Experimental evaluation of irrigation methods for soil desalinization

Soil salinization has provided a serious threat for global agriculture throughout human history. It is becoming ever more prevalent as human land use intensifies in recent years, and the reclamation is one of major challenges in agroecology. Flood irrigation is a typical method for leaching saline soil. Yet the practice needs a large amount of water, and it is difficult to remove salt uniformly throughout soil layers. In this study, an experiment was conducted to evaluate leaching efficiencies of four different methods, namely: flood irrigation, spray irrigation, paper-covered flood irrigation, and puddling irrigation. Flood irrigation was applied at three plots with different infiltration capacities. Spray irrigation, paper-covered flood irrigation, and puddling irrigation were applied at other three plots with medium infiltration capacities. Results showed that salt removal rates of flood irrigation tended to be higher near the surface of soil with smaller infiltration capacity, and that spray irrigation, paper-covered flood irrigation, and puddling irrigation were more efficient in removing salt than flood irrigation. Paper-covered irrigation was the only leaching method that reduced horizontal heterogeneities in salt content, while flood irrigation and puddling irrigation significantly increased the horizontal heterogeneities. The present study indicated that leaching efficiencies were highly affected by irrigation intensity and also by irrigation water volume only when irrigation intensity was considerably low, and that paper-covered irrigation is an efficient method in removing salt homogeneously from soil profile. Further studies need to be conducted to optimize irrigation intensity and water volume for given soil and water environmental conditions.