DIRECT AND RESIDUAL EFFECT OF DIFFERENT ORGANIC FERTILIZERS ON POTATOAND CEREALS

Field experiment with 8 different organic fertilizers (cattle dung wit h and without litter, pig slurry, peat compost formed from hen and pig slurry, sawdust-duck manure, noncomposted peat and straw litter with pig slurry) was carried out on loamy brown podzoluvisol since 1985. Th e organic fertilizers were applied in the spring of 1985 on two backgr ounds: with and without mineral fertilizers. The material is based on the data of four years (1985-1988). The arrangement of crops was the f ollowing: potato, spring wheat, barley and early barley. On both backg rounds cattle dung with litter turned out to be the best organic ferti lizer, while noncomposted peat manure had a low direct and residual ef fect. However, before the application it must be composted with pig or hen slurry. The effect of peat composts was dependent on the backgrou nd of mineral fertilizers. Pig slurry had a low residual effect and ac ted only as a liquid nitrogen fertilizer. The joint application of str aw and pig slurry can be a suitable opportunity for diminishing their undesirable effects.