Effects of fertilizer combinations of nitrogen, phosphorus and potassium on the forage yield of Medicago sativa

In order to provide the scientific basis for alfalfa fertilization, a field experiment was conducted to investigate the forage yield of alfalfa under different fertilizer combinations of nitrogen, phosphorus and potassium in Qihe, Shandong province. Orthogonal experiment design was used with 2 replicates. The results showed that there was no significant effect of nitrogen and potassium fertilizer on forage yield of alfalfa, however, phosphorus fertilizer significantly increased the alfalfa forage yield. The interactive effects between phosphorus and nitrogen on forage yield under the first cut and second cut were significant, and phosphorus fertilizer mixed with low level of nitrogen fertilizer effectively improved alfalfa forage yield. According to the total forage yield of alfalfa, the proper combination of nitrogen, phosphorus and potassium applied for alfalfa in experiment field was 60 kgha-1 N， 90 kgha-1 P2O5 and 100 kgha-1 K2O.