Mitigation of N2O and CH4 emission from rice and wheat cropping systems using dicyandiamide and hydroquinone

Agriculture contributes considerably to the emission of greenhouse gases, such as N2O and CH4. Here we summarize results from previous pot experiments assessing the effectiveness of urease and nitrification inhibitors reducing both N2O and CH4 emissions from wheat and rice cropping systems fertilized with urea (U). For the wheat cropping system, using a cambisol, we observed that the application of U with hydroquinone (HQ, a urease inhibitor), U with dicyandiamide (DCD, a nitrification inhibitor) and U with HQ plus DCD decreased the N2O emissions by 11.4, 22.3 and 25.1%, respectively. For the rice copping system, using a luvisol, we found that the application of U with HQ, U with DCD and U with HQ plus DCD decreased N2O emissions by 10.6, 47.0 and 62.3%, respectively, and CH4 emissions by 30.1, 53.1 and 58.3%, respectively. In terms of total global warming potential (GWP) a reduction of 61.2% could be realized via the combined addition of HQ and DCD. The addition of wheat straw reduced the activity of HQ and DCD in the rice cropping experiments. In terms of total GWP only a reduction of 30.7% could be achieved. In general, both in upland and flooded conditions, the application of HQ and DCD alone was less effective than HQ in combination with DCD, but not significantly for U plus DCD treatment. Our observations may be further constrained, however, by practical, economic or social problems and should therefore be tested at the scale of a region (e.g. a watershed) and related to an integrated abatement of agricultural N losses.