This paper deals with saving water resources and improving irrigation water quality for agricultural development in and areas. An experiment on the recycling use of irrigated water using earth-air heat exchange distillation is described. The experimental apparatus is similar to a solar greenhouse using underground heat exchange. The air in the greenhouse which is nearly saturated by plant transpiration is refrigerated along the underground pipe and the vapour in it is condensed into waterdrops. The condensed water is collected. This recovered water is water distilled from the moist air, which is originally from irrigated water, and is available for re-use in irrigation. The experiment was carried out in the vinyl film tunnel culture with lettuce plant. In the experiment, 30% of the supplied water was recovered. In addition to the re-use of this water, the vapor retentivity of the vinyl film can also result in a water savings of about 40% in comparison with open-field culture. Furthermore, it is expected that the accumulation of salt in soils can be reduced to about 40% compared with open-field culture conditions, because of the high quality of the distilled water which was recovered is mixed with irrigation water.
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