Soil phosphorus is an important indicator to measure the soil fertility, because the content of soil phosphorus has an important effect on physical and chemical properties of soil, plant growth, and microbial activity in soil. In this study, the soil samples collecting and indoor analysis were conducted in Zhoukou City located in the flooded area of the Yellow River. By using GIS combined with geo-statistics, we tried to analyze the spatial variability and content distribution of soil total phosphorus (TP) and soil available phosphorus (AP) in the study area. Results showed that TP and AP of both soil layers (0-20 cm and 20-40 cm) were rich, and the contents of TP and AP in surface layer (0-20 cm) were higher than in the second layer (20-40 cm). TP and AP of both soil layers exhibited variation at medium level, and AP had varied much higher than TP. TP of both layers showed medium degree of anisotropy which could be well modeled by the Gaussian model. TP in the surface layer showed strong spatial correlation, but that of the second layer had medium spatial correlation. AP of both layers had a weaker scope in anisotropy which could be simulated by linear model, and both soil layers showed weaker spatial correlations. TP of both soil layers showed a slowly rising change from southwest to northeast of the study area, while it gradually declined from northwest to southeast. AP in soil surface layer exhibited an increase tendency firstly and then decrease from southwest to the northeast, while it decreased firstly and then increased from southeast to the northwest. AP in the second soil layer had an opposite change in the southwest to the northeast, while it showed continuously increasing tendency from northwest to the southeast. The contents of TP and AP in the surface layer presented high grades and the second layer of TP belonged to medium grade, but the second layer of AP was in a lower grade. The artificial factors such as land use type, cropping system, irrigation and fertilization were the main factors influencing the distribution and spatial variation of soil phosphorus in this area.
土壤中的磷是衡量土壤肥力的重要指标,其含量的高低对土壤理化性质、植物生长以及微生物的活动等都有重要影响.本文以周口黄泛区土壤为例,通过土样采集和室内试验分析,运用地统计分析及GIS空间模拟等方法,分析土壤全磷和速效磷的空间分布特征.结果表明: 研究区土壤全磷和速效磷含量比较高,且表层(0～20 cm)含量均高于第二层含量(20～40 cm).两层土壤全磷和速效磷均属于中等程度变异,并且速效磷的变异程度高于全磷;两层土壤全磷为中等程度的各向异性,最适模型为高斯模型,表层具有较强的空间相关性,第二层则具有中等的空间相关性. 两层土壤速效磷的各向异性均较弱,最适模型为线性模型,两层均呈现较弱的空间相关性. 两层全磷含量从西南到东北方向呈现缓慢上升的变异趋势,而从西北到东南方向呈逐渐下降的变异趋势. 表层速效磷含量在西南到东北方向先升后降,在东南到西北方向呈先降后升的变异趋势;第二层速效磷含量在西南到东北方向上呈现先降后升的趋势,而在西北到东南方向则呈上升趋势.表层土壤全磷含量较高,第二层含量属于中等水平;表层速效磷含量较高,而第二层含量较低.土地利用方式、耕作制度和施肥等人为因素是影响该区土壤磷分布趋势和空间变异的主要因素.
Keywords: Kriging interpolation; flooded area of the Yellow River; semi-variance function; soil phosphorus; spatial variation.