C. Pelerents

Influence of cow manure and composts on the effects of chlorfenvinphos on field crops.

Cauliflower crops were grown in several regions and seasons (spring and summer). Five days after planting, the plants were treated against the root fly by pouring onto soil around the plant stem an emulsion of chlorfenvinphos [2-chloro-1-(2,4-dichlorophenyl) ethenyl diethyl phosphate] in water. The fields were divided into plots. Onto each plot, one of the organic fertilizers, city refuse compost, mushroom cultivation compost, or cow manure was applied at the rate of 100 tons/ha, 1 or 3.5 months before the insecticide treatment. There were also control plots which were not treated with any of the organic fertilizers. During the first 50 days crop period which followed the insecticide treatment, the chlorfenvinphos soil concentrations were always greater in the organic fertilizer-treated plots, than in the untreated ones (controls). The intensity of the organic fertilizers effect as to the increase of chlorfenvinphos soil persistence was in the following increasing order: city refuse compost < cow manure < mushroom cultivation compost. The organic fertilizer effects were greater when they had been soil-incorporated 3.5 months—instead of 1 month—before the chlorfenvinphos soil treatment. The increase of the insecticide soil concentrations—due to the organic fertilizers treatments—should increase the plant protection efficiency during the period of the first 50 days, during which time the young plants are the most sensitive to insects. During the following period of the 2 or 3 last crop weeks, the effects of the organic fertilizers onto the rate of chlorfenvinphos soil metabolism were levelled off; at harvest, the very low soil-resting residues were similar in the organic fertilizers treated and untreated plots. At harvest, no chlorfenvinphos nor its metabolites were detected in the ‘flower’ of cauliflower of all the plots, the analytical limit of sensitivity being 0.02 mg kg−1 fresh weight for all of these compounds.

Chlorpyrifos Soil and Plant Metabolisms in Cauliflower Crops Grown On Cow Manure and Composts Soil Fertilized Fields

Several cauliflower crops were grown on fields located in different regions. Cauliflower plants were treated against the root fly by applying, some days after planting, chlorpyrifos onto the soil around the stem of the plant. Fields were divided into plots. Either one or 3.5 months before planting, one of the organic fertilizers city refuse compost, or mushroom cultivation compost, or cow manure was incorporated into the soil of each plot; there were also soil unamended control plots. The rates of chlorpyrifos soil metabolism were smaller in the organic fertilizers amended plots, than what they were in the unamended plots. In the summer cauliflower crop made on loamy sand soil, the chlorpyrifos soil half‐lives were 41, 44, 53 and 25 days, respectively in the plots amended either with the city refuse compost, or cow manure, or the mushroom cultivation compost, and in the unamended plots. The organic fertilizers effects were slightly greater when the amendments had been soil incorporated 3.5 months before p...

Soil Metabolism of Carbofuran in Cauliflower and Brussels-sprouts Cultures

Cauliflower and brussels sprouts were treated after planting by pouring an emulsion of carbofuran around the stem of the plant. Carbofuran and its metabolites 3‐hydroxycarbofuran, 3‐ketocarbofuran, carbofuran phenol and 3‐ketocarbofuran phenol were measured in soil during plant growth. Oxidation and hydrolysis thus were the major metabolism pathways. Crops were made in four regions different as to their soil type, and during spring and summer. No carbofuran, nor its metabolites were observed in the flower or in the sprout itself. The rate of soil carbofuran metabolism, and the efficiency of plant protection depended on soil type, season and rainfall.

Insecticide soil persistence and efficiency in cauliflower field crops: Influence of organic fertilizer and organic matter properties

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—relative 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...

Influence of field histories of continuous soil insecticide treatments on the rate of soil biodegradation of Carbofuran in cauliflower, Brussels sprouts, Chinese cabbage and sugar beet crops

In the soil of cauliflower, Brussels sprouts, Chinese cabbage and sugar beet crops, carbofuran was metabolized into the insecticide compounds 3‐hydroxycarbofuran and 3‐ketocarbofuran, and into the non insecticide carbofuran phenol and 3‐ketocarbofuran phenol. The rate of soil biodegradation of carbofuran and of the sum of insecticide carbamate compounds was multiplied by 3 when continuous monoculture and soil treatments with organophosphorus insecticides had been done previously during several years.

Effects of the soil organic fertilizers onto the carbofuran soil and plant metabolisms in field cauliflower crops

A spring cauliflower crop was made on the loamy sand soil of a field whose plots had been amended, one month before planting, with one of the organic fertilizers: city refuse compost, or mushroom cultivation compost, or cow manure; there were also unamended control plots. Some days after planting, an emulsion of carbofuran in water was applied onto soil, around the stem of the plant, for protection against the root fly. During growth of the crop, the rates of carbofuran soil biodegradation were smaller in the organic fertilizers amended plots, than in the unamended controls; the intensity of the effect was in the increasing order: city refuse compost < cow manure < mushroom cultivation compost. The organic fertilizers thus increased the insecticide soil concentrations; they thus should increase the insecticide protection efficiency against soil insects. During the final period of the crop, the rates of carbofuran soil biodegradation increased, and the organic fertilizers effects were levelled off; at harv...