| Soil water balance of farmland in east Gansu was calculated,the results show that: crop yield were closely related with soil water profit,but the relation degrees between crops were varied with climate change from year to year,the degree of crop' needed mor water,such as maize and soghum,was higher than that needed less water,such as winter wheat and potato.The water affecting degree also varies with crop growth stages,meanwhile disturbed by other affecting factors. |