Effects of intercropping green manure forages and nitrogen-reduction on corn yield and soil fertility in Hexi Oasis Irrigation

To study the effects on corn yield,economic benefit and soil fertility in different proportions nitrogen-reduction by the planting system using two kinds of leguminous green manure forages,needle leaf pea and hairy vetch intercropping corn were employed for duration of three years in Hexi Oasis Irrigation. The results showed that effects from applying 90% of the fertilizer amount that farmers often used were the best in corn / needle leaf pea intercropping system,which though resulted in a corn grain yield loss by 0. 63%,not at a significant level. Nevertheless,this helped additional harvests of needle leaf pea grain by 1 987. 34 kg·hm- 2and needle leaf pea hay by 1 374. 35 kg·hm- 2. The economic benefits were the highest,reaching 36 364 yuan·hm- 2,18.05% higher than that of the farmlands farmers often fertilized. Corn grain yields with nitrogen-reduction treatments were all lower than those with often fertilization in corn / hairy vetch intercropping system. But reduction in yield was minimum by only 2. 76% less,reaching a yield of 14 263kg·hm- 2using 90% of the nitrogen fertilizer farmers often utilized,not at a significant level. This caused additionalharvest of hairy vetch hay by 3 175. 47 kg·hm- 2and the economic benefit was the highest as 32 136 yuan·hm- 2,4. 33% higher than that of the farmlands farmers often fertilized. With these two kinds of planting systems,the contents of soil organic matter,total nitrogen,available nitrogen,available phosphorus and available potassium were not significantly different from those with often fertilizations by farmers. It could be seen that the intercropping systems of corn /needle leaf pea and corn / hairy vetch could reduce 10% of the nitrogen fertilizer use and the economic benefit of the former was higher than that of latter in Hexi Oasis Irrigation.