渭北旱塬区不同年限苜蓿对土壤主要养分及微生物量的影响

以渭北旱塬区生长年限为6年、11年、16年和21年的紫花苜蓿(Medicago sativa)人工草地为研究对象,天然草地为对照,通过研究土壤主要养分及微生物生物量的变化特征来揭示紫花苜蓿人工草地生长年限对渭北旱塬区土壤质量的影响。结果表明,种植紫花苜蓿能够显著改善土壤有机质、全氮、全磷及土壤微生物量C和N(P<0.05),且随种植年限的延长均呈先升后降的趋势,最高点出现在第11年。相关性分析表明,土壤养分与微生物生物量存在一定的相关性,而且微生物生物量可以更灵敏地反映土壤质量变化。综合考虑,渭北旱塬区紫花苜蓿人工草地在恢复11年后应当进行合理利用或进行其他人工干预以延长草地使用寿命。

Effects of Medicago sativa on Soil Nutrients and Microbial Biomass under Different Years in the Arid Area of Northern Weihe River Basin

The soil nutrients and soil microbial biomass of artificial Medicago sativa grasslands at 6, 11, 16, 21 years were analyzed in the arid area of Northern Weihe river basin with the nature grassland as control. The results showed that planting Medicago sativa could significantly improve the soil quality (P<0.05). The soil organic carbon, total nitrogen, total phosphorus, microbial biomass C and microbial biomass N all increased firstly and then decreased, and the highest point happened at the 11th year. The correlation analyses showed that there was some correlation between the soil nutrients and the microbial biomass, and the extent was different. These results indicated that the microbial biomass was more sensitive to the changes of soil quality than the soil nutrients. Therefore, the artificial Medicago sativa grassland needed rational utilization and some human intervention for prolonging the service life of the grassland after 11 years in the arid area of Northern Weihe river basin.