陕北丘陵区农田蒸散规律及对土壤水环境的影响与防治对策

为了探讨陕北黄土高原农田土壤蒸散规律及水分环境现状,提高土壤水分利用效率,采用TDR法测定了土壤水分,对陕北峁状丘陵区旱梯田裸露地、作物地以及农田覆盖地土壤水分进行系统监测,并结合野外自动气象哨资料,分析了该区农田土壤水分蒸散规律。结果表明,裸露地周年存在两个蒸发高峰期,年蒸发量占降水量的74.4%;土地空闲期对恢复土壤水分亏缺贡献很大;地面采取部分覆盖(地膜覆盖,覆盖率60%)有利于土壤水分环境的恢复与保护,而采取全覆盖(组合覆盖和秸秆覆盖,覆盖率100%)有利于土壤水分的高效利用。在此基础上提出了提高该区土壤水分利用率的有效技术途径:采取双料沟垄组合覆盖技术最大限度地抑制裸露地表的无效蒸发,草粮轮作、避免耕地荒芜提高土壤水分利用率。

Study on the effect of cropland evaporation on soil water environment and the preventive measures in the Loess Plateau hilly and gullied area of North Shaanxi

In order to explore the evaporation and transpiration law of soil moisture in cropland in Loess Plateau of North Shaanxi,and to improve the efficiency of soil moisture use,by using TDR sensor to measure water content,the soil moisture of bare land,crop land and covered cropland in the drought terrace were watched systematically,then integrating the data of field automatic weather station,we analyzed the water evaporation law of farm land of the Loess Plateau hilly and gullied area:there are two intense evaporation periods in one year,vaporized volume in one year is 74.4% of annual precipitation.The period when there is no crop contributes more to water storage.Partially covered soil (film cover,covering ratio is 60%) is in favor of the conservation of soil water,and fully covered soil (combined cover and straw cover,covering ratio is 100%) is in favor of highly efficient use of soil water.Based on these studies,an efficient technological way of increasing soil water use is put forward:the utility of soil water can be enchanced by the cover technology of ditch and ridge covered with two materials,rotating crops between grass and grain avoiding the desolation of tillable field.