Abstract
The dry drainage system (DDS) is an alternative technique for controlling salinization. To quantify its role in soil salinity control, a five-year field observation from 2007 to 2011 was completed in a 2900 ha experimental plot in Yonglian Experimental Station, Hetao Irrigation District, China. Results showed that the groundwater table depth in the fallow areas quickly responded to the lateral recharge from the surrounding croplands during irrigation events. The groundwater electrical conductivity (GEC) of fallow areas increased from 5 mS·cm−1 to 15 mS·cm−1, whereas the GEC below croplands produced small fluctuations. The analysis of water and salt balance showed that the excess water that moved to fallow was roughly four times that moved by an artificial drainage system and with 7.7 times the corresponding salt. The fallow areas act as a drainage repository to receive excess water and salt from surrounding irrigated croplands. Slight salt accumulation occurred in irrigated croplands and salts accumulated, with an accelerating trend over the final two years. The evaporation capability weakened, partly due to the salt crust in the topsoil, and the decrease in soil permeability in the soil column, which was almost impermeable to water. Using halophytes may be an effective method to remove salts that have accumulated in fallow areas, having great economic and ecological value. A DDS may be effective and sustainable in situations where the fallow areas can sustain an upward capillary flux from planted halophytes.
Highlights
Salinization is a long-standing problem that has threatened crop production and food security in many arid and semi-arid regions, and has impeded sustainable irrigation over the past 2000 years
The dry drainage system (DDS) is a potential approach for controlling soil salinity induced by irrigation, and can contribute to attaining and sustaining the salt balance in irrigated lands with insufficient artificial drainage system (ADS)
Of the fallow areas increased from 5 mS·cm−1 to 15 mS·cm−1, the excess water moving to the fallow lands was roughly four times greater than that moved by an ADS, and it contained 7.7 times more salts
Summary
Salinization is a long-standing problem that has threatened crop production and food security in many arid and semi-arid regions, and has impeded sustainable irrigation over the past 2000 years. To alleviate the impact of soil salinity, various technical measures and strategies have been developed since the early 1900s. Irrigation systems can be sustainable if excess salt and drainage water are adequately removed from the subsoil [8]. Many soil-related problems could be minimized by installing various types of drainage ditches. An artificial drainage system (ADS) is a popular method used to drain salt away from the root zone by deliberate flood irrigation events [9,10,11,12,13]. Conventional drainage methods produce seemingly intractable economic [14] and environmental problems [9,10,11,12,15,16,17]
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