Analysis of Economic and Environmental Benefits of Agricultural Straw Preparation for Biochar Returned to the Field: A Case Study at the County Scale in China

Abstract

Through field investigations and field experiments under different modes, the local cost composition and sources of income of agricultural straw carbonization and returning to the field in Xiangfen County, China, were analyzed, and an economic evaluation was carried out. The results showed that the preparation cost of biochar at the county scale was ¥ 1107/t, and it could be reduced to ¥ 507/t after excluding the straw cost. When considering only the income from yield increase, it is difficult to achieve profitability in both the mode of returning the field in batches with equal amounts and the mode of returning the field with a large dose at one time. However, when considering the combined income from yield increase, carbon sequestration, and emission reduction, the annual profit could reach up to ¥ 269/ha. If the straw is owned by farmers (the straw cost is not included), the highest annual income can reach ¥ 1241/ha. Although the upfront cost of agricultural straw carbonization and returning to the field is relatively high, in the long run, it has significant environmental benefits and economic potential in terms of increasing yields, sequestering carbon and reducing the use of chemical fertilizers.