Conservation tillage and optimized fertilization reduce winter runoff losses of nitrogen and phosphorus from farmland in the Chaohu Lake region, China

摘要

In order to test the efficacy of conservation tillage and optimized fertilization on reducing N and P runoff losses, a 4-year (2007-2011) runoff plot experiment was conducted in the Chaohu Lake region, East China. There were four treatments including: (1) conventional tillage (CT, basal fertilization without mulch), (2) conventional tillage with straw mulching (CTS), (3) optimized fertilization (OPF, split applications) and (4) no-tillage with straw mulching plus optimized fertilization (NTS + OPF). Results showed that CTS and NTS + OPF exhibited significant reduction of seasonal runoff and soil losses compared with CT (P 0.05). OPF decreased runoff by 6-10 and soil loss by 9-27 % in the various years, but differences were not always statistically significant. Interestingly, winter wheat and rapeseed yields were on average higher in the conservation tillage and optimized fertilization treatment than in the CT treatment. Compared with CT, CTS reduced N losses by 14-25 %, OPF by 12-21 % and NTS + OPF 20-28 %. Similarly, CTS reduced P losses by 20-32 %, OPF by 11-21 % and NTS + OPF by 23-30 %. NTS + OPF was the most effective treatment for reducing nutrient losses. The reduction of runoff volume was mainly responsible for the decreased nutrient losses. Our findings indicates that conservation tillage and optimized fertilization may reduce N and P losses via runoff while maintaining or enhancing crop yields during the winter-crop growing seasons in the Chaohu Lake region.