Maize yield and nitrogen-use characteristics were promoted as consistently improved soil fertility: 6-year straw incorporation in Northeast China

Abstract

Long-term impacts of straw incorporation on soil fertility, and maize production and nitrogen (N) use status had not been thoroughly investigated in Northeast China, the most vital agricultural base across the nation. We conducted a consecutive 6-year field experiment, including straw amendment at 4 000, 8 000 and 12 000 kg/ha, and no straw incorporation was set as the control. Our experiment confirmed that the grain yield and crop N uptake in straw treatments were raised due to consistently improved soil fertility indices (associated with soil N cycling), and larger straw addition generally exerted more profound influences. Boosted nitrogen harvest index (NHI) indicated that nitrogen use efficiency (NUE) was gradually enhanced if applying more straw. More specifically, greater straw amendment caused higher N recovery efficiency from straw N, even though the N recovery efficiency of accumulated N addition declined accordingly (considering fertiliser N besides straw N). Thus, these trends suggested that more efficient utilisation of straw N by crop was the probable reason for elevated NUE over multi-year time series. Our research offered helpful insight to optimally employ straw incorporation and N fertilisation for coordinating agricultural sustainability and environmental protection.