An improved PADDY model including uptake by rice roots to predict pesticide behavior in paddy fields under nursery-box and submerged applications

Abstract

We developed an improved version of the PADDY model for predicting pesticide behavior in paddy fields, which includes pesticide uptake by rice roots. We applied the model to nursery-box and submerged pesticide applications. A paddy field was divided into root-zone and inter-plant areas, and paddy soil containing pesticides was vertically separated into three layers. Pesticide behavior was modeled with mass fractions of the pesticides in paddy water and the soil layers immediately after rice transplanting obtained from field experiments, and uptake by rice roots was described using the transpiration stream concentration factor. The improved model successfully simulated measured concentration changes in a paddy field, including rice plants, under nurserybox and submerged applications. The model evaluated the difference in the concentrations of nursery-box-applied pesticides between root-zone and inter-plant soil samples with several key parameters. Our study provides a useful solution for simulating the uptake of pesticides in soil by rice roots.

Challenges and ways forward in pesticide emission and toxicity characterization modeling for tropical conditions

“…These substances can largely increase impact on freshwater ecosystems (Vázquez-Rowe et al 2012), but another approach is required to integrate their specific behavior in the environment into the adapted PestLCI model (Renaud-Gentié et al 2015;Peña et al 2018). Adapting the PestLCI model for special cropping systems is finally relevant, for example for flooded crops as rice, with specific pesticide field emissions, getting inspiration from models specifically parameterized for such cropping systems (Capri and Miao 2002;Inao et al 2018).…”

Use of mathematical modeling and its inverse analysis for precise assessment of pesticide dissipation in a paddy environment

“…Indeed, various mathematical models predicting the fate and transport of paddy pesticides in Japan have been developed and their applicability verified. [8][9][10][11][12][13] However, the major drawback of these models is that model prediction easily loses accuracy without appropriate calibration of numerous model parameters to site-specific conditions. Unlike research purpose modeling, where input parameters are usually well prepared, regulatory modeling must pro-vide a generic assessment with limited data and limited relevant information.…”