marling

Marling is the agricultural practice of applying marl to soil to improve acidity and fertility. Marl is a sedimentary deposit rich in calcium carbonate and clay, formed in marine environments. It varies in composition, with calcareous marl high in calcium carbonate and dolomitic marl containing magnesium carbonate.

Historically, marling was common in parts of Europe, particularly in regions with acidic soils and nearby marl deposits. The practice involved spreading marl on fields or pastures and incorporating it with tillage. Because marl contains both clay and carbonate, its effects are gradual; over time it raises soil pH, supplies calcium, and can improve soil structure, especially on heavy or compacted soils.

Application rates depend on soil tests and local guidelines; marl is slower to react than quicklime and may require multiple seasons to reach the desired pH. In addition, high carbonate content or impurities can affect water infiltration and workability. Access to marl sources and transport costs also influence its use.

In modern agriculture, marling has largely been superseded by standardized lime products (calcitic or dolomitic lime) and other soil amendments, which offer more predictable performance. Nonetheless, marling remains of historical interest and may still occur in regions with accessible marl deposits or where sustainable practices rely on local materials.

See also: lime, soil pH, soil amendment.