Premium
Reduced Surface Runoff Losses of Metolachlor in Narrow‐Row Compared to Wide‐Row Soybean
Author(s) -
Krutz L. Jason,
Koger Clifford H.,
Locke Martin A.,
Steinriede Robert W.
Publication year - 2007
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2006.0548
Subject(s) - metolachlor , surface runoff , sowing , agronomy , environmental science , growing season , mathematics , chemistry , pesticide , biology , atrazine , ecology
Cultural management practices that reduce the off‐site transport of herbicides applied to row crops are needed to protect surface water quality. A soybean [ Glycine max (L.) Merr.] field study was conducted near Stoneville, MS on Sharkey clay to evaluate row spacing (50 cm vs. 100 cm) effects on metolachlor [2‐chloro‐ N ‐(2‐ethyl‐6‐methylphenyl)‐ N ‐(methoxy‐1‐methylethyl) acetamide] transport. One day after the foliar application of metolachlor to 2.03 m wide by 2.43 m long plots, 60 mm h −1 of simulated rainfall was applied until 25 min of runoff was generated per plot. The calculated mass of metolachlor intercepted by the soybean foliage was greater in narrow‐row than wide‐row soybean, 0.39 kg ha −1 vs. 0.23 kg ha −1 , respectively. Field and laboratory studies indicated that less than 2% of the metolachlor intercepted by the soybean foliage was available for foliar wash‐off 1 d after application. Antecedent soil water content at the start of the simulations was lower in narrow‐row soybean. In turn, there was a 1.7‐fold greater time to runoff on narrow‐row plots. The greater time to runoff likely contributed to lower metolachlor concentration in runoff from narrow‐row plots. Cumulative metolachlor losses were significantly greater in wide‐row than narrow‐row soybean, 3.7% vs. 2.2%, respectively. Findings indicate that narrow‐row planting systems may reduce metolachlor runoff following a post‐emergence application.