青藏高原东北缘不同土地利用类型土壤质量综合评价

土壤质量评价是合理利用土壤资源的重要前提。通过采集青藏高原东北缘甘肃省天祝县境内林地(n=9)、草地(n=18)和耕地(n=38)土壤样品,并测定土壤容重、田间持水量和有机质等13项土壤理化性质指标,采用主成分分析和相关性分析构建最小数据集(MDS),建立土壤质量评价指标体系,对3个不同土地利用类型的土壤质量进行综合评价。结果表明: 林地的总孔隙度、毛管孔隙度、田间持水量、毛管持水量、饱和含水量、有机质、全氮和速效钾含量显著高于草地和耕地。林地土壤质量评价指标体系包括田间持水量、有机质、全氮、速效氮和速效钾,土壤质量指数(SQI)介于0.329～0.678,平均值为0.481;草地土壤质量评价指标体系包括田间持水量和速效氮,SQI介于0.302～0.703,平均值为0.469;耕地土壤质量评价指标体系包括毛管持水量、非毛管孔隙度、速效氮、速效磷和速效钾,SQI介于0.337～0.616,平均值为0.462。影响林地、草地和耕地土壤质量的最大障碍指标分别为速效钾、田间持水量和毛管持水量。基于MDS的土壤质量指数能够实现研究区不同土地利用类型土壤质量的准确评价,土壤质量整体上表现为林地>草地>耕地,评价结果对该区域土壤可持续管理具有重要参考价值。

Comprehensive evaluation of soil quality of different land use types on the northeastern margin of the Qinghai-Tibet Plateau,China

Soil quality evaluation is an important prerequisite for the rational soil resource utilization. We collected soil samples from forest (n=9), grassland (n=18) and cropland (n=38) in Tianzhu County, Gansu Province, which is located on the northeastern edge of the Qinghai-Tibet Plateau. Soil quality was evaluated based on thirteen soil physical and chemical indicators, including soil bulk density, field capacity, and organic matter. A minimum data set (MDS) was constructed using principal component analysis and correlation analysis to establish a soil qua-lity evaluation index (SQI) system, which was used in the soil quality evaluation for the three land-use types. The results showed that total porosity, capillary porosity, field capacity, capillary water capacity, saturated water content, organic matter, total nitrogen and available potassium content were significantly higher in forest than those in grassland and cropland. The SQI system of forest was based on field capacity, organic matter, total nitrogen, available nitrogen, and available potassium, and the SQI ranged between 0.329 to 0.678, with a mean value of 0.481. Grassland SQI system was based on field capacity and available nitrogen, with the SQI ranging between 0.302 to 0.703 and a mean value of 0.469. Cropland SQI system was based on capillary water capacity, non-capillary porosity, available nitrogen, available phosphorus, and available potassium, and the SQI ranged from 0.337 to 0.616 with a mean value of 0.462. The most important barriers to soil quality improvement in forest, grassland, and cropland were available potassium, field capacity, and capillary water capacity, respectively. The MDS-based SQI enabled an accurate evaluation of soil quality across different land-use types in the study area, which was best in forest followed by grassland and cropland. The evaluation results would provide important reference for sustainable soil management in the local area.