黄土丘陵区退耕地土壤水分入渗特征及影响因素

为评价退耕还林（草）工程的成效及认识下垫面改变对土壤水文过程的影响，采用圆盘入渗仪以4．6、8年退耕地为对象，长芒草草地为对照在黄土丘陵区分层（表层、20cm、40cm）研究退耕地土壤水分入渗特征，并探讨其影响因素。结果表明：1）较短年限退耕地表层土壤入渗能力较天然草地差，而下层入渗能力较天然草地强；2）退耕地下层的初始入渗速率是表层的1．2—1．4倍，稳定入渗率是表层的1．9—2．8倍，饱和导水率是表层的1．9—3．0倍；3）随着退耕年限增加，表层土壤入渗能力下降，而下层入渗能力增强；4）土壤结皮阻碍退耕地表层土壤的入渗。

Infiltration characteristics of soil and its influencing factors in abandoned farmland in the Hilly-gully region of Loess Plateau

Studying on infiltration characteristics of abandoned farmland in Loess Plateau will provide scientific basis for evaluating benefits of abandoned farmland during vegetation restoration and cognizing the influence by variations of underlying surface on soil hydrological processes.This paper studied the characteristics of soil infiltration by disc-permeameter and discussed its influencing factors in 4、6、8 years abandoned farmland.Taking the natural grassland as CK,the characteristics of soil infiltration were tested and its influencing factors were discussed in 4、6、8 years abandoned farmland in this paper.The results indicate: 1) the permeability of surface layer in natural grassland is better than that in short-term abandoned land,but in the lower layers(20 cm、40 cm)they are just contrary to that in surface layer;2) The initial infiltration rate in lower layer is 1.2 to 1.4 times faster than that in surface layer,and the final infiltration rate in lower layers is 1.9 to 2.8 times faster than that in surface layer,and the saturated hydraulic conductivity in lower layers is 1.9 to 3.0 times faster than that in surface layer;3) The permeability of surface layer drop with the increasing of years,but the opposite trend appear in lower layers;4) Soil crust is an important factor which effect permeability of surface layer.