Field Duration of Chlorsulfuron Bioactivity in the Central Great Plains

Abstract

AbstractThe duration of chlorsulfuron {2‐chloro‐N [(4‐methoxy‐6‐methyl‐1,3,5‐triazin‐2‐yl)aminocarbonyl]benzenesulfonamide} bioactivity in Central Great Plains soils was determined by measuring the influence of several environmental factors on chlorsulfuron degradation. Chlorsulfuron was applied at 35 and 70 g ha−1 to four soils: Platner sandy loam and Weld (Aridic Paleustolls) loam at Akron, CO; Roxbury (Cumulic Haplustoll) silt loam at Jetmore, KS; and Rosebud (Aridic Argiustolls) sandy loam at Chugwater, WY. Soil pH, organic matter level, number of precipitation events >0.25 cm, and leaching were the major environmental factors influencing chlorsulfuron duration of bioactivity. A chlorsulfuron rate × soil × year interaction occurred, but this interaction was not consistent over all soils. A model developed for predicting chlorsulfuron duration of bioactivity would be more accurate if designed for soils with similar organic matter levels, as organic matter level influenced duration of bioactivity and leaching of chlorsulfuron. Chlorsulfuron leaching was also affected by soil type and year of study. In greenhouse bioassay studies, sunflower (Helianthus annuus L.) did not differ from corn (Zea mays L.) in sensitivity to chlorsulfuron residues in soil.