Maize production and field CO<sub>2</sub> emission under different straw return rates in Northeast China

Abstract

In order to understand and clarify the impacts of straw return on maize production and field CO<sub>2</sub> emission in Northeast China, the most important agricultural base of the nation, a field experiment was conducted in 2012–2015, including no straw return (CK), straw amendment at 4000 kg/ha (S<sub>4</sub>), and at 8000 kg/ha (S<sub>8</sub>). The average grain yield was found significantly promoted by the two straw treatments, with comparably increased magnitudes of 11.0% and 12.8% for S<sub>4</sub> and S<sub>8</sub>, respectively, and the benefits were gradually enlarged with increasing experimental duration. Although straw return tends to reduce slightly the harvest index, it was detected that it exerted significantly positive impacts on nitrogen harvest index. These results implied that added straw could lead to raising grain yield and enhancing nitrogen use efficiency simultaneously. In 2015, our monitoring showed that CO<sub>2</sub> emission was elevated with intensified use of straw, and S<sub>4</sub> and S<sub>8</sub> decreased carbon emission efficiency by 7.3% and 13.6%, respectively. However, there was no statistical difference between S<sub>4</sub> and CK. Overall, straw addition at the rate of 4000 kg/ha accompanied with inorganic fertilizer was recommended to be adopted in Northeast China, which was considered as a sustainable and relatively environment-friendly agricultural technique during maize production.