Click for RRes home page
About us
Resources
Research
Into practice
For the public
Careers

Pesticide Chemistry


Degradation, movement and effects of pesticides in soil


In an experiment lasting over 20 years at Rothamsted, soil fertility was not damaged by repeated annual applications of several pesticides, and indeed soil microorganisms became adapted to rapidly degrade the active oxidation products of the insecticide aldicarb.


Degradation of aldicarb in moist soil at 15ºC taken from Rothamsted plots either not receiving or receiving aldicarb annually for 20 years



Pesticides applied to soil are ultimately degraded by microorganisms to carbon dioxide or to fragments that are incorporated into soil organic matter. Before these processes are complete, the pesticide and its metabolites can be leached by rainfall though this movement is limited by sorption to soil.
Such information gained from laboratory, lysimeter and field experiments enables potential contamination or carryover problems to be identified and assists in guiding the registration process for pesticides so as to minimise risk to the environment.
Studying the persistence of triazole fungicides on plots at Woburn Experimental Farm.
References:

BROMILOW, R. H., EVANS, A. A., NICHOLLS, P. H., TODD, A. D. AND BRIGGS, G. G. (1996) The effect on soil fertility of repeated applications of pesticides over 20 years. Pesticide Science, 48, 63-72.

BROMILOW, R.H., EVANS, A.A. & NICHOLLS, P.H. (1999). Factors affecting degradation rates of five triazole fungicides in two soil types: 1. Laboratory incubations. Pesticide Science, 55, 1129-1134.

BROMILOW, R.H., EVANS, A.A. & NICHOLLS, P.H. (1999). Factors affecting degradation rates of five triazole fungicides in two soil types: 2. Field studies. Pesticide Science, 55, 1135-1142.