Various methods have been applied to utilize semicoke - a by-product of oil shale production - harmless for environment. Use of compost, manufactured with semicoke, as agricultural soil improvement substance, would be one of the options available. This paper is an attempt to assess the economic effect obtained by applying different compost mixtures to several horticultural crops: swede (Brassica napus), beetroot (Beta vulgaris) and strawberry Fragaria x ananassa), using the gross margin calculation method. The following compost mixtures were used: recultivation substance and solid fraction of pig manure (1:2); recultivation substance and sewage sludge (1:2) and selvage sludge alone. Composts applied increased the yield of swede, beetroot and strawberry: positive after effect of composts was notable also in the second year. Positive effect oil gross margin became obvious only (hiring the second year. Sewage sludge and compost mixed with recultivation substance was economically more expedient for swede cultivation while sewage sludge compost was more efficient for beetroot cultivation. As for strawberry cultivation, use of mixture of re-cultivation substance and solid fraction of pig manure seemed to be most effective.