Availability and Transformations of Phosphorus in Calcareous Sandy Soil as Affected by Farmyard Manure and Elemental Sulfur Applications

An incubation experiment was conducted to study the effects of farmyard manure (FYM) and elemental sulfur (S) on availability, fractionation and transformation of phosphorus in calcareous sandy soil. Soil samples were treated with FYM at levels: 0 (FYM0), 2.5 (FYM1), 5 (FYM2) and 7.5 (FYM3) g pot^ -1 and S at levels: 0 (S0), 0.1 (S1), 0.2 (S2) and 0.3 (S3) g pot^ -1. The soil was incubated for ten weeks under field capacity conditions. Additions of FYM caused significant increases in the amount of available P (Olsen P) from 34.57 to 44.54 mg kg^ -1. The S with FYM application significantly increased Olsen P ofthis soil at S1FYM1 from 42.95 to 52.70 mg kg^ -1. Significant reduction in Olsen P was observed at S2 and S3 levels, but the addition of S at S1 level led to itsinsignificant increase. FYM application transformed HCl-Pi, NaOH II-Pi and residual P to NH4Cl-P, NaHCO3-Pi, NaHCO3-Po, NaOH I-Pi, NaOH I-Po and NaOH II-Po fractions. Application of S converted the NH4Cl-P, NaOH I-Pi and HCl-Pi fractions to NaHCO3-Pi, NaHCO3-Po, NaOH I-Po, NaOH II-Pi, NaOH II-Po and residual Pfractions. It s recommended adding FYM to calcareoussandy soils as well as adding S combined with FYM to improve the soil properties.