AqYield-N: A simple model to predict nitrogen leaching from crop fields

•We developed a nitrogen module to the simple crop model AqYield to predict N leaching.•The formalisms chosen for each process were based on published and validated work.•The new N module was kept as simple as possible with a limited addition of new input data.•AqYield-N estimated satisfactorily nitrate leaching for contrasted cropping systems, despite its simplicity. Evaluating and improving cropping systems is essential to reduce nitrate leaching, improve drinking water quality and prevent eutrophication. Since the intensity of nitrogen (N) leaching varies greatly spatially and is difficult to measure, crop models are useful tools to quantify the influence of climate, soil and agricultural practices on N leaching. Our objective was to develop a simple model with low input data and calibration requirements to predict nitrate leaching from a variety of crop fields over large areas, such as watersheds, for which data are often limited. The AqYield model is a simple model with few inputs that has estimated sufficiently well drainage and water flows for several crops and rotations. Based on this model, we developed AqYield-N, which considers the major N flows in the soil–plant system, including mineralization, plant uptake and leaching at a daily time step. The present study presents the development and formalisms of AqYield-N. We developed AqYield-N based on simple and robust formalisms and low requirements for input data and parameters. As much as possible, we used equations already published and validated in the scientific literature. We then evaluated AqYield-N using observed experimental N leaching data. Its estimates were satisfactory for three contrasting pedoclimatic situations and for various crops and bare soil. Although the model is simple and requires only a few inputs, it was as accurate as more complex crop models widely used and evaluated in the agronomic literature, such as STICS. The study demonstrated the potential of AqYield-N to estimate the influence of management practices on N leaching. AqYield-N, whether alone or integrated in larger-scale modeling approaches, can be used to predict leaching during crop rotations at field and large scale to evaluate the influence of various agroecological practices on N leaching.