关键词: 玉米, 毛叶苕子, 绿肥, 产量, 肥料贡献率

Abstract: 【Objective】Effects of long-term intercropping hairy vetch and its stubble returning on corn yield and nitrogen fertilizer contribution rate under nitrogen fertilizer reduction were studied, in order to provide scientific basis for nitrogen fertilizer substitution and nitrogen resource efficient management in corn/hairy vetch intercropping system.【Method】The field experiment was carried out in 2014-2019 at scientific observing and experimental station of arable land conservation and agriculture environment of Gansu province, ministry of agriculture monocropped corn treatment was set under the levels of no fertilization and conventional nitrogen fertilization, the intercropping system of corn with hairy vetch were set under 90%, 80%, 70%, 60% and 0% of conventional nitrogen application levels, and there were 7 treatments and 3 replicates in a field experiment with a randomized block design. The changes of crop yield, economic benefits, partial productivity of nitrogen fertilizer, nitrogen agronomic efficiency and nitrogen fertilizer contribution rate were studied in long-term intercropping of corn with hairy vetch under different nitrogen fertilizer reduction.【Result】The results showed that, the long-term intercropping system of corn with hairy vetch and hairy vetch stubble returning had the obvious advantage of increasing corn yield, the yield increase advantage increased with the lengthening of intercropping years..Compared with conventional nitrogen fertilization, the hay yield of hairy vetch could be increased by 2273.20 kg·hm^-2 under the condition of ensuring stable corn grain yield, the total profit was 29 686 yuan/hm² and increased by 0.89%, partial productivity of nitrogen fertilizer and nitrogen agronomic efficiency were significantly increased by 20.69% and 14.65% in the long-term intercropping system of corn with hairy vetch and hairy vetch stubble returning under the condition of reduced 20% nitrogen fertilizer. Compared with conventional nitrogen fertilization, although the corn grain yield was significantly reduced by 7.74%, the hay yield of hairy vetch could be increased by 2319.34 kg·hm^-2, the total profit was 28 652 yuan/hm², which was equivalent to that of conventional nitrogen fertilization, partial productivity of nitrogen fertilizer and nitrogen agronomic efficiency were significantly increased by 31.79% and 16.30% in the long-term intercropping system of corn with hairy vetch and hairy vetch stubble returning under the condition of reduced 30% nitrogen fertilizer. Compared with conventional nitrogen fertilization, although the hay yield of hairy vetch could be increased by 2303.09 kg·hm^-2, partial productivity of nitrogen fertilizer and nitrogen agronomic efficiency were significantly increased by 48.78% and 23.75%, but the corn grain yield was significantly decreased by 10.71%, the total profit was only 27 929 yuan/hm², which was significantly lower than that of conventional nitrogen fertilization in the long-term intercropping system of corn with hairy vetch and hairy vetch stubble returning under the condition of reduced 40% nitrogen fertilizer.【Conclusion】If only corn grain yield was considered, 20% chemical nitrogen fertilizer can be substituted, and if total output value of maize and hairy vetch was considered, 30% chemical nitrogen fertilizer can be substituted, in corn/hairy vetch intercropping and hairy vetch stubble returning for 9 years under nitrogen fertilizer reduction in the production process of corn in Hexi oasis irrigation area.

Key words: corn, hairy vetch, green manure, yield, fertilizer contribution rate