Assessment of Soil Phosphorus Sorption and Desorption Characteristic of Tropical Acid Soil Amended With Rice Straw Compost

Phosphorus is an essential crop macronutrient because of the relatively large amount of P required by plants. Application of organic amendment is highly recommended to minimize the phosphorus sorption in the acidic soils. The research examined changes in phosphorus sorption and desorption and compost pH buffering capacity. Thus, the objective of this study are to determine the changes in the soil phosphorus sorption and desorption upon application of rice straw compost and to determine the soil phosphorus maximum buffering capacity that is resistant to change in
phosphorus concentration of the soil of the labile solid phase. Rice straw compost was used and the sorption data were fitted to Langmuir equation. The result showed
phosphorus sorbed was decreased as the phosphorus concentration increased whereas phosphorus desorption increase significantly with increasing the phosphorus application rates (10 to 30 mg L ̄1). The sorption of phosphorus increase due to increase in soil organic matter which are highly negatively charged thus cause the precipitation of exchangeable aluminium and iron in soil. Besides, high pH buffering capacity of compost was reported in this study. This was due to increase cation exchangeable
capacity thus can help in increasing the pH of acidic soil. Amendment of rice straw compost with soil can repay for phosphorus losses in soil through leaching of tropical
acid soil by increase phosphorus availability and reduced phosphorus fixation.