markskikt

Markskikt is a term used in Swedish soil science to describe the upper part of the soil profile that has been affected by soil-forming processes. It typically covers the layers closest to the surface, including organic-rich material and the mineral topsoil, and it can extend to the depth where root penetration and biological activity begin to diminish. The exact thickness and composition of the markskikt vary with climate, vegetation, parent material, and land use.

The markskikt is characterized by properties such as texture, structure, organic matter content, moisture regime, and nutrient status. In many soils it encompasses the organic O-horizon and the mineral A-horizon, with variations where E-horizons or deeper subsoil layers are present. The material in the markskikt greatly influences water holding capacity, drainage, nutrient availability, and root development, making it central to plant growth and ecosystem functioning.

Assessment of the markskikt is typically part of soil surveys and classification efforts. Field descriptions, soil sampling, and laboratory analyses of texture, organic matter, pH, cation exchange capacity, and porosity help determine its properties and depth. Management practices such as tillage, drainage, liming, and addition of organic matter can modify the markskikt, affecting productivity and environmental impact.

In practice, the term is used in agriculture, forestry, and environmental planning in Swedish-language literature and Nordic soil science. It is often related to, and sometimes used interchangeably with, the concept of topsoil, though topsoil in some contexts may refer to a narrower layer.