Loams

Loam is a soil texture category characterized by a balanced mixture of sand, silt, and clay. In practice, loams typically contain roughly equal proportions of the three particle sizes, providing a texture that is drier than clay but retains more moisture than sandy soils. While exact ranges vary regionally, loams are often described as having about 40% sand, 40% silt, and 20% clay, plus or minus several percentage points. Within the loam category, subtypes such as sandy loam, silty loam, and clay loam are used to describe soils that are close to the balanced texture but with a bias toward one particle size.

Loams exhibit properties favorable to plant growth. They generally have a crumbly, granular structure that promotes aeration and easy root penetration. The balanced texture provides good drainage while retaining sufficient moisture and nutrients. The presence of clay and organic matter contributes to a higher cation exchange capacity, which enhances nutrient holding capacity and fertility. Loams often respond well to the addition of organic matter and to pH adjustments as needed.

Formation and distribution: Loams form through weathering of parent material aided by climate, biology, and time. They occur in many regions worldwide and can develop from alluvial, glacial, or loess deposits, among others. Because of their versatility, loams are common in agricultural lands, gardens, and peri-urban soils.

Management and use: Due to their balance of drainage and nutrient-holding capacity, loams are highly valued for crops and horticultural plants. Management practices emphasize maintaining soil organic matter, minimizing compaction, and providing appropriate irrigation to avoid compaction or waterlogging. Regular soil testing helps monitor nutrient status and pH to maintain productive loams.