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Titolo:
Adsorption and degradation of metolachlor and metribuzin in a no-till system under three winter crop covers
Autore:
Johnson, AB;
Indirizzi:
Mississippi River Res Ctr, Alcorn State, MS 39096 USA Mississippi River Res Ctr Alcorn State MS USA 39096 n State, MS 39096 USA
Titolo Testata:
SOIL & SEDIMENT CONTAMINATION
fascicolo: 5, volume: 10, anno: 2001,
pagine: 525 - 537
SICI:
1532-0383(2001)10:5<525:AADOMA>2.0.ZU;2-R
Fonte:
ISI
Lingua:
ENG
Soggetto:
SOILS; EFFICACY; SORPTION; MOBILITY; IMPACT;
Keywords:
adsorption; degradation; half-life; herbicide; isotherm; rate constant;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Agriculture,Biology & Environmental Sciences
Citazioni:
24
Recensione:
Indirizzi per estratti:
Indirizzo: Johnson, AB Mississippi River Res Ctr, 1000 ASU Dr 750, Alcorn State, MS 39096 USA Mississippi River Res Ctr 1000 ASU Dr 750 Alcorn State MS USA 39096
Citazione:
A.B. Johnson, "Adsorption and degradation of metolachlor and metribuzin in a no-till system under three winter crop covers", SOIL SEDIM, 10(5), 2001, pp. 525-537

Abstract

The objective of this study was to quantify adsorption and degradation of metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl) acetamide] and metribizun [4-amino-6-(1,1-dimethylethyl)-3-(methylthio)-1,2,4-trazine-5(4H)-one] in a soil planted to winter covers clover (Trifolium sp.), vetch (Vicia villosa), and wheat (Triticum aestivum). Surface soil samples (0 to 5 cm) from Memphis silt loam (fine-silty, mixed, thermic Typic Hapludalf) were collected and equilibrated with herbicide at initial concentrations ranging from 0 to 20 mg L-1 that were then applied for a batch experiment. Soils were treated either with a single herbicide or a mixture of the two herbicides. For the degradation experiments, herbicides at a concentration of 10 mg kg(-1) soil were applied and incubated for 21 d at similar to 23 degreesC. Metolachlor by the Freundlich isotherm. Average Freundlich distribution coefficient (K-f) for metolachlor was significantly higher (p greater than or equal to 0.05) than that of metribuzin in soils under the three crop covers irrespective of method of application. The K-f for metolachlor ranged from 18.38 to 11.18 L kg(-1), and K-f for metribuzin ranged from 1.80 to 0.93 L kg(-1). Average normalized distribution coefficient (K-oc) for metolachlor was significantly higher (p greater than or equal to 0.05) than average K-oc for metribuzin irrespective of crop cover. After 21 days of incubation, average half-life of metolachlor across soil under the three crop covers was significantly higher than the average half-life of metribuzin (p greater than or equal to 0.05). Half-life values ranged from 20.6 to 24.9 days for metolachlor, and 4.4 to 12.4 days for metribuzin. In soils treated with metribuzin, the half-life was highest for soil under wheat and lowest for soil under clover (p greater than or equal to 0.05).

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Documento generato il 29/01/20 alle ore 19:27:30