Soil Structure of Different Land Use Types in Wind-eroded Region in the Outskirt of Beijing

摘要

Changes in soil structure have a great effect on soil erosion and soil degradation.The soil structure under different vegetation types was studied in Kangzhuang Town, Yanqing County, which is the primary wind-eroded region in the outskirt of Beijing. The vegetation types studied were woodland, forest-grass mixture, arbor-shrub-grass mixture, vegetable (cabbage) plot, fruit-cabbage intercrop plot, no-tillage plot and stubble mulch farming plot. The result showed that the soil bulk density, stable aggregates, soil organic matter and soil particlesize distribution could denote the soil structure of Yanqing County. The effect of different land use types on the soil structure varied. The content of organic matter in vegetable and no-tillage plots was 22.7% - 43.8%, which was more than the other plots. The organic matter content of surface soil varied as follows: vegetable plot ＞ no-tillage plot ＞ fruit-cabbage intercrop plot＞ stubble mulch farming plot in the cropped plots, and arbor-shrub -grass mixture ＞ forestgrass mixture ＞ sparse woodland in the shelterbelt. The soil bulk density varied in the order:arbor-shrub-grass mixture ＞ forest-grass mixture and sparse woodland. For the cropped plots,the order was: stubble mulch farming plot ＞ fruit-cabbage intercrop plot and vegetable plot ＞no-tillage plot. For the soil micro-aggregate in surface soil in shelterbelt, arbor-shrub-grass mixture soil had higher (94.34%) micro-aggregate than forest-grass mixture (86.59%) and sparse woodland (89. 86%). In the cropped plots the micro-aggregates were in the order: vegetable plot ＞ no-tillage plot ＞ stubble mulch farming plot ＞ fruit-cabbage intercrop plot. Soil erosion was most severe in the stubble mulch farming and least severe in the forest-grass mixture.