Short-rotation tree forests are irrigated with landfill leachate to reduce
both leachate volume and nutrient content. It is of interest both for leach
ate treatment and energy recovery to optimise the productivity of such plan
tations. This study's aim was to investigate the effects of irrigation on s
oil quality, tree growth and on emissions of landfill gas (LFG) produced in
the wastes.
Soils irrigated with leachate had a higher average nutrient and organic mat
ter contents, and a lower dry solids content. Larger trees occur on plots i
rrigated with leachate, presumably due to the positive effect of water and
nutrient supply. The willows used in this experiment seemed to be tolerant
of high carbon dioxide concentrations, as no statistically effect arising f
rom LFG emissions could be linked to tree growth.
Methane oxidation levels between 50 and 950 mol m(-2) yr(-1) were observed.
The positive correlation between soil methane oxidation capacity and tree
presence is an interesting perspective on reduction of methane emissions by
landfill's top cover vegetation type. Optimising methane oxidation using v
egetation as a 'cover crop' could reduce the amount of methane discharged i
nto the atmosphere.