林下生草对林芝市黑钻苹果园土壤理化性质的影响

Effects of Grass Growing Under Forest on Soil Physical and Chemical Properties of Black Diamond Apple Orchard in Linzhi City

为探究果园生草对西藏高原苹果园土壤理化性质的影响,以林芝市特殊经济作物黑钻苹果园为试验地,对不同草种种植后的土壤理化性质进行分析研究。结果表明:与对照组相比,果园生草导致土壤pH值和电导率降低,有机质仅在单种紫花苜蓿后有所增加,土壤养分整体上有所下降,土壤中Cu、Zn、Cd含量降低,Pb、Ni、As含量增加,其中Cu、Zn、Cd含量高于西藏土壤元素背景值,土壤重金属污染等级为轻微污染,各处理下土壤重金属综合潜在生态风险指数有所下降。由此可见,不同生草栽培对土壤的理化性质影响各不相同,单种紫花苜蓿能提高土壤养分、降低土壤重金属含量,混种箭筈豌豆和燕麦、单种燕麦、单种鸭茅、混种紫花苜蓿和鸭茅能降低土壤Cu、Zn、Cd含量,单种箭筈豌豆能提高土壤中有效磷、降低Cd含量,各处理均可降低土壤重金属综合潜在生态风险。综上,在改善林芝市黑钻苹果园土壤理化性质方面,应根据实际情况,合理选择果园生草模式。

In order to explore the effects of orchard grass on the soil physical and chemical properties of Black Diamond apple orchard on Xizang Plateau,the soil physical and chemical properties of different grass species were analyzed and studied in Linzhi special cash crop Black Diamond apple orchard.The results showed that compared with the control group,the soil pH value and electrical conductivity decreased,the organic matter increased only after single planting of Medicago sativa L,the soil nutrients decreased,the contents of Cu,Zn and Cd decreased,and the contents of Pb,Ni and As increased.The contents of Cu,Zn and Cd were higher than the background values of Xizang soil elements,the soil heavy metal pollution grade was slight pollution and the combined potential ecological risk index of soil heavy metals decreased under each treatment.It can be seen that different grass cultivation had different effects on soil physical and chemical properties.Single planting of Medicago sativa L could increase soil nutrients and reduce soil heavy metal content.Mixed planting of Vicia sati-va L and Avena sativa L,single planting of Avena sativa L,single planting of Dactylis glomerata L,mixed planting of Medicago sativa L and Dactylis glomerata L could reduce soil Cu,Zn,Cd content,single planting of Vicia sati-va L could increase soil available phosphorus,reduce soil Cd content,and all treatments could reduce the potential ecological risk of soil heavy metal synthesis.In conclusion,in improving the soil physical and chemical properties of Black Diamond apple orchards in Linzhi City,the orchard grassing mode should be rationally selected according to the actual situation.