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How can irrigation and drainage reclaim soil damaged by salt buildup?
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land reclamation
The Yser River flowing through reclaimed farmland in Belgium.
To reclaim soil damaged by salt buildup, it is necessary to reverse the accumulation process by facilitating the downward movement of water through the soil profile. This is achieved through a two-step approach involving drainage and leaching:1
- Improve Drainage: The first step is to establish or improve drainage systems. This prevents saline groundwater from rising to the surface and ensures that water applied to the surface can move downward through the soil, carrying dissolved salts away.1
- Leaching: Once drainage is secured, the soil is flushed with fresh, nonsaline irrigation water. This process, known as leaching, washes excess salts out of the root zone.12
For "sodic soils"—where sodium ions have been adsorbed by clay particles—leaching alone is insufficient. In these cases, chemical amendments such as gypsum are added to the soil. These amendments provide calcium, which replaces the adsorbed sodium, allowing the sodium to be leached out of the soil profile along with other salts.1