Indiscriminate fertilizer and pesticide usage, coupled with mono-cropping and non-application of base manure like cow dung and green manure (dead plants), has taken a severe toll on the organic content in soil and thereby soil fertility across the state, says the draft organic farming policy of the state government, which is yet to be rolled out. The issue has come into focus now in the wake of Kerala raising concerns of high pesticide level on vegetables grown in Tamil Nadu.
Experts in the field say organic matter in the soil dropped from 1.2% in 1971 to 0.68% in 2002. Organic matter has further reduced to 0.5 % in several districts, according to a study conducted a year ago by the Department of Soil Science and Agriculture Chemistry of TNAU. This is against a desirable level of 0.8% to 1.3% of organic carbon, say experts.
Madurai is the worst with just 0.23% of organic content in soil, followed by Krishnagiri (0.36). Erode and Vellore are well above the ideal limit with 4.04% and 4.2% respectively. Scientists at Tamil Nadu Agricultural University say that carbon content of soil depends on the amount of carbon matter that is replenished. "Is some districts in the Cauvery delta region, farmers leave behind the rest of the crop after harvest. This recharges the carbon content. However, this practice is dwindling across the state," said vice chancellor of TNAU K Ramasamy.........Read more
Source web page: The Times of India