These nitrogenous chemical fertilizers ( namely urea ) have corrosive effect on the soil and make the soil ‘hard’ ! The microbes living in the soil are killed. Such hard soils become hot quickly and add to global warming ! And the use of pesticides makes the soil add to this as it kills the earthworms. Nowadays the crop fields are devoid of earthworms. Earthworms are termed as “friends of farmers”. Now the young farmers are perhaps unaware of this ! The earthworms dig the soil, aerate the soil making it more fertile. Very simply. The earthworms are dying out of starvation and poisoning . The herbicides and pesticides kills the soil microbes which are actually the food of the earthworms.
The earthworms consume soil with microbes and excrete. The excreta makes the soil fertile. They also aerate the soil through burrowing. When these earthworms are gone, the soil health is deeply hampered.
Nowadays earthworms are not found in paddy fields! This is very serious indication to te damage to soil ecology that we have overlooked for decades while we have become health and fitness-freak ! The earthworms are bio-indicators . When they are gone, the signal is grave that something is wrong !