Soil salinity control

Soil salinity control is the management of soluble salts in soil to limit crop damage. It commonly combines water management, drainage, and amendments suited to the soil and water.

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Leaching requirement: The fraction of applied irrigation water that must drain below the root zone to control salt accumulation. It estimates the extra irrigation needed to carry salts below crops’ active roots.
Irrigation water quality: The suitability of water for irrigation, assessed by its salinity, sodicity, and other properties. Salty or sodic irrigation water can undermine leaching and add hazards that require different management.
Electrical conductivity: A measure of a solution’s ability to conduct electric current, commonly used to estimate dissolved salts. Soil-paste electrical conductivity is the standard measure used to classify saline conditions.
Waterlogging: The saturation of soil with water that deprives roots of adequate oxygen. Leaching without sufficient drainage can raise water tables and suffocate crop roots.
Soil leaching: The downward movement of dissolved substances through soil with percolating water. Leaching moves soluble salts from the root zone toward drainage outlets.
Subsurface drainage: A system of buried drains that removes excess water from below the soil surface. It provides an outlet for saline water displaced by leaching and helps prevent waterlogging.
Sodic soil: Soil with excessive exchangeable sodium, often marked by poor structure and reduced water infiltration. Sodicity can accompany salinity but requires attention to sodium-driven structural damage, not salt leaching alone.
Secondary salinization: The human-driven accumulation of salts in soil, often caused by irrigation and inadequate drainage. It is a major long-term risk when irrigation adds salts faster than drainage removes them.
Salt balance: An accounting of salt inputs, outputs, and storage within a soil or water system. Control succeeds when salt removal keeps pace with irrigation, groundwater, and other salt inputs.
Gypsum amendment: The application of calcium sulfate to supply calcium and improve sodic soil structure. Gypsum can replace exchangeable sodium so that water can infiltrate and leach salts more effectively.