Effects Of Different Ratio Of Nitrogen, Phosphorus And Potassium Fertilizer On Yield, Quality And Root Nodule Bacteria Number Of Alfalfa (Medicago Sativa L.)

Xinmu No.4 alfalfa(Medicago sativa L.cv.Xinmu No.4) plants were used as materials in this study. The agronomic characters, yield and quality, number of nodule bacteria were characterized under different ratio of nitrogen, phosphorus and potassium fertilizer treatment to explore the correlation between them, in order to provide reference data for scientific fertilization in alfalfa production. Using "3414" quadratic regression optimum design, that is 3 factors(N, P, K) 4 levels 14 treatments of complete randomized block. There were 3 repeats per treatment, totally 42 plots, and the plot area(4m*5m). 4 levels of nitrogen application(0, 60, 120, 180 kg/hm2, respectively denoted as N0, N1, N2, N3); 4 levels of Phosphorus application(0, 45, 90, 135 kg/hm2, respectively denoted as P0, P1, P2, P3); 4 levels of potassium application(0, 30, 60, 90 kg/hm2, respectively denoted as K0, K1, K2, K3). Seeds was sown on October 22, 2014, soil background values were determined before sowing. Next year in the seedling stage, fertilized according to the "3414" scheme. Soil fertility was determined after mowing every time, and added fertilizer to the background value+ "3414" scheme of the fertility level. The results were as followed:(1) Effects of different ratios of nitrogen phosphorus and potassium fertilization on alfalfa yield The first crop in 14(14.79 t/hm2) fresh yield was the highest, followed by 13(14.37 t/hm2), both difference was not significant(P<0.05), and two processing of fresh and dry ratio was 24%. Dry weight of the largest was the treatment No.11(3.94 t/hm2), the second was treatment No.14(3.55 t/hm2), and difference was significant(P<0.05); In the second stubble, treatment 9(21.31 t/hm2) of fresh grass yield was the highest, the dry and fresh ratio was 30%, followed by 8(21.28 t/hm2), which dry and fresh ratio was 29%, and there was no significant differences between them(P<0.05). The largest dry weight was No.13(8.34 t/hm2), the second was No.8(6.17 t/hm2), and the difference was significant(P<0.05). The highest of annual output of fresh alfalfa was treatment No.14(35.27 t/hm2), and dry weight of treatment 13 was the highest(12.10 t/hm2).(2) Effects of different nitrogen, phosphorus and potassium fertilization on the nutritional quality of Alfalfa The first stubble alfalfa grass in treatment 9 of good quality than the other treatments, the crude protein(18.47%) and crude fat(4.00%) was high,and low content of NDF(28.95%) and ADF(21.10%),and the difference was significant(P<0.05).The second crop of grass to treatment 13 fertilizer is better than the quality of other treatments, the crude protein content of high(18.58%) and ADF content was the lowest(21.77%), crude fat content was relatively high(3.52%) and difference with the controls significantly(P<0.05).(3) Effects of different nitrogen, phosphorus and potassium fertilization on Rhizobium in alfalfa After harvesting the first crop of alfalfa, the number of the root nodule bacteria to treatment 14,was 21.90/plant, followed by the treatment of 13,was 18.90/plant; The second stubble to treatment the maximum of 12,was 14.53/plant, followed by the treatment of 13,for 12.60/plant, there were significant difference between the control(P<0.05).(4) Effects of different ratios of nitrogen, phosphorus and potassium fertilizer on the utilization rate of alfalfa The highest utilization rate of nitrogen fertilizer and potassium fertilizer was 13, and the utilization rate of nitrogen fertilizer and potassium fertilizer was 70.56% and 68.03%, the highest utilization rate of phosphate fertilizer was 6, which was 36.29%; The highest nitrogen and potassium fertilizer utilization rate in second stubble was 13, the nitrogen fertilizer, potassium fertilizer utilization rate reached 77.75%,70.51%, the highest utilization rate of phosphate fertilizer was 7, which was 33.38%, and the two treatments were significantly different from the control(P<0.05).(5) Correlation analysis of alfalfa yield, quality and root nodule bacteria The measured alfalfa forage yield and plant height was positively correlated; hay yield and plant height, branch number of positive correlation. Alfalfa crude protein content and the branch number, branch leaf display significant positive correlation; content of NDF and ADF were crude fat and extremely significant negative correlation, and between ADF and NDF significantly positive correlation; crude ash content and crude fat showed extremely significant positive correlation, but with NDF and ADF has significant negative correlation. The number of alfalfa nodule bacteria and leaf area,the number of branches was significantly(P<0.05) positive correlation,and the single branch number was significantly negative correlation(P<0.05),and the plant height showed a very significant negative correlation(P<0.01).