Adult collembolans we:re fed with two different food types. Leaves of Taraxacum officinale and Dactylis glomerata were given as food sources in two physical forms: either as intact leaves or as powder. Foods were labelled with 15N. The 15N uptake curves were measured. Turnover rates and turnover times were calculated. Results show that Taraxacum leaves are preferred to Dactylis leaves. The physical condition of the leaves influenced the nitrogen turnover of the animals to a large extent. Fragmentation of Dactylis leaves enhanced nitrogen utilization by roughly two-fold and decreased turnover time by nearly half. Consumption of Taraxacum leaves has synergic effect on the nitrogen utilization of Dactylis leaves. Simultaneous consumption of Taraxacum and Dactylis enhanced the nitrogen uptake rate from Dactylis leaves compared to the treatment where Dactylis was the only food source.