Effects of fertilizer on insecticides adsorption and biodegradation in crop soils.

Recent organic fertilizer treatments (cow manure, pig slurry, composts, or green manure) simultaneously increase insecticide adsorption onto soil and the insecticide soil persistence, indicating a mechanism of slow release of insecticide into soil by the organic matter. This occurred in sugar beet crops with aldicarb, thiofanox and imidacloprid; also, in leek, cauliflower and brussels sprouts crops with chlorpyrifos and chlorfenvinphos. In contrast, organic fertilizer treatments applied once or repeatedly in the past, have no significant influence on adsorption or persistence of insecticides; the same is observed for the old soil organic matter, when its soil concentrations change in limited ranges