【作者】 赵云；

【导师】 李向林；

【作者基本信息】 中国农业科学院 ， 草学， 2013， 博士

【摘要】 紫花苜蓿（Medicago sativa L.）是一种优良的多年生豆科牧草，在我国北方地区一年可以刈割2至4茬，随收获而从土壤中带走大量养分，如果养分补充不足土壤肥力便会慢慢枯竭，导致苜蓿产量下降。在苜蓿施肥方面，目前国内外较多的研究主要集中在单一肥料对苜蓿产量和品质的影响方面，但是对肥料间协同作用对苜蓿产量和品质、土壤肥力、肥料利用率以及土壤理化性质和微生物特征对苜蓿营养的影响研究甚少。基于此，本文以内蒙古赤峰地区紫花苜蓿为研究对象，系统深入地研究了旱作条件下不同施肥制度对紫花苜蓿产量与品质以及土壤理化性质的影响，探索了土壤对N、P、K肥的响应及肥效的变化规律，并试图通过分析不同N、P、K肥的组合互作效应和替代效应来剖析肥料、作物、土壤三者之间的关系，并在此基础上建立起内蒙古赤峰地区旱作条件下苜蓿生产的肥效模型。主要得出以下几点结论：不同施肥处理对株高、根粗、分枝数以及茎叶比等生长指标都有不同程度的影响。试验各处理主根直径在不同处理间存在较大的差异，其中以N₃₀P_120K150处理的主根直径最粗,为0.46cm，不施肥处理的主根直径最小，为0.20cm；施氮肥处理组与不施氮肥处理组茎叶比的差异不显著（P>0.05），而磷肥与钾肥组合对茎叶比的影响较为明显，随着磷钾肥施用量的增加，茎叶比显著降低（P<0.05）；氮、磷、钾肥对苜蓿产量都有一定作用，氮-磷、磷-钾、氮-钾之间的互作效应较显著。施氮肥可明显提高第一年产量，单施氮肥处理的产量从2.90t/hm2提高至3.16t/hm2，增幅8%；但施氮肥对于第二年产量的提高并不明显；施氮肥与不施氮肥处理组的产量均与施磷量有明显的相关性，随着施磷量的增加，所有产量都得到提升。施氮肥使苜蓿粗蛋白质含量从17.74%显著提高至18.72%（P<0.05），单施磷肥也可以提高粗蛋白含量，但差异不显著（P>0.05），当施磷量超过一定水平之后反而会抑制粗蛋白含量的提高。在分析了氮磷钾肥之间的互作效应与可替代关系后，结合紫花苜蓿产量与氮磷钾肥施用量之间的关系建立了统计模型：Y=41279.289—108.022X₁＋271.194X₂－204.316X₃－379.082X₁X₂＋352.176X₁X₃＋243.572X₂X₃—421.327X₁²＋609.377X₂²—342.596X₃²（R²=0.6249，P=0.0418）经过模型检验发现，试验中以N₃₀P_120K150，N₃₀P_200K50，N₃₀P₂₀₀K₁₀₀，N₃₀P₂₀₀K₁₅₀等四个处理的紫花苜蓿产量最高，表明以上处理的施肥量可以使赤峰地区紫花苜蓿生产获得最大产量。结合经济收益与环境保护等因素，本文认为赤峰地区紫花苜蓿生产中的最佳施肥组合为N₃₀P₁₂₀K₁₅₀。更多还原

【Abstract】 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.更多还原