This study, based on a literature review and simulations, shows the efficiency of cover crops at catching nitrate in most agriculture situations. It also analyzes both the negative impacts they can have and the ecosystem services they can provide. The introduction of a cover crop between two main crops helps catch the soil mineral nitrogen before the period of drainage and consequently reduces nitrate leaching and nitrate concentration in the drainage water. This study allows quantifying the efficiency of cover crops at catching nitrate and optimizing their implantation conditions over a large range of French pedoclimatic conditions. The presence of high nitrate levels in surface and ground waters, due to excessive nitrogen fertilization and natural production of nitrate by soil organic matter mineralization, is a double challenge for public health and environment protection.

There is no similar book studying precisely the role of cover crops in leaching nitrate in such a large range of agronomic conditions

Foreword.- 1. Study context and methodology.- 1.1. Fallow period: definition, management practices and regulatory aspects.- 1.2. Study objectives and approach.- 2. Main lessons drawn from the study of the literature.- 2.1. Cover crop management techniques.- 2.2. Nitrate and water during fallow periods.- 2.3. Effects of cover crops on erosion, physical soil properties and carbon balance.- 2.4. Biotic effects of cover crops on weeds, microflora and fauna.- 2.5. Conclusion: a rich but incomplete analysis of the literature.- 3. Main lessons drawn from the simulation study.- 3.1. Objectives of the simulation study using a dynamic crop model.- 3.2. Methodology of the three parts of the simulation study.- 3.3. Generic and specific lessons drawn from the simulation study.- 3.4. Discussion of study results.- 4. Conclusions and outlook.