Effects Of Water And Phosphorus Coupling On Alfalfa Production Performance,Forage Quality And Soil Fertility In Mining Area

In order to investigate the water and phosphorus coupling effect on yield of alfalfa and the improvement of the soil,the alfalfa pot experiment with a two-factor completely random design was conducted under the greenhouse in the coal mining subsidence area of Xiaoyi,Shanxi Province.The experiment was setted 3levels phosphorus treatment with,respectly P1(90 kg/hm2),P2(180 kg/hm2)and P3(270 kg/hm2)and 3 levels water treatment,respectly low water level W1(40%~45%FC),medium water level W2(60%~65%FC)and high water level W3(80%~85%FC).Alfalfa production performance,forage quality,photosynthetic characteristics,phosphorus utilization efficiency and soil nutrients were determined.The results showed that :(1)Under the treatment of 80%~85%FC and phosphorus application rate of 270 kg/hm2,the hay yield of alfalfa is the highest.It was 102.23% higher than the control group.Under the treatment of 60%~65FC and phosphorus application rate of 180 kg / hm2,the content of crude protein and phosphorus of the alfalfa are the highest,respectly 21.87% and 0.22%.Under the treatment of 40%~45%FC and phosphorus application rate of 90 kg/hm2,the ADF,NDF and RFV of alfalfa were the best,which were 26.35%,40.83%and 157.110%.According to the comprehensive evaluation of hay yield and nutrient quality,the optimal treatment was 80%~85%FC and phosphorus application rate of 180 kg/hm2.(2)Under the treatment of 40%~45%FC and 60%~65%FC,the utilization efficiency of phosphate decreased with increasing the amount of phosphatefertilizer.Under the treatment of 80%~85%FC and phosphorus application rate of 180 kg/hm2,the phosphorus utilization efficiency of alfalfa was the highest(57.15%).(3)Increasing the application of water and phosphate fertilizers can increase soil nutrients,and soil nutrients gradually decrease with increasing soil depth.According to the comprehensive assessment of soil nutrient content of 0-30 cm,the soil nutrient content was the highest under the treatment of 80%~85%FC and phosphorus application rate of 270 kg/hm2 and it has the best effect on soil improvement in mining area.The organic matter,the total nitrogen,the available phosphorus and the alkaline phosphatase activity were respectly 36.18 g/kg,1.41 g/kg,71.32 mg/kg,9.08 mg/(g·24h).