Aims Our goal was to assess how management and sward functional diversity affect nitrogen response efficiency (NRE), the ratio of plant biomass production to supply of available nitrogen (N) in temperate grassland. Methods A three-factorial design was employed: three sward compositions, two mowing frequencies, and two fertilization treatments. Results NRE was largely influenced by fertilization followed by mowing frequency and sward composition. NRE was larger in unfertilized than fertilized plots, in plots cut thrice than plots cut once per year, and in control swards than in monocot-or dicotenhanced swards. Fertilization decreased NRE through decreases in both N uptake efficiency (plant N uptake per supply of available N) and N use efficiency (NUE, biomass produced per plant N uptake) whereas mowing frequency and sward composition affected NRE through N uptake efficiency rather than NUE. The largest NRE in the control sward with 70 % monocots and 30 % dicots attests that these proportions of functional groups were best adapted in this grassland ecosystem. Conclusions Optimum NRE may not be a target of most farmers, but it is an appropriate tool to evaluate the consequences of grassland management practices, which farmers may employ to maximize profit, on environmental quality.

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Purpose In this study, the ecotoxicological effects of the soil contaminations at an uncovered landfill site are assessed with two biological tests (earthworm avoidance test and luminous bacteria test). Furthermore, the state of rotting of the organic substance is estimated. Therefore, total organic carbon (TOC) contents and basal respiration rates are measured. Materials and methods The study has been carried out with polluted samples originating from the old deposit I 27 in Bielefeld, North Rhine-Westphalia, Germany. To assess the ecotoxicological effects, heavy metal contents were determined and earthworm avoidance tests were conducted. Luminous bacteria tests with Vibrio fischeri were applied to the soil eluates. Furthermore, the TOC contents and the basal respiration rates were measured regarding to the stability of the organic substance. Results and discussion Although the determined heavy metal contents showed high values, the results of the biotests do neither indicate an emission of contaminants with the seepage water nor a toxic disturbance of the soil function as a biological habitat. Beyond that, the respiration rates turned out to be in a range that is typical for natural soils. Conclusions Due to the aerobic decomposition of the organic matter and the associated development of humic substances, the contaminants contained in the material seem to be mainly immobile. The organic matter is stabilised to a large part. Altogether the results accord to the long-term perspective for the environmental behaviour of artificially aerated waste.

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