Carbofuran In Soil Research Articles

Carbofuran Persistence in Soil and Adult Corn Rootworm (Coleoptera: Chrysornelidae) Susceptibility: Relationship to the Control of Damage by Larvae

The relationship between control of Diabrotica virgifera virgifera LeConte feeding damage and both chemical persistence of carbofuran in soil and adult susceptibility to carbofuran was studied. A significant correlation was found between 50% disappearance time (DT-50%) for carbofuran and the percentage of reduction of feeding damage. Carbofuran persistence curves exhibited either lag or nonlag periods. The nonlag pattern was associated with repeated annual use of carbofuran and low effectiveness. When DT-50% was less than 20 days, control of D. v. virgifera was <50% in most fields. Adults collected from the field plots showed an increase in tolerance to carbofuran from previously reported levels, but there was no correlation between percentage of control and LD50 between 1980 and 1982. Bioassay of adult bettles was not a good indicator for determining if the development of resistance to carbofuran had affected control of larval feeding damage.

Simplified Method for Liquid Chromatographic Determination of Carbofuran in Soils

Abstract A simple, direct method is described for determining carbofuran (CF), 2,3-dihydro-2,2-dimethyl-7-benzofuranyl methylcarbamate, in soils. Methanol extraction is followed by hexane–methanol–water (2 + 4 + 1) partition and liquid chromatographic analysis of the aqueous layer with UV detection at 280 nm. The method specifies dilution of the partitioned extract with water to methanol–water (20 + 80), and injection of 1000 μL sample volumes. This technique allowed a 10-fold increase in sensitivity over direct injection from the partition step. Recovery of CF by the method is about 90%, and less than 0.4 μg CF/ g soil can be detected at a medium detector sensitivity of 0.04 AUFS.

Influence of Soil Temperature and Soil Moisture on Degradation and Metabolism of Carbofuran in Soils

AbstractThis study was conducted to determine the effects of soil moisture and soil temperature on mineralization rate and the solvent‐extractable 14C‐activity disappearance rate of 14C‐carbofuran (2,3‐dihydro‐2, 2‐dimethyl‐7‐benzofuranyl‐N‐methylcarbamate) and the formation of nonextractable 14C‐activity in six U.S. soils, to evaluate the difference between the two rates, and to statistically correlate these rates with key soil factors.Both mineralization rate and solvent‐extractable 14C‐activity disappearance rate approximated to first‐order kinetics. The solvent‐extractable 14C‐activity disappearance rates were much higher than the mineralization rates. The difference was reflected in the formation of nonextractable 14C‐activity in soils. As high as 94.5% of 14C‐activity became nonextractable at the end of 28 days of incubation. Four metabolites, 3‐hydroxycarbofuran, 3‐ketocarbofuran, carbofuran phenol, and 3‐ketocarbofuran phenol were detected in the solvent extracts. 14C‐activity associated with these metabolites in the extracts were generally &lt;5% of the 14C‐carbofuran applied, so that the difference between the solvent‐extractable parent‐chemical disappearance rate and the solvent‐extractable 14C‐activity disappearance rate was insignificant. In general an increase in temperatures from 15 to 27°C had a greater influence on solvent‐extractable 14C‐activity disappearance rate than did an increase from 27 to 35°C, and the temperature for maximum rate was between 27 to 35°C. Logarithmic k1 values of solvent‐extractable 14C‐activity appeared to be inversely correlated with logarithmic soil‐water tension (Ψ). No statistical correlation with key soil factors was observed for either the solvent‐extractable 14C‐activity disappearance rate or minralization rate.

Influence of Soil Properties on the Adsorption of Carbofuran in Soil.

In an Experiment for Studying the influence of soil it was found that gacorpu carbofuran was highest in laterite soil and decreased sequentially in black alluvial land red soils. Soil organic matter was a more potent adsorber of carbofuran than the minernal traction. The Multiple linear regression analysis showed that soil organic matter alone contributed 98 per cent of the total adsorption of carbofuran in soils.

Leaching and Movement of Carbofuran in Soils.

Carbofuran movement in soils was studied by employing soil TLC technique with natural soil and alwin the soil in which organic matter was destroyed. The mobility, as Rf values, of 16 sails (Red, black, alluvial and laterite) showed that the movement in red, alluvial and black soils was rapid while in laterite soil it was slow. A striking increase in the mobility of carbofuran was recorded in soils in which the organic matter was oxidised. Carbofuran teaching was high in red, alluvial and black soils and the effluents 55, 41.50 and 36.5 per cent of the added carbofuran, respectively. In laterite soils a major portion of the added toxicant was retained in the soil of the first column section and the effluents did not contain any residues. Both the soil TLC and leaching studies revealed that there was a general trend towards reduced mobility of carbofuran with incressed organic matter content of coils. Based on the Rf value recorded in red, block and alluvial soils with organic matter content below 1 per cent, carbofuran was classified under class IV and designated as "mobile" insecticide while in respect of laterite soils with 1.50 to 4,29 per cent opranic matter its mobility was moderate (class III).

Enhanced microbial degradation of carbofuran in soils with histories of Furadan use.

Enhanced microbial degradation of carbofuran in soils with histories of Furadan use.

Residues of Carbofuran in Soil, Rice Grain, and Straw As Affected By Rates and Number of Applications

Residues of Carbofuran in Soil, Rice Grain, and Straw As Affected By Rates and Number of Applications

Acid Ammonium Acetate Extraction and Electron Capture Gas Chromatographic Determination of Carbofuran in Soils

Abstract A method is presented for determining carbofuran residues in soils that gives improved recovery, especially in weathered soils, and allows quantitation of as little as 0.1 ppm without cleanup. The soil is extracted with 0.5M acid ammonium acetate and the carbamate in the extract is determined by electron capture gas chromatography as the dinitrophenyl ether. A systematic study was conducted to optimize extraction conditions. In tests of soils fortified with 1 ppm carbofuran, using optimized extraction conditions, recoveries varied with soil type, ranging from 61% in a peat to 92% in a silt loam. Recoveries of the metabolites 3-hydroxy- and 3-ketocarbofuran from field soils were at least as efficient as by HCl extraction. In addition to carbofuran, other methylcarbamate insecticide residues that may be determined by this method include Landrin, propoxur, and Bux.

Persistence and Degradation of Carbofuran in Soil

The persistence and degradation of 14C-carbofuran and 14C-2,3-dihydro-2,2-dimethyl-7-hydroxy benzofuran were examined in several soils under laboratory conditions. The time required for 50% breakdown of the insecticide varied from 3 weeks to more than 50 weeks. Persistence was influenced by soil sterilization and soil p H. Carbofuran degraded 7–10 times faster in alkaline soil ( p H 7.9) than in acid and neutral soils ( p H 4.3–6.8). 14CO2 was rapidly expired from degraded carbonyl-labeled insecticide in both radiation-sterilized and nonirradiated soils. Degradation of ring-labeled carbofuran was associated with an accumulation of nonextractable radioactivity in the soil residue followed by a gradual evolution of 14CO2. Only minute quantities of carbofuran phenol, the expected hydrolysis product of the insecticide, were recovered from treated soils. Addition of 14C-carbofuran phenol to soil resulted in an accumulation of tightly adsorbed nonextractable radioactivity followed by slow expiration of 14CO2. Indirect evidence suggests carbofuran is hydrolyzed to its phenol which is immediately bound to soil constituents and slowly metabolized by microorganisms.