Assessing nitrate leaching in cropping systems based on integrated weed management using the STICS soil-crop model

Agriculture in Europe and other parts of the world is currently under strong pressure to reduce its reliance on pesticides. Regarding arable crops, strategies based on integrated weed management (IWM) combine several agronomic practices aimed at reducing herbicide use, but these strategies can generate negative collateral effects, such as increased nitrate leaching. An evaluation of nitrate leaching in a long-term experiment set up in 2000 was performed for five tested cropping systems: four IWM-based systems and one reference system. After the validation of the predictive performance of the STICS soil-crop model, nitrate leaching was simulated for the five cropping systems tested over the 12 years of the experiment and over 12 years of implementing alternative scenarios (i.e. the introduction of early sowing for winter cereals, ceasing deep tillage and the introduction of a mustard catch crop). The results showed that the total amount of nitrate leaching varied between cropping systems and was lowest in the cropping system using no herbicide and that with no tillage, two systems combining several agronomic practices. Alternative scenarios based on both early sowing of winter crops and the introduction of catch crops can reduce the total amount of nitrate leached by 25 to 43% over the 12 years of simulations, although early sowing can, in some cases, increase nitrate leaching. This study contributes to the multi-criteria evaluation of innovative cropping systems. (C) 2014 Elsevier B.V. All rights reserved.