Effect of rice husk Biochar (RHB) on some of chemical properties of an acidic soil and the absorption of some nutrients

The purpose of this study is to evaluate the biochemical effects of rice husk biochar (RHB) obtained from pyrolysis of rice husk under limited oxygen conditions for three hours at temperature of 500 °C. Then, the effect of addition of 2 and 4% biochar to acidic soil was studied. The samples were stored in greenhouse conditions for three months, and then soil characteristics including pH, electrical conductivity, cation exchange capacity and organic carbon content, potassium forms and total nitrogen content of soil were measured. The results showed that RHB caused a significant increase in soil pH. RHB also increased significantly the organic carbon content and electrical conductivity. Soluble, exchangeable and non-exchangable potassium were affected by the addition of RHB. RHB caused 5-fold increased soluble potassium. The exchange rate of potassium increased from 76 mg / kg, with a RHB of 2% to 112 mg / kg with a 4% RHB application. Non- exchangable potassium also increased from 290 in control to 532 mg / kg in 4% RHB. The usability of nitrogen and phosphorus was not affected by biochar. Considering the significant increase in the amounts of different forms of potassium and considering the lack of potassium in some acidic soils of Mazandaran province, we can consider the use of biochar as a source of potassium in soil fertility management