Each plant and its soil life form have a particular soil pH it is used to. It is like blood pressure in our bodies, that varies many levels even within a day. Any change can lead to complications in the organism’s metabolism. Decrease in pH modifies top soils, a major source of crop nutrients.
Soil pH declined significantly from the 1980s to 2000s in nearly all crop production areas in India and China. Average decline was between 0.13 and 0.8. Typically pH value hovers at an average of eight across most lands of the world.
Acidity increased more in soils growing vegetables which need more fertilizers than soils cultivating cereals. Grain production increased 54 per cent from 1981 to 2007. During this time nitrogen fertilizer consumption increased 200 per cent.
In India there are 100 million hectares [or a million sq km of lands] suffering from acidity. Of this, about 25 million hectares are in critical condition and 12 million hectares need immediate attention. The problem is evident in hilly areas and coastal regions and the Deccan area. Soil liming, or addition of lime to soils is one solution.