连作对棉田土壤物理性质的影响

以新疆南疆地区50团棉花连作5年、10年、15年20年的土壤为研究对象，分别测定不同连作年限土壤比重、容重、孔隙度以及团聚体结构和机械组成等物理性状。结果表明：棉花连作对其土壤各种物理性状产生了较大的影响。比重、容重随着连作年限的增长呈上升趋势，而孔隙度则反之；土壤团聚体中粒径小于0.25mm的微团聚体占了较大比重，良好团聚体的含量随着连作年限的增长呈下降趋势，而微团聚体则相反；土壤机械组成中砂粒的含量占了较大比重，而砾石没有，砂粒的含量随着连作年限的增长呈上升趋势，粉粒呈下降趋势，而粘粒呈无规律的波动状。

The Influence of the Continuous Cropping to the Physical Properties of Cotton Soil

Taking the cotton soil which have been planted cotton five years, 10, 15, 20 years in the 50 Mission in South Xingjian region as a target, we respectively measured the proportion of cotton soil, density, porosity and the reunion of the structure and mechanical components and other physical properties with the different continuous cropping years. The results showed that: The continuous cropping with cotton have a great influence on various physical properties. The proportion and density of cotton soil has an upward trend with years of growth. And the porosity of the contrary. The micro-aggregates which is less than 0.25 mm in the soil aggregate a larger proportion. The good proportion of the aggregate has a declining trend with years of growth, while micro-aggregates the contrary; the sand of the soil mechanical components have a larger proportion; but not gravel, the sand content showed an upward trend with years of growth, but the downward trend of silt, and clay showed no fluctuations in-law.