Solonchak

A Solonchak is identified by its high soluble-salt content, frequently expressed as salt crusts and as poor, patchy plant growth. Salinity, rather than any physical property, is the overriding feature that governs how these soils behave and how they can be used.

Solonchaks form where soluble salts accumulate faster than they are removed. In arid and semi-arid climates, evaporation draws saline groundwater upward and concentrates salts near the surface; in irrigated lands with inadequate drainage, salts in irrigation water build up in the root zone. They are common in dry regions worldwide, in interior basins and salt flats, and around the margins of salt lakes and low coasts.

High soluble salts

Elevated concentrations of soluble salts in the profile, the defining and dominant property of the soil.

Salt crusts

White salt accumulations that often form at or near the surface as water evaporates.

Osmotic stress

High salinity lowers the ability of roots to take up water, effectively causing drought stress even in moist soil.

Variable structure

Physical properties vary with texture and parent material, but salinity overrides them as the key limitation.

Reclaiming and using Solonchaks centres on reducing salinity in the root zone and preventing its return, which requires both good-quality water and the drainage to carry salts away.

• Leach salts below the root zone using good-quality water, which is only effective with adequate drainage
• Install and maintain drainage so leached salts and shallow saline groundwater are removed rather than recycled
• Manage irrigation to avoid re-accumulation of salts, applying enough water to leach without waterlogging
• Where reclamation is impractical, restrict use to salt-tolerant crops or non-cropping land uses

Most crops are unsuited to Solonchaks in their natural state, and their agricultural value is low without reclamation. Where they are cropped, only relatively salt-tolerant species are viable: barley is among the more salt-tolerant cereals, and the date palm tolerates saline conditions in some desert oasis settings. Both still perform best once salinity has been reduced.