Slow-release formulations of sulfometuron incorporated in micelles adsorbed on montmorillonite.
The design and tests of slow-release formulations of sulfometuron (SFM), an anionic sulfonylurea herbicide, are described. The formulations are based on incorporation of the herbicide in octadecyltrimethylammonium (ODTMA) micelles, which adsorb on a clay mineral, montmorillonite. An optimization of herbicide/micelle clay ratios yielded high adsorption of SFM (95%), and at a 1% (w/w) water suspension only 0.5% of the adsorbed SFM was released at times varying from hours to 9 days. An analytical test in Seville soil showed that under excessive irrigation (400 mm) 100% of the commercial formulation leached, whereas the micelle-clay formulations showed only 50-65% elution. A plant bioassay in Rehovot soil showed that the commercial dispersible granule formulation (Oust, 75% ai sulfometuron methyl) yielded only 23% root elongation inhibition at the top 5 cm of the soil, whereas complete inhibition was achieved with the micelle-clay formulation. The detected concentration of SFM for the micelle-clay formulation at a depth of 15-20 cm was half of that detected for the commercial one, indicating a reduction in leaching when applying the micelle-clay formulation. A 10-fold reduction in the applied dose of SFM in the micelle-clay formulations resulted in good herbicidal activity of 60-87% inhibition. These characteristics make the new formulation promising from the environmental and economic points of view.
Mishael
Yael Golda
YG
Seagram Center for Soil and Water Sciences, and Department of Field Crops, Vegetables and Genetics, Faculty of Agricultural, Food and Environmental Sciences, Hebrew University of Jerusalem, Rehovot 76100, Israel.
Undabeytia
Tomas
T
Rabinovitz
Onn
O
Rubin
Baruch
B
Nir
Shlomo
S
D000327:Adsorption; D001546:Bentonite; D004787:Environmental Pollution / Q000517:prevention & control; D006540:Herbicides / Q000008:administration & dosage*; D008823:Micelles; D018517:Plant Roots / Q000187:drug effects; D012987:Soil; D013453:Sulfonylurea Compounds / Q000008:administration & dosage* / Q000737:chemistry
D006540:Herbicides; D008823:Micelles; D012987:Soil; D013453:Sulfonylurea Compounds; D001546:Bentonite; C042031:sulfometuron methyl