The Effect of Non-full Irrigation to Soil Moisture and Output of Alfalfa Field

From 2002 to 2005,The effect of non-full irrigation to soil moisture and output of Alfalfa was researched in the western desert grassland areas of Loess Plateau.The results showed that under the non-full irrigation conditions,supplementary water mainly affected moisture of soil that was above 80cm.There was almost no impact on moisture content of the 80200 cm soil.But the amount of supplementary irrigation affected water consumption and yield of alfalfa significantly.The more amount of supplementary irrigation,the more water consumption and yield of alfalfa.It meant that supplementary water mainly was used for alfalfa growth.Zahua from United States,Gannong No.1 and Debao had high yield under non-full irrigation conditions.These three alfalfa varieties were suitable for western areas of Loess Plateau.