Optimizing Nitrogen and Residue Management to Reduce GHG Emissions while Maintaining Crop Yield: A Case Study in a Mono-Cropping System of Northeast China

Abstract

Reducing the use of nitrogen fertilizers and returning straw to field are being promoted in northeast China (NEC). In this paper, the agricultural production system model (APSIM) was applied to assess the long-term variations of crop yield and soil GHG emissions in a maize mono-cropping system of NEC, and the simulation results were combined with lifecycle assessment to estimate annual GHG emissions (GHG L ) and GHG emission intensity (GHG I , GHG emissions per unit yield) of different agricultural practices. Under current farmers' practice, emissions due to machinery input (including production, transportation, repair, and maintenance) and soil organic carbon (SOC) decline accounted for 15% of GHG L , while emissions from nitrogen fertilizer input (production and transportation) and direct N 2 O emissions from soil accounted for the majority (~60% of GHG L ). Current farmers' practice in terms of N application and residue management are nearly optimal for crop production but not for climate change mitigation. Reducing N input by 13% and increasing straw retention by 20% can maintain crop yield and SOC, and also reduce GHG L and GHG I by 13% and 11%, respectively. However, it is not feasible to incorporate the straw used as household fuel into soil, which could incur substantial fossil CO 2 emissions of 3.98 Mg CO 2 -eq ha −1 resulting from the substitution of coal for straw. APSIM was successful in simulating crop yield, N 2 O emissions, and SOC change in NEC, and our results highlight opportunities to further optimize management strategies (especially for the nitrogen and straw management) to reduce GHG emissions while maintaining crop yield.

Study on Mechanisms Underlying Changes in Agricultural Carbon Emissions: A Case in Jilin Province, China, 1998–2018

“…First, carbon emissions can be reduced by government policies, such as modifying greenhouse gas emission caps, optimizing management practices, increasing carbon taxes, and increasing regulatory efforts [30][31][32]. Second, carbon emissions can be mitigated by using green fertilizers, avoiding crop burning, adjusting the soil's physical and chemical properties, and minimizing agricultural resource inputs so as to achieve a circular and sustainable ecological environment [33][34][35]. Finally, low-carbon agriculture can be further achieved by adopting conservation tillage, enhancing the use of agricultural input resources, facilitating the optimization and upgrading of the industrial structure, and introducing new technological means such as biochar [36][37][38][39][40].…”

Investigation into the Effects of Straw Retention and Nitrogen Reduction on CH4 and N2O Emissions from Paddy Fields in the Lower Yangtze River Region, China

“…However, some researchers surmised that N fertilizer reduced the paddy field's CH 4 emission by stimulating the methanotroph's growth and activity [27,28]. Therefore, knowledge of how GHG emissions and rice yields respond to straw retention and N management is helpful to assess the potential of rice-wheat rotation system to sustain rice yields and mitigate GHG emissions [29].…”