TY - BOOK
T1 - Willow and poplar for bioenergy on former cropland
T2 - Biomass production, soil carbon, nutrients and water
AU - Georgiadis, Petros
PY - 2017
Y1 - 2017
N2 - Climate change is one of the 21st century’s greatest challenges and calls for immediate actionthrough the implementation of mitigation strategies.A shift from fossil fuel to renewable energy is a key factor for reducing greenhouse gasemissions to the atmosphere, with bioenergy being the predominant sector of renewables in thecurrent European and global energy markets. Dedicated energy crops, such as short rotationwoody crops (SRWC), are promising bioenergy feedstock in southern Scandinavia due to theirhigh yields. Such cropping systems have high demands for land, water, and nutrients andtherefore, along with high yields, it is necessary to maintain low environmental impacts.The objective of this thesis was to assess biomass production of SRWC established on formercropland, and further identify the effects of these systems on soil, water and nutrients during thefirst two decades after establishment. Two fertilization trials were established on nutrient-richsoils; one in short rotation coppice (SRC) willow and one in short rotation forest (SRF) poplar,The trials provided results on biomass production, water fluxes, and nutrient leaching andbudgets under different fertilization regimes, and allowed comparisons between the two croppingsystems. In addition, a soil survey was conducted in SRC willow and SRF poplar stands, toassess the accumulation of soil organic carbon and changes in soil properties after conversion.The results indicated that the potential for biomass production in unfertilized SRC willow wasgreater than in unfertilized SRF poplar during the first decade, but the overall production wassubstantially higher in SRF poplar over two decades. Annual fertilization corresponding to 60 kgN ha-1 yr-1 in SRC willow increased biomass production by 33%, after which the biomassproduction was comparable to the unfertilized SRF poplar over two decades. Fertilization of theSRF poplar on the other hand, showed inconsistent effects on biomass production.Differences in temporal biomass production patterns between SRC willow and SRF poplar hadfurther implications for the nutrient and water demands of the trees.The water requirements of SRWCs are generally high, and high evapotranspiration rates in bothSRC willow and SRF poplar decreased deep percolation, which along with low N concentrationsled to low N leaching. Excessive N leaching was only observed when SRC was fertilized withhigh doses of mineral fertilizer corresponding to 240 or 360 kg N ha-1 per rotation. Comparisonof adjacent cropland and SRWC stands indicated that soil organic carbon contents increase in theformer plough layer after conversion of cropland to SRWC, with no difference found betweenSRC willow and SRF poplar.The results from SRC willow trial indicated that suitable fertilization regimes on nutrient-richsoils can further stimulate biomass production, have low leaching rates, and maintain soilnutrient stocks balanced between inputs and outputs. The effects of fertilization on biomassproduction of SRF poplar were not consistent, indicating that further research is recommended,for improving the fertilization regimes in such plantations.Cropland conversion to SRWC had overall limited undesired impacts on the soil, and nutrientfluxes. There were no substantial differences between SRC and SRF for any of the examined soilparameters. The timing for desired biomass harvests and management intensity remain the mainfactors of establishment of either of the two cropping systems.
AB - Climate change is one of the 21st century’s greatest challenges and calls for immediate actionthrough the implementation of mitigation strategies.A shift from fossil fuel to renewable energy is a key factor for reducing greenhouse gasemissions to the atmosphere, with bioenergy being the predominant sector of renewables in thecurrent European and global energy markets. Dedicated energy crops, such as short rotationwoody crops (SRWC), are promising bioenergy feedstock in southern Scandinavia due to theirhigh yields. Such cropping systems have high demands for land, water, and nutrients andtherefore, along with high yields, it is necessary to maintain low environmental impacts.The objective of this thesis was to assess biomass production of SRWC established on formercropland, and further identify the effects of these systems on soil, water and nutrients during thefirst two decades after establishment. Two fertilization trials were established on nutrient-richsoils; one in short rotation coppice (SRC) willow and one in short rotation forest (SRF) poplar,The trials provided results on biomass production, water fluxes, and nutrient leaching andbudgets under different fertilization regimes, and allowed comparisons between the two croppingsystems. In addition, a soil survey was conducted in SRC willow and SRF poplar stands, toassess the accumulation of soil organic carbon and changes in soil properties after conversion.The results indicated that the potential for biomass production in unfertilized SRC willow wasgreater than in unfertilized SRF poplar during the first decade, but the overall production wassubstantially higher in SRF poplar over two decades. Annual fertilization corresponding to 60 kgN ha-1 yr-1 in SRC willow increased biomass production by 33%, after which the biomassproduction was comparable to the unfertilized SRF poplar over two decades. Fertilization of theSRF poplar on the other hand, showed inconsistent effects on biomass production.Differences in temporal biomass production patterns between SRC willow and SRF poplar hadfurther implications for the nutrient and water demands of the trees.The water requirements of SRWCs are generally high, and high evapotranspiration rates in bothSRC willow and SRF poplar decreased deep percolation, which along with low N concentrationsled to low N leaching. Excessive N leaching was only observed when SRC was fertilized withhigh doses of mineral fertilizer corresponding to 240 or 360 kg N ha-1 per rotation. Comparisonof adjacent cropland and SRWC stands indicated that soil organic carbon contents increase in theformer plough layer after conversion of cropland to SRWC, with no difference found betweenSRC willow and SRF poplar.The results from SRC willow trial indicated that suitable fertilization regimes on nutrient-richsoils can further stimulate biomass production, have low leaching rates, and maintain soilnutrient stocks balanced between inputs and outputs. The effects of fertilization on biomassproduction of SRF poplar were not consistent, indicating that further research is recommended,for improving the fertilization regimes in such plantations.Cropland conversion to SRWC had overall limited undesired impacts on the soil, and nutrientfluxes. There were no substantial differences between SRC and SRF for any of the examined soilparameters. The timing for desired biomass harvests and management intensity remain the mainfactors of establishment of either of the two cropping systems.
UR - https://rex.kb.dk/primo-explore/fulldisplay?docid=KGL01010819225&context=L&vid=NUI&search_scope=KGL&tab=default_tab&lang=da_DK
M3 - Ph.D. thesis
BT - Willow and poplar for bioenergy on former cropland
PB - Department of Geosciences and Natural Resource Management, Faculty of Science, University of Copenhagen
ER -