Effects of winter irrigation on soil salinity and jujube growth in arid regions.

The considerably high evapotranspiration and the low leaching fraction of the soil in arid regions are likely the primary causes of the enhanced soil salinity in such regions. Winter irrigation has proven to be very effective for promoting the leaching of salts from the rooting-zone. In this study, we investigated the effects of different irrigation methods (flood irrigation and drip irrigation) and winter irrigation quotas (450, 1350, 2250, 3150, 4050, and 4950 m3/hm2) on soil salinity and plant growth in an arid region. The sum of ECe in the 0-100 cm soil layer was 56.26-29.32 ms/cm under flood irrigation, 61.37-17.90 ms/cm under drip irrigation, and 64.13 ms/cm under no irrigation. The survival rates of jujube trees reached 65% and 77%, respectively, for drip irrigation and flood irrigation with a quota of 2250 m3/hm2. Furthermore, at irrigation quotas in excess of 3150 m3/hm2 the ground diameter and height of jujube trees were significantly greater than those observed under nonwinter irrigation and several other winter irrigation treatments. These findings indicated that winter irrigation significantly reduced soil salinity, changed the soil salt distribution, created a good environment for the growth of jujube trees and improved the survival rate of young jujube trees, especially under winter drip irrigation with a quota of 3150 m3/hm2. In addition, 1-year-old jujube trees emerging in spring may benefit from an ECe lower than 5 ms/cm.