Soil Acidity and Alkalinity : Biogeography
Soil Acidity and Alkalinity Soil pH is a measure of the concentration of hydrogen ions in the soil solution. The lower the pH of soil, the greater the acidity. pH should be maintained at above 5.5. pH between 6.5 and 7.5 is considered to be neutral soils. Soil acidity 5-6 pH is common in humid soils like Laterite soils. Strongly acidic soils with pH 4-5 are found in some podzols due to high organic action and formation of humic acid. Impact : Extremely acidic soils are toxic due to high aluminium concentration. When soil pH drops, aluminium becomes soluble. A small drop in pH can result in a large increase in soluble aluminium. In this form, aluminium retards root growth, restricting access to water and nutrients. Mild acidic soils can be treated by Lime and turned into cultivable soils. Soil alkalinity. Sub humid and semi arid regions have alkalinity of range 8 to10. These soils are rich in minerals and hence fertile like Chernozem, Chestnut and Prairies...