Articles | Volume 13, issue 9
https://doi.org/10.5194/bg-13-2701-2016
https://doi.org/10.5194/bg-13-2701-2016
Research article
 | 
10 May 2016
Research article |  | 10 May 2016

Global warming potential and greenhouse gas intensity in rice agriculture driven by high yields and nitrogen use efficiency

Xiaoxu Zhang, Xin Xu, Yinglie Liu, Jinyang Wang, and Zhengqin Xiong

Abstract. Our understanding of how global warming potential (GWP) and greenhouse gas intensity (GHGI) is affected by management practices aimed at food security with respect to rice agriculture remains limited. In the present study, a field experiment was conducted in China to evaluate the effects of integrated soil–crop system management (ISSM) on GWP and GHGI after accounting for carbon dioxide (CO2) equivalent emissions from all sources, including methane (CH4) and nitrous oxide (N2O) emissions, agrochemical inputs and farm operations and sinks (i.e., soil organic carbon sequestration). The ISSM mainly consisted of different nitrogen (N) fertilization rates and split, manure, Zn and Na2SiO3 fertilization and planting density for the improvement of rice yield and agronomic nitrogen use efficiency (NUE). Four ISSM scenarios consisting of different chemical N rates relative to the local farmers' practice (FP) rate were carried out, namely, ISSM-N1 (25 % reduction), ISSM-N2 (10 % reduction), ISSM-N3 (FP rate) and ISSM-N4 (25 % increase). The results showed that compared with the FP, the four ISSM scenarios significantly increased the rice yields by 10, 16, 28 and 41 % and the agronomic NUE by 75, 67, 35 and 40 %, respectively. In addition, compared with the FP, the ISSM-N1 and ISSM-N2 scenarios significantly reduced the GHGI by 14 and 18 %, respectively, despite similar GWPs. The ISSM-N3 and ISSM-N4 scenarios remarkably increased the GWP and GHGI by an average of 69 and 39 %, respectively. In conclusion, the ISSM strategies are promising for both food security and environmental protection, and the ISSM scenario of ISSM-N2 is the optimal strategy to realize high yields and high NUE together with low environmental impacts for this agricultural rice field.

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Short summary
The intensive agriculture is facing environmental problems due to low nitrogen use efficiency (NUE) in China. Integrated soil-crop system management (ISSM) has been developed to increase crop yield and NUE. We investigated greenhouse gas intensity after accounting for CO2 emissions from all sources, including methane and nitrous oxide emissions, agrochemical inputs and farm operations and sinks. We found that the ISSM strategies are promising for both food security and environmental protection.
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