Effects of organic fertilizers on aldicarb soil biodegradation in sugar beet crops.

In the present work, the influences of several organic fertilizer treatment regimens were compared as to their slowing down effect on aldicarb soil metabolism in a sugar beet crop. The organic fertilizers treatment schemes had been repeatedly applied in the past 30 years, according to a 3-year rotation cycle. The following organic fertilizers treatment regimens--which are the main ones used in the agronomy practice--were compared: Treatment 1: no organic fertilizer at all; treatment 2: 40 tons cow manure ha-1; treatment 3: 40 tons pig slurry ha-1 + green manure + crop wastes; treatment 4: green manure + crop wastes; treatment 5: straw cereal wastes alone. A sugar beet crop was sown in April 1991, 1 kg aldicarb ha-1 being applied in granulates in the sowing furrow. During the 2.9 first crop months, the soil half-lives of the sum of the insecticide S(-)+SO(-)+SO2-aldicarb in the sowing line in the 0-25 cm surface soil layer were 21.6, 44.4, 39.6, 35.7, and 30.3 days in the treatments 1, 2, 3, 4, and 5 treated plots, respectively. The organic fertilizers soil treatments thus increased the persistence of the total insecticide compounds soil concentrations, and probably also the insecticide protection efficiencies. Comparison of the results obtained here with the ones previously obtained with other crop trials, herbicides and soil insecticides, suggests that the soil organic matter is the most efficient to slow down the insecticides soil biodegradation, compared to the old humus originating from the organic fertilizers treatments made more than one year ago.(ABSTRACT TRUNCATED AT 250 WORDS)

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 less than cow manure less than 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.(ABSTRACT TRUNCATED AT 250 WORDS)