[Effects of long-term fertilization on wheat yield on Loess Plateau]

The effect of long-term fertilization on the yield of winter wheat was studied on the basis of 18-year located experiment on the Loess Plateau. The results showed that the winter wheat yield increased 418.1 kg.hm-2 under N fertilization, and the average increasing rate was different with precipitation. In average and rain rich year, the average increasing rate were 30.3% and 58.9%, respectively, but in drought year, the yield decreased, and its average decreasing rate was 13.9%. The winter wheat yield under P fertilizer increased in drought year, and decreased in average and rain rich year. The average increasing rate was 6.5% in drought year, and the average decreasing rate was 15.4% and 10.0%, respectively. The average increasing rate in M, NP, PM, NM and NPM was 82.8%, 127.8%, 18.9%, 144.4%, and 169.3%, respectively. In addition, precipitation affected the amount of spike, grains per spike, and weight of thousand-grains.