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Opportunities for enhancing yield and soil carbon sequestration while reducing N2O emissions in rainfed cropping systems

Luo, Zhongkui, Wang, Enli, Xing, Hongtao, Smith, Chris, Wang, Guocheng, Cresswell, Hamish
Agricultural and forest meteorology 2017 v.232 pp. 400-410
agroecosystems, carbon, carbon dioxide, carbon sequestration, climatic factors, grain yield, greenhouse gas emissions, models, nitrogen, nitrous oxide, rainfed farming, soil, stakeholders, temperature, wheat
Producing the food required to feed the growing global population will inevitably put pressure on the environment and requires sustainable management of agroecosystems. The management strategies should be context-specific, and will require consideration of different stakeholders’ interests, and of the local soil and climatic conditions. We developed a framework to analyse nitrogen (N) management options with the objective of increasing crop production while reducing CO2 and nitrous oxide (N2O) emissions from soil, and applied this framework to Australian rainfed wheat systems using a systems modelling approach. The results indicated that modified N management strategies in Australian rainfed wheat systems could increase average grain yield by up to 76% (from 1.7 to 3.0Mgha−1) while substantially reducing net soil and N2O emissions (expressed in CO2 equivalents, CO2-eq), compared with current farming practice. Meta-modelling of the simulation results from 613 sites across the Australian wheat-growing regions indicated that site-specific best N management aimed at increasing yield and reducing net soil CO2-eq emissions significantly correlated with water availability, temperature, and antecedent soil carbon content. The results emphasise the opportunity for well-managed intensification to simultaneously increase yield and reduce soil CO2 and N2O emissions in Australian rainfed cropping regions. The ‘win-win’ N management recommendations should, and can be specified according to local climate and soil conditions.