Influence of Straw Incorporation on Maize Yield, N Accumulation and Remobilization on Slope Farmland in Northeast China

Slope farmland is a main type of agricultural land throughout northeast China. Long-term high intensity utilization and unreasonable farming have caused the deterioration of soil resources and a decrease in crop production. Here, it was hypothesized that crop straw incorporation might help to reduce nutrient losses and increase maize yields across time and space. A field experiment for testing straw management practices on maize across three slope positions（top, back and bottom slopes） was conducted in Northeast China in 2018 and 2019. In this study, the dry matter accumulation（DMA）, N accumulation（NA）, N remobilization, postsilking N uptake and grain yield were measured under SI（straw incorporation） and NSI（no straw incorporation） across three slope positions of 100-m-long consecutive black soil slope farmland during the maize（Zea mays L.） growth stages. Compared with NSI, SI significantly increased DMA and NA at the silking and maturity stages. SI typically increased the N remobilization in all slope positions, and significantly increased N remobilization efficiency and contribution of N remobilization to grain on the back and bottom slopes. However, post-silking N uptake was only increased by SI on the top slope. SI generally increased the crop yield in three slope positions. In the SI treatments, the bottom slope was the highest yield position, followed by the top, and then the back slopes, suggesting that the bottom slope position of regularly incorporated straw might have increased the potential for boosting maize yield. Overall, the study demonstrated the outsized potential of straw incorporation to enhance maize NA and then increase the grain yield in black soil slope farmland.