Adsorption, Mobility, and Degradation of Cyanazine and Diuron in Soils

Abstract

In the field, surface applied cyanazine 2-[[4-chloro-6-(ethylamino)-s-triazin-2-yl] amino]-2-methylpropionitrile and diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea] did not move below 5 cm in a Monona silty clay loam (Typic Hapludoll) which received 20 cm of water over a 54-day period. In hand-packed soil columns in the laboratory, surface-applied diuron and cyanazine penetrated to depths of 10 and 20 cm, respectively, when leached over a comparable time period and with amounts of water similar to that used in the field. Soil thin layer chromatography and adsorption isotherm studies showed that diuron was adsorbed more strongly than was cyanazine. In general, both compounds were degraded more rapidly at the higher temperatures when incubated at 5, 20, 35, and 50 C over a 20-week period. Degradation was slowest at 5 C in a Valentine loamy fine sand (Typic Ustipsamment). Diuron appeared to break down most readily at 35 C. Cyanazine was usually decomposed by the 10th week at 5 C and the 5th week at higher temperatures.

Phytotoxicity of Alachlor, Bromacil and Diuron as single or mixed herbicides applied to wheat, melon, and molokhia

“…Moreover, application of herbicides in soil may result in their adsorption on clay minerals (Majka and Lavy 1977 ; Franco et al 1997 ), soil organic matter (Grover 1975 ; Sánchez-Camazano et al 2000 ), and organoclay complexes (El-Nahhal et al 1998 , 1999 ). This process may enhance the accumulation of herbicide concentrations in the topsoil and may endanger crops in the next growing season, or generate weed resistant genotypes that complicates the weed control process and makes control more costly (Thurman et al 1996 ).…”

Carryover Potential of Pyrithiobac to Rotational Crops on a Mississippi Black Belt Region Clay Soil

“…Several herhicides with Al.JS activity are persistent and can cause phytotoxicity to rotational crops, including corn (Zell Inays L.) (5, 13, 17,22, 25, 27~37), cotton (4, 13,22,37), grain sorghulll (13,22,25,37), and wheat (17,37). Many factors influcncc degradation in soil, including: tenlperature (20,30,35), Jllicrohial activity (30,31), soil texture (12,18,23), pH (6,8,12,18,23, 28, 35~36), and soil nl0isture (8, 18,30,31,35).…”

Carryover of DPX-PE350 to Grain Sorghum (Sorghum bicolor) and Soybean (Glycine max) on Two Arkansas Soils

“…Persistence of herbicides can be influenced by en vironmental factors such as soil water content and temperature (13,14,15,21,25). Imazaquin {2-[4,5dihydro-4-methyl-4-( 1 -methylethyl)-5-oxo-1/J-imidazol-2-yl]-3-quinolinecarboxylic acid} was more persistent under low than high rainfall (13).…”