Effect of saline land reclamation by constructing the "Raised Field-Shallow Trench" pattern on agroecosystems in Yellow River Delta

Efficient utilization of the limited water and land resources is critical for global development with a growing population. The widespread saline land remains an important reserved land resource for food security. This study investigated the performance of the raised field-shallow trench pattern on salt removal and water budget in the cotton field by a virtual experiment. The widely-used physically-based HYDRUS (2D/3D) model was used to implement different raise field elevations and slopes. Results showed that the raised land could control the soil salinity in the unsaturated root zone by intensifying the drainage. Compared with the flat land, the desalination effect of the raised land was more effective with the gentler slope and higher raised elevation. Without irrigation, the 30 and 45 slope-raised lands had slight effect on the soil salinity in the unsaturated root zone. Salt removal would be more effective with the addition of irrigation, with the desalination ratio ranging from 10.60% to 41.01% under fresh irrigation, or from 6.76% to 25.92% under saline irrigation, respectively. More importantly, the implementation of irrigation effectively improved the cotton root water uptake, and saline water irrigation for the 15 slope-raised field was proved to nearly meets the cotton water requirement. Therefore, the raised field-shallow trench pattern combined with saline water irrigation may provide local farmers with an alternative solution to saline land reclamation under fresh water scarcity.