Candidate: Tang YuanZheng
Major: Crop Culture and Farming System
Supervisor: Zu Wei
This experiment was carried out in the experimental plot in Northeast Agricultural University, the soil type is black soil, four treatments of rotation system were set up, the first treatment is corn-wheat-soybean, the second treatment is wheat-soybean-soybean, the third treatment is soybean- wheat-soybean, the fourth treatment is soybean-soybean- soybean, and the previous four years was als...