Agricultural Applications of Biochar

Abstract

Biochar is a promising soil amendment for persistently enhancing soil health and crop productivity. This chapter aims to summarize the desirable effects of biochar amendment on the physical, chemical, and biological health of soil and recommend appropriate agricultural biochar application programs. Intensive literature review indicates that biochar amendment ameliorates agricultural soils by reducing soil bulk density, compaction, acidity, and nutrient leaching while improving soil porosity, water and nutrient retention, and microbial activity and structure. Differently sourced biochar products vary significantly in physiochemical characteristics and soil health enhancement capabilities. The 3R principles (right biochar source, right application rate, and right soil placement) need to be strictly followed in agricultural biochar applications to attain the optimal, long-term benefits. Biochars in small particles with pH more than 7.0, organic carbon (OC) content more than 30%, and molar H/OC less than 0.7 should be preferentially selected and applied with priority to cropland with acidic, less productive soils. Effective application rates of biochar are soil specific, ranging from 40 to 100 t ha−1 in single or cumulative applications. Land application of biochar should be carried out by evenly broadcasting the moistened material to the field under low-wind weather conditions followed by immediate incorporation of the applied biochar in the soil through multi-round tillage.