Abstract

Chemicals such as herbicides used in agriculture, can be a source of soil and ground water pollution. Computer simulation models provide an efficient and cost-effective alternative that can be easily adapted to many field situations with varying soil types and different land uses. In the present study HYDRUS-1D and modified PRZM-3 (Pesticide Root Zoone Model) models were used to simulate clodinafop-propargyl (Topik) herbicide in soil profile and plant uptake under vetiver cultivation The measured data were obtained from treatments with two concentrations of the herbicide applied to the vetiver grass (C1V and C2V) and without vetiver grass (C1S and C2S). The vetiver grass uptake of clodinafop-propargyl was 1198.8 and 1107.4 mg.ha-1. The observed data showed that in surface layer, 0-10 cm, clodinafop-propargyl concentration was increased because of volatilization of herbicide from the deeper soil layer to soil surface, upward flow of water in soil and cracks in soil surface. The measured data for C2V treatment was used for calibration and the measured data from the other treatments were used for validation of above models. The statistical parameters showed that modified PRZM-3 model was more accurate than HYDRUS-1D for predicted of herbicide concentration in soil and vetiver uptake. The error of HYDRUS-1D model was about 2.5 times higher than the modified PRZM-3 model. The predicted cumulative uptake of clodinafoppropargyl by vetiver grass through modified PRZM-3 model was about 1.5 times higher than that predicted by HYDRUS-1D model. In general, plant uptake of herbicide estimated by HYDRUS-1D model was more accurate than modified PRZM-3 model.

Keywords: Herbicide; Modeling; Phytoremediation; Soil pollution; Vetiver