Assessment of Soil Organic Carbon Storage in Vegetable Farms Using Different Farming Practices in the Kanto Region of Japan

Agricultural fields can store substantial amounts of atmospheric carbon in the soil. In 2011, the Environmentally Friendly Farming Direct Payment Program (EFFDPP) began as a way to promote sustainable agriculture, but the approved methods for receiving the subsidy are limited to the use of manure and cover crops. For evaluating other options for the EFFDPP, we calculated soil carbon inputs and CO2 emissions in four nature farming (NF) systems for comparisons with conventional farming (CF) and environmentally friendly farming (EF) systems. In 2015, we collected data on farm management from interviews and conducted a field experiment for NF. According to the calculations using a modified Roth C model, the ability for soil carbon sequestration predicted over the next 20 years is the highest in a no-till NF system with grass mulching. CO2 emission per ha for CF was 4.8 tCO(2)/ha, which was eight times higher than that for NF. However, the highest CO2 emission per kg of crop was noted in NF with no grass mulching due to very low yield. The total CO2 emission for CF was similar to that for EF. The NF systems were beneficial in reducing CO2 emission, but a combination of other approaches is required for satisfying EFFDPP criteria.