In general, for Populus spp. maximum yields resulted
from a mixed application of mineral fertiliser and compost:
an average of only 2–2.6 tha−1 dry biomass was calculated
for poplars after application of mineral fertiliser without
compost, whereas, a maximum biomass accumulation of
3–3.9 tha−1 was reached when applying mineral fertiliser and
compost. The annual productivity of Populus spp. at Helmstedt
was approximately two times higher as compared to
those at the study site Lusatia when only mineral fertiliser
was applied. The biomass accumulationwas even three to four
times higher at Helmstedt for subplots of poplars treated with
mineral fertiliser and compost. This points out on the importance
of the amendment of organic matter for the productivity
on post-mining sites.