新垦赤红壤结构特性的演化

本文探讨新垦赤红壤结构特性的变化，定位试验结果表明：在亚热带生物气候条件下垦殖赤红壤，由于耕作管理扰动土壤，将不可避免地产生土壤砂化或粉砂化现象。

CHANGES OF STRUCTURAL CHARACTERISTICS OF NEWLY CULTIVATED LATERITIC RED SOIL

This paper primarily discusses the changes of structural characteristics of newly cultivated lateritic red soil. Results are summarized as follows: (1)Under subtropical bioclimate condition, it was unavoidable for newly cultivated lateritic red soil to be sandified due to distrubance by tillage and other managemen practice. It was found that aftrr cultivation, the contents of <0.001mm clay and <0.01mm physical clay in newly cultivated red soil reduced by 35-72% and 10-20% respectively, 0.05-0.01mm silt increased by 20-55%,while 3-0.05mm sand increased or decreased with the changes of silt content.(2) Waterstable aggregate composition of the lateritic red soil changed after cultivation.>1mm aggregates increased more than one time over before cultivation, while <0.5mm aggregates decreased by 3-25%.The increase of>1mm aggregates in 0-20cm soil layer under different patterns of crop rotation was in the descending sequence of perenial Taiwan grass >1:1>1:2>2:1^* (3) Reasons for increase of larger aggregates were different for soils under different use patterns. For soils with legume and non-legume crop rotation the increase of larger aggregates might be attributed to the increase of organic matter, while for soil grown with perenial Taiwan grass it might be due to the grass root peneratration and cutting, It was indicated that the more the soil organic matter, the more the >1mm aggregates would be in the soil with legume and non-legume crop rotauon.(4) The bulk density and porosity in the soils with legume and non-legume crop rotation gradually became more suitable for the growth of crops. Generally, the bulk density and capillary porosity rose in the 0-10cm soil layer but decreased in the 10-20cm layer. But no increase in bulk density and porosity was found in the soil grown with perenial Taiwan grass.