Winter hairy vetch-spring maize rotation can improve nitrogen-utilization efficiency on the North China Plain

Background and aims Understanding the contributions of winter cover crops (CCs) to nitrogen (N) uptake of succeeding spring maize will help achieve more efficient soil N use. Methods A single-factor field experiment was conducted to quantify residual N effects of contrasting cover crop tops on spring maize N utilization and environmental benefits. N-15-labeled fertilizers were applied at the time of CC establishment in a microplot experiment to determine the contribution of aboveground residue N of winter cover crops (hairy vetch (HV), February orchid (OV), hairy vetch/ February orchid mixture (HO)) to the following spring maize. Results Compared with the winter fallow, HV, OV and HO treatments decreased N fertilizer input by 30%, 9%, and 28%, respectively. The spring maize N derived from the residues was 27 (HV), 6 (OV) and 22 (HO) kg ha(-1) and the total contribution to the N uptake of spring maize from the aboveground residues was 2.2 similar to 10.3%. The fallow treatment had the highest N surplus (167 kg N ha(-1)), and HV, OV and HO treatments significantly reduced them to 78, 127 and 102 kg N ha(-1), respectively. Conclusions Introducing hairy vetch or hairy vetch/ February orchid mixture in the sole spring maize cropping system will deliver significant improvements in nitrogen use efficiency on the North China Plain.