Suojamultana

Suojamultana is a Finnish term used to refer to a protective mulch layer placed on the soil around plants to shield the soil and root zone from temperature swings, moisture loss, and erosion. The practice is common in gardening, horticulture, and forestry nurseries; materials used vary from organic mulches such as bark, wood chips, straw, compost, to inorganic coverings like stones, gravel, or plastic sheeting. The mulch is typically spread as a surface layer to a depth of roughly 5–10 centimeters, kept a few centimeters away from the base of stems or trunks to prevent rot.

Benefits include improved soil moisture retention, moderated soil temperature, reduced weed growth, and slower soil erosion; as mulches decompose, they can also improve soil structure and fertility. Drawbacks include the potential for pest habitat, disease risk in damp conditions, and, with high-carbon materials, temporary nitrogen immobilization that can affect plant growth. Maintenance involves replenishing the layer as it breaks down, avoiding overly thick layers that suffocate roots, and monitoring for pests, diseases, and drainage issues.

Suojamultana is especially valued in regions with pronounced seasonal variation, where protecting the topsoil helps establish seedlings, preserve moisture during dry periods, and reduce soil erosion on slopes. The term is part of broader mulching practices used worldwide to promote sustainable soil management.