| 摘 要： |
Because of the presence of shallow water tables and consequent secondary salinization in irrigated areas of Xinjiang China, there is an urgent need for installation of drainage systems to control the salinity levels in the crop rootzone. The goal of this study was to compare the midterm effects of the open ditch (depth of 2.2 m) and subsurface pipe (depth of 2.2 m) drainages on soil salinity, drainage, groundwater, cotton biomass, yield, and economic benefits while using drip irrigation under mulch (plastic film). We conducted a field experiment for eight consecutive years (2012-2019) in Shawan County of Xinjiang, China. Our experimental results indicated that open ditch and subsurface pipe drainages each reduced total soil salinity, improved saline-sodic soils, and controlled groundwater level, which caused a significant increase in the cotton biomass and yield. The open ditch drainage treatment (ODDA) represented a better desalination effect than the subsurface pipe drainage treatment (SPDA) at 73% and 81%, respectively. The electrical conductivity and pH of ODDA and SPDA water samples decreased as the soil salinities decreased over time. We used the farmland conditions from 2012 as the baseline for our experiment and evaluated how these baseline conditions changed over time in response to these treatments. Compared to this baseline, the cotton yield of ODDA and SPDA treated farmland increased by 18.30 times and 19.96 times in 2019, respectively. The investment payback periods for ODDA and SPDA treatments were 7.59 and 6.34 years, respectively, and their returns on investment were 12% and 30%, respectively. The midterm economic benefits of subsurface pipe drainage were more prominent than those of open ditch drainage. These results provide a reference for improving, developing, and utilizing soil saline-sodic land, and the sustainable development of agriculture in arid areas. |
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