liming

In agriculture, "liming" refers to the process of reducing soil acidity by adding calcium and magnesium. This is crucial in humid regions where rainfall leaches these essential nutrients from the soil, creating an acidic condition that hinders plant growth.1

Liming materials, such as ground limestone (calcium carbonate), react with the soil to neutralize acidity and make calcium available for plant uptake. Other materials like basic slag, marl, chalk, and oyster shells can also be used. However, calcium sulfate (gypsum) and calcium chloride are unsuitable because their residues are harmful.1

Soil acidity is measured by pH, with a pH below 7 indicating acidity. Acidic soils can be infertile for most crops and may contain harmful levels of aluminum and manganese. Liming is a common practice to "sweeten" or neutralize acidic soils, making them more suitable for agriculture. The application typically involves mixing the liming material with the soil's surface layer.21