Formulation and adjuvant effects on leaching of atrazine and metolachlor

• Published in: Journal of environmental quality Vol. 27; no. 6; pp. 1334 - 1347
• Main Authors: Hall, J.K, Jones, G.A, Hickman, M.V, Amistadi, M.K, Bogus, E.R, Mumma, R.O, Hartwig, N.L, Hoffman, L.D
• Format: Journal Article
• Language: English
• Published: Madison, WI American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America 01-11-1998; Crop Science Society of America; American Society of Agronomy
• Subjects: agrochemicals; Agronomy. Soil science and plant productions; Applied sciences; Atrazine; Biological and medical sciences; Biological and physicochemical properties of pollutants. Interaction in the soil; Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; Herbicides; Leaching; pesticides; Pollution; Pollution, environment geology; Soil and sediments pollution; Soil and water pollution; soil chemistry; soil physics; Soil science; United States; North America; America; Pennsylvania; Monocotyledones; Soil tillage; Zea mays; Pollutant behavior; Pesticides; Alfisols; Zero tillage; Soil pollution; Herbicide; Pesticide adjuvant; Silt loam soil; Gramineae; Chlorine Organic compounds; Angiospermae; Triazine derivatives; Chemical formula; Lixiviation; Spermatophyta; Atrazine
• ISSN: 0047-2425; 1537-2537
• DOI: 10.2134/jeq1998.00472425002700060010x

Atrazine (6-chloro-N-ethyl-N'-(methyethyl)-1,3, 5-triazine-2,4-diamine) and metolachlor (2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy- 1-methylethyl) acetamide) levels in pan lysimeter leachates, collected 1.2 m deep in a Hagerstown silt loam (fine, mixed, mesic Typic Hapludalf), were used to evaluate leaching of these chemicals applied in combination (1.7 + 1.7; 3.4 kg a.i. ha(-1)) as a commercial formulation (CF) or adjuvant (polyacrylate polymer)-amended (AA)-CF and as a microencapsulated (ME) or starch-encapsulated (SE) formulation in conventional tillage (CT) and no-tillage (NT) planted corn (Zea mays L.). Atrazine leached more under NT than CT conditions. Areal losses of atrazine in 1992 from NT at the low rate were 4, 66, and 277 microgram m(-2) for the treatment sequence (CF, SE, and AA-CF); at the high rate, losses were 887, 488, and 334 microgram m(-2). These amounts represented losses of < 0.01 to 0.16% and 0.26 to 0.10%, respectively, of applied rates. In 1993, areal losses for the treatment succession (lesser rate) were 888, 253, and 497 microgram m(-2) of atrazine (0.52, 0.15, and 0.29%); these treatments (greater rate) yielded 5440, 1220, and 1600 microgram m(-2) of applied chemical (1.60, 0.36, and 0.47%). Application of ME (polyurea polymer) and AA-metolachlor reduced mobility of this chemical at both rates in 1993, but their effect was especially exemplified at the greater rate where a loss of 2.29% (CF) was reduced to 0.83% (ME) and 0.54% (AA). Where herbicide leaching was reduced, greater concentrations, particularly atrazine, were detected in the surface 15 cm of soil in late-season and in leachates, 6 to 12 mo following application.