我国干旱沙漠地区不同类型土壤结皮的理化性质研究

本研究对我国干旱沙漠地区不同类型土壤结皮的理化性质特征进行了系统研究。研究结果表明:无论是不同地区还是同一地区不同发育程度的土壤结皮机械组成,它们的共同特征都是砂粒和粗粉粒含量相对较多,细粉粒和粘粒含量相对较少;从流沙到土壤结皮的形成过程中,粗粉粒是土壤结皮形成的关键基础。通过对同一地区不同发育程度的结皮机械组成比较说明结皮形成初期对颗粒组成有一定的要求,组成达到一定范围才能形成结皮,结皮一旦形成,随时间的增加,结皮厚度在不断增加,但质地基本不变。土壤结皮的形成过程是土壤养分和有机质不断富积的过程。各研究区的土壤结皮pH值相差不大,均在8左右,呈弱碱性;碱化度均≥5,处于碱化发育过程中。由于各地降水量和土壤母质发育的不同,不同地区以及同一地区不同发育程度的土壤结皮之间的CaCO3含量差异较大;同一地区土壤结皮的全盐量差异不大;不同地区土壤结皮的阴阳离子交换量差异较大,同一地区之间差异不大。该文对进一步研究土壤结皮的形成有一定的参考价值。

The Physical and Chemical Characteristics of Different Soil Crusts in Arid Desert Area of China

The physical and chemical characteristics of different kinds of soil crusts in arid desert areas of China were analysed.The results showed that mechanical compositions of soil crusts in different area or same area had a common characteristics that was the contents of sand and coarse silt were relatively more and the contents of fine silt and grain were little.In the process of soil crusts formation,coarse silt was the key factor.By contrasting and analysing the mechanical composition of soil crusts with different growth degree,it was found at the beginning of soil crusts formation,the mechanical composition must extend to a definite range,soil crusts would form.Once the soil crusts formed,the thickness of crusts were increasing with the time,but the texture did not change.The process of soil crusts formation was the process of enrichment of soil nutrients and organic matter.The pH of soil crusts in each area was around 8.Their ESP was ≥5.These were in process of basify development.Because of the difference of rainfall and soil parent material in each area,the amount of CaCO_3 in soil crusts in different or same area had big difference.The salinity of soil crsust in same area had little difference.The amount of exchange of anion and cation had big difference in different area,little difference in same area.The result is a scientific reference for farther study on soil crusts formation.