Modeling pesticide dissipation half-lives in plants with effects of fertilizer application: A flexible simulation tool

Abstract

Fertilizer is commonly applied to plants alongside pesticides, which can significantly affect pesticide dissipation behavior in plants. Taking into account the fertilizer effect when modeling pesticide dissipation from plants is crucial for accurately predicting pesticide residue levels in crops, which is essential for ensuring agricultural food safety, conducting consumer exposure assessments, and protecting environmental health. However, mechanistic modeling approaches for estimating dissipation half-lives in plants while taking fertilizer application into account are currently lacking. To address this research gap, we simulate pesticide dissipation half-lives using mechanistic models, and the method can be tabulated in spreadsheets to help users perform modeling exercises by modifying fertilizer application conditions. In addition, a spreadsheet simulation tool with a step-by-step procedure is provided, allowing users to easily estimate pesticide dissipation half-lives in plants. The simulation results for the cucumber plant demonstrated that plant growth dynamics played a significant role in the overall elimination kinetics for the majority of pesticides, indicating that fertilizer application could significantly affect pesticide dissipation half-lives in plants. On the other hand, some moderately or highly lipophilic pesticides may reach their peak concentrations in plant tissues over a longer period of time following pesticide application, depending on their uptake kinetics and dissipation rates on plant surfaces or soil. Therefore, the first-order dissipation kinetic model, which generated pesticide dissipation half-lives in plant tissues, must be fine-tuned with respect to its initial concentrations. With chemical-, plant-, and growth-specific model inputs, the proposed spreadsheet-based operational tool can assist users in estimating pesticide dissipation half-lives in plants with fertilizer application effects. To enhance the effectiveness of our modeling approach, it is recommended that future research investigate rate constants for other types of plant growth dynamics, chemical degradation, horticultural methods, and environmental conditions (such as temperature). These processes can be characterized using first-order kinetic rate constants as model inputs in the operational tool, which can significantly improve the simulation results.