Improving potassium (K) retention in acidic soil by amending muriate of potash fertilizer with rice straw biochar

Potassium (K) in the tropical acid soil is prone to extensive leaching during intense rainfall due to the high mobility of K in soil. Due to the low retention capacity and K availability in the soil, farmers tend to apply excessive K fertilizer to attain higher yield and saturate K in the soil. The objective of this study were (1) To sample and characterize selected physic-chemical properties of soil sample to be used in laboratory leaching of Potassium (K) study (2) To characterize the selected chemical properties of rice straw biochar (3) To determine the effect of amending MOP with rice straw biochar at different rates on K retention in soil and selected chemical properties of soil. A leaching experiment to assess the effect of K fertilizer amended with difference rates of rice straw biochar on the K leaching and retention in soil, was carried out for 30 days. Leachate was collected every 3 days and analysed for K content. Soil sample were collected after the leaching study stopped to determine the amount of K retained in the soil after leaching. Treatments with rice straw biochar application were able to improve the K retention in the soil. Application rate of 15-20 t/ha of rice straw biochar was found to provided better retention K in the soil. The treatment with rice straw application also decreased to the soil acidic by raising the soil pl l to clear neutral. The indicates the potential of rice straw biochar in amending the chemical properties of acidic soil and reduce the K leaching for the soil after application of MOP fertilizer.