Atrazine, mesosulfuron‐methyl, and topramezone persistence in North Carolina soils

Abstract

Investigating the effects of soil properties on herbicide persistence can aid in evaluating the carryover potential of herbicides in soil and the consequent injury risk to rotational crops. Laboratory incubation experiments were conducted to quantify the persistence of atrazine, mesosulfuron-methyl, and topramezone in five regional soils under aerobic conditions at 23 ˚C. Additionally, mesosulfuron-methyl persistence was tested at 7 ˚C, which is representative of regional average winter soil temperature. Herbicide half-life was calculated with the logarithmic form of first-order rate of degradation using linear regression and was correlated with soil properties. Halflives of atrazine (37-73 d) and topramezone (15-19 d) varied among soil types at 23 ˚C. Mesosulfuron-methyl half-life varied among soils at 7 ˚C (8.8-9.8 d) and 23 ˚C (5.4-5.8 d) and between temperatures. Atrazine and topramezone half-lives were shortest in Candor sand (4% clay, 1.8% organic matter [OM], pH 5.1) and longest in Portsmouth sandy loam (13% clay, 5.3% OM, pH 4.3). Mesosulfuron-methyl halflife was longer at lower soil temperature. Half-lives of atrazine, mesosulfuron-methyl, and topramezone were correlated with soil OM content (r = .83, −.53, and .63, respectively) and pH (r = −.86, .55, and −.57). Additionally, atrazine and topramezone half-lives were positively correlated with soil clay content (r = .83 and .71), and mesosulfuron-methyl half-life was negatively correlated with temperature (r = −.97).

Characterizing atrazine, mesosulfuron‐methyl, and topramezone bioavailability in North Carolina soils using greenhouse bioassays

“…In the selected soil types, estimated mesosulfuron‐methyl concentrations for 30%, 50%, or 80% visual injury or aboveground dry biomass reduction in soybean and canola at all evaluation timings always exceeded the predicted average carryover concentration of 0.06 g ai ha −1 (Table 5). This concentration was calculated from linear regression equations describing mesosulfuron‐methyl persistence in the selected soil types in a previous study (Ramanathan et al., 2022). However, Grey and McCullough (2012) found that carryover residue from chlorsulfuron and metsulfuron‐methyl when applied in combination at rates of 88.0 and 18.0 g ai ha −1 , respectively, caused significant height reduction in soybean, and height and yield reduction in cotton.…”

“…The objective of this research was to evaluate herbicide carryover injury risk in varying soils based on differences in herbicide bioavailability. Of the regional soils in which atrazine, mesosulfuron-methyl, and topramezone persistence were quantified in previous research by Ramanathan et al (2022), Candor sand, Creedmoor sandy loam, and Portsmouth sandy loam were selected as soils of interest for the present study owing to the range in herbicide half-life among these soil types and their varying textural and physicochemical properties. Bioassays are powerful tools by which measurements of such plant responses to herbicides can be used to evaluate soil-herbicide-plant relationships (Jeffries & Gannon, 2016;Loux, 1990;Sandín-España et al, 2011;Strebig & Kudsk, 1993).…”

“…To select herbicide treatment concentrations, the average herbicide carryover concentration at the time of soybean planting was first calculated using linear regression equations describing the first-order rate of degradation of atrazine, mesosulfuronmethyl, and topramezone in the same soil types established in a previous study (Ramanathan et al, 2022). The equations described in Ramanathan et al (2022) relate the initial concentration of each herbicide to the concentration remaining after degradation over time at a specific degradation rate unique to each soil type. Therefore, respective equations for atrazine, mesosulfuron-methyl, and topramezone degradation in Candor sand, Creedmoor sandy loam, and Portsmouth sandy loam were used to calculate the average carryover concentration remaining at the time of soybean planting across soils, assuming the initial herbicide concentration to be the maximum application rate applied to previous season corn (atrazine and topramezone) or winter wheat (mesosulfuron-methyl) and estimating 335, 90, and 212 days between atrazine, mesosulfuron-methyl, and topramezone application, and soybean planting in the region, respectively (USDA-NASS, 2022).…”

“…The reported field half‐life range for topramezone is between 11 and 69 days (Lewis et al., 2016; Shaner, 2014c). Previous research shows that atrazine half‐life ranged from 37 to 73 days and topramezone half‐life ranged from 15 to 19 days in regionally relevant NC soil types, and their persistence was found to be dependent on soil OM content, clay content, and pH, while mesosulfuron‐methyl persistence was also influenced by soil temperature (Ramanathan et al., 2022). Collectively, half‐life ranges of these herbicides suggest that they can persist in soil and become available for uptake by rotational crops long after their application, depending on edaphic factors and environmental conditions (Frank, 1966; Rahman et al., 2014).…”

“…Quantification of atrazine, mesosulfuron‐methyl, and topramezone persistence in regional soil types allows the estimation of average carryover residue concentration that may be present at the time of soybean planting in NC (Ramanathan et al., 2022). Characterizing the bioavailability of atrazine, mesosulfuron‐methyl, and topramezone will provide needed insight regarding differences among representative regional soils in their potential for carryover herbicide injury depending on the influence of their properties on the availability of carryover herbicide concentration for plant uptake.…”