Effects of Controlled Release Fertilizer on Alfalfa Grassland Yield and Soil Nutrients in Saline-alkali Soil Region of Yellow River Delta

The field randomized block experiment method was used to apply fertilizer to alfalfa fields in saline-alkali reclamation areas of the Yellow River Delta,in order to obtain the effects of fertilizer types on alfalfa yield and the changes of soil nutrients,and provide scientific basis for the restoration and delaying recession of alfalfa fields in the Yellow River Delta,and this research had important ecological significance for maintaining the functions of alfalfa fields and the surrounding environment in the Yellow River Delta.The results showed that the application of different types of fertilizers could significantly improve the alfalfa yield,with an average increase of 19%.For different types of fertilizers,the quick-acting fertilizer could get better biological yield of alfalfa in a short period.However,for the annual production,controlled release fertilizer I(AF)and controlled release fertilizer II(BF)could promote the increase of branch number,root length,volume and dry weight,while controlled-release fertilizer II(BF)was the best in improving the alfalfa yield,it improved the yield by 22%compared with the CK,and there was a significant difference in the yield between controlled release fertilizer I(AF)and quick-acting fertilizer(HF)(P<0.05).The different type fertilizer had different effects on soil nutrient characteristics,the content of soil available potassium and available phosphorus in 0-20 cm depth of fertilizer treatment plots was 1.5~3.0 times higher than that of CK,and this was also the material basis for the increase of total alfalfa yield in the fertilization area,which indicated that reasonable fertilization measures could promote the increase of alfalfa yield and the change of soil nutrients in the Yellow River Delta area,and the increase of forage yield laid a foundation for grassland restoration and delaying recession.