The current increase in the organic agriculture sector has created a new market for fertilisers approved for organic farming. Off-farm N sources for organic farming are scarce considering the restriction on the use of chemical fertilisers. Thus, when some commercial products are allowed for organic agriculture, commercial opportunities became available. In this study we compare the behaviour of Vegethumus (Veg) and Phenix (Phe), which are two manures allowed for organic farming, with several other manures, ammonium nitrate (AN) and control treatments. A three year field trial and a pot experiment were carried out in order to estimate dry matter yield, N uptake, and N nutritional status of the crops, as well as soil N availability by using anion exchange membranes inserted into the soil. Apparent N recoveries in the field trial were 6.3 % and 58.2 % in Veg and AN plots, respectively, after the application of 380 kg N/ha in the previous 5 growing seasons. In the pot experiment the ANR of Veg and Phe were -5.0 % and 13.6 %, respectively, while in AN pots it was 37.1%. The other organic manures used in the pot experiment gave higher apparent N recoveries than Veg and Phe if their C:N ratios or inorganic-N contents were taken into account. This work stresses that the use of manures approved for organic farming must first be carefully considered by farmers, with reference to price and agronomic value.