塔里木河上游典型绿洲不同土地利用方式下土壤质量评价

Soil Quality Assessment under Different Land Use Types in Typical Oasis of the Upper Reaches of the Tarim River

以塔里木河上游阿拉尔垦区为靶区,选择8a棉田、30a棉田、人工林、天然林、荒草地、撂荒地及盐碱地等不同土地利用方式的样地为研究对象,综合考虑土壤物理、化学和生物学性质,选择土壤含水量、容重、pH、有机质、全氮、速效磷、速效钾等7个理化指标和过氧化氢酶、多酚氧化酶、碱性磷酸酶、脲酶、转化酶等5个酶活性指标进行实验室分析并解析其分异规律;基于因子分析和聚类分析法评价绿洲不同土地利用方式下土壤质量的差异并划分等级。研究表明,不同土地利用方式下的土壤的理化性质和酶活性均存在一定差异;不同土地利用方式下的土壤质量的评价结果显示:天然林>人工林>8a棉田>30a棉田>撂荒地>荒草地>盐碱地;不同土地利用方式对土壤性质影响的空间差异有助于解释人-地关系的复杂性。

Soil quality assessment under different land use types is important for ecologically sustainable development.In 2008,soil samples from 0-20 cm layers for different land use types,i.e.,8-year cotton field,30-year cotton field,plantation forest,natural forest,grassland,abandoned land,and saline-alkali land,across the Aler reclamation area of the upper reaches of the Tarim River were collected.By analyzing seven soil physical and chemical properties,including soil water content,bulk density,pH,organic matter,total N,available P,available K,and five soil enzymatic activities,including catalase,polyphenol oxidase,urease,invertase,and alkaline phosphatase,this study made an attempt to evaluate soil quality under different land use types.Soil quality assessment values（SQAV）were calculated using principal component analysis（PCA）.Soil quality grades were classified by clustering diagram.The sustainable yield indexes（SYI）were calculated to verify the evaluation results.Results show that there were differences in the physical,chemical,and enzymatic properties under different land use types.Land use had a great influence on various soil properties.The influence of varying land use types in descending order is natural forest〉plantation forest〉8-year cotton field〉30-year cotton field〉abandoned land〉grassland〉 saline-alkali land.The higher nutrients and enzymatic activities were observed in forest land whereas the lower ones were observed in saline-alkali land.Soil quality of cotton field was worse than that of forest land.Different land use intensity and cropping patterns would have a significant impact on soil quality of cotton field.Extensive cultivation for more than 10 years may have caused the decline of soil quality to varying degrees under unreasonable tillage practices.The soil quality assessment values decreased from-0.003 for 8-year cotton field to-0.406 for 30-year cotton field.The assessment values for abandoned land and grassland were close to those of 30-year cotton field.Spatial differences in soil quality assessment under different land use types reflected influences of human activities.Therefore,management practices need to take into account increasing soil quality,such as returning cultivated land to forests,building natural reserve in arid land areas,strengthening forest construction,and improvement in salinized soil.This study could be beneficial in an enhanced understanding of complexity of the interactions between human and land systems.