Environmental Engineering Reference
In-Depth Information
12.4 Conclusion
Pesticide residues in soil, in addition to eliminating or reducing parasitic microbes, are
also toxic to the nonparasitic and ecologically useful soil microbial and vertebrate popula-
tion. Pesticides may reduce certain microorganism populations while they stimulate the
growth of others, especially the saprophytic and spore-forming types. Soil chemical prop-
erties may also be altered by accumulation of residual pesticides and their metabolites.
These processes may disrupt the ecological balance in the soil microenvironment, first by
simplifying the microbial population and possibly by reducing soil fertility and its ability
to support life. Nontarget or residual pesticide toxicity would also disrupt the population
of some of the valuable soil invertebrates such as earthworms, predatory mites, centipedes,
and carabid beetles. The accumulation of pesticides in resistant or tolerant species may
provoke episodes of toxicity to organisms higher in the food chain. The chlorinated hydro-
carbons are likely to be most ecotoxic. The use of such pesticides ought to be restricted.
Efforts to find alternatives to pesticides, especially research into biological control, should
be intensified.
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