Twenty-five 200 L lysimeters were filled with a sandy soil and used to compare five fertilisation regimes (5 replicates): unfertilised control, manure compost, urban compost, brushwood compost and mineral NPK, with comparable nitrogen supplies. Crops (mixed grass, wheat, carrot, lettuce, wheat, lettuce, wheat, vetch-oats) were grown successively during five years and nitrates leached under the soil were continuously collected and quantified monthly. The overall amount of nitrates leached under crops was in the following decreasing order: mineral NPK, manure compost, urban compost, control, brushwood compost. The highest yields were obtained with manure compost and mineral NPK. The present data thus demonstrate the high efficiency of manure compost and the beneficial reduction of nitrate leaching elicited by organic fertilisers during a five year rotation.