DIRECT AND RESIDUAL EFFECT OF DIFFERENT ORGANIC FERTILIZERS ON POTATO AND CEREALS

Field experiment with 8 different organic fertilizers (cattle dung with 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. The organic fertilizers were applied in the spring of 1985 on two backgrounds: with and without mineral fertilizers. The material is based on the data of four years (1985-1988). The arrangement of crops was the following: potato, spring wheat, barley and early barley. On both backgrounds cattle dung with litter turned out to be the best organic fertilizer, while noncomposted peat manure had a low direct and residual effect. However, before the application it must be composted with pig or hen slurry. The effect of peat composts was dependent on the background of mineral fertilizers. Pig slurry had a low residual effect and acted only as a liquid nitrogen fertilizer. The joint application of straw and pig slurry can be a suitable opportunity for diminishing their undesirable effects.