黄土高原沟壑区土壤养分空间变异及其与地形因子的相关性

Spatial variability of soil nutrients and its relations to topographical factors in hilly and gully area of Loess Plateau

【目的】研究黄土高原沟壑区土壤养分空间分布特征及变异规律,分析地形因子对土壤养分空间分布的影响,为土壤养分的有效利用与管理提供理论依据。【方法】运用地统计学和GIS技术相结合的方法,研究地处黄土高原沟壑区的安塞县土壤有机质、碱解氮、有效磷和速效钾的空间变异特征,并利用数字高程模型(DEM)提取坡度、水平曲率、垂直曲率、地形湿度指数和河流动能指数等5个地形因子,分析土壤养分含量与这些地形因子之间的相关性。【结果】(1)土壤有机质、碱解氮、有效磷和速效钾4种土壤养分的变异系数为14.14%～26.84%,块金效应值为16.45%～45.87%。(2)研究区西南部土壤养分含量较高,北部土壤养分含量相对较低。(3)坡度与有机质、碱解氮和有效磷含量呈显著或极显著负相关;水平曲率与有机质和速效钾含量呈显著负相关;地形湿度指数与有机质和速效钾含量呈显著正相关。【结论】安塞县土壤有机质、碱解氮、有效磷和速效钾养分均具有中等变异性,速效钾具有很强的空间相关性;坡度较小、土壤水分较多、水土流失较轻微的地区,土壤养分含量较高;在施肥时,应增大研究区北部氮、磷的施用量。

【Objective】 The spatial distribution and variability of soil nutrients were analyzed in hilly and gully area of Loess Plateau,and the influences of topographical factors on spatial distribution of soil nutrient were also analyzed.This study provided a theoretical basis for the effective use and management of soil nutrients.【Method】 Geostatistics combined with geographical information system（GIS） technique were applied to analyze the spatial variability of organic matter,available nitrogen,available phosphorus and available potassium in Ansai county which belongs to hilly and gully area of Loess Plateou.5 topographical factors gradient（β）,horizontal curvature（Ch） vertical curvature（Cv）,topographical wetness index（Ψ）,river kinetic energy index（Ω） which were extracted from DEM data,were adopted to explore the correlation between soil nutrients contents and topographical factors.【Result】（1）The variation coefficient of soil organic matter,available nitrogen,available phosphorus and available potassium was between 14.14% and 26.84%,the nugget effect value was between 16.45% and 45.87%.（2）The soil nutrient contents were relatively high in southwest of study area,but in the north,they were relatively low.（3）Gradient（β） had significant or highly significant negative correlation with the contents of organic matter and available phosphorus;Horizontal curvature（Ch） had significant negative correlation with the contents of organic matter and available potassium;Topographical wetness index（Ψ） had significant positive correlation with the contents of organic matter and available potassium.【Conclusion】 These 4 kinds of soil nutrients in Ansai county had medium variability;The spatial correlation of available potassium was highly dependent;Those areas with lower gradient,more soil moisture,slighter soil and water loss were abundant in soil nutrients;In the north area,the soil nitrogen and phosphorus fertilizer should be increased.