Insecticide soil persistence and efficiency in cauliflower field crops: influence of organic fertilizer and organic matter properties
1992
Rouchaud, J. | Gustin, F. | Metsue, M. | Touillaux, R. | Steene, F. van de | Pelerents, C. | Journey Man. | Benoit, F. | Ceustermans, N.
Cauliflower crops were treated some days after planting against the root fly by pouring onto soil around the plant stem an emulsion of chlorpyrifos or of carbofuran in water. The fields were divided into plots; each plot was treated with one of the organic fertilizers: cow manure, city refuse compost, or mushroom cultivation compost; there were also control plots not treated with organic fertilizers. During the first 50 days crop period, the insecticide soil persistence was greater in the organic fertilizers treated plots relatively to the untreated control plots--probably giving better insecticide protection of the young plants. Thereafter and till harvest, the soil insecticide concentrations became similar in the organic fertilizers treated plots and in the controls. The organic fertilizer soil treatments increased--relative to the controls--the total soil organic matter and the humic acids soil concentrations, and the humic acids nitrogen content. The organic fertilizer soil treatments generated humic acids which contained according to their 13C NMR spectra--more ketonic, carboxylic acid and ester, aromatic phenolic and amines, and aromatic carbons, relative to the humic acids from the controls. These chemical functions are able to bind insecticides in soil. This fact supports the hypothesis that the organic fertilizer soil treatments increase the pesticide adsorption onto the soil organic matter, protecting the insecticides against the metabolizing soil microbial activity.
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