Lowering carbon footprint of winter wheat by improving management practices in North China Plain

Increasing awareness of climate change and food security has spurred an interest in low-carbon agriculture. Studies on low-carbon agriculture should consider both greenhouse gas emissions and crop yield. Improving management practices may help mitigate greenhouse gas emissions from crop system while also achieving higher crop yields. The objective of this study was to assess the impact of diverse management practices on grain yield and carbon footprint from an in-situ field experiment, identify the best management practices for low-carbon technology, and explore the major source of greenhouse gas emissions during winter wheat production, which would offer key information for pursuing low-carbon agriculture in the future. In this study, the field experiment was conducted during the winter wheat (Triticum aestivum L.) season from 2011 to 2014 on the North China Plain. Conventional nitrogen fertilizer application and irrigation rates were 240 kg/ha and 225 mm respectively, and these along with rotary tillage were used as the control. The experimental treatments included nitrogen fertilization (180, 120, 60, and 0 kg/ha), irrigation (150 and 75 mm), and tillage (conventional tillage and no tillage). The results showed that with a decrease in the nitrogen application and irrigation rates, the grain yield decreased, but the carbon footprint tended to decrease and then increase. The conventional tillage treatment gave the highest grain yield and lowest carbon footprint among the different tillage treatments. Furthermore, the main components of greenhouse gas emissions were electricity for irrigation (25.6-75.4%), nitrogen fertilizer (0-32.8%), direct nitrous oxide emissions (2.6-9.8%), and phosphorus fertilizer (5.2-8.2%), which accounted for 85.8-90.8% of the total greenhouse gas emissions. Therefore, reducing electricity for irrigation, decreasing nitrogen and phosphorus fertilizer application rates, and lowering direct nitrous oxide emissions are the priority measures that will result in low-carbon agriculture. The treatments of nitrogen 180 kg/ha, irrigation of 150 mm, and conventional tillage were the best management practices that produced a lower carbon footprint with a favorable grain yield. This study highlights that improving farming practices could be an efficient option to mitigate the greenhouse gas emission in China's crop production.