科尔沁沙地旱作农田土壤退化的过程和特征

在一个较小的时空尺度上对科尔沁沙地典型旱作农田土壤物理和化学特性在风蚀沙化过程中的演变特征及其退化过程进行了的探讨。结果表明 :旱作农田由于周边沙质草地的开垦而发生风蚀沙化 ,3～ 5年的时间就会使 5 %～ 15 %的细粒物质吹蚀 ,表土粗化 ,向风沙沉积特征发展 ,土体结构破坏 ,容重增加 0 .0 5～ 0 .15 g/ cm3,总孔隙度降低 3%～ 5 % ,持水性能变劣 ,养分也随之丧失 ;<0 .0 5 mm的粘粉粒吹蚀 1% ,土壤有机质和全氮含量下降 0 .2 5 9g/ kg和 0 .0 16 4 g/ kg;土壤退化的演变 ,既有系统本身的自然属性决定的内在原因 ,更重要的是人为的外部干扰体系的驱动 ;退化的过程既有渐变型 ,又有跃变型

Process and Character of Soil Degradation of Rainfed Farmland in Horqin Sandy Land

From the aspects of physics and chemistry, the processes and characteristics of soil degradation of typical rainfed farmland in the Horqin sandy land were discussed. Results showed that in the desertification process of rainfed farmland, a series of physical and chemical properties worsened associated with losses of soil fine particle materials, including bulk density and pH raised, total porosity reduced, aeration and non capillary porosity increased, water holding capacity relented, soil organic matter, total N and P, available N and P contents decreased. One percent of silt and clay contents (<0.05mm) were removed, could result in the decreases of 0.259 g/kg soil organic matter and 0.016 4 g/kg total N contents. Disturbances induced by farmers (i.e. cultivation of sandy grassland in the edge of farmland) was the main force of soil wind erosion and degradation. Two models of soil degradation process was put forward, namely, gradual degradation course and leap degradation course.