黄土高原沟壑区小流域土壤养分空间变异特征及其影响因素

了解表层土壤有机质与全量养分的空间变异规律及其影响因素,能够为黄土高原生态脆弱带的土壤养分管理提供参考。基于王东沟的93个野外采样点,综合多种地统计学方法,分析了土壤养分的空间变异特征及其影响因素。结果表明:研究区表层土壤养分含量处于中等水平,空间变异大小依次为全磷>全氮>有机质>全钾,均由结构性因素主导;有机质、全氮较全磷、全钾变异尺度小、空间自相关性弱、空间复杂程度高。有机质、全氮的分布格局为南高北低,主要影响因素包括海拔、坡度、曲率和土地利用;全磷呈现相反的北高南低分布,海拔、坡度、土地利用、土壤机械组成和人类活动对其影响较大;全钾则为内部高四周低,分布较破碎,坡向和土壤机械组成作用较强。据此建立了9个环境因子与土壤养分之间的回归预测模型,以期为研究区土壤资源的可持续利用提供数据支持。

Spatial variability of soil nutrients and its affecting factors at small watershed in gully region of the Loess Plateau

Studying the spatial variability and its affecting factors of surface soil organic matter and total nutrients can provide reference for soil management in the ecological fragile zone of the Loess Plateau. Based on the 93 soil sampling points in Wangdonggou watershed, this paper used a variety of geostatistical methods to analyze the spatial variability and its influencing factors of soil nutrients in the gully region of the Loess Plateau. The results showed that soil nutrient contents in the study area were at a moderate level. The spatial variability was in the following order: Total phosphorus > total nitrogen > organic matter > total potassium, and they were dominated by structural factors. Compared with total phosphorus and total potassium, organic matter and total nitrogen had smaller variation scale, weaker spatial autocorrelation and higher spatial complexity. Soil organic matter and total nitrogen presented a distribution pattern of high in the south and low in the north, and their main influencing factors included elevation, slope, curvature and land use. Total phosphorus was opposite to the former two, namely high in the north and low in the south. Elevation, slope, land use, soil mechanical composition and human activity had great influence on it. Total potassium was high in the center and low in the periphery, and its distribution was relatively scattered, and aspect and soil mechanical composition had a stronger effect on it. In view of the above results, regression prediction models between nine environmental factors and soil nutrients were established to provide data support for the sustainable use of soil resources in the study area.