Jordmaterial

Jordmaterial, or soil material, is the natural loose solid matter at the surface of the earth, composed of mineral particles, organic matter, air, and water. It originates through weathering of rocks and accumulation of organic residues, and its properties vary with mineralogy, texture, structure, moisture content, and density. In geotechnical and environmental contexts, jordmaterial is often categorized as mineral soil (dominated by mineral grains) or organic soil (rich in decomposed plant material).

Texture and particle size determine key behaviors. Soils are commonly described by particle size classes such as gravel, sand, silt, and clay, and by whether they are cohesive or non-cohesive. The mechanical properties of jordmaterial—strength, stiffness, compressibility, and permeability—affect construction stability, drainage, and habitat suitability.

Common laboratory tests measure grain-size distribution, Atterberg limits for fine-grained soils, compaction characteristics (Proctor tests), shear strength (direct shear or triaxial tests), and hydraulic conductivity. Classification systems such as the USDA soil taxonomy and international standards group soils by texture, composition, and behavior, providing a framework for analysis and reporting.

Formation and horizons: jordmaterial forms a soil profile with horizons labeled O, A, E, B, and C, reflecting organic content, mineral weathering, and depth from the surface. It plays a central role in agriculture, groundwater filtration, nutrient cycling, and as a foundation material in construction, requiring site-specific assessment to manage risks such as settlement, shrink-swell, and liquefaction.