The effects of lime on adsorption and desorption of phosphate in five Colombian soils

Abstract

The effects of lime (applied in the field) on the amounts of total and isotopically-exchangeable phosphate adsorbed from solutions were measured in five soils. The total amount of phosphate adsorbed without lime was in the range 200 to 1700 pg P per g of soil at 0.05 pg P cm-3 of solution. Lime diminished the amount of phosphate adsorbed at all concentrations of solution in an oxisol and a dystropept; in an ultisol and another dystropept, lime tended to increase sorption at small concentrations and diminish it at large concentrations; in a dystrandept that contained spheroidal allophane and a great deal of organic matter, lime increased adsorption at all concentrations up to I pg P ~n -~. Lime increased the proportion of added phosphate that was isotopically exchangeable in the oxisol and one dystropept, had no effect in the other dystropept, and diminished the proportion in the ultisol and dystrandept.Adsorbed phosphate was subsequently desorbed by suspending the soils in solutions without phosphate. After desorption the quantity of exchangeable phosphate in all soils was closely correlated with aluminium extracted by ammonium oxalate; buffer power was correlated in all except the dystrandept, in which it was larger per unit of aluminium than in the other soils; possibly the cause was aluminium associated with organic matter. In all soils lime diminished buffer power allowing a specific amount of exchangeable phosphate to maintain a larger concentration in solution. The beneficial effects of lime on exchangeable phosphate after desorption were consistent among soils, despite inconsistent results when the phosphate was adsorbed.

Comparative Effects of Soil Amendments on Phosphorus Use and Agronomic Efficiencies of Two Maize Hybrids in Acidic Soils of Molo County, Kenya

“…Rowell [50] reported that P in the MPR is available in the first season after application but remains over long periods of time hence their residual effects. This has also been reported by other workers [76,77,78,79,80]. In terms of improving the soil P status, rock phosphates have both immediate and residual effects [1].…”

Simulating phosphorus responses in annual crops using APSIM: model evaluation on contrasting soil types

“…Air-dried soil (0-15 cm) had a pH of 5.3 (1:2.5 soil:water); organic carbon 105 g kg -1 ; exchangeable calcium 3.05 cmol c kg -1 , magnesium 0.96 cmol c kg -1 , potassium 0.28 cmol c kg -1 ; bicarbonate-EDTA extractable phosphorus 1.27 mg kg -1 . P sorption is very high; based on sorption isotherms, 1,000 mg P kg -1 of soil was required to raise soil solution P to 0.2 mg l -1 for 0-15 cm soil (Le Mare and Leon 1989).…”

Some Unique Properties of Andisols that Influence Interpretations for Use and Management and Their Comparison with Certain Soils Formed in Loess

“…Thus, adsorption and desorption of cations and anions is influenced by soil pH (McBride, 1989). The change of a soil pH by the addition of a basic soil amendment (lime) or by use of an acidifying fertilizer (ammonium) or any management practice that changes the soil pH effectively changes the cation exchange capacity (CEC) and anion exchange capacity (AEC) of certain soils (Wright et al, 1989; Le Mare and Leon, 1989). Some colloids have a point of zero charge (PZC) (Wada, 1989).…”