Simulating the Transport and Fate of Trifluralin in Soil

  • Ying Ouyang USDA Forest Service, 100 Stone Blvd, Thomson Hall, Room 309, Mississippi State, MS 39762, USA
  • Jia-En Zhang Department of Ecology, College of Agriculture, South China Agricultural University, 510642 Guangzhou, China
  • Li Hua Cui Department of Environmental Science and Engineering, South China Agricultural University, Guangzhou 510642, China
  • Peter Nkedi-Kizza Department of Soil and Water Sciences, University of Florida, Gainesville, FL 32611, USA
Keywords: Degradation, Model, Leaching, Runoff, Herbicide, Soil, STELLA, Volatilization


Understanding herbicide dynamics in agricultural soils is crucial to evaluate herbicide application efficiency and its environmental consequences. A model for herbicide trifluralin (α,α,α-reifluoro-2,6-dinitro-N,N-dipropyl-ρtoluidine) dynamics namely runoff, erosion, leaching, volatilization, and degradation losses in agricultural soils was developed using the software package Structural Thinking and Experiential Learning Laboratory with Animation (STELLATM). The model was calibrated using field data with a good agreement between model predictions and field measurements before its applications. A simulation scenario was then performed to predict trifluralin dynamics in a 1.26 ha soybean field. Simulation results showed that in general, the rate of water runoff decreased with the rate of rainfall; however, the rates of trifluralin and sediment losses in runoff depended not only on the rate of rainfall but also on the content of trifluraline in the liquid and solid phases. The rates of trifluralin leaching and volatilization decreased sharply within the first couple of days following the surface spray of trifluralin due to its strong adsorption and soil incorporation. Simulation results further revealed that the rate of trifluralin degradation in the soil decreased exponentially with time. About 6% of the total applied trifluralin remained in the soil at the end of the simulation period (120 days). This study suggests that the model, developed with STELLATM, is a useful tool for estimating herbicide dynamics in agricultural soils.


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