The pre-crop effect of legumes is the positive effect a legume crop has on the performance of the following crop. This effect on the following crop, usually a cereal, is often presented as a reason to grow legumes. Full use of this precrop effect requires a good understanding of its size and its causes. Factors affecting this include the site conditions, crop management practices, cropping sequences (rotation), and the legume species and cereals grown. Making efficient use of the pre-crop effect can save considerable amounts of nitrogen fertiliser, enable reduced tillage and pesticide application, enhance soil structure, and increase the yield and quality parameters of the following cereal crops. These effects allow cost, energy and time savings, and increase production and revenues for the farmer. It reduces impacts on the environment.