The Effect of Phosphate Applications on the Diffusion Coefficients and Available Phosphate in an Acid Soil

Kunishi, H. M.; Taylor, A. W.

doi:10.1111/j.1365-2389.1975.tb01951.x

Cited by 7 publications

(8 citation statements)

References 13 publications

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“…The best simulation was obtained with a P diffusion coefficient of 0.0025 cm 2 h -1 , which is equivalent to 6.94 × 10 -7 cm 2 s -1 . This is much lower than the diffusion coefficient of P in water, mainly because of the tortuosity of the diffusion path, but higher than the apparent diffusion coefficients of P estimated in literature for most soils (Kunishi and Taylor 1975;Eghball et al 1990;Bhadoria et al 1991;Villani et al 1998). This is mainly because the diffusion coefficient in this model does not reflect the retardation due to precipitation and adsorption reactions, since the effects of such reactions are explicitly accounted for in the model.…”

Section: Model Simulation Of Cation and Anion Profilesmentioning

confidence: 73%

Phosphorus diffusion from monocalcium phosphate co-applied with salts in a calcareous soil

Kumaragamage¹,

Akinremi²,

Cho³

et al. 2004

Can. J. Soil. Sci.

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. 2004. Phosphorus diffusion from monocalcium phosphate coapplied with salts in a calcareous soil. Can. J. Soil Sci. 84: 447-458. Mixing non-phosphatic salts with fertilizer P influences the solubility and mobility of P in soils. Little evidence, however, is available regarding the mechanisms causing such effects. The objectives of this study were to investigate the effects of mixing fertilizer P with (NH 4 ) 2 SO 4 , MgSO 4 or (NH 2 ) 2 CO on the diffusion of P in a calcareous soil (Gleyed Rego Black Chernozem), and to identify the causes for such effects. To the surface of 50-mm-long soil columns, maintained at field capacity water content, 32 P-labelled monocalcium phosphate (MCP) was applied alone or in combination with (NH 4 ) 2 SO 4 , MgSO 4 or (NH 2 ) 2 CO. Ratios of applied P:N, P:Mg and P:S were 1:5, 1:4.5 and 1:6, respectively. Extraction and analysis of each 2-mm layer of the columns after incubation for 1, 2, 3, and 4 wk revealed that the addition of (NH 4 ) 2 SO 4 and MgSO 4 with MCP significantly increased P diffusion whereas (NH 2 ) 2 CO had little or no effect. The mechanisms of such effects were identified using a multi-ionic, mechanistic, diffusion model. According to model predictions, the dissolution of MCP was increased by more than twofold when mixed with (NH 4 ) 2 SO 4 and MgSO 4 , and by 1.2-fold when mixed with urea. The main difference between SO 4 salts and urea in affecting P diffusion was the competition between the anion of the salt and P for precipitation with Ca. Sulphate competed strongly with P, reducing the precipitation of Ca phosphates. Application of urea increased soil pH initially, but eventually soil pH decreased with nitrification of NH 4 . Initial increase in pH to above 8.0 favoured precipitation of Ca phosphate, but the pH was not high enough to favour CaCO 3 precipitation. The application of P fertilizers with fertilizers containing SO 4 could be beneficial in calcareous soils due to enhancement of P solubility and mobility. Mélanger des sels non phosphatés à un engrais phosphaté (P) modifie la solubilité et la mobilité du P dans le sol. Toutefois, on sait peu de choses sur les mécanismes à l'origine de ce phénomène. L'étude devait préciser comment le fait de mélanger un engrais P avec du (NH 4 ) 2 SO 4 , du MgSO 4 ou du (NH 2 ) 2 CO agit sur la diffusion du P dans un sol calcaire (tchernoziom noir gléyifié Rego) et établir les causes des modifications observées. À cette fin, les auteurs ont appliqué du phosphate monocalcique (PMC) marqué au 32 P avec ou sans (NH 4 ) 2 SO 4 , MgSO 4 ou (NH 2 ) 2 CO au sommet de colonnes de sol de 50 mm de hauteur dont la teneur en eau était maintenue à la capacité maximale du terrain. Les ratios appliqués étaient respectivement de 1:5, 1:4,5 et 1:6 pour P:N, P:Mg et P:S. Après incubation pendant 1, 2, 3 ou 4 semaines, l'extraction et l'analyse de chaque tranche de 2 mm des colonnes révèle que l'addition de (NH 4 ) 2 SO 4 et de MgSO 4 au PMC accroît sensiblement la diffusion du P alors que le (NH 2 ) 2 CO n'a pas d'effet sur ce phénom...

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Section: Model Simulation Of Cation and Anion Profilesmentioning

confidence: 73%

Phosphorus diffusion from monocalcium phosphate co-applied with salts in a calcareous soil

Kumaragamage¹,

Akinremi²,

Cho³

et al. 2004

Can. J. Soil. Sci.

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“…It is obvious, however, that a relatively low surface layer is able to supply the runoff or flood water with P, because the diffusion of P in soil is very slow (LEWIS andQUIRK 1967, KUNISHI andTAYLOR 1975).…”

Section: Methodsmentioning

confidence: 99%

Watersoluble phosphorus in Finnish mineral soils and its dependence on soil properties

Hartikainen

1982

AFSci

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Abstract. Water soluble phosphorus ranged from 0.2 mg to 117.8 mg/kg in 104 surface soil samples studied. On the average, water extracted less P from the heavy clay soils (4.8 ± 2.2 mg/kg) than from the coarser clays (12.8 ± 4.6 mg/kg) and non-clay soils (13.3 + 7.2 mg/kg).Water extraction seemed to illustrate ''the effective" P status, it is that determined by the quantity and quality of sorption components in soil, soil pH and the content of organic carbon. These factors did not affect the amounts of P dissolved in water directly but inderectly by controlling the nature of P bonding which, in turn, seems to be of decisive importance in the extractability of P into water.The P supplying power of a given fraction is obviously controlled by the quantity of corresponding sorption agent. Water extractable P correlated most closely with the molar ratio of NH,F soluble P to oxalate extractable A 1 (r=o.93***, n= 103). However, according to the theory presented, with progressing desorption, P starts to mobilize also from the NaOH soluble fraction, its significance being the more apparent the greater the corresponding molar ratio NaOH-P/Fe is. In addition, the role and significance of other inorganic P fractions were discussed.

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“…Plant-available or 'labile' soil P was measured in terms of that extractable by anionic resin (Kunishi and Taylor, 1975). A 0.75 g soil sample (<60 mesh) was suspended in 10-ml water with 3.0g Dowex 21K (20-50 mesh, chloride form) anion exchange resin and gently stirred for 16 h. The resin was separated with a 60-mesh sieve, transferred to a 50-ml burette, and eluted with 5 0 m l of 0.25 M Na2SO4.…”

Section: Methodsmentioning

confidence: 99%

Interpretation of Phosphorus Uptake by Barley From Acid Soils Using a Diffusion Model

Kunishi

Taylor

Vickers

1979

Journal of Soil Science

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Phosphorus uptake by barley @er cent of dry tissue) grown on four acid soils each treated with four amounts of lime and P, correlated equally well with EPC (equilibrium P concentration = concentration of P supported in solution at field capacity) and with diffusion supply of P to root cylinder surfaces calculated from the soil indices including EPC, a soil capacity factor maintaining that concentration, and a diffusion coefficient.Calculated rates of P supplied by diffusion to primary root cylinder surfaces were too low to account for P found in plants. If the remainder of the observed P uptake was assigned to root hairs, the ratios of calculated root hair surface area to estimated root cylinder surface areas necessary to account for the difference were in reasonable agreement with ratios for barley reported by other workers. IntroductionPLANT P uptake has been empirically correlated with soil P in solution, with labile P content of soil, and with the P buffering capacity (the ratio between labile P and solution P) of soil (CUMV and Sutton, 1967, Ozanne and Shaw, 1968;Dalal and Hallsworth, 1976;Holford and Mattingly, 1976). In a theoretical analysis of the factors controlling P uptake, Olsen et al. (1962; 1963; 1965; 1968) derived an equation for the diffusion rate of P through soil to the root surfaces. Applying this equation to calcareous soils, they predicted the minimum solution P concentration that would allow plants to take up P at a rate reportedly optimal for good growth. Their equation included the soil diffusion coefficient, the soil buffering capacity to replenish solution P, and the P-concentration difference between soil solution and root surface. Using the same variables, Brewster et al. (1977) simulated Pdelivery to plant roots by diffusion processes.We tested the applicability of this equation to four acid soils from southeastern U. S. These soils are rich in kaolinite, differ widely in their concentrations of A1 and Fe oxides and have a more complex P chemistry than calcareous soils. We measured P uptake by barley and tested the correlations of per cent P in barley values with Equilibrium P concentrations (EPC = Concentration of P supported in solution at field capacity) and the amount of diffusible P calculated from measured soil indices. These were compared with estimates from the plant -uptake data.

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The Effect of Phosphate Applications on the Diffusion Coefficients and Available Phosphate in an Acid Soil

Cited by 7 publications

References 13 publications

Phosphorus diffusion from monocalcium phosphate co-applied with salts in a calcareous soil

Phosphorus diffusion from monocalcium phosphate co-applied with salts in a calcareous soil

Watersoluble phosphorus in Finnish mineral soils and its dependence on soil properties

Interpretation of Phosphorus Uptake by Barley From Acid Soils Using a Diffusion Model

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