Phosphorus release kinetics of applied phosphate is influenced by time and organic sources in clay loam and sandy clay loam soils

Abstract

Adsorption and precipitation are major mechanisms that play an imperative role in immobilization of phosphorus (P) in various texture soils thus limiting the crop yields. Soil organic matter (SOM) can improve P bioavailability by decreasing its sorption in soils. The aim of current experiment was to investigate best organic source to reduce P sorption in different texture soils. Press mud (PM), farmyard manure (FYM), processed city waste (CW) and poultry litter (PL) were used to examine P availability in clay loam and sandy clay loam soils. Organic sources were added at the rate of 10 t ha-1 according to organic matter content in clay pots having 10 kg soil capacity. Phosphorus was added at the rate of 200 mg P kg-1 soil by using KH2PO4 and moisture was maintained at 60% water holding capacity. Results showed higher adsorption of P (122 mg kg-1) in clay loam soil as compared to the sandy clay loam (132 mg kg-1) soil. The Olsen P influenced by organic amendments was in the order of CW > PL > FYM > PM > control. There was a significant correlation between P released by organic sources with time and soil texture. It is concluded that application of CW is best regarding P release in different texture soils.

Keywords

• Phosphorus availability
• sorption
• manures
• soil textures