农田土壤质地空间分布的三维随机模拟及其不确定性评价

3-D Stochastic Simulation and Uncertainty Assessment of Soil Texture at Field Scale

定量描述土体三维构型对于土地利用及农田水肥管理研究极其重要。本研究根据华北山前冲积平原区一块农田内的109个土壤剖面观测数据,运用马尔科夫地质统计学方法构建了土壤质地种类的三维空间分布模型,在100次随机模拟的基础上,分别得到了土壤质地种类的优化分布图及其概率分布图。结果表明,一维嵌入转移概率模型能很好地描述农田水平和垂直方向上各土壤质地种类的空间连续性及毗邻转移趋势。优化分布图虽能直观反映土壤质地种类的空间分布特征,但存在明显的平滑效应,不能刻画土壤质地种类空间分布的不确定性。而采用概率分布的方式来描述土壤质地种类空间分布的不确定性,能够有效地克服该缺点。

Quantitative description spatial distribution of soil texture in three dimensional is very important for the studies of land use and water and fertilizer management. In this study, we constructed 3-D Markov chain model based on observation of 109 soil profiles in piedmont alluvial plain on the North China, and then optimal prediction map and occurrence probability map of soil textural classes in 3-D were obtained based on the 100 stochastic simulations. The results indicated that one-dimensional embedded Markov chain model could well describe the spatial continuity and juxtapositional tendencies of different textural classes both in horizontal and vertical directions. 3-D optimal distribution of soil texture could directly reflect the spatial distribu- tion of soil textural classes. However, it existed obvious smoothing effect and could not describe the uncertainty of spatial distri- bution of soil textures. The probability distribution map was applied to analyze the uncertainty of spatial distribution of textural classes and it could effectively overcome this shortcoming.