黄土坡面土壤性质随退耕时间的动态变化研究

退耕还林还草是控制水土流失和防治土壤退化的关键措施,黄土高原退耕还林还草从试验到推广已有几十年历史。该文通过对黄土高原地区退耕区的实地调查,测定不同地区不同退耕年限植被恢复区表层土壤的理化性质,分析黄土坡面土壤理化性质随退耕时间的动态变化规律。结果表明:随着退耕植被恢复时间的增长,土壤物理结构将日趋改善,土壤养分含量水平将逐渐的提高,并主要集中在植被恢复10~20年期间,20年后,尤其是30年后,土壤理化性质较为稳定,而且,植被维护的好坏往往影响其稳定性。同时,水热条件较好的安塞地区土壤理化性质随退耕时间的改善程度更明显,而水热条件较差的皇甫川流域土壤理化性质随植被类型和植被恢复程度的影响更为显著。结果可为退耕的环境影响评价预测以及土地利用的调控提供科学依据。

Research on Soil Property Dynamics in Retired Farmland in the Loess Sloping Land

Returning farmland to forest or grassland is the key to control soil and water loss and prevent soil degeneration,and from test to application the project have had conducted several decades in the loess plateau.According to survey the retired farmlands under different areas and different vegetation restoration years,soil samples from depth intervals of 0~20cm were collected for laboratory assessment to measure the physical and chemical properties of soil,and analyze soil properties changes with farmlands years retireing in this paper.The results showed that soil physical texture were improved much more and soil nutrients increased with the time prolonging of the Returning farmland to forest or grassland;Soil properties change was mainly accurred in the 10~20 years of vegetation restoration after abandoned farmlands,after 20 years,specially after 30 years,physical and chemical properties of soil became stable,and vegetation restoration quality affected its stable.Meanwhile,in the Ansai country of Shanxi province with preferably condition of water and quantity of heat,vegetation restoration years significantly affected soil properties.Moreover in the Huangfuchuan valley located north of the loess plateau,the soil quality improving degree with different vegetation was more distinct than with the years.The results might have contribution to evaluate the environmental efficiency,and make and modify the policy of retiring the farmland.