meliorant

A meliorant is any substance, material, or management measure applied to land to improve its physical, chemical, or biological properties to increase productivity or enable cultivation. In soil science, meliorants are used to correct adverse soil conditions such as acidity, salinity, poor structure, low fertility, or moisture problems. The term derives from Latin meliorare meaning to make better.

Common chemical meliorants include lime (calcium carbonate) and dolomitic lime to raise soil pH; gypsum (calcium sulfate) to improve sodic or saline soils by displacing sodium and improving structure; sulfur to lower the pH of alkaline soils; and various nutrient fertilizers for fertility.

Organic meliorants include farmyard manure, compost, peat, and biochar, which add organic matter, improve soil structure, moisture retention, and nutrient holding capacity. Biological approaches include cover crops and green manures to build soil organic matter and suppress pests.

Physical meliorants involve drainage, subsoiling, deep chiseling, and trenching to relieve compaction and improve water movement, often integrated into land reclamation projects.

Uses and considerations: Meliorants are selected based on soil tests, climate, crop needs, and environmental impact. Over-application can cause nutrient leaching, groundwater contamination, or salts buildup; improper use can alter pH beyond crop tolerance.

See also: amelioration, soil amendment, soil conditioner, land improvement.