Geography – Soils in hot arid and hot semi-arid environments | e-Consult

Solonetz soils are formed in cold arid and semi-arid climates, typically in areas with permafrost or seasonally frozen ground. Their formation is a complex process involving the following key stages:

• Weathering of parent material: The parent material, often glacial till or weathered bedrock, undergoes intense chemical weathering due to freeze-thaw cycles. This releases minerals.
• Illuviation: Water percolates through the soil profile, carrying dissolved minerals (primarily calcium, magnesium, and potassium) downwards. These minerals accumulate in the subsoil (the B horizon).
• Vertification: The presence of clay minerals (particularly smectite) causes the soil to shrink and swell with changes in moisture content. This leads to cracking and the development of a characteristic "sticky" texture.
• Gleying: Reduced oxygen conditions in the subsoil lead to the reduction of iron and other minerals, resulting in the formation of greyish-green (gley) layers.

Key Characteristics:

• High salt content: The accumulation of minerals in the subsoil results in a high concentration of salts.
• Sticky texture: Due to vertification, the soil becomes very sticky when wet and hard when dry.
• Greyish-green subsoil (gley): Indicates anaerobic conditions.
• High nutrient content: Despite the salt content, solonetz soils are often rich in nutrients like potassium, calcium, and magnesium.

Relationship to Arid Climate: The cold temperatures and freeze-thaw cycles are crucial for the weathering process. The limited rainfall means that water percolates deeply, leading to the accumulation of minerals in the subsoil. The permafrost or seasonally frozen ground restricts drainage, further contributing to the formation of gley layers and the characteristic sticky texture.