Reduced tillage influences the distribution of OM in the soil profile, as more plant residues are left at or near the soil surface. A mulch of dead vegetation near the surface, often with a wide C/N ratio, may affect the availability of applied and mineralized N. Dry matter yield and uptake of soil N and fertilizer N were tested in five field experiments comparing soil under shallow tillage (ST) with moldboard ploughing (MP). One of the field experiments had been running for 36 years, the remaining four from five to eight years. 15N-labelled mineral fertilizer was applied in spring to microplots established in spring barley and winter wheat. The upper soil layer in plots with ST contained generally more OM than the deeper soil layer and the soil under MP. Correspondingly, N mineralization (0-20 cm) determined in an incubation study with soil from two of the five sites was slightly higher (1-2 g NO3-N m-2 after 31 days) with ST than with MP. Dry matter yield was unaffected by tillage management with no significant differences in grain production between MP and ST. Total N uptake in grain and straw was likewise little influenced with only one site showing lower N uptake in plots with ST. The total recovery of 15N in the aboveground plant parts was 37-44% for spring barley and 59-64% for winter wheat. Two of the five crops grown under ST had significantly lower 15N recovery than under MP, but as total N uptake at these sites was unaffected by tillage, the lower recovery was mainly ascribed to dilution with unlabelled soil N. The results indicate that, on the soil types investigated, ST has only a minor influence on crop yields and fertilizer utilization.