Comparison of three pesticide fate models with respect to the leaching of two herbicides under field conditions in an irrigated maize cropping system

• Published in: Science of the total environment 2014-11, Vol.499, p.533-545
• Main Authors: Marín-Benito, J.M., Pot, V., Alletto, L., Mamy, L., Bedos, C., Barriuso, E., Benoit, P.
• Format: Article
• Language: English
• Subjects: Agriculture - methods; Agronomy. Soil science and plant productions; Applied sciences; Biological and medical sciences; Biological and physicochemical properties of pollutants. Interaction in the soil; Computer simulation; Exact sciences and technology; Field experiment; France; Fundamental and applied biological sciences. Psychology; Herbicide; Herbicides; Herbicides - analysis; Leaching; Life Sciences; Lysimeters; Mathematical models; Mesotrione; Model comparison; Models, Chemical; Parametrization; Pesticide fate models; Pollution; S-metolachlor; Soil (material); Soil - chemistry; Soil and sediments pollution; Soil and water pollution; Soil Pollutants - analysis; Soil science; Water Pollutants, Chemical - analysis; Water pressure; Zea mays; Zea mays - growth & development
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2014.06.143

The ability of three models (PEARL, MACRO and PRZM) to describe the water transfer and leaching of the herbicides S-metolachlor and mesotrione as observed in an irrigated maize monoculture system in Toulouse area (France) was compared. The models were parameterized with field, laboratory and literature data, and pedotransfer functions using equivalent parameterization to better compare the results and the performance of the models. The models were evaluated and compared from soil water pressure, water content and temperature data monitored at 0.2, 0.5 and 1m depth, together with water percolates and herbicide concentrations measured in a tension plate lysimeter at 1m depth. Some hydraulic (n, θs) parameters and mesotrione DT50 needed calibration. After calibration, the comparison of the results obtained by the three models indicated that PRZM was not able to simulate properly the water dynamic in the soil profile. On the contrary, PEARL and MACRO simulated generally quite well the observed water pressure head and volumetric water content at the three different depths during wetting periods (e.g. irrigated cropping period) while a poorest performance was obtained for drying periods (fallow period with bare soil and beginning of crop period). Similar water flow dynamics were simulated by PEARL and MACRO in the soil profile although in general, and due to a higher evapotranspiration in MACRO, PEARL simulated a wetter soil than MACRO. For the whole simulated period, the performance of all models to simulate water leaching at 1m depth was poor, with an overestimation of the total water volume measured in the lysimeter (ranging from 2.2 to 6.6 times). By contrast, soil temperature was properly reproduced by the three models. The models were able to simulate the leaching of herbicides at 1m depth in similar appearance time and order of magnitude as field observations. Cumulative observed and simulated mesotrione losses by leaching were consistently higher than the observed and simulated losses of the less mobile herbicide, S-metolachlor. In general, PRZM predicted the highest concentrations for both herbicides in the leachates while PEARL simulated the observed herbicide concentrations better than MACRO and PRZM. •The performances of PRZM, PEARL and MACRO are rigorously compared.•Simulated evapotranspiration plays a major role in the prediction of water dynamic.•The three models overestimated the total water volume leachate at 1m depth.•PEARL and MACRO predicted