On-farm nitrogen fixation is a driving force in organic agriculture. The efficiency with which this nitrogen is used can be increased by using alfalfa or grass-clover crops directly as fertilizer on other fields: cut-and-carry fertilizers. In two crops in two years, the use of several types of alfalfa and grass-clover as fertilizer is compared with the use of poultry manure and slurry. The nitrogen use efficiency at crop level is comparable or better for the cut-and-carry fertilizers as compared to the animal manures. The relative P and K content of these fertilizers comes closer to the crop demand than that of the poultry manure. Crop yields are comparable or better when using the alfalfa or grass-clover as fertilizer. It is concluded that the cut-and-carry fertilizers are a serious alternative for manure as part of an overall farm soil fertility strategy.