Amelioration Technology for Agricultural Efficiency: Biochar and Compost Amendments for Soil sustainability

Background

Soil amendment with biochar can be proposed as a means to sequester C and improve soil fertility. Application of charcoal to soils is hypothesized to increase bio-available water, build soil organic matter, enhance nutrient cycling, lower bulk density, act as a liming agent and reduce leaching of pesticides and nutrients to surface and ground water. Leach et al. (2010) also documented that application of biochar to the soil enabling increases in agricultural productivity without, or with much reduced, applications of inorganic fertilizer. Furthermore, Harley (2010) indicted that biochar is a promising amendment for ameliorating drastically disturbed soils due to its microchemical, nutrient, and biological properties. Biochar-based strategies are thus being seen to offer valuable routes to building sustainable agricultural futures, particularly for resource poor farmers for whom soil fertility and water availability are seen as key constraints on crop production and food security. The extent of the effect of biochar on crop productivity and soil carbon sequestration is, however, variable due mainly to the different biophysical interactions and processes that occur when biochar is applied to soil, which are not yet fully understood (Sohi et al.,2009). For instance, in nitrogen limited soils, application of high rates of biochar may affect growth negatively due to immobilization effect (Lehmann et al., 2006). Moreover, feedstock and pyrolysis conditions (temperature, holding time, etc.) may affect both stability and nutrient content and availability of biochar (Novak et al., 2009).