of metals in the extract was determined by ICP-MS [22]. The PRC of soils were determined using the Phosphate retention test [38]. In the case of
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CCPs, the CaCO3 equivalence (CCE) was determined using Rayment and Higginson [39]. Olsen P was measured for all CCPs and soil samples
2.2. Incubation study
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[40].
The soils (5 g each) were initially treated with the three P sources (PP, PM and PR) at the rates of 0 and 200 mg P kg-1 soil. The P treated soils
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were incubated with CCPs at the rates of 0 and 5 % (w/w) for FA, and 0 and 15 % for FBC and FGD in plastic pots for 21 days at 80 % WHC. The incubated samples (1 g each) were air-dried immediately after the incubation period and analysed for pH before conducting the fractionation experiment.
2.2.1 Fractionation experiment
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The fractionation experiment was used to study the distribution of P fractions for soils treated with various P sources as affected by CCPs. A fractionation scheme as used by McDowell [22] was employed, which involved a sequential extraction of incubated soil (1 g). The extracted
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inorganic P fractions were analysed for P concentration using the colorimetric method of Murphy and Riley [41], using Agilent 8453 UV-visible spectroscopy system (Germany) at 882 nm and the total P (TP) was determined by analysing the acid-digested samples using ICP-OES. The bioavailable P in the fractionation scheme can be defined as the P present in non-adsorbed forms, which is soluble in water and sodium bicarbonate solution [22]. It is a measure of P with agronomic significance, which is readily taken up by plants. The bioavailable P from the P
2.3.1 Greenhouse trials
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2.3. Plant-growth experiments
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fractions was calculated by adding the P concentration of H2O-P and NaHCO3-P fractions.
A greenhouse experiment was set up to investigate the effect of CCPs on plant uptake of P and their consequent influence on plant-growth in P
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treated (organic and inorganic) soil. The plants were grown separately under non-leaching and leaching set ups to understand the effect of FBC on (im)mobilisation of applied P and to estimate the amount of labile P that may be potentially available to plants. The incubation was performed as mentioned in Section 2.2 with 200 g of ADL soil, with only FBC and two P sources (PP and PM). The selection of FBC was based on high pH and CCE values, and their influence in increasing bioavailable P in soils. The plant used for the study was Indian mustard (Brassica hirta L.).
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The method developed by Stanford and DeMent [42] was used for this plant-growth study. Transparent round plastic pots (700 mL capacity) with bottoms removed were nested in similar pots which had intact bottoms. The inner pot was filled with 300 g sand and 16 mustard seeds were
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surface-sown. The pots were covered loosely with lids for three days to maintain moisture for germination. Each treatment was carried out in triplicate and the trial was performed in a temperature-controlled greenhouse environment (25±3ºC; 16 h light). The plants were watered twice daily for first week and were thinned to 10/pot and the moisture was maintained with Hoagland solution (P excluded) thereafter. After four weeks of plant-growth, the sand-grown plants were carefully transferred to another intact pot containing 200 g of incubated soils. The soils were
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wetted to field capacity before the transfer and the root-mats were carefully placed on the soil to gain access to the soil elements. The pots containing the soils were prepared in two sets – one for leaching and the other was not allowed to leach. The soil pots for leaching were
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cut at the bottom and a cotton mesh was placed for each pot before adding soil to avoid any soil loss. All the pots were leached with 100 mL of deionized water at three intervals (1, 2 and 3 weeks) during the experiment and the leachates were collected. Plants were harvested after three weeks of growth in the soil media and were dried to a constant weight at 70°C. Dry weight was recorded and
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the dried plant samples were ground to a fine powder for P analysis. Seeds from the same source were re-sown in the harvested pots and similar procedure was followed as in the first crop. 2.3.2. Field trials
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A field experiment was conducted to examine the effects of FBC on P bioavailability in SLB soil, treated with inorganic (SSP) and organic (BS) P sources, with an overall objective to study fresh and residual effects of the treatments. The experimental site (17 ha) is located at St.Kilda,
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South Australia, approximately 23 km NNE from Adelaide CBD. The experiment was conducted between August and November 2010; the average temperature during the experiment was 34ºC and the humidity varied from 27 to 63 %; the highest rainfall recorded was in the month of August at 56 mm. A 10x10 m plot was cleared-off a week before the experiment commencement, which was equally divided into 1 m2 plots, in two blocks and each plot in a block was treated with the treatments at different combinations (nil-control, SSP alone, BS alone, SSP+FBC and
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BS+FBC). Application rates were: BS - 0 and 6.5 Mg ha-1, SSP - 0 and 0.5 Mg ha-1 and FBC - 0 and 25 Mg ha-1. Amendments were mixed to the top 20 cm of the soil. After three weeks, 4 g of sunflower (Helianthus annuus “Yellow Impress”, Yates Australia) and 3 g of Indian mustard
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(Brassica hirta, Department of Primary Industries, Victoria) seeds were added to the designated plots. In total, 30 experimental plots were used with 15 per plant species, including three replicates.
The plots were irrigated alternative days with water from Salisbury Council and hand-weeding was undertaken twice. The plants were harvested
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after three months, dried to a constant weight at 70°C. The plant samples were weighed and ground to a fine powder for P analysis. The plots were re-cultivated immediately with seeds from the same sources and harvested after three months for P analysis. 2.3.2. Plant, leachate and soil analyses
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Plant samples from glasshouse and field experiments were quantified for biomass yields and analysed for P accumulation. The ground plant materials (0.4 g) were digested with concentrated HNO3 (5 mL) in a temperature-controlled digestion block (AI Scientific Block Digestion
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System AIM 500) at 140°C, until 1 mL (approximate) of digest remained in the tube. After cooling, the samples were mixed thoroughly and filtered with a syringe filter directly into plastic containers. The digested plant extracts were analysed for P by inductively coupled plasmaoptical emission spectroscopy (ICP-OES, Agilent). For the leaching part of glasshouse experiment, the collected leachates were stored at 4° C for P analysis as mentioned in Section 2.2.1.
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The soil samples from field experiment were collected from each plot immediately after the first cropping; Olsen P and phosphatase activity were determined using air-dried and field moist soils (FMS), respectively. The phosphatase activity of the incubated soil samples were
[43].
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2.4. Statistical analysis
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determined by measuring the release of para-nitrophenol (ρ-NP) from para-nitrophenyl phosphate (PNP) as described by Tabatabai and Bremner
All measurements [pH, PRC (%), CCE (%), Olsen P and elemental composition (mg kg-1)] were calculated for triplicates of each treatment. All calculations including standard deviations of replicates and analysis of variance were determined using PASW Statistics (Version 18.0.0; SPSS, Inc., Chicago, IL) at a significance level of p < 0.05. The relationships for Olsen P Vs. P uptake and Phosphatase activity Vs. Olsen P were evaluated by simple-linear regression analysis.
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3. Results
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3.1. Chemical properties of soil, CCPs and P sources
The chemical properties of the soils, CCPs and P sources used in this study are given in Table 1. The soil pH of ADL and KPD were 5.6 and 7.1, respectively and field soil (SLB) - 7.3. The Olsen P for ADL, KPD and SLB were 3.82, 9.6 and 19.42 mg kg-1, respectively with elemental P contents ranging from 34.1 to 48.4 mg kg-1 (w/w) (Table 1). The ADL soil had highest PRC (23.4 %), with KPD and SLB having a PRC of
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around 7 % (Table 1).
The three CCPs had high pH (>10) values, with FBC measuring the highest pH (12.7). The CCE value was the highest in FBC (23.25 %),
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followed by FA (16.75 %) and FGD (11.25 %). The Olsen P for FA, FBC and FGD were 16.44, 11.52 and 2.25 mg kg-1 (Table 1). The Al and Fe contents were high in the FBC and FA, whereas FGD values were relatively low (Table 1). The FBC had a high Ca content (49.68 %). The total P content in PM and PR were 14.78 % and 10.87 %, respectively (Table 1).
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3.2. Fractionation experiment
3.2.1. Effect of CCPs on P distribution in soils The pH of the P treated ADL soil ranged from 6.66-6.91 for FA amended soils; 6.92-7.19 for FBC and 5.97-6.23 in FGD amended soils; the increase was highest for FBC. The effect of CCPs on KPD soil also showed similar trends as ADL (Table 2).
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The sequential extraction results indicated that for PP treated ADL soil, CCPs increased NaHCO3 and H2SO4-P fractions and NaOH decreased only for FBC amendment, compared to control (Figure 1a). In the case of PM treatment, CCPs increased NaHCO3-P fraction and FBC showed
observed on the remaining fractions (Figure 1c).
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the highest increase (Figure 1b). For PR treatment, the P was largely (> 70 %) associated to H2SO4-P fraction and no effect of CCPs was
For the KPD soils, CCPs decreased H2O- and NaHCO3-P in PP treated samples but increased in PM treatment; the H2SO4-P fraction increased in PP and PR treated samples, whereas decreased in the PM treatment (Figures 2 a, b and c). In PP treatment, H2O-P and NaHCO3-P was largely
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shifted to H2SO4-P for all three amendments (Figure 2a). In the case of PM treatment, CCPs increased both H2O- and NaHCO3-P, by shifting from H2SO4-P (Figure 2b). The NaHCO3-P fractions increased in the following order: FBC (18 %) > FA (11 %) > FGD (3 %) compared to
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control, and NaOH-I-P increased by up to 75 % for all CCPs. For PR treated soil, H2SO4-P fractions were the highest for all CCPs and there was no effect of CCPs on other fractions (Figure 2c). The residual P fractions were minimal in FBC-amended soils and P shifts to residual P fractions were almost similar in both FA and FGD amended soils.
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3.2.2. Effect of CCPs on Bioavailable P
The bioavailable P was calculated by adding the values of H2O- and NaHCO3-P fractions. For ADL soil, the CCPs increased the bioavailable P in PP and PM treated soils with no effect in PR treatment. The increasing order was FBC>FA>FGD for both PP and PM treatments and FBC increased bioavailable P in PP-59 and PR-91 % compared to control (Figure 3a). In the case of KPD soil, the CCPs decreased bioavailable P in
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PP treated samples and increased for PM treatment (Figure 3b). In both the cases, FBC was most effective in decreasing up to 41 % (PP) and increasing around 49 % (PM) of applied P.
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3.3. Plant-growth experiments 3.3.1. Glass house experiment
The P in the leachates of first crop decreased significantly after FBC application in PP treated soil (35 %) but marginally in PM treatments (16 %)
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(Figure 4). In the second crop, the percentage reduction was higher for PM treated soil (41 %) compared to PP (24 %). The biomass yields for PP and PM treated pots as affected by FBC are shown in Figures 5 and 6, respectively. The fresh P applied as PP
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increased the yield in both unleached and leached pots, but FBC application decreased the yield only in unleached pots by about 27 %. In leached PP treatments, yields were similar for both presence and absence of FBC (Figure 5). In the case of PM treatment, there was a significant increase (about 48 %) in yields for FBC-amended pots for unleached pots (Figure 5).
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In the second crop, FBC increased the yields for both unleached and leached pots of PP treatment. For unleached pots, PP gave higher yield (about 70 %) in the presence than absence of FBC and for leached pots (up to 40 % increase) (Figure 5). Under PM treatment, unleached pots amended with FBC showed highest yields among all the treatments (Figure 5). In the case of leached pot, the FBC increased the yield by about 17 %. The influence of FBC on cumulative yields (first and second crops) for P treatments was positive for both leached and unleached pots (Figure 6). For PP treatment, the percentage increase in cumulative yield was higher in leached pots than the unleached ones (Figure 6). In PM
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treated pots, cumulative biomass yield for unleached pot showed highest increase (about 49 %). The overall effect of FBC in PM treated soil was slightly higher compared to PP treatment.
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3.3.2. Fields trials
The biomass yields of sunflower plants varied amongst the treatments (Figure 7a). For fresh P treatment (first crop), the biomass increased for all the treatments, and yield for SSP alone was the highest (2.79 Mg ha-1); with FBC addition, the yield reduced to 18 %. The combination of BS
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and FBC yielded a slight increase (about 14 %) in biomass, compared to BS alone. In the second cropping, the yield was of the following order: BS+FBC > SSP+FBC > BS alone > SSP alone > Nil (Figure 7a). The FBC addition to SSP and BS increased the yields by about 37 and 40 %,
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respectively compared to first cropping. The mustard plants also showed similar trends with sunflower plants (Figure 7b). The effect of FBC on P-induced yield was also examined using the relative agronomic effectiveness (RAE), which expresses the agronomic potential of the farm inputs to produce a yield response (Bolan et al., 1990). The RAE was calculated using Eq. 1.
( yield for specific treatment – yield for control ) x100 yield for SSP alone – yield for control
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RAE
(1)
Less than 100 % RAE indicates poor agronomic efficiency compared to SSP, and RAE higher than 100 % signifies the agronomic potential of the amendment. In the case of fresh application, the RAE decreased for all treatments in both plant species and the order of effectiveness was SSP > BS+FBC > BS > SSP+FBC > Nil). The residual effect (second crop) was highest for the BS+FBC treatment for both sunflower (around
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462 %) and mustard (around 481 %) (Table 3). The agronomic effectiveness of the treatments for residual effect was in the following order: BS+FBC > SSP+FBC > BS alone > SSP alone > Nil.
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At the end of first cropping, air-dried soils were analysed for Olsen P and plant samples were analysed for P accumulation/uptake. A regression analysis between Olsen P and P uptake shows a positive correlation (R2=0.8743) (Figure 8). The phosphatase activity of FMS analysed at the end of first cropping confirmed the effect of FBC on increasing P mineralisation, in the
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following order: BS+FBC > SSP+FBC > BS alone > SSP alone > Nil. The effects were higher in BS treated plots with about 54 and 51 % increases for sunflower and mustard plants, respectively. A combined regression analysis between phosphatase activity and Olsen P of soils
4. Discussion
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grown with sunflower and mustard plants showed a regression coefficient of 0.6498 (Figure 9).
Data from sequential fractionation experiments showed the influence of CCPs on P transformation, as affected by pH. In the case of P treated
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ADL soils, CCPs increased the pH to near-neutral pHs (Table 2), whereas, the KPD soil was already slightly alkaline and hence CCPs increased the pH further (Table 2). Therefore, CCPs increased the bioavailable P fractions in ADL soil and transformed the P treated KPD soil mainly through immobilisation of inorganic P and mobilisation of organic P. There was a general shift from the labile P forms (H2O- and NaHCO3- P) to the adsorbed fractions (NaOH- and H2SO4- P). The NaOH and H2SO4 fractions are associated to Fe-/Al- and Ca- associated P, respectively [22]. McDowell [22] observed increases in tightly bound P (H2SO4-, NaOH-II- and residual- P fractions) on FA application to grassland soils.
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Stout et al. [44] observed similar shifts for FBC and FGD treated soils and indicated that the high pH and Ca induced Fe and Al displacement to the solution. Zhang et al. [45] found that CCPs-induced increases in pH and Ca concentrations are the major contributing factors for shifts from
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H2O-P to NaHCO3 fractions, when amended with organic materials (dairy, swine and poultry manures). But application rates were higher (FBC40 % and FGD-25 %) compared to 15 % used in this experiment and 1 % used in McDowell [22]. Dou et al. [46] also observed similar results with FBC and FGD, but found that FA was ineffective in converting H2O-P to bioavailable (NaHCO3) form. They concluded that FBC and FGD additions can be beneficial in retarding P loss from manures, thereby improving their agronomic value in soil. The limited effectiveness of FGD
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in this experiment may be attributed to the relatively low pH and CCE values. The effect of CCPs (especially, FBC) on increasing the bioavailable P was higher on ADL soil compared to KPD and hence it was chosen for plant-growth experiments.
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For the plant experiments, FBC was preferred for its higher efficiency in increasing the bioavailable (NaHCO3-P) fractions in P treated soils, compared to FA [46]. The FBC addition has decreased leachate P for all P treatments used in the plant-growth experiments. Stout et al. [26] applied 1 % of FBC (CCE - 31 %) to a loamy soil and observed around 60 % decrease in the concentration of water-soluble P. They attributed
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this reduction in soluble P to the neutralising capacity of FBC, resulting in P transformation to calcium phosphates. Overall, the effect of FBC on PP was attributed to the immobilisation of inorganic P and in the case of PM, the increase in leachate P concentration was related to the mineralisation of organic P due to increase in phosphatase activity [47, 48]. A higher FBC-induced P concentration in the leachates was observed for PM treated soils, compared to PP treatment which is attributed to the mineralisation of organic P and the slow release
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characteristics of PM [47, 49]. But, PM used by Moore and Edwards [50] and Dou et al. [46] contained water soluble P, which was reduced using amendments such as alum and FBC.
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The percentage increase in cumulative yields was highest in the leached set up for PP treatment and unleached for PM treatment. This suggests that FBC application to PP treatment helped in increasing the bioavailability of immobilised P in second crop; for PM treatment, unleached showed maximum increase suggesting that it is relatively less effective under leaching conditions. Yang et al. [51] examined the effects of Ca and Al based amendments (CaCl2, CaCO3, Al(OH)3) and observed a reduction in the leaching loss of P applied as KH2PO4. However, Stout et al.
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[26] studied the effectiveness of CCPs in controlling P export from high P soils and observed negligible effect on the yield of canola plants as
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measured by their dry matter yield, although there was a reduction in P loss through runoff. In the field experiment, the yield response to the various treatments for fresh P application showed that SSP alone had the highest biomass yield. On the addition of FBC, yield decreased for SSP and slightly increased for BS. McDowell [15] and Dou et al. [46] observed a similar effect of CCPs for inorganic and organic P, respectively. The decrease in biomass yields in SSP alone treatment for second cropping may be because of P
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utilisation in the first crop. However, the addition of FBC to SSP increased the biomass yields significantly in second crop, which may be attributed to the mobilisation of the previously immobilised P, in the first cropping. The bioavailable P (Olsen P) increased in the combination of FBC and BS for both the plants and a relationship between Olsen P and P uptake suggested that the plants accumulated P based on the availability of P. In a large-scale P fertiliser trial, Rowarth and Gillingham [52] associated
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Olsen P and plant P by linking plant uptake to depletion of inorganic P pool with a regression coefficient of 0.96. Few researchers reported slowrelease of P from BS and the resultant residual P effect in subsequent crops [53-55]. The phosphatase activity was enhanced in BS treatments in
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the presence of FBC. Yu et al. [56] related phosphatase activity with basic soil properties and soil P fractions and observed a correlation between natural phosphatase activity and plant available P with a regression coefficient of 0.688. 4. Conclusions
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The results reported in this research indicate the rate and extent of CCPs-induced P transformation, where FBC was the most effective enhancer of bioavailable P. In the greenhouse experiments, FBC increased bioavailable P fraction and decreased water soluble P, thereby reducing
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leachate P. The effect of FBC on bioavailable P was also evident from the increased crop yields in second cropping. The plant P uptake increased with both inorganic and organic P application in the first crop; in the second cropping, plants utilised more P from organic P application than their inorganic counterpart. This is because of FBC-induced increases in mineralisation of organic P and immobilisation of inorganic P. Hence, FBC was effective in P transformation (i) by immobilising inorganic P and later mobilising the bound P into available P for
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the second crop; (ii) by mineralising organic P into available P forms favourable for P uptake. In the field experiment, bioavailable P increased in the second crop for both plants due to the mobilisation of adsorbed P from first cropping. Phosphatase activity played an important role in increasing the bioavailable P and consequently higher yields. Overall, waste materials used in this study can be cautiously utilised for mitigating P related issues in agriculture and environment. The main threats in using these materials will be accumulation of heavy metals in soil if excessively used and hence judicious application of CCPs (15 % w/w) is recommended for better soil and environmental health.
Page 19 of 42
ip t cr us
Acknowledgements
The authors would like to thank Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRCfunding
this
research
work
in
collaboration
M an
for
with
University
of
South
Australia,
Australia.
ce pt
ed
Australia
Ac
CARE),
Page 20 of 42
ip t cr F.A.O.,
How
to
feed
the
World
in
2050,
Food
M an
[1]
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[23] H. Wang, N. Bolan, M. Hedley, D. Horne, Potential Uses of Fluidised Bed Boiler Ash (FBA) as a Liming Material, Soil Conditioner and Sulfur Fertilizer, in: K.S. Sajwan, I. Twardowska, T. Punshon, A.K. Alva (Eds.), Coal Combustion Byproducts and Environmental Issues, Springer, New York, USA, 2006, pp. 202-215. [24] ADAA - Ash Development Association of Australia, Australian experience with fly ash in concrete: Applications and opportunities, Ash Development Association of Australia. Fly ash Technical Note No.8, November 2009 (2009) 1-3.
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[26] W.L. Stout, J. Landa, A.N. Sharpley, Effectiveness of coal combustion by-products in controlling phosphorus export from soils, J. Environ. Qual. 29 (2000) 1239-1244.
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[36] P.M. Haygarth, L.M. Condron, A.L. Heathwaite, B.L. Turner, G.P. Harris, The phosphorus transfer continuum: Linking source to impact with an interdisciplinary and multi-scaled approach, Sci. Total Environ. 344 (2005) 5-14. [37] R.L. Parfitt, G.W. Yeates, D.J. Ross, A.D. Mackay, P.J. Budding, Relationships between soil biota, nitrogen and phosphorus availability, and pasture growth under organic and conventional management, Appl. Soil. Ecol. 28 (2005) 1-13.
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31-36.
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[41] J. Murphy, J.P. Riley, A modified single solution method for the determination of phosphate in natural waters, Anal. Chim. Acta 27 (1962)
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[45] G.Y. Zhang, Z. Dou, J.D. Toth, J. Ferguson, Use of flyash as environmental and agronomic amendments, Environ. Geochem. Health 26
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[48] K.M. Lai, D.Y. Ye, J.W.C. Wong, Enzyme activities in a sandy soil amended with sewage sludge and coal fly ash, Water Air Soil Pollut.
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different soils, Biores. Technol. 62 (1997) 25-28.
[50] P.A. Moore, D.R. Edwards, Long-term effects of poultry litter, alum-treated litter, and ammonium nitrate on phosphorus availability in soils, J. Environ. Qual. 36 (2007) 163-174. [51] J. Yang, Z. He, Y. Yang, P. Stoffella, X. Yang, D. Banks, S. Mishra, Use of amendments to reduce leaching loss of phosphorus and other nutrients from a sandy soil in Florida, Environ. Sci. Pollut. Res. 14 (2007) 266-269.
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[55] T. Krogstad, T.A. Sogn, Å. Asdal, A. Sæbø, Influence of chemically and biologically stabilized sewage sludge on plant-available phosphorous in soil, Ecol. Eng. 25 (2005) 51-60.
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[56] S. Yu, Z.L. He, P.J. Stoffella, D.V. Calvert, X.E. Yang, D.J. Banks, V.C. Baligar, Surface runoff phosphorus (P) loss in relation to
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phosphatase activity and soil P fractions in Florida sandy soils under citrus production, Soil Biol. Biochem. 38 (2006) 619-628.
Page 27 of 42
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Table 2. Effect of CCPs on the pH of P treated soils.
M an
Table 1. Chemical characterisation of soils, CCPs and P sources used
us
List of tables
Ac
ce pt
ed
Table 3. Effect of FBC on the relative agronomic effectiveness of various P treatments in sunflower and mustard plants
Page 28 of 42
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CCE
(mg kg-1)
(%)
(%)
pH
Total elemental concentration (mg kg-1)
M an
Samples
Olsen P
us
Table 1. Chemical characterisation of soils, CCPs and P sources used
P
Ca
Fe
Al
34.12±3.62
52.02±4.16
16364.53±45.12
19474.83±49.12
5.65±0.29
3.82±0.09
23.4
-
KPD
7.14±0.42
9.62±0.34
7.43
-
48.41±9.89
5996.13±29.67
18174.36±35.11
25865.69±51.45
SLB
8.74±0.04
19.42±0.02
7.41
-
35.43±4.56
97.06±5.38
18276.82±196.47
14572.73±23.55
FA
10.23±0.17
17.11±8.23
-
16.75
507.33±18.38
18035.33±51.52
121343.94±185.54
25170.92±50.77
FBC
12.72±0.12
11.52±1.62
-
23.25
154.31±3.75
49675.84±76.18
157621.11±173.15
34015.43±57.72
FGD
10.14±0.07
2.25±0.93
-
11.25
623.84±12.38
220804.44±196.12
2530.62±23.66
1164.77 ±14.45
PP
-
-
-
-
227621.21±199.23
-
-
-
PM
5.12±0.23
-
-
-
147834.63±171.17
50541.63±22.71
24892.19±19.62
43514.62±21.12
PR
6.81±0.36
-
-
-
108712.41±139.12
85623.57±39.27
59914.37±23.71
74311.33±26.83
Ac
ce pt
ed
ADL
Page 29 of 42
ip t -
-
-
94741.84 ±108.11
BS
6.64±0.01
21.67±0.03
-
-
7823.91±81.62
cr
6.12±0.02
-
us
SSP
-
-
-
-
-
M an
ADL – Adelaide hills; KPD – Kapunda; SLB – Salisbury; FA – Fly ash; FBC – Fluidised bed combustion ash; FGD – Flue gas desulphurisation gypsum; PP – Potassium dihydrogen phosphate; PM – Poultry manure; PR – Phosphate rock; SSP – Single super phosphate; BS – Biosolid; PRC
Ac
ce pt
ed
– Phosphorus retention capacity; CCE – Calicum carbonate equivalence.
Page 30 of 42
1
Table 2. Effect of CCPs on the pH of P treated soils.
No CCPs
FA
FBC
FGD
Treatments KPD
ADL
KPD
ADL
KPD
ADL
5.65±0.29 7.14±0.42 6.76±0.33 7.82±0.17 7.02±0.32 8.06±0.05 6.02±0.31 7.63±0.26
PP
5.89±0.31 7.31±0.11 6.91±0.11 7.99±0.24 7.19±0.37 8.22±0.09 6.23±0.15 7.92±0.21
PM
5.43±0.28 7.09±0.31 6.66±0.25 7.77±0.25 6.92±0.04 7.91±0.41 5.97±0.14 7.82±0.19
PR
5.67±0.21 7.16±0.34 6.84±0.08 7.83±0.08 7.11±0.16 8.01±0.11 6.08±0.26 7.76±0.12
an
us
cr
No P
ADL – Adelaide hills; KPD – Kapunda; FA – Fly ash; FBC – Fluidised bed combustion ash;
3
FGD – Flue gas desulphurisation gypsum; PP – Potassium dihydrogen phosphate; PM – Poultry
4
manure; PR – Phosphate rock; CCPs – Coal combustion products
Ac ce p
te
d
M
2
5
KPD
ip t
ADL
31 Page 31 of 42
5
Table 3. Effect of FBC on the relative agronomic effectiveness of various P treatments fin
7
sunflower and mustard plants
ip t
6
Relative agronomic effectiveness (RAE %)
Fresh
application
effect
application
cr
Residual
Residual effect
0
0
100
100
200
39
211
328
31
330
462
62
481
0
SSP alone
100
100
BS alone
52
SSP+FBC
45
BS+FBC
88
an
0
d
FBC – Fluidised bed combustion ash; SSP – Single super phosphate; BS – Biosolids
te
9
Fresh
Ac ce p
8
Mustard
M
Nil
Sunflower
us
Treatments
32 Page 32 of 42
Figure 1.
11
Figure 2.
13
PM and PR. Figure 4.
17 18
Figure 5.
Figure 6.
24 25 26 27
Effect of FBC on cumulative (first and second crops) biomass yields for PP and PM treatments.
Ac ce p
23
Effect of FBC on biomass yields in PP and PM treated ADL soils grown with mustard plants under leached and unleached conditions – first and second crops.
21 22
Cumulatively leached P as affected by FBC in first and second crops of mustard plants grown in ADL soil.
19 20
Effect of CCPs on Bioavailable P values of a. ADL and b. KPD soils, treated with PP,
us
Figure 3.
cr
PP, b. PM and c. PR treatments.
15 16
Distribution of P fractions in Kapunda (KPD) soil, amended with CCPs (w/w) for a.
an
14
ip t
for a. PP, b. PM and c. PR treatments.
M
12
Distribution of P fractions in Adelaide hills (ADL) soil, amended with CCPs (w/w)
d
10
List of figures
te
9
Figure 7. Effect of FBC on the biomass yields of a. sunflower and b. mustard plants, and their relative yield increases.
Figure 8.
Relationship between Olsen P and P uptake as affected by the treatment combinations (Nil, SSP alone, BS alone, SSP+FBC and BS+FBC) in both sunflower and mustard plants (n=10).
Figure 9.
Relationship between phosphatase activity and Olsen P in the SLB soil as affected by
28
the treatment combinations (Nil, SSP alone, BS alone, SSP+FBC and BS+FBC) in
29
both sunflower and mustard plants (n=10).
33 Page 33 of 42
Fig-1
1
Figure 1 Distribution of P fractions in Adelaide hills (ADL) soil, amended with CCPs (w/w)
us
cr
ip t
for a. PP, b. PM and c. PR treatments.
Ac ce p
te
d
M
an
a.
b.
c.
Page 34 of 42
Fig-2
1
Figure 2 Distribution of P fractions in Kapunda (KPD) soil, amended with CCPs (w/w) for
us
cr
ip t
a. PP, b. PM and c. PR treatments.
Ac ce p
te
d
M
an
a.
b.
c.
Page 35 of 42
Fig-3
1
Figure 3 Effect of CCPs on bioavailable P values of a. ADL and b. KPD soils, treated with
an
us
cr
ip t
PP, PM and PR.
Ac ce p
te
d
M
a.
b.
Page 36 of 42
Fig-4
1
Figure 4 Cumulatively leached P as affected by FBC in first and second crops of mustard
Ac ce p
te
d
M
an
us
cr
ip t
plants grown in ADL soil.
Page 37 of 42
Fig-5
1
Figure 5 Effect of FBC on biomass yields in PP and PM treated ADL soils grown with mustard plants under leached and unleached conditions – first and second crops. 12
Leached
ip t
Unleached
cr
8
us
6
2 0 0 200 0 200
FBC-
FBC-
FBC+
FBC+
Second crop
0 200 0 200
0 200 0 200
FBC-
FBC-
FBC+
First crop
FBC+
Second crop PM
te
PP
d
First crop
M
0 200 0 200
an
4
Ac ce p
Biomass yield (g pot-1)
10
Page 38 of 42
Fig-6
1
Figure 6 Effect of FBC on cumulative (first and second crops) biomass yields for PP and PM treatments.
FBC+
ip t
FBC-
20
cr
15
us
10 5 0 Unleached
Leached
Unleached
Leached PM
Ac ce p
te
d
M
PP
an
Cumulative biomass yields (g pot-1)
25
Page 39 of 42
Fig-7
1
Figure 7 Effect of FBC on the biomass yields of a. sunflower and b. mustard plants, and
M
an
us
cr
ip t
their relative yield increases.
Ac ce p
te
d
a.
b.
Page 40 of 42
Fig-8
1
Figure 8 Relationship between Olsen P and P uptake as affected by the treatment combinations (Nil, SSP alone, BS alone, SSP+FBC and BS+FBC) in both sunflower and
Ac ce p
te
d
M
an
us
cr
ip t
mustard plants (n=10).
Page 41 of 42
Fig-9
1
Figure 9 Relationship between phosphatase activity and Olsen P in the SLB soil as affected by the treatment combinations (Nil, SSP alone, BS alone, SSP+FBC and BS+FBC) in both
Ac ce p
te
d
M
an
us
cr
ip t
sunflower and mustard plants (n=10).
Page 42 of 42
S0304-3894(13)00317-8 http://dx.doi.org/doi:10.1016/j.jhazmat.2013.04.051 HAZMAT 15088
To appear in:
Journal of Hazardous Materials
Received date: Revised date: Accepted date:
15-8-2012 16-4-2013 21-4-2013
Please cite this article as: B. Seshadri, N. Bolan, G. Choppala, R. Naidu, Differential effect of coal combustion products on the bioavailability of phosphorus between inorganic and organic nutrient sources, Journal of Hazardous Materials (2013), http://dx.doi.org/10.1016/j.jhazmat.2013.04.051 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ip t cr
us
Differential effect of coal combustion products on the bioavailability of phosphorus between inorganic and organic nutrient sources Balaji SeshadriA,B,*, Nanthi BolanA,B , Girish ChoppalaA,B and Ravi NaiduA,B
Centre for Environmental Risk Assessment and Remediation, Building–X, University of South Australia, Mawson Lakes, South Australia 5095,
M an
A
Australia. B
Cooperative Research Centre for Contamination Assessment and Remediation of the Environment, PO Box 486, Salisbury, South Australia
5106, Australia.
ed
* Corresponding author at: Centre for Environmental Risk Assessment and Remediation (CERAR), University of South Australia, SA 5095, Australia.
ce pt
Tel.: +61-8-8302-6218, fax: +61-8-8302-3124 Email address: [email protected]
Highlights
Ac
Examined effect of CCPs on increasing P bioavailability in P treated soils CCPs decreased soluble P from inorganic P; increased bioavailable P from organic P FBC emerged as the best CCP in enhancing the bioavailability of P in the soil FBC decreased leachate P by increasing bioavailable P and reducing water soluble P Plants utilised more P during second cropping because of increase in bioavailable P
Page 1 of 42
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Abstract
In farming systems, all the applied phosphorus (P) is not available to plants because they are either adsorbed in soil or lost to the environment through leaching or runoff. The effect of coal combustion products (CCPs) for enhancing the bioavailability of applied phosphorus (P) in soil
ed
was examined separately for inorganic (KH2PO4 - PP) and organic (poultry manure - PM) P treatments, where fluidised bed combustion (FBC) ash emerged as the most effective amendment. Greenhouse study was conducted by growing mustard plants on FBC amended soils under
ce pt
leaching and non-leaching setups. The FBC increased the biomass yield for organic P treatments in the first crop and increased for both inorganic and organic P in the second cropping. The increase in cumulative yield was highest in leached PP and unleached PM treatments. Field experiment assessed the effectiveness of FBC on inorganic (single super phosphate – SSP) and organic P (biosolids – BS) uptake by mustard and sunflower plants. In the first cropping, the yield was higher in crops treated with SSP alone. In the second crop, yields were higher in the
Ac
presence than absence of FBC, as reflected by the high relative agronomic effectiveness (RAE) exhibited by BS+FBC (462 %) combination. Overall, FBC used in these experiments enhanced bioavailability of P in soil through adsorption and mineralisation of inorganic and organic P, respectively as evident from phosphatase activity and Olsen P relationship. Hence the differential effect of CCPs has not only decreased the loss of applied P (from inorganic and organic sources) to the environment, but also enhanced the P bioavailability in the soil. Among the three CCPs
Page 2 of 42
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environmental applications targeting P issues. coal
combustion
M an
bioavailability;
products;
residual
effect;
mineralisation.
ce pt
ed
phosphorus;
Ac
Keywords:
us
used in the preliminary experiments, FBC proved to perform better than the other two and hence can be recommended for agricultural and
Page 3 of 42
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1. Introduction
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The incessant growth in global population and consequent rise in the demand for food production have increased pressure on land and water resources [1]. As a result, soils are turning out to be the direct calamity of anthropological activities such as intensive cultivation and waste disposal. Firstly, the intensive use of agricultural inputs for maximising crop yields has not only provided nutrients to the growing crops, but also added undesirable nutrients and heavy metals into the soil [2, 3]. On the other hand, agricultural and industrial activities release toxic
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contaminants to soil, thereby impacting the environment [4, 5]. Selection of ideal agricultural amendments (including industrial byproducts) and
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optimal usage of these products are critical in terms of productivity [6]. The direct effect of intensive agriculture is loss of nutrients from soil, which is usually managed by the addition of fertilisers [7-9]. However, indiscriminate fertiliser application can be detrimental to the soil environment. Phosphorus (P) being one of the major plant nutrients, is an important growth limiting factor for plants [10]. Soil P loss through runoff/leaching results in land and water degradation [11, 12]. Generally, P
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is transported from soil in both particulate and dissolved forms. Although the former can be decreased through riparian buffers, the soluble inorganic P loss had been an issue in low P-retaining soils [13]. An understanding of P retention capacity (PRC) of soils is vital for fertiliser management [14] and safeguarding water quality [12]. Optimal pH and high concentration of P sorptive components such as calcium (Ca), iron (Fe) and aluminium (Al) in soil solution are good prerequisites for enhancing soil’s PRC [15]. Generally, at alkaline pH, Ca precipitates with P; in acidic conditions, P adsorbs to Al and Fe oxides. Traditionally, lime (CaCO3) has been widely used to alleviate soil acidity by increasing soil
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pH [16]. Several studies have investigated the positive impact of liming on P adsorption in soils through addition of Ca+ to the soil solution [1719].
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Several researchers explored the possibility of using coal combustion products (CCPs) for mitigating P loss in soil, mainly because of their liming value and Ca content [20-22]. There are different types of CCPs based on the combustion processes and the consequent end products; conventional byproducts include fly ash (FA) and bottom ash (BA) collected from electrostatic precipitators and boilers, respectively; and the clean coal technology products such as fluidised bed combustion (FBC) ash and flue gas desulphurisation (FGD) gypsum, collected from lime-
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based scrubbing systems [21, 23, 24]. Most studies were focussed towards the agronomic and environmental benefits of the CCPs such as increasing the soil pH and reducing P in the surface run off and subsurface drainage, sustaining bioavailability of P (i.e. Olsen P concentrations),
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and deducing optimal application rates [15, 25, 26]. Since CCPs have the potential to transform P in soils through (im)mobilisation (either immobilisation or mobilisation) of P compounds, they can be effective in improving P bioavailability when applied along with organic amendments [27-29]. The CCPs (FA, FBC and FGD) have proven capabilities on overall P transformation in soils [21, 22, 26]. Most of the
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studies on plant P availability in CCPs amended soils were conducted at laboratory scale and a very few research was conducted at the field level. For example, Ram et al. [30] used lignite FA for long term field trials on an experimental agricultural plot and observed increased Olsen P content in soil and a consequent increase in maize yields. Plants assimilate P only in their orthophosphate forms (HPO4-/HPO42-), but most soils contain P (organic and mineral P) in non-available forms. Generally, around 20 % of applied P becomes immediately available to crops and the remaining is unavailable because of
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adsorption/precipitation or conversion to organic forms [31, 32]. Hence, P pool needs to be replenished during successive crops to produce the desired yield [13, 33]. The use of organic P fertilisers will help reduce P through slow conversion to orthophosphates by phosphatase activity
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[34], which helps in the mineralisation process [34-36]. Although organic P mineralisation provide significant P source for plants [37], an adequate level of P in solution is the prerequisite for plant uptake, especially at early growth stage. Hence, there is a need for specific amendments which could mineralise organic P forms and immobilise the orthophosphate P forms. The CCPs can be an effective replacement for their natural counterparts (lime and gypsum) for mitigating P related issues in soil, if used
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judiciously. Therefore, development of strategies to minimise P loss from soils require detailed understanding of the CCPs-induced P transformation in soil under various P treatments. This paper addresses the effect of CCPs on bioavailability of both inorganic and organic P,
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explained using P fractionation experiment and plant studies (using greenhouse and field trials). The greenhouse study was set up under leaching and non-leaching conditions to study the immobilising effects of CCPs on applied P. The plant studies also focus on the effects of CCPs in P treated soils during the second cropping, which may help in understanding their long term (aging) effects.
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2. Materials and Methods
2.1. Characterisation of soils, CCPs and P sources The soils (0–10 cm depth) were collected around Adelaide, Australia – Adelaide hills (ADL) and Kapunda (KPD) (Table 1), air-dried and sieved to <2mm. The CCPs used were FA from Port Augusta Power Station, South Australia; FBC from Redbank Power Limited, Queensland, and
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FGD from Illinois, USA (Table 2). The P sources used in the experiment were laboratory KH2PO4 (PP), commercial poultry manure (PM) and phosphate rock (PR) from Nutri-Tech Solution, Queensland. The field study was conducted at Salisbury (location details in Section 2.3.2) by
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treating the soil (SLB) with an inorganic P source (single super phosphate–SSP), an organic amendment (biosolids–BS) and a CCP (FBC). The pH and EC for all samples were determined by end-over-end equilibration of soils with water at a ratio of 1:5 for an hour and measured with a pH/conductivity meter. For the total metal analysis, the samples were digested using aqua-regia (3:1 – HNO3:HCl) and the concentration of metals in the extract was determined by ICP-MS [22]. The PRC of soils were determined using the Phosphate retention test [38]. In the case of
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CCPs, the CaCO3 equivalence (CCE) was determined using Rayment and Higginson [39]. Olsen P was measured for all CCPs and soil samples
2.2. Incubation study
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[40].
The soils (5 g each) were initially treated with the three P sources (PP, PM and PR) at the rates of 0 and 200 mg P kg-1 soil. The P treated soils
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were incubated with CCPs at the rates of 0 and 5 % (w/w) for FA, and 0 and 15 % for FBC and FGD in plastic pots for 21 days at 80 % WHC. The incubated samples (1 g each) were air-dried immediately after the incubation period and analysed for pH before conducting the fractionation experiment.
2.2.1 Fractionation experiment
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The fractionation experiment was used to study the distribution of P fractions for soils treated with various P sources as affected by CCPs. A fractionation scheme as used by McDowell [22] was employed, which involved a sequential extraction of incubated soil (1 g). The extracted
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inorganic P fractions were analysed for P concentration using the colorimetric method of Murphy and Riley [41], using Agilent 8453 UV-visible spectroscopy system (Germany) at 882 nm and the total P (TP) was determined by analysing the acid-digested samples using ICP-OES. The bioavailable P in the fractionation scheme can be defined as the P present in non-adsorbed forms, which is soluble in water and sodium bicarbonate solution [22]. It is a measure of P with agronomic significance, which is readily taken up by plants. The bioavailable P from the P
2.3.1 Greenhouse trials
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2.3. Plant-growth experiments
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fractions was calculated by adding the P concentration of H2O-P and NaHCO3-P fractions.
A greenhouse experiment was set up to investigate the effect of CCPs on plant uptake of P and their consequent influence on plant-growth in P
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treated (organic and inorganic) soil. The plants were grown separately under non-leaching and leaching set ups to understand the effect of FBC on (im)mobilisation of applied P and to estimate the amount of labile P that may be potentially available to plants. The incubation was performed as mentioned in Section 2.2 with 200 g of ADL soil, with only FBC and two P sources (PP and PM). The selection of FBC was based on high pH and CCE values, and their influence in increasing bioavailable P in soils. The plant used for the study was Indian mustard (Brassica hirta L.).
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The method developed by Stanford and DeMent [42] was used for this plant-growth study. Transparent round plastic pots (700 mL capacity) with bottoms removed were nested in similar pots which had intact bottoms. The inner pot was filled with 300 g sand and 16 mustard seeds were
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surface-sown. The pots were covered loosely with lids for three days to maintain moisture for germination. Each treatment was carried out in triplicate and the trial was performed in a temperature-controlled greenhouse environment (25±3ºC; 16 h light). The plants were watered twice daily for first week and were thinned to 10/pot and the moisture was maintained with Hoagland solution (P excluded) thereafter. After four weeks of plant-growth, the sand-grown plants were carefully transferred to another intact pot containing 200 g of incubated soils. The soils were
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wetted to field capacity before the transfer and the root-mats were carefully placed on the soil to gain access to the soil elements. The pots containing the soils were prepared in two sets – one for leaching and the other was not allowed to leach. The soil pots for leaching were
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cut at the bottom and a cotton mesh was placed for each pot before adding soil to avoid any soil loss. All the pots were leached with 100 mL of deionized water at three intervals (1, 2 and 3 weeks) during the experiment and the leachates were collected. Plants were harvested after three weeks of growth in the soil media and were dried to a constant weight at 70°C. Dry weight was recorded and
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the dried plant samples were ground to a fine powder for P analysis. Seeds from the same source were re-sown in the harvested pots and similar procedure was followed as in the first crop. 2.3.2. Field trials
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A field experiment was conducted to examine the effects of FBC on P bioavailability in SLB soil, treated with inorganic (SSP) and organic (BS) P sources, with an overall objective to study fresh and residual effects of the treatments. The experimental site (17 ha) is located at St.Kilda,
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South Australia, approximately 23 km NNE from Adelaide CBD. The experiment was conducted between August and November 2010; the average temperature during the experiment was 34ºC and the humidity varied from 27 to 63 %; the highest rainfall recorded was in the month of August at 56 mm. A 10x10 m plot was cleared-off a week before the experiment commencement, which was equally divided into 1 m2 plots, in two blocks and each plot in a block was treated with the treatments at different combinations (nil-control, SSP alone, BS alone, SSP+FBC and
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BS+FBC). Application rates were: BS - 0 and 6.5 Mg ha-1, SSP - 0 and 0.5 Mg ha-1 and FBC - 0 and 25 Mg ha-1. Amendments were mixed to the top 20 cm of the soil. After three weeks, 4 g of sunflower (Helianthus annuus “Yellow Impress”, Yates Australia) and 3 g of Indian mustard
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(Brassica hirta, Department of Primary Industries, Victoria) seeds were added to the designated plots. In total, 30 experimental plots were used with 15 per plant species, including three replicates.
The plots were irrigated alternative days with water from Salisbury Council and hand-weeding was undertaken twice. The plants were harvested
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after three months, dried to a constant weight at 70°C. The plant samples were weighed and ground to a fine powder for P analysis. The plots were re-cultivated immediately with seeds from the same sources and harvested after three months for P analysis. 2.3.2. Plant, leachate and soil analyses
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Plant samples from glasshouse and field experiments were quantified for biomass yields and analysed for P accumulation. The ground plant materials (0.4 g) were digested with concentrated HNO3 (5 mL) in a temperature-controlled digestion block (AI Scientific Block Digestion
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System AIM 500) at 140°C, until 1 mL (approximate) of digest remained in the tube. After cooling, the samples were mixed thoroughly and filtered with a syringe filter directly into plastic containers. The digested plant extracts were analysed for P by inductively coupled plasmaoptical emission spectroscopy (ICP-OES, Agilent). For the leaching part of glasshouse experiment, the collected leachates were stored at 4° C for P analysis as mentioned in Section 2.2.1.
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The soil samples from field experiment were collected from each plot immediately after the first cropping; Olsen P and phosphatase activity were determined using air-dried and field moist soils (FMS), respectively. The phosphatase activity of the incubated soil samples were
[43].
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2.4. Statistical analysis
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determined by measuring the release of para-nitrophenol (ρ-NP) from para-nitrophenyl phosphate (PNP) as described by Tabatabai and Bremner
All measurements [pH, PRC (%), CCE (%), Olsen P and elemental composition (mg kg-1)] were calculated for triplicates of each treatment. All calculations including standard deviations of replicates and analysis of variance were determined using PASW Statistics (Version 18.0.0; SPSS, Inc., Chicago, IL) at a significance level of p < 0.05. The relationships for Olsen P Vs. P uptake and Phosphatase activity Vs. Olsen P were evaluated by simple-linear regression analysis.
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3. Results
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3.1. Chemical properties of soil, CCPs and P sources
The chemical properties of the soils, CCPs and P sources used in this study are given in Table 1. The soil pH of ADL and KPD were 5.6 and 7.1, respectively and field soil (SLB) - 7.3. The Olsen P for ADL, KPD and SLB were 3.82, 9.6 and 19.42 mg kg-1, respectively with elemental P contents ranging from 34.1 to 48.4 mg kg-1 (w/w) (Table 1). The ADL soil had highest PRC (23.4 %), with KPD and SLB having a PRC of
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around 7 % (Table 1).
The three CCPs had high pH (>10) values, with FBC measuring the highest pH (12.7). The CCE value was the highest in FBC (23.25 %),
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followed by FA (16.75 %) and FGD (11.25 %). The Olsen P for FA, FBC and FGD were 16.44, 11.52 and 2.25 mg kg-1 (Table 1). The Al and Fe contents were high in the FBC and FA, whereas FGD values were relatively low (Table 1). The FBC had a high Ca content (49.68 %). The total P content in PM and PR were 14.78 % and 10.87 %, respectively (Table 1).
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3.2. Fractionation experiment
3.2.1. Effect of CCPs on P distribution in soils The pH of the P treated ADL soil ranged from 6.66-6.91 for FA amended soils; 6.92-7.19 for FBC and 5.97-6.23 in FGD amended soils; the increase was highest for FBC. The effect of CCPs on KPD soil also showed similar trends as ADL (Table 2).
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The sequential extraction results indicated that for PP treated ADL soil, CCPs increased NaHCO3 and H2SO4-P fractions and NaOH decreased only for FBC amendment, compared to control (Figure 1a). In the case of PM treatment, CCPs increased NaHCO3-P fraction and FBC showed
observed on the remaining fractions (Figure 1c).
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the highest increase (Figure 1b). For PR treatment, the P was largely (> 70 %) associated to H2SO4-P fraction and no effect of CCPs was
For the KPD soils, CCPs decreased H2O- and NaHCO3-P in PP treated samples but increased in PM treatment; the H2SO4-P fraction increased in PP and PR treated samples, whereas decreased in the PM treatment (Figures 2 a, b and c). In PP treatment, H2O-P and NaHCO3-P was largely
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shifted to H2SO4-P for all three amendments (Figure 2a). In the case of PM treatment, CCPs increased both H2O- and NaHCO3-P, by shifting from H2SO4-P (Figure 2b). The NaHCO3-P fractions increased in the following order: FBC (18 %) > FA (11 %) > FGD (3 %) compared to
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control, and NaOH-I-P increased by up to 75 % for all CCPs. For PR treated soil, H2SO4-P fractions were the highest for all CCPs and there was no effect of CCPs on other fractions (Figure 2c). The residual P fractions were minimal in FBC-amended soils and P shifts to residual P fractions were almost similar in both FA and FGD amended soils.
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3.2.2. Effect of CCPs on Bioavailable P
The bioavailable P was calculated by adding the values of H2O- and NaHCO3-P fractions. For ADL soil, the CCPs increased the bioavailable P in PP and PM treated soils with no effect in PR treatment. The increasing order was FBC>FA>FGD for both PP and PM treatments and FBC increased bioavailable P in PP-59 and PR-91 % compared to control (Figure 3a). In the case of KPD soil, the CCPs decreased bioavailable P in
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PP treated samples and increased for PM treatment (Figure 3b). In both the cases, FBC was most effective in decreasing up to 41 % (PP) and increasing around 49 % (PM) of applied P.
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3.3. Plant-growth experiments 3.3.1. Glass house experiment
The P in the leachates of first crop decreased significantly after FBC application in PP treated soil (35 %) but marginally in PM treatments (16 %)
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(Figure 4). In the second crop, the percentage reduction was higher for PM treated soil (41 %) compared to PP (24 %). The biomass yields for PP and PM treated pots as affected by FBC are shown in Figures 5 and 6, respectively. The fresh P applied as PP
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increased the yield in both unleached and leached pots, but FBC application decreased the yield only in unleached pots by about 27 %. In leached PP treatments, yields were similar for both presence and absence of FBC (Figure 5). In the case of PM treatment, there was a significant increase (about 48 %) in yields for FBC-amended pots for unleached pots (Figure 5).
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In the second crop, FBC increased the yields for both unleached and leached pots of PP treatment. For unleached pots, PP gave higher yield (about 70 %) in the presence than absence of FBC and for leached pots (up to 40 % increase) (Figure 5). Under PM treatment, unleached pots amended with FBC showed highest yields among all the treatments (Figure 5). In the case of leached pot, the FBC increased the yield by about 17 %. The influence of FBC on cumulative yields (first and second crops) for P treatments was positive for both leached and unleached pots (Figure 6). For PP treatment, the percentage increase in cumulative yield was higher in leached pots than the unleached ones (Figure 6). In PM
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treated pots, cumulative biomass yield for unleached pot showed highest increase (about 49 %). The overall effect of FBC in PM treated soil was slightly higher compared to PP treatment.
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3.3.2. Fields trials
The biomass yields of sunflower plants varied amongst the treatments (Figure 7a). For fresh P treatment (first crop), the biomass increased for all the treatments, and yield for SSP alone was the highest (2.79 Mg ha-1); with FBC addition, the yield reduced to 18 %. The combination of BS
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and FBC yielded a slight increase (about 14 %) in biomass, compared to BS alone. In the second cropping, the yield was of the following order: BS+FBC > SSP+FBC > BS alone > SSP alone > Nil (Figure 7a). The FBC addition to SSP and BS increased the yields by about 37 and 40 %,
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respectively compared to first cropping. The mustard plants also showed similar trends with sunflower plants (Figure 7b). The effect of FBC on P-induced yield was also examined using the relative agronomic effectiveness (RAE), which expresses the agronomic potential of the farm inputs to produce a yield response (Bolan et al., 1990). The RAE was calculated using Eq. 1.
( yield for specific treatment – yield for control ) x100 yield for SSP alone – yield for control
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RAE
(1)
Less than 100 % RAE indicates poor agronomic efficiency compared to SSP, and RAE higher than 100 % signifies the agronomic potential of the amendment. In the case of fresh application, the RAE decreased for all treatments in both plant species and the order of effectiveness was SSP > BS+FBC > BS > SSP+FBC > Nil). The residual effect (second crop) was highest for the BS+FBC treatment for both sunflower (around
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462 %) and mustard (around 481 %) (Table 3). The agronomic effectiveness of the treatments for residual effect was in the following order: BS+FBC > SSP+FBC > BS alone > SSP alone > Nil.
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At the end of first cropping, air-dried soils were analysed for Olsen P and plant samples were analysed for P accumulation/uptake. A regression analysis between Olsen P and P uptake shows a positive correlation (R2=0.8743) (Figure 8). The phosphatase activity of FMS analysed at the end of first cropping confirmed the effect of FBC on increasing P mineralisation, in the
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following order: BS+FBC > SSP+FBC > BS alone > SSP alone > Nil. The effects were higher in BS treated plots with about 54 and 51 % increases for sunflower and mustard plants, respectively. A combined regression analysis between phosphatase activity and Olsen P of soils
4. Discussion
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grown with sunflower and mustard plants showed a regression coefficient of 0.6498 (Figure 9).
Data from sequential fractionation experiments showed the influence of CCPs on P transformation, as affected by pH. In the case of P treated
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ADL soils, CCPs increased the pH to near-neutral pHs (Table 2), whereas, the KPD soil was already slightly alkaline and hence CCPs increased the pH further (Table 2). Therefore, CCPs increased the bioavailable P fractions in ADL soil and transformed the P treated KPD soil mainly through immobilisation of inorganic P and mobilisation of organic P. There was a general shift from the labile P forms (H2O- and NaHCO3- P) to the adsorbed fractions (NaOH- and H2SO4- P). The NaOH and H2SO4 fractions are associated to Fe-/Al- and Ca- associated P, respectively [22]. McDowell [22] observed increases in tightly bound P (H2SO4-, NaOH-II- and residual- P fractions) on FA application to grassland soils.
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Stout et al. [44] observed similar shifts for FBC and FGD treated soils and indicated that the high pH and Ca induced Fe and Al displacement to the solution. Zhang et al. [45] found that CCPs-induced increases in pH and Ca concentrations are the major contributing factors for shifts from
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H2O-P to NaHCO3 fractions, when amended with organic materials (dairy, swine and poultry manures). But application rates were higher (FBC40 % and FGD-25 %) compared to 15 % used in this experiment and 1 % used in McDowell [22]. Dou et al. [46] also observed similar results with FBC and FGD, but found that FA was ineffective in converting H2O-P to bioavailable (NaHCO3) form. They concluded that FBC and FGD additions can be beneficial in retarding P loss from manures, thereby improving their agronomic value in soil. The limited effectiveness of FGD
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in this experiment may be attributed to the relatively low pH and CCE values. The effect of CCPs (especially, FBC) on increasing the bioavailable P was higher on ADL soil compared to KPD and hence it was chosen for plant-growth experiments.
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For the plant experiments, FBC was preferred for its higher efficiency in increasing the bioavailable (NaHCO3-P) fractions in P treated soils, compared to FA [46]. The FBC addition has decreased leachate P for all P treatments used in the plant-growth experiments. Stout et al. [26] applied 1 % of FBC (CCE - 31 %) to a loamy soil and observed around 60 % decrease in the concentration of water-soluble P. They attributed
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this reduction in soluble P to the neutralising capacity of FBC, resulting in P transformation to calcium phosphates. Overall, the effect of FBC on PP was attributed to the immobilisation of inorganic P and in the case of PM, the increase in leachate P concentration was related to the mineralisation of organic P due to increase in phosphatase activity [47, 48]. A higher FBC-induced P concentration in the leachates was observed for PM treated soils, compared to PP treatment which is attributed to the mineralisation of organic P and the slow release
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characteristics of PM [47, 49]. But, PM used by Moore and Edwards [50] and Dou et al. [46] contained water soluble P, which was reduced using amendments such as alum and FBC.
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The percentage increase in cumulative yields was highest in the leached set up for PP treatment and unleached for PM treatment. This suggests that FBC application to PP treatment helped in increasing the bioavailability of immobilised P in second crop; for PM treatment, unleached showed maximum increase suggesting that it is relatively less effective under leaching conditions. Yang et al. [51] examined the effects of Ca and Al based amendments (CaCl2, CaCO3, Al(OH)3) and observed a reduction in the leaching loss of P applied as KH2PO4. However, Stout et al.
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[26] studied the effectiveness of CCPs in controlling P export from high P soils and observed negligible effect on the yield of canola plants as
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measured by their dry matter yield, although there was a reduction in P loss through runoff. In the field experiment, the yield response to the various treatments for fresh P application showed that SSP alone had the highest biomass yield. On the addition of FBC, yield decreased for SSP and slightly increased for BS. McDowell [15] and Dou et al. [46] observed a similar effect of CCPs for inorganic and organic P, respectively. The decrease in biomass yields in SSP alone treatment for second cropping may be because of P
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utilisation in the first crop. However, the addition of FBC to SSP increased the biomass yields significantly in second crop, which may be attributed to the mobilisation of the previously immobilised P, in the first cropping. The bioavailable P (Olsen P) increased in the combination of FBC and BS for both the plants and a relationship between Olsen P and P uptake suggested that the plants accumulated P based on the availability of P. In a large-scale P fertiliser trial, Rowarth and Gillingham [52] associated
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Olsen P and plant P by linking plant uptake to depletion of inorganic P pool with a regression coefficient of 0.96. Few researchers reported slowrelease of P from BS and the resultant residual P effect in subsequent crops [53-55]. The phosphatase activity was enhanced in BS treatments in
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the presence of FBC. Yu et al. [56] related phosphatase activity with basic soil properties and soil P fractions and observed a correlation between natural phosphatase activity and plant available P with a regression coefficient of 0.688. 4. Conclusions
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The results reported in this research indicate the rate and extent of CCPs-induced P transformation, where FBC was the most effective enhancer of bioavailable P. In the greenhouse experiments, FBC increased bioavailable P fraction and decreased water soluble P, thereby reducing
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leachate P. The effect of FBC on bioavailable P was also evident from the increased crop yields in second cropping. The plant P uptake increased with both inorganic and organic P application in the first crop; in the second cropping, plants utilised more P from organic P application than their inorganic counterpart. This is because of FBC-induced increases in mineralisation of organic P and immobilisation of inorganic P. Hence, FBC was effective in P transformation (i) by immobilising inorganic P and later mobilising the bound P into available P for
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the second crop; (ii) by mineralising organic P into available P forms favourable for P uptake. In the field experiment, bioavailable P increased in the second crop for both plants due to the mobilisation of adsorbed P from first cropping. Phosphatase activity played an important role in increasing the bioavailable P and consequently higher yields. Overall, waste materials used in this study can be cautiously utilised for mitigating P related issues in agriculture and environment. The main threats in using these materials will be accumulation of heavy metals in soil if excessively used and hence judicious application of CCPs (15 % w/w) is recommended for better soil and environmental health.
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Acknowledgements
The authors would like to thank Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRCfunding
this
research
work
in
collaboration
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for
with
University
of
South
Australia,
Australia.
ce pt
ed
Australia
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CARE),
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How
to
feed
the
World
in
2050,
Food
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[13] R.W. McDowell, B.J.F. Biggs, A.N. Sharpley, L. Nguyen, Connecting phosphorus loss from agricultural landscapes to surface water quality, Chem. Ecol. 20 (2004) 1-40.
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[18] N.S. Bolan, D.C. Adriano, D. Curtin, Soil acidification and liming interactions with nutrient and heavy metal transformation and
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[20] M.P. Callahan, P.J.A. Kleinman, A.N. Sharpley, W.L. Stout, Assessing the efficacy of alternative phosphorus sorbing soil amendments, Soil Sci. 167 (2002) 539.
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[21] W.L. Stout, A.N. Sharpley, S.R. Weaver, Effect of amending high phosphorus soils with flue-gas desulfurization gypsum on plant uptake and soil fractions of phosphorus, Nutr. Cycl. Agroecosys. 67 (2003) 21-29. [22] R.W. McDowell, The effectiveness of coal fly-ash to decrease phosphorus loss from grassland soils, Soil Res. 43 (2005) 853-860.
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[23] H. Wang, N. Bolan, M. Hedley, D. Horne, Potential Uses of Fluidised Bed Boiler Ash (FBA) as a Liming Material, Soil Conditioner and Sulfur Fertilizer, in: K.S. Sajwan, I. Twardowska, T. Punshon, A.K. Alva (Eds.), Coal Combustion Byproducts and Environmental Issues, Springer, New York, USA, 2006, pp. 202-215. [24] ADAA - Ash Development Association of Australia, Australian experience with fly ash in concrete: Applications and opportunities, Ash Development Association of Australia. Fly ash Technical Note No.8, November 2009 (2009) 1-3.
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Conditioners, Marcel Dekker, New York, USA, 1998, pp. 309-331.
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[25] L.D. Norton, X. Zhang, Liming to improve chemical and physical properties of soil, in: A. Wallace, R. Terry (Eds.), Handbook of Soil
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[26] W.L. Stout, J. Landa, A.N. Sharpley, Effectiveness of coal combustion by-products in controlling phosphorus export from soils, J. Environ. Qual. 29 (2000) 1239-1244.
[27] S.S. Bhattacharya, G.N. Chattopadhyay, Increasing bioavailability of phosphorus from fly ash through vermicomposting, J. Environ. Qual. 31 (2002) 2116-2119.
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[28] S.M. Pathan, T.D. Colmer, L.A.G. Aylmore, Properties of several fly ash materials in relation to use as soil amendments, J. Environ. Qual. 32 (2003) 687-693.
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[29] Urvashi, R.E. Masto, V.A. Selvi, L.C. Ram, N.K. Srivastava, An international study: Effect of farm manure on the release of phosphorus from fly ash, Remed. J. 17 (2007) 69-81.
[30] L.C. Ram, S.K. Jha, R.C. Tripathi, R.E. Masto, V.A. Selvi, Remediation of fly ash landfills through plantation, Remed. J. 18 (2008) 71-90.
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[31] I.C.R. Holford, Soil phosphorus: its measurement, and its uptake by plants, Aus. J. Soil Res. 35 (1997) 227-240. [32] J.K. Syers, A.E. Johnston, D. Curtin, Efficiency of soil and fertilizer phosphorus use, FAO Fert. Plant Nut. Bullet. 18 (2008). [33] F.W. Smith, The phosphate uptake mechanism, Plant Soil 245 (2002) 105-114. [34] B. Fuentes, N. Bolan, R. Naidu, M.L. Mora, Phosphorus in organic waste-soil systems, J. Soil Sci. Plant. Nutr. 6 (2006) 64-83.
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[36] P.M. Haygarth, L.M. Condron, A.L. Heathwaite, B.L. Turner, G.P. Harris, The phosphorus transfer continuum: Linking source to impact with an interdisciplinary and multi-scaled approach, Sci. Total Environ. 344 (2005) 5-14. [37] R.L. Parfitt, G.W. Yeates, D.J. Ross, A.D. Mackay, P.J. Budding, Relationships between soil biota, nitrogen and phosphorus availability, and pasture growth under organic and conventional management, Appl. Soil. Ecol. 28 (2005) 1-13.
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[38] W.M.H. Saunders, Phosphate retention by New Zealand soils and its relationship to free sesquioxides, organic matter, and other soil properties, New Zeal. J. Agr. Res. 8 (1965) 30-57.
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[39] G.E. Rayment, F.R. Higginson, Australian laboratory handbook of soil and water chemical methods, Inkata Press Pty Ltd, 1992. [40] S.R. Olsen, C.V. Cole, F.S. Watanabe, L.A. Dean, Estimation of available phosphorus in soils by extraction with sodium bicarbonate, USDA Washington, DC, 1954.
31-36.
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[41] J. Murphy, J.P. Riley, A modified single solution method for the determination of phosphate in natural waters, Anal. Chim. Acta 27 (1962)
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[45] G.Y. Zhang, Z. Dou, J.D. Toth, J. Ferguson, Use of flyash as environmental and agronomic amendments, Environ. Geochem. Health 26
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[48] K.M. Lai, D.Y. Ye, J.W.C. Wong, Enzyme activities in a sandy soil amended with sewage sludge and coal fly ash, Water Air Soil Pollut.
[49] G.S. Toor, G.S. Bahl, Effect of solitary and integrated use of poultry manure and fertilizer phosphorus on the dynamics of P availability in
Ac
different soils, Biores. Technol. 62 (1997) 25-28.
[50] P.A. Moore, D.R. Edwards, Long-term effects of poultry litter, alum-treated litter, and ammonium nitrate on phosphorus availability in soils, J. Environ. Qual. 36 (2007) 163-174. [51] J. Yang, Z. He, Y. Yang, P. Stoffella, X. Yang, D. Banks, S. Mishra, Use of amendments to reduce leaching loss of phosphorus and other nutrients from a sandy soil in Florida, Environ. Sci. Pollut. Res. 14 (2007) 266-269.
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[52] J.S. Rowarthr, A.G. Gillingham, Effects of withholding fertiliser on pasture production and ljhosphate cycling in hill country, in: Proc. New Zeal. Grassland Assoc. pp. 17-20.
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[53] E. Frossard, S. Sinaj, L.M. Zhang, J.L. Morel, The fate of sludge phosphorus in soil-plant systems, Soil Sci. Soc. Am. J. 60 (1996) 12481253.
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[55] T. Krogstad, T.A. Sogn, Å. Asdal, A. Sæbø, Influence of chemically and biologically stabilized sewage sludge on plant-available phosphorous in soil, Ecol. Eng. 25 (2005) 51-60.
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[56] S. Yu, Z.L. He, P.J. Stoffella, D.V. Calvert, X.E. Yang, D.J. Banks, V.C. Baligar, Surface runoff phosphorus (P) loss in relation to
Ac
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Page 27 of 42
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Table 2. Effect of CCPs on the pH of P treated soils.
M an
Table 1. Chemical characterisation of soils, CCPs and P sources used
us
List of tables
Ac
ce pt
ed
Table 3. Effect of FBC on the relative agronomic effectiveness of various P treatments in sunflower and mustard plants
Page 28 of 42
ip t cr PRC
CCE
(mg kg-1)
(%)
(%)
pH
Total elemental concentration (mg kg-1)
M an
Samples
Olsen P
us
Table 1. Chemical characterisation of soils, CCPs and P sources used
P
Ca
Fe
Al
34.12±3.62
52.02±4.16
16364.53±45.12
19474.83±49.12
5.65±0.29
3.82±0.09
23.4
-
KPD
7.14±0.42
9.62±0.34
7.43
-
48.41±9.89
5996.13±29.67
18174.36±35.11
25865.69±51.45
SLB
8.74±0.04
19.42±0.02
7.41
-
35.43±4.56
97.06±5.38
18276.82±196.47
14572.73±23.55
FA
10.23±0.17
17.11±8.23
-
16.75
507.33±18.38
18035.33±51.52
121343.94±185.54
25170.92±50.77
FBC
12.72±0.12
11.52±1.62
-
23.25
154.31±3.75
49675.84±76.18
157621.11±173.15
34015.43±57.72
FGD
10.14±0.07
2.25±0.93
-
11.25
623.84±12.38
220804.44±196.12
2530.62±23.66
1164.77 ±14.45
PP
-
-
-
-
227621.21±199.23
-
-
-
PM
5.12±0.23
-
-
-
147834.63±171.17
50541.63±22.71
24892.19±19.62
43514.62±21.12
PR
6.81±0.36
-
-
-
108712.41±139.12
85623.57±39.27
59914.37±23.71
74311.33±26.83
Ac
ce pt
ed
ADL
Page 29 of 42
ip t -
-
-
94741.84 ±108.11
BS
6.64±0.01
21.67±0.03
-
-
7823.91±81.62
cr
6.12±0.02
-
us
SSP
-
-
-
-
-
M an
ADL – Adelaide hills; KPD – Kapunda; SLB – Salisbury; FA – Fly ash; FBC – Fluidised bed combustion ash; FGD – Flue gas desulphurisation gypsum; PP – Potassium dihydrogen phosphate; PM – Poultry manure; PR – Phosphate rock; SSP – Single super phosphate; BS – Biosolid; PRC
Ac
ce pt
ed
– Phosphorus retention capacity; CCE – Calicum carbonate equivalence.
Page 30 of 42
1
Table 2. Effect of CCPs on the pH of P treated soils.
No CCPs
FA
FBC
FGD
Treatments KPD
ADL
KPD
ADL
KPD
ADL
5.65±0.29 7.14±0.42 6.76±0.33 7.82±0.17 7.02±0.32 8.06±0.05 6.02±0.31 7.63±0.26
PP
5.89±0.31 7.31±0.11 6.91±0.11 7.99±0.24 7.19±0.37 8.22±0.09 6.23±0.15 7.92±0.21
PM
5.43±0.28 7.09±0.31 6.66±0.25 7.77±0.25 6.92±0.04 7.91±0.41 5.97±0.14 7.82±0.19
PR
5.67±0.21 7.16±0.34 6.84±0.08 7.83±0.08 7.11±0.16 8.01±0.11 6.08±0.26 7.76±0.12
an
us
cr
No P
ADL – Adelaide hills; KPD – Kapunda; FA – Fly ash; FBC – Fluidised bed combustion ash;
3
FGD – Flue gas desulphurisation gypsum; PP – Potassium dihydrogen phosphate; PM – Poultry
4
manure; PR – Phosphate rock; CCPs – Coal combustion products
Ac ce p
te
d
M
2
5
KPD
ip t
ADL
31 Page 31 of 42
5
Table 3. Effect of FBC on the relative agronomic effectiveness of various P treatments fin
7
sunflower and mustard plants
ip t
6
Relative agronomic effectiveness (RAE %)
Fresh
application
effect
application
cr
Residual
Residual effect
0
0
100
100
200
39
211
328
31
330
462
62
481
0
SSP alone
100
100
BS alone
52
SSP+FBC
45
BS+FBC
88
an
0
d
FBC – Fluidised bed combustion ash; SSP – Single super phosphate; BS – Biosolids
te
9
Fresh
Ac ce p
8
Mustard
M
Nil
Sunflower
us
Treatments
32 Page 32 of 42
Figure 1.
11
Figure 2.
13
PM and PR. Figure 4.
17 18
Figure 5.
Figure 6.
24 25 26 27
Effect of FBC on cumulative (first and second crops) biomass yields for PP and PM treatments.
Ac ce p
23
Effect of FBC on biomass yields in PP and PM treated ADL soils grown with mustard plants under leached and unleached conditions – first and second crops.
21 22
Cumulatively leached P as affected by FBC in first and second crops of mustard plants grown in ADL soil.
19 20
Effect of CCPs on Bioavailable P values of a. ADL and b. KPD soils, treated with PP,
us
Figure 3.
cr
PP, b. PM and c. PR treatments.
15 16
Distribution of P fractions in Kapunda (KPD) soil, amended with CCPs (w/w) for a.
an
14
ip t
for a. PP, b. PM and c. PR treatments.
M
12
Distribution of P fractions in Adelaide hills (ADL) soil, amended with CCPs (w/w)
d
10
List of figures
te
9
Figure 7. Effect of FBC on the biomass yields of a. sunflower and b. mustard plants, and their relative yield increases.
Figure 8.
Relationship between Olsen P and P uptake as affected by the treatment combinations (Nil, SSP alone, BS alone, SSP+FBC and BS+FBC) in both sunflower and mustard plants (n=10).
Figure 9.
Relationship between phosphatase activity and Olsen P in the SLB soil as affected by
28
the treatment combinations (Nil, SSP alone, BS alone, SSP+FBC and BS+FBC) in
29
both sunflower and mustard plants (n=10).
33 Page 33 of 42
Fig-1
1
Figure 1 Distribution of P fractions in Adelaide hills (ADL) soil, amended with CCPs (w/w)
us
cr
ip t
for a. PP, b. PM and c. PR treatments.
Ac ce p
te
d
M
an
a.
b.
c.
Page 34 of 42
Fig-2
1
Figure 2 Distribution of P fractions in Kapunda (KPD) soil, amended with CCPs (w/w) for
us
cr
ip t
a. PP, b. PM and c. PR treatments.
Ac ce p
te
d
M
an
a.
b.
c.
Page 35 of 42
Fig-3
1
Figure 3 Effect of CCPs on bioavailable P values of a. ADL and b. KPD soils, treated with
an
us
cr
ip t
PP, PM and PR.
Ac ce p
te
d
M
a.
b.
Page 36 of 42
Fig-4
1
Figure 4 Cumulatively leached P as affected by FBC in first and second crops of mustard
Ac ce p
te
d
M
an
us
cr
ip t
plants grown in ADL soil.
Page 37 of 42
Fig-5
1
Figure 5 Effect of FBC on biomass yields in PP and PM treated ADL soils grown with mustard plants under leached and unleached conditions – first and second crops. 12
Leached
ip t
Unleached
cr
8
us
6
2 0 0 200 0 200
FBC-
FBC-
FBC+
FBC+
Second crop
0 200 0 200
0 200 0 200
FBC-
FBC-
FBC+
First crop
FBC+
Second crop PM
te
PP
d
First crop
M
0 200 0 200
an
4
Ac ce p
Biomass yield (g pot-1)
10
Page 38 of 42
Fig-6
1
Figure 6 Effect of FBC on cumulative (first and second crops) biomass yields for PP and PM treatments.
FBC+
ip t
FBC-
20
cr
15
us
10 5 0 Unleached
Leached
Unleached
Leached PM
Ac ce p
te
d
M
PP
an
Cumulative biomass yields (g pot-1)
25
Page 39 of 42
Fig-7
1
Figure 7 Effect of FBC on the biomass yields of a. sunflower and b. mustard plants, and
M
an
us
cr
ip t
their relative yield increases.
Ac ce p
te
d
a.
b.
Page 40 of 42
Fig-8
1
Figure 8 Relationship between Olsen P and P uptake as affected by the treatment combinations (Nil, SSP alone, BS alone, SSP+FBC and BS+FBC) in both sunflower and
Ac ce p
te
d
M
an
us
cr
ip t
mustard plants (n=10).
Page 41 of 42
Fig-9
1
Figure 9 Relationship between phosphatase activity and Olsen P in the SLB soil as affected by the treatment combinations (Nil, SSP alone, BS alone, SSP+FBC and BS+FBC) in both
Ac ce p
te
d
M
an
us
cr
ip t
sunflower and mustard plants (n=10).
Page 42 of 42