Abstract: 【Objective】An experiment was carried out to study the rule of soil water consumption in poplar agroforestry system in water-lacking plain area in order to provide the arguments for the sustainability of poplar agroforestry from the viewpoint of water. 【Method】 Soil water content was measured by neutron machine and production of crops and poplar was measured. 【Result】Results indicated that in 2-5 years tree system: (1) the water consumption of poplar ageoforestry system is higher than the mode of sole wheat-corn by 24%; The pondage decreased by 32.1 mm in 0-4 m depth, which equaled 3.3% of the total pondage; It trended that soil from 2 to 4 m depth was becoming dry because no water supplement. (2) The production of crops in agroforestry decreased seriously because of lacking of soil water and illumination and so on, production of wheat and corn in 3 years agroforestry system decreased by 35%.【Conclusion】Poplar agroforestry system popularized in Haihe low plain threatens the security of water and food production.

Key words: poplar-agroforestry, soil water content, water consume, productivity