Improvement in soil properties and soil water content due to the application of rice husk biochar and straw compost in tropical upland

Purpose Rice biomass waste can be used as a soil amendment. This study examined the effect of the application of rice husk biochar and straw compost on several soil properties and yields of rice and soybeans in tropical upland.Method Field experiments were carried out with two applications of rice husk biochar and straw compost on upland rice and soybean cultivation, respectively. Three-levels of rice husk biochar application (5, 10, and 20 t ha-1) and straw compost (5 t ha-1) along with the control. The changes in soil chemical properties like pH, C, N, CEC, P, K, Mg, Ca, Na, and physical properties including soil bulk density, particle density, total porosity, ma-cropores, micropores, permeability, and soil water content at various pressures were measured. The grain yields of rice and soybean were also recorded.Results Total-C and exchangeable-K increased after the second application of rice husk biochar and straw com-post. There was a significant improvement in total porosity and micro-pores, soil water content especially at PF 2.54 (0.33 Pa) and PF 4.2 (15 Pa), and increased soybean yield compared to control. Based on the overall results, we got a significant effect of rice husk biochar at higher doses (10 and 20 t ha-1).Conclusion The application of rice husk biochar (at doses 10 or 20 t ha-1) and straw compost 5 t ha-1 gave a positive effect on several soil properties including total-C, soil porosity, and soil water content, especially at pF 2.54 and pF 4.2, and also increased soybean yields.