Phosphate adsorption by soils 1. Influence of time and ionic environment on phosphate adsorption

Rājan, S. S. S.; Fox, R. L.

doi:10.1080/00103627209366406

Cited by 52 publications

(17 citation statements)

References 17 publications

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“…Three grams of airdried soil that passed a 2-mm sieve were equilibrated in 50-mL plastic centrifuge tubes with 30-mL KH 2 PO 4 solution containing 0, 2.5, 5, 10, and 20 mg P per liter for 6 days. An electrolyte concentration of 0.01 M CaCl 2 was selected to represent the soil solution environment of tropical soils with low ion exchange capacity (Rajan and Fox, 1972). Two drops of toluene was added in each sample.…”

Section: P Sorption Curvesmentioning

confidence: 99%

A Survey of Soil Fertility Status of Four Agroecological Zones of Mozambique

Maria¹,

Yost²

2006

Soil Science

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Mozambique includes 10 agroecological zones with distinct climate and cropping systems (INIA, 1980). Agricultural production is more intensively practiced in the central and northern parts of the country where agroecological conditions are favorable. As a result of 16 years of civil war and low funding for agricultural research few assessments of soil nutrient status have been possible. To assess soil nutrient status, four agriculturally promising agroecological zones were selected for a survey. Sixty-two sites were sampled, and composite samples of surface and subsurface soils were taken and analyzed for properties considered critical for the production of food crops. The sample points were recorded with a differential global position system and mapped. The results indicate that most of the soils are low in effective cation exchange capacity, moderate in organic matter, moderate to strongly acidic, moderately weathered, and moderate to high in P sorption capacity. In general, these soils can be classified as having low to moderate fertility. Findings of this study indicate limitations of the existing map of soil resources of Mozambique. The results of this study suggest that additional sampling and soil survey will be required to improve the quality of soil surveys for site-specific applications. A site-specific soil survey is recommended that would provide additional information on soil resources and would greatly improve the current soil map that has an inadequate soil database. Furthermore, calibration and correlation studies are recommended for better decisions on soil nutrient management for ensuring food security. (Soil Science 2006;171:902-914)

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Section: P Sorption Curvesmentioning

confidence: 99%

A Survey of Soil Fertility Status of Four Agroecological Zones of Mozambique

Maria¹,

Yost²

2006

Soil Science

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“…Over time, P initially adsorbed on easily accessible surfaces diffuses further into the soil pores (Rajan and Fox 1972) and gets out of the reach of soil organisms. Upon ageing, bonding of P onto the oxide surfaces also becomes stronger (Kaila 1965) as monodentate bonds are converted to bidentate and binuclear ones (Kafkafi et al 1967).…”

Section: P Stock and P Supply To Plantsmentioning

confidence: 99%

Fate of Fertilizer P in Soils: Inorganic Pathway

Yli‐Halla

2016

Phosphorus in Agriculture: 100 % Zero

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Soils never fertilized with P have usually a low P concentration (<0.02 mg l −1 ) in soil solution, which is below the crop needs. In acid soils, added P is adsorbed on the surfaces of iron and aluminum (hydr)oxides or, in calcareous soils, predominantly precipitated as calcium phosphates. Abundant organic and inorganic P fertilization in the industrial world has elevated the P status of agricultural soils and the large P surplus remains at least partly available to plants. In acidic soils Degree of P Saturation (DPS) can be used to indicate to which extent the potential sites for P sorption are already occupied. Repeated P applications increase the DPS and decreases P retention, and in calcareous soils, relatively easily soluble calcium phosphates are accumulated. Abundant residual fertilizer P results in a higher P concentration in soil solution. P supplying power in such soils is sufficient to meet the crop needs for several years, even decades, with P additions equaling to or smaller than the crop P uptake and apparently 100 % utilization of fresh fertilizer P can be achieved.

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“…At the pH range of 5.0-6.0 the increase in P adsorption can be attributed to the formation of basic calcium phosphorus complex at the surface of col loid [44,[58][59] and to the formation of precipitates of these compounds in solution at pH values near neutral [60]. Calcium ion is specifically adsorbed on oxide and clay surfaces at pH values above 6.0, and it helps the adsorption of P by forming the surface complexes of basic calcium phosphorus at high concentrations of Ca 2+ [61][62], thus Ca 2+ fits in the cavity between two adjacent P ions and as a result reducing the electrostatic repulsion between the negatively charged ions, allowing more P to be adsorbed [24]. The results of the present study are in agreement with what have been intensively discussed by a number of researchers.…”

Section: +mentioning

confidence: 99%

Adsorption of Phosphorus by Modified Clay Mineral Waste Material Relating to Removal of it from Aquatic System

Jiang¹,

Su²,

Ruan

et al. 2014

IJEMA

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This study examined the application of modified clay mineral waste material (MCMWM) for removal of phosphorus (P) from aquatic systems including surface water and wastewater related to the application of recycled solid waste materials. The effects of ionic strength and pH on P adsorption by MCMWM were investigated at pH values of 3, 5, 6, 7 and 9 with P concentrations of 10, 20, 40, 100 and 200 mg/L in solution. The P adsorption was rapidly at the early stage with 95% of P in solution being adsorbed for 10 mg/L P in solution at a high pH range within 0.5 hr. The amount of P adsorbed increased with increasing ionic strength. The amount of P adsorbed increased continuously as pH values increased from 3 to 9 for P adsorption at 10 mg/L. Other series of P concentrations in solution showed variable trends due to the rates of P adsorption being affected by pH associated with the effect of ionic strength. The maximum amounts of P adsorbed and the highest percentages of P adsorbed were obtained at pH 9 for all levels of P concentrations, and at pH 7 for the lower P concentrations in solution. Calcium (Ca) ion was found to form a bridge for P adsorption in solution as the increases in the amount of P adsorbed at high pH values was related to the performance of Ca in favoring P to be adsorbed either onto the surfaces or incorporated into the structural bonds of MCMWM. Ionic strength, pH and modification process have been found to be the important factors that influenced P adsorption in solution.

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Phosphate adsorption by soils 1. Influence of time and ionic environment on phosphate adsorption

Cited by 52 publications

References 17 publications

A Survey of Soil Fertility Status of Four Agroecological Zones of Mozambique

A Survey of Soil Fertility Status of Four Agroecological Zones of Mozambique

Fate of Fertilizer P in Soils: Inorganic Pathway

Adsorption of Phosphorus by Modified Clay Mineral Waste Material Relating to Removal of it from Aquatic System

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