Long-term field experiment to follow various effects of conservation soil tillage is conducted at Biotechnical faculty in Ljubljana. The soil is Eutric Gleysol. Conventional treatment with plowing, 22 cm deep P, and conservation treatment by rotary harrow to a depth of 10 cm N, and subplots with compost amendment (-c) and without fertilization (-n) were observed. After 5 years nutrient contents and organic matter were higher in N than P. Compost addition had a positive effect on microbial biomass, but the tillage system did not affect it. However, nitrogen mineralization and decomposition of straw were higher in P as in N, and in the soil depth of 15 - 20 cm than in the 5 - 10 cm. V dolgoletnem poljskem poskusu na BF v Ljubljani, na evtričnih oglejenih tleh, merimo različne učinke ohranitvene obdelave tal. Obravnavamo konvencionalno obdelavo z oranjem 22 cm globoko P in ohranitveno obdelavo z vrtavkasto brano do 10 cm globine N, in podploskvi z dodatkom komposta (-c), in brez gnojenja (-n). Po 5 letih so bile višje vsebnosti hranil in organskih snovi v N v primerjavi P. Kompost je imel pozitiven učinek na mikrobno biomaso, obdelovani sistem pa nanjo značilno ni vplival. Mineralizacija dušika in razgradnja slame sta bila večja v P kot v N, ter v globini tal od 15 - 20 cm kot v 5-10 cm.