我国东部水蚀区坡耕地土壤质量现状分析

土壤质量是土地生产力的基础,为探讨我国东部水蚀区坡耕地土壤质量现状,笔者采集36个样点表层0 ～20 cm土样,测定28项土壤理化指标,利用主成分分析法确定表征土壤质量的关键指标,根据指标隶属度与权重采用加权连乘法计算各采样点的土壤质量指数.结果表明:1)速效磷的变异系数最大,微团聚体体积分数的变异系数最小,绝大部分指标属于中等强度变异,土壤物理指标的变异系数明显小于土壤化学指标.2)黏粒体积分数、粉粒体积分数、微团聚体体积分数、有机质、pH值、Cd、Cr是表征土壤质量的关键指标,Cr隶属度最高,而pH值隶属度最低,Cd隶属度在二级水蚀分区间差异显著.3)36个采样点的土壤质量指数均值为0.64 ±0.16指数,6个二级水蚀分区间不存在显著差异.36个采样点土壤质量指数属较低、中等、较高和高等级的比例分别为8.33％、38.89％、36.11％、16.67％.总体而言,我国水蚀区坡耕地的土壤质量整体状况良好,但仍需要加强对土壤质量偏低地区的培肥改良.本研究对认识和维系我国东部水蚀区坡耕地土壤质量、分等定级与区划,合理开发利用坡耕地土地资源具有重要意义.

Present condition analysis of sloping farmland soil quality in the eastern water erosion zone of China

Background]Soil quality is the foundation of land productivity.Sloping farmland is an important kind of cultivable land resource in the water erosion zone of China.The current study is aimed at investigating the general situation of sloping farmland soil quality in this region.Methods] We collected 36 soil samples from the soil layer of 0-20 cm in this region dispersedly and tested 28 soil physical and chemical indicators for each soil sample.The method of principal component analysis (PCA) was used to select the key indicators for soil quality analysis.Membership functions were used to transform the key indicators into dimensionless data,and the weighted multiplication method was applied to calculate soil quality index (SQI) for each sampling point.Results] 1) The variation coefficient of available P was the maximum,and the variation coefficient of microaggregate volume fraction was the minimum.Most of the indicators had intermediate variability.The mean variation coefficient of soil physical indicators was much smaller than soil chemical indicators.2) The key indicators for assessing soil quality were clay volume fraction,silt volume fraction,microaggregate volume fraction,soil organic matter,pH,Cd and Cr.Cr had the highest membership value,while pH had the lowest membership value.The membership values of Cd were significantly different between the six secondary partition regions.3) The mean value of the SQI was 0.64 ±0.16.There was no significant difference about SQI between the six secondary partition regions.The proportions of SQI ranked as low,middle,high,higher level were 8.33％,38.89％,36.11％ and 16.67％ of the total area of sloping farmland,respectively.Conclusions] On the whole,the general situation of sloping farmland soil quality in the region was fine,but we still need to strengthen fertilization and amelioration in the regions with low soil quality.These findings of the study had great significance for understanding and maintaining sloping farmland soil quality,soil quality grade classification and regionalization,exploiting and utilizing land resource reasonably in the eastern water erosion zone of our country.