Effects of nitrogen, phosphorus and potassium ratio fertilizer on the the yield and quality of Aohan alfafa

Randomized block design and 32 different fertilizer treatments combination were used to analyze the effect of different N， P and K combined fertilizer applied on the yield and quality of Aohan alfalfa (Medicago sativa cv. Aohan) in Chifeng region. The results showed that N fertilizer significantly increased the yield of the first year alfalfa（P0.05）, from 2.90 tha-1 to 3.16 tha-1 , but the rate of the increase decreased in the second year. P and K fertilizer also significantly improved the yield of alfalfa（P0.05）, but the effect of K fertilizer was poor than the effect of N and P fertilizer. The crude protein content of alfalfa increased from 17.74% to 18.72% after applied N fertilizer. When applied P and K fertilizer, the crude protein content of alfalfa also increased and the difference were not significant（P0.05）.