Effect of two moisture regimes on P-release from P treated soils

Abstract

ABSTRACTUnderstanding phosphorus (P) release under different climatic or moisture regimes will facilitate effective management of plant nutrition. The objective of this study is to evaluate the effect of two soil moisture regimes on P release from Ogun rock phosphate (ORP) and Sokoto rock phosphate (SRP) in two soil types. Soil was poured into soil columns to form lower and top layers. Top layer was mixed with 400 kg ha−1 P from ORP, SRP, single super phosphate (SSP) and leached with 35.4 cm3 water representing low moisture regime (LMR; 400 mm rainfall) and 106.1 cm3 water for high moisture regime (HMR; 1200 mm rainfall). P concentrations of leachates, available P in soil and soil pH were determined. Cumulative P leached was higher under HMR than LMR in both soils. There was more leaching with SSP (0.41–0.97 mg P) than both phosphate rocks (0.008–0.19 mg P) indicating leaching potential of SSP. Cumulative P leached from SSP treated Olokemeji soils was twice that of acidic Sapoba under LMR while they were similar (Olokemeji, 0.97 mg P; Sapoba, 0.94 mg P) under HMR suggesting that LMR enhances fixation of P in acidic soils. Irrigation of P fertilized soils may reduce P sorption in acidic soils.