Ameliorants for the Management of Soil Acidity – A Review

Abstract

Soil acidity is one of the major yield limiting factors in rice crop production. The H+ and Al3+ ions in the soil must be neutralized by the release of OH-ions on application of liming materials for the management of soil acidity. Liming material is the substance, which can increase the soil pH by combining with H+ ions in the soil solution. Lime is the most widely used ameliorant for management of soil acidity. There are alternative products, such as dolomite, rice husk ash, gypsum, phosphogypsum and calcium magnesium silicates having high reactivity than lime in increasing the pH, supply of nutrients like Ca, Mg, Si etc., and have the potential to reduce iron and aluminium toxicity and reduce methane emission. Fineness and chemical purity of the liming material are the major factors affecting the ability of the material to neutralise soil pH. Method and timing of application of liming material depend on the place of origin, nutrients and other elements associated with it, and amount of neutralising power. Relative worth of the liming material also depends on the cost of the same.