Influence of Soil Texture and Tillage on Herbicide Transport

Department of Agricultural Engineering, University of Maryland, College Park, MD, USA
Chemosphere (Impact Factor: 3.34). 12/2000; 41(9):1327-1332. DOI: 10.1016/S0045-6535(00)00028-X


Two long-term no-till corn production studies, representing different soil texture, consistently showed higher leaching of atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine] to groundwater in a silt loam soil than in a sandy loam soil. A laboratory leaching study was initiated using intact soil cores from the two sites to determine whether the soil texture could account for the observed differences. Six intact soil cores (16 cm dia by 20 cm high) were collected from a four-year old no-till corn plots at each of the two locations (ca. 25 km apart). All cores were mounted in funnels and the saturated hydraulic conductivity (Ksat) was measured. Three cores (from each soil texture) with the lowest Ksat were mixed and repacked. All cores were surface treated with [ring−14C] atrazine, subjected to simulated rainfall at a constant intensity until nearly 3 pore volume of leachate was collected and analyzed for a total of . On an average, nearly 40% more of atrazine was leached through the intact silt loam than the sandy loam soil cores. For both the intact and repacked cores, the initial atrazine leaching rates were higher in the silt loam than the sandy loam soils, indicating that macropore flow was a more prominent mechanism for atrazine leaching in the silt loam soil. A predominance of macropore flow in the silt loam soil, possibly due to greater aggregate stability, may account for the observed leaching patterns for both field and laboratory studies.

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    • "Atrazine, one of the most extensively used herbicides, is widely considered persistent and has been detected in water bodies with direct and indirect effects on growth and activity of aquatic organisms (Graymore et al., 2001). Soil texture and management practices may influence sorption and movement of herbicides (Sadeghi et al., 2000; Rae et al., 1998). "
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    ABSTRACT: Surfactants in herbicide formulations eventually enter soil and may disrupt various processes. Research examined effects on nutrient uptake in corn caused by surfactants, herbicides, and surfactant-herbicide combinations applied to silt loam and silty clay loam soils in the greenhouse. Surfactants evaluated were Activator 90, Agri-Dex, and Thrust; herbicides were glyphosate, atrazine, and bentazon. Corn was planted in fertilized soils with moisture content maintained for optimum growth. Foliage (V8 growth stage) was collected for elemental analyses. Nutrient uptake differed with soil texture. Nutrient uptake from silty clay loam was more affected by surfactants and/or herbicides than in silt loam. Potassium uptake was significantly (P = 0.05) decreased in silt loam only by Thrust but uptake of phosphorus (P), potassium (K) calcium (Ca), sulfur (S), copper (Cu), and zinc (Zn) decreased by ≤30% in silty clay loam treated with surfactants. Surfactants and/or herbicides may interact with soil texture to affect nutrient uptake. Long-term field studies to validate changes in nutrient uptake and grain yields after annual applications of surfactants plus herbicides are needed.
    Journal of Plant Nutrition 12/2014; 38(7):141223092238007. DOI:10.1080/01904167.2014.881878 · 0.49 Impact Factor
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    • "In addition to the predisposing conditions present at the horizon surface caused by nontillage system, the pedological conditions of the underlying horizons can provide continuity to the ways of fast flow water. Cracks developed during wetting-drying cycles in a clayed subsurface horizon favours fast circulation of soil solution (Flury and Flühler, 1994; McGarry, 2000; Sadeghi et al., 2000; Hang et al., 2010). It is considered that degradation of herbicides migrating from soils requires microorganisms with suitable degradative capabilities, appropriate environmental conditions for microorganisms to function and sufficient residence time for biodegradation to occur (Topp et al., 1995). "

    Herbicides: properties, crop protection and environmental hazards., Nova Science Publishers, Inc. N.Y., USA edited by K. D. Piotrowski, 01/2011: chapter Herbicide behaviour in non tillage systems.;
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    • "On the other hand, Veeh et al. (1994) showed that the transport of Br − and chlorsulfuron is similar through undisturbed or sieved soil columns. Sadeghi et al. (2000) found a faster transport of atrazine in either the undisturbed or sieved soils depending upon the soil's physico-chemical properties. Finally, Griessbach et al. (1998) showed that the leaching of a silicone-polyether was lower in undisturbed than in sieved soil columns. "
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    ABSTRACT: In this study, displacement experiments of isoproturon were conducted in disturbed and undisturbed columns of a silty clay loam soil under similar rainfall intensities. Solute transport occurred under saturated conditions in the undisturbed soil and under unsaturated conditions in the sieved soil because of a greater bulk density of the compacted undisturbed soil compared to the sieved soil. The objective of this work was to determine transport characteristics of isoproturon relative to bromide tracer. Triplicate column experiments were performed with sieved (structure partially destroyed to simulate conventional tillage) and undisturbed (structure preserved) soils. Bromide experimental breakthrough curves were analyzed using convective-dispersive and dual-permeability (DP) models (HYDRUS-1D). Isoproturon breakthrough curves (BTCs) were analyzed using the DP model that considered either chemical equilibrium or non-equilibrium transport. The DP model described the bromide elution curves of the sieved soil columns well, whereas it overestimated the tailing of the bromide BTCs of the undisturbed soil columns. A higher degree of physical non-equilibrium was found in the undisturbed soil, where 56% of total water was contained in the slow-flow matrix, compared to 26% in the sieved soil. Isoproturon BTCs were best described in both sieved and undisturbed soil columns using the DP model combined with the chemical non-equilibrium. Higher degradation rates were obtained in the transport experiments than in batch studies, for both soils. This was likely caused by hysteresis in sorption of isoproturon. However, it cannot be ruled out that higher degradation rates were due, at least in part, to the adopted first-order model. Results showed that for similar rainfall intensity, physical and chemical non-equilibrium were greater in the saturated undisturbed soil than in the unsaturated sieved soil. Results also suggested faster transport of isoproturon in the undisturbed soil due to higher preferential flow and lower fraction of equilibrium sorption sites.
    Journal of Contaminant Hydrology 01/2008; 94(3-4):261-76. DOI:10.1016/j.jconhyd.2007.07.002 · 2.20 Impact Factor
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