Achieving low methane and nitrous oxide emissions with high economic incomes in a rice-based cropping system

Abstract

Rice cultivation faces increasing challenges to enhance the net ecosystem economic budget (NEEB), which is the balance between economic benefits and environmental costs. Plastic film mulching cultivation (MC) was evaluated for its ability to decrease the global warming potential (GWP) while increasing economic benefits relative to rainfed (RF) and traditional irrigation (TI). To comprehensively assess the effect on NEEB, the CH4 and N2O emissions and grain yields in a rice-based cropping system were measured from 2010 to 2014. The effects of urease and nitrification inhibitors (UNIs) and controlled release fertilizer (CRF) were also estimated. Shifting the field management from RF to MC had unclear impact on CH4 emissions, but increased N2O emissions by 77%. In contrast, switching TI to MC caused a significant reduction (45–85%) in CH4 emissions, producing a strong decrease in GWP, although N2O emissions substantially increased (206–1153%). The decrease in CH4 emissions was attributed to the reduced dissolved organic carbon and CH4 production, whereas the increase in N2O emissions might have resulted from the higher NH4+ concentrations and more favorable soil water content. Integrated assessment showed that MC significantly enhanced NEEB by 6136–8362 CNY ha−1 y−1 relative to RF as the yields increased and input costs reduced. Although MC reduced the yields, the much lower input and GWP costs led to a substantial increase in NEEB (2607–5593 CNY ha−1 y−1) relative to TI. Under MC conditions, applying UNIs and CRF obviously increased input costs though it always tended to enhance grain yields, thus decreasing NEEB by approximately 490–960 CNY ha−1 y−1, except CP addition, which had a positive effect on NEEB. The results demonstrate that MC, particularly MC + CP, are effective management strategies to reduce the environmental costs and increase the economic benefits of rice fields suffering from a lack of water supply.