Effect of biochar on physicochemical properties of red and yellow brown soils in the South China Region

Biochar is a key by-product of chemical processes with a huge potential for application in environmental and soil science studies. In recent years, biochar has received considerable attention as soil conditioner, fertilizer carrier and carbon sequestration agent. However, the role of biochar in improving the fertility of different soil types has remained unclear. This has especially been the cause for the red and yellow brown soils in the South China Region (SCR), where any such studies have been largely lacking. In this study, biochar from peanut shells was used to determine biochar effect on different soils. In the pot experiment, the dynamics of the physicochemical properties of the two representative soils (red and yellow brown soils) in the SCR were investigated after treatments with different doses (0, 0.5%, 1.0% and 2.0%) of biochar. The results showed that red soil was strongly acidic, but the acidity significantly reduced under treatments of different doses of biochar. Furthermore, biochar increased soil organic matter, available phosphorus, available potassium and alkaline hydrolyzed nitrogen contents. With increasing biochar dose, these influence became more obvious. Yellow brown soil was weakly acidic. Biochar treatments significantly improved pH, and contents of organic matter, available phosphorus and available potassium of yellow brown soil. Also increasing biochar dose enhanced the positive effects of biochar on yellow brown soil. However, different biochar doses resulted in different effects on physicochemical properties of the two soils. At 2% of biochar aplication dose, the impact of biochar on the physicochemical properties of the two soils was most obvious. For the red soil, pH increased by 0.61. Also organic matter, available phosphorus, available potassium, and alkaline hydrolyzed nitrogen increased by 203.4%, 369.3%, 368.0% and 30.4%, respectively, in red soil. In addition to alkaline hydrolyzed nitrogen, pH, organic matter, available phosphorus, and available potassium respectively increased by 0.55, 124.2%, 57.5% and 50.3% in yellow brown soil. Based on the above results, it was concluded that biochar application favored red soil more than yellow brown soil in the SCR. Moreover, complex specific data on each index suggested that biochar application most influenced soil available potassium, followed by soil organic matter, pH, available phosphorus, and alkaline hydrolyzed nitrogen in the representative soil types in SCR.