On the use of unsaturated flow and transport models in nutrient and pesticide management

Abstract

Nutrient and pesticide emissions from agricultural land significantly impact surface and groundwater resources all over the world. These emissions should therefore be controlled by an appropriate management of agricultural practices. Effective agricultural management builds on a thorough understanding of the fate and behavior of nutrients and pesticides in the soil–crop system. Unsaturated flow and transport models may therefore be used as tools to predict fate and behavior of chemicals in soil, supporting decision making in the area of nutrient and pesticide management. In this paper, we show how flow and transport models are introduced in the nutrient and pesticide management decision-making process. Examples are given of the use of flow and transport models in (i) field-scale nutrient and pesticide management; (ii) the identification and evaluation of fertilization and pesticide application practices supporting the implementation of regional-scale environmental management plans; and (iii) the registration of plant-protection products. Examples are selected across different eco-regions elucidating the generality of the presented approaches. Particular emphasis is put on (i) the limitations of the current modeling approaches for management applications, (ii) the handling of uncertainty in the data flow, (iii) the problems associated with the estimation of the required modeling data and parameters, and (iv) the transfer of scientific know-how into operational decisionmaking tools. Opportunities are presented for improving the process descriptions, the data generation methods, and the modeling practice. Finally, threats are summarized on the use of flow and transport models in future nutrient and pesticide management studies