黄灌沙区农田耕层土壤性状空间异质性分析

用地统计学的方法,研究了黄灌沙区农田耕作层(030 cm)土壤的有机质、全氮、碱解氮、速效磷、速效钾、pH和电导率的空间变异规律。结果表明,农田耕作层土壤养分的空间异质性主要由随机性因子如土壤耕作措施,包括施肥、灌溉和作物轮作等造成,这与该区农田耕作层土壤是引黄灌溉改良的结果有关。土壤养分含量的变异函数均可很好地拟合成线性模型,块金值和基台值之比(C0/C0 C)均为1,说明随机性因子是导致该区土壤性状空间变异的主要因素,在整个尺度上具有恒定的变异,造成了土壤性状的相对均一。pH的变异函数为指数模型,其空间异质性组成中随机性和结构性因子各占50%。电导率的变异函数为球状模型,空间变异主要由结构性因子导致,结构性因子引起的空间异质性占总空间异质性的67%。分维数也表明耕层土壤性状空间依赖性较小,随机因子如农业活动是引起黄灌沙区土壤性状空间异质性的关键原因。Moran s I系数表现为除了pH和电导率受结构性和随机性因子共同作用外,其余土壤性状均呈较弱的相关关系。因此,干旱沙区通过人为措施改良的土壤性状空间上的变异主要受人为活动如灌溉、施肥和耕作等影响,在农业活动中更应该注重施肥和灌溉方式、灌溉水源等问题,以避免因土壤性状的变异导致的肥料利用效率降低。

Spatial Heterogeneity Analysis of Soil Property at Plough Horizon of Farm Land by Irrigating Using Yellow River in Arid Desert Region

Spatial patterns of soil property at plough horizon of farm land by irrigating using Yellow river in arid desert region were studied by means of geo-statistics.The results showed that soil nutrient content of organic matter,total nitrogen,available N,available P and K could be well expressed by linear model;pH and electric conductivity was exponential and spherical model,respectively.The all of the null/sill of soil nutrient properties was equal 1.These results mean that weak spatial auto-relation existed.The spatial heterogeneity was mostly control by stochastic factors such as fertilizer application,irrigation and crop rotation et al.The spatial variability of soil pH was made of stochastic and structure factors.The stochastic and structure factors accounted for 50%,respectively.However,the structure factors of 67% and the stochastic factors of 33% constituted the spatial heterogeneity of electric conductivity.Fractal dimension and Moran's I coefficient also proved soil properties were weak spatial auto-relation and dependence.From another point of view,these results tested that the spatial variability of soil properties of shifting sand by improvement on the relative homogeneous matrix matrices were dominating made of stochastic factors.So,soil properties of cultural improvement soil in arid desert region undergone artificialness effects such as fertilizer application,irrigation and crop rotation et al.Farmers should pay more attention to these for preventing soil properties from in-homogeneity,and more resulted in lower efficiency for fertilizer.