不同生长年限对紫花苜蓿产量及土壤养分的影响

Effects of Growth Years on the Yield of Medicago sativa L.and Soil Nutrient

研究了不同生长年限（2、5、6、7和10年生）对紫花苜蓿（Medicago sativa L.）草产量及土壤养分的影响。结果表明,随生长年限的增加,紫花苜蓿产量呈先增加后降低趋势,以7年生紫花苜蓿产量最高,与其他生长年限均达显著差异水平（P〈0.05）;土壤含水量和电导率呈先增加后降低趋势,而土壤容重、总孔隙度和p H呈先降低后增加趋势,表明了紫花苜蓿具有显著的脱盐功能;土壤养分随生长年限的增加呈先增加后降低趋势,整体表现为：7年生〉10年生〉6年生〉5年生〉2年生,各生长年限紫花苜蓿土壤氮素和钾素变化幅度较大,土壤全磷和有效磷含量差异并不显著（P〉0.05）;垂直方向随着土层深度的增加,各生长年限紫花苜蓿土壤养分呈降低趋势,表现出明显的＂表聚性＂,并且各生长年限紫花苜蓿土壤养分储存于0-20 cm土层。相关性分析表明,紫花苜蓿土壤养分与相应的有效养分和含水量呈极显著正相关（P〈0.01）,与电导率和pH呈极显著的负相关（P〈0.01）,而p H和电导率之间极显著正相关（P〈0.01）,由此可见,生长年限对紫花苜蓿土壤养分的影响是土壤理化等因子的共同作用结果。

The number of growth years（2, 5, 6, 7 and 10 years） of the yield and soil nutrient of Medicago sativa were measured. The results showed that the yield of Medicago sativa were first increased and then decreased with the increase of growth years which the 7 growth years of the yield of Medicago sativa was the highest, and the 7 growth years of the yield was significant higher than other growth years of Medicago sativa（P 0.05）. Soil water content and electrical conductivity were first increased and then decreased, and soil bulk density, total porosity and p H showed the opposite trend with the increase of growth years which showed that Medicago sativa had a significant function of desalination. The soil nutrient of Medicago sativa were first increased and then decreased with the increase of growth years showed 7 years10 years6years5 years2 years. It also showed that the number of growth years of rangeability of soil nitrogen and potassium were larger, and soil total phosphorus and available phosphorus had no significant difference（P 0.05） of the number of growth years of Medicago sativa. The soil nutrient of the number of growth years of Medicago sativa decreased with the increase of soil depth which were mainly concentrated in the 0-20 cm depth and showed the ＂surface accumulation＂. Correlation analysis showed that the soil nutrient and effective nutrient were extremely significant positive correlation with moisture content（P 0.01） and were extremely significant negative correlation with soil electrical conductivity and p H（P 0.01）, while the soil electrical conductivity was extremely significant positive correlation with p H（P 0.01）, It turned out that the effects of the number of growth tears of the soil nutrient of Medicago sativa was the interaction result of soil physical and chemical factors.