Abstract: A stationary field experiment was carried out to investigate effect of water treatment on farmland water regime,using a neutron probe.Results show that after a long-term experiment soil water storage in the 0—110 cm soil layer followed an order of suitable water treatment>rainfall treatment>dry treatment with the first two being 23.4% and 12.9%,respectively,higher than the last.During the soybean growing season,soil water storage in all the treatments displayed a trend of seasonal variation,such as declining-rising-declining-rising,which was closely related to rainfall distribution during the season.In terms of moisture consumption by soybean,the three treatments followed a decreasing order of suitable water treatment>rainfall treatment>dry treatment,and their value was 459.4,420.3,and 326.4 mm,respectively.Soybean water consumption varied slightly between treatments at all growth stages,during the period(2008-05-01—2008-06-15) when they were free of the influence of water control,but significantly in the period when they were under the influence of water control.The water-inflow/water-consumption ratio demonstrated that the black soil was quite high in capability of adjusting water regime.Water use efficiency of the dry treatment,the rainfall treatment and the suitable water treatment was 3.9,4.8 and 5.4 kg·hm^-2·mm^-1,respectively,indicating that irrigation could enhance water use efficiency in normal years in black soil.

Key words: water treatment, black soil, farmland, soil moisture