黄土高原小流域土壤养分空间特征及其与地形因子的相关性

Spatial characteristics of soil nutrients in the Loess Plateau watershed and its correlation with terrain factors

【目的】分析黄土高原地区小流域内土壤养分含量的空间特征及其与地形因子的相关性,为养分精确管理和土地资源高效利用提供参考依据。【方法】以位于黄土高原的陕西彬县红岩河小流域为例,于2011年结合GPS共采集了121个田间土样,对其土壤养分(有机质、碱解氮、速效磷、有效钾)含量进行测定,并应用地统计学方法对土壤养分含量半方差函数模型及其参数进行了确定,用普通克里格插值(Kriging)绘制了研究区土壤养分空间分布图,统计分析高程、坡度、坡向、坡形等地形因子与土壤养分含量的相关性,并进行了插值结果检验。【结果】陕西彬县红岩河小流域土壤碱解氮的空间变异性很弱,有机质、速效磷和有效钾具有强烈的空间变异性。各养分含量空间分布均呈斑块状,条带性分布趋势不明显。总体上土壤有机质和速效养分含量与高程和坡度呈负相关,与坡向呈正相关,与坡形相关不显著。【结论】随机性变异(人为因素)对碱解氮的空间变异起主导作用,且变程较小,有机质、速效磷和有效钾的空间变异主要由结构性变异(自然因素)引起,且变程较大。高程、坡度及坡向明显影响土壤养分的含量和分布。

【Objective】This study investigated the relationship between topographic factors and spatial characteristics of soil nutrients in the Loess Plateau watershed,in order to improve the efficient use of land resources and accurate nutrient management.【Method】Hongyan River watershed in Bin County,Shaanxi province,was selected and a total of 121 soil samples were collected with the use of GPS in 2011.SOM,available N,available P and available K contents were measured.Semivariogram theoretical models and their parameters for soil nutrients in the surface layer were analyzed using geostatistical method.Furthermore,spatial distribution of soil nutrients was plotted using Kriging interpolation,and the correlations between terrain factors such as elevation,gradient,slope direction,slope and soil nutrient contents were statistical analyzed.At last,the interpolation results were verified.【Result】Soil available N showed weak spatial variability while SOM,available P and available K showed strong spatial variability.The spatial distribution of all soil nutrients were spotted,without zonal trend.Generally,all soil nutrients were negatively correlatedwith elevation and gradient,and positively correlated with slope aspect.The correlation with slope shape was not significant.【Conclusion】Random factors played a dominating role in spatial variability of available N,and the variation range was short.The spatial variability of SOM,available P and available K were mainly caused by structural factors,and the variation range was long.In addition,Elevation,gradient and slope aspect showed significant impacts on contents and distribution of soil nutrients.