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How does subsurface drainage help remove salt from the root zone?
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Irrigation
Specialized irrigation equipment watering crops in a field.
Subsurface drainage is a critical component of irrigation management used to prevent and reverse the accumulation of salts in the root zone, which can otherwise inhibit plant growth and render land unproductive.12
The process works through the following steps:
- Lowering the Water Table: Subsurface drainage systems, often consisting of tile conduits installed below the ground, are used to lower high water tables that would otherwise draw saline groundwater toward the surface.12
- Leaching: Once the drainage system is in place, fresh, nonsaline water is applied to the soil surface through irrigation. This water moves downward through the soil profile, dissolving accumulated salts as it percolates.13
- Removal: The drainage system intercepts this water—now carrying the dissolved salts—and carries it away from the root zone through the subsurface drainage network, typically via gravity feed to an outlet.413
By maintaining a favorable salt balance where the amount of salt leaving the area equals or exceeds the amount received through irrigation, farmers can sustain the productivity of their land.5