Response Of Alfalfa Productivity To Different Fertilization Management And Balanced Fertilization Models

Alfalfa （Medicago sativa L.） is a high quality perennial legume, which can be cutted2-4stubblesinnorth China per year.Large amount of nutrients are taken away fromsoil along with the harvest, and ifthe nutrientswere not supplemented the soil fertility will be slowly dried up, resulting in alfalfa yielddecreasing.In aspect of alfalfa fertilization, most researches mainly focused on the effect of singlefertilizer on yield and quality of alfalfaat present, but few research work is conducted for the fertilizersynergistic effect on alfalfa yield,fertilizer efficiency, soil physical and chemical properties andmicrobial characteristics.Based on this consideration, the effects of different fertilization systems underarid conditions on the yield and quality of alfalfa, soil physicochemical properties were systematicallystudied in Chifeng of Inner Mongolia in order to explore the soil responses to N, P, K fertilizers,variation pattern of fertilization efficiency and to study the the relationship amongfertilizers, alfalfa andsoil through analyzing the interaction effectand substitution effect of different combinations of N, P, Kfertilizers.And on this basis, the model of fertilization efficiency of alfalfa production under arid dryconditions in Chifengof Inner Mongolia could be established. The main conclusions are as follows:Fertilizer treatments showed impacts on plant height, root diameter, number of branches and stemsat varying degrees. The differences of taproot diameter among treatments were significant. In which, themaximum value was found in treatment of N₃₀P_120K150（0.46cm）and the minimum was in control group（no application of N, P, K,0.20cm）. The difference of stem to leaf ratiowas notsignificant between Nfertilizer treatment and no N fertilizer treatment （P>0.05）.As for the combination of P and Kfertilizers,the differences among treatments were much significant. And the stem to leaf ratiosignificantly decreased along with the increase of P and K application amount（P<0.05）. N, P and Kfertilizers showed the improving effect on yield and the interaction effects between N and P, and N andK were significant. Nitrogen fertilizer could significantly increase the alfalfa yieldin first year andtheyieldwasincreased from2.90t/ha to3.16t/ha under single nitrogen application but not for the secondyear. The yield under N fertilization and no N fertilization was significantly related to P applicationamount and it was increased along with the P application amount..The crude protein content wasincreased from17.74%to18.72%under single nitrogen application. It could also be increasedby singleP fertilization, but the difference was not significant, especially when P application amount was over acertain amount, it would be inhibited.The following statistical modelwasestablished based on the analysis of the interaction between Nand P fertilizers and alternative relationship, and the relationship betweenyield and the applicationamount of N, P and K:Y=41279.289—108.022X₁＋271.194X₂－204.316X₃－379.082X₁X₂＋352.176X₁X₃＋243.572X₂2X₃—421.327X₂1＋609.377X₂2—342.596X₃（R2=0.6249，P=0.0418） Based on the model test, the yield under following4treatments was the highest: N₃₀P_120K150，N₃₀P_200K50，N₃₀P₂₀₀K₁₀₀，N₃₀P_200K150. It could be concluded that the highest alfalfa yield could beachieved under above mentioned4fertilization patterns in Chifeng. The best fertilization combinationwas N₃₀P_120K150.