Soil
Many of the chemicals used in pesticides are persistent soil contaminants, whose impact may endure for decades and adversely affect soil conservation.
The use of pesticides decreases the general biodiversity in the soil. Not using the chemicals results in higher soil quality, with the additional effect that more organic matter in the soil allows for higher water retention. This helps increase yields for farms in drought years, when organic farms have had yields 20-40% higher than their conventional counterparts. A smaller content of organic matter in the soil increases the amount of pesticide that will leave the area of application, because organic matter binds to and helps break down pesticides.
Degradation and sorption are both factors which influence the persistence of pesticides in soil. Depending on the chemical nature of the pesticide, such processes control directly the transportation from soil to water, and in turn to air and our food. Breaking down organic substances, degradation, involves interactions among microorganisms in the soil. Sorption affects bioaccumulation of pesticides which are dependant on organic matter in the soil. Weak organic acids have been shown to be weakly sorbed by soil, because of pH and mostly acidic structure. Sorbed chemicals have been shown to be less accessible to microorganisms. Aging mechanisms are poorly understood but as residence times in soil increase, pesticide residues become more resistant to degradation and extraction as they lose biological activity.
Read more about this topic: Environmental Impact Of Pesticides
Famous quotes containing the word soil:
“Africa is a paradox which illustrates and highlights neo-colonialism. Her earth is rich, yet the products that come from above and below the soil continue to enrich, not Africans predominantly, but groups and individuals who operate to Africa’s impoverishment.”
—Kwame Nkrumah (1900–1972)
“But the nomads were the terror of all those whom the soil or the advantages of the market had induced to build towns. Agriculture therefore was a religious injunction, because of the perils of the state from nomadism.”
—Ralph Waldo Emerson (1803–1882)
“The civilized nations—Greece, Rome, England—have been sustained by the primitive forests which anciently rotted where they stand. They survive as long as the soil is not exhausted. Alas for human culture! little is to be expected of a nation, when the vegetable mould is exhausted, and it is compelled to make manure of the bones of its fathers. There the poet sustains himself merely by his own superfluous fat, and the philosopher comes down on his marrow-bones.”
—Henry David Thoreau (1817–1862)