半干旱区柠条林利用土壤水分深度和耗水量

植物根系利用土壤水分深度和耗水量是研究植物与土壤水关系的基础.以柠条为对象,采用中子仪,对撂荒地和柠条林地土壤水分进行长期定位观测和分析.结果表明,2002年内,随着时间推移,柠条利用土壤水分深度从播种时的2 cm左右,迅速增加到9月1日的90 cm,10月15日的110 cm,11月1日的170 cm,到11月15日柠条利用土壤水分深度为220 cm;除丰水年(2年生)柠条土壤储水量增加了122.8mm外,随着林龄的增加和降雨量等的变化,植物利用土壤水分的深度和耗水量增加,土壤储水量下降.到2004年生长季末,3年生柠条林地100 cm土层出现土壤干层,5年生柠条林地剖面60-300 cm土层出现土壤干层.此时需要采取措施,控制柠条生长、密度和耗水量,实现土壤水资源的可持续利用.

Using Depth of Soil Water and Water Consumption by Littleleaf Peashrub in the Semiarid Area of Loess Hilly Region

The using depth of soil water and water consumption by littleleaf Caragana korshinskii is the base of studying the relationship between soil water and the plant growth. The dynamic of soil water were continuously measured with a neutron probe in wasteland and young peashrub forest land during the period from 2002 to 2006. Results showed that in 2002, the depth to which plant use soil water was increased from about 2 cm sowing on 24th June to 90 cm on 1st Sep, 110cm on 15th Oct, 170 cm on 1st Nov, and 220 cm on 15th Nov. The using depth of soil water and water consumption by littleleaf peashrub were increased and the amount of soil water storage was reduced with increasing age apart from the wet year (2003) in which the amount of soil water storage was increased by 122.8 mm in the 2-year-old peashrub forest land. It was also discovered that soil desiccation at which water content was smaller than and equal to the upper limit of wilting coefficient occurred at the soil depth of 100 cm in the 3-year-old peashrub land and soil desiccation occurred in the soil layer from 60 to 300 cm in 5-year-old peashrub land. Some effective measures should be taken to control plant density and growth in order to reduce soil water consumption and realize sustainable use of soil water.