It is a key problem to balance the water demand of shelterbelt and farmland crops reasonably in the construction of shelterbelts forest network system in Hetao irrigation district due to the arid climate conditions.In order to study the influence of typical farmland shelterbelts on the water source of farmland crops in Hetao irrigation district

three typical shelterbelt systems in Hetao irrigation district were selected

and the soil moisture content

hydrogen and oxygen isotope values of soil and crop stem water at 0.3 H

0.4 H

0.6 H and 2 H away from the edge of nearby farmland were measured and analyzed.The results showed that:(1) From July to September

the soil moisture contents of all farmland plots were generally low.The soil moisture contents of 4 and 5 row plots at the near end of forest were lower than that at the far end of forest

and there was no significant difference in the soil moisture content of the 8 row plots.(2) The hydrogen and oxygen isotopes of soil water in all plots were depleted with the increase of soil depth as a whole.Among them

the 40—60 cm soil layer at 0.4~0.6 H away from the edge of farmland in the 8 row plots showed greater isotope enrichment.(3) The soil water of 40—80 cm soil layer was mainly used for maize at 0.3~0.4 H away from the edge of farmland in the 4 row plots

and the soil water of 0—40 cm soil layer was used for maize at 0.6~2.0 H.The soil water of 20—60 cm soil layer was used for maize at 0.3 H and the soi lwater of 0—60 cm soil layer was used for maize at 0.4~2.0 H in row 5 plots.The maize in row 8 at 0.3 H and 2 H mainly used soil water in 0—40 cm soil layer

while the maize at 0.4~0.6 H mainly used more soil water in 20—80 cm soil layer.According to the study

the shelter forest with 8 row configuration had a wider impact on the water use range of farmland crops

while the influence range of 4 and 5 row of shelterbelts on the growth water of farmland crops was smaller on the premise of not affecting the protection effect.The results can provide theoretical reference for the rational allocation of farmland shelterbelt system.