Institute of Crop Science (340)
Department of Biobased Products and Energy Crops 340b)
Supervisor: Prof. Dr. Iris Lewandowski
How can miscanthus be integrated most
efficiently into agricultural production
systems?
Dissertation
In fulfilment of the requirements for the degree
Doctor scientiarum agriculturae (Dr. sc. agr.)
submitted to the
Faculty of Agricultural Sciences
by Anja Mangold
Date of the acceptance of the dissertation: 26.07.2019
Date of oral exam: 09.10.2019
Dean Faculty of Agricultural Science
Prof. Dr. Ralf T. Vögele
Thesis Committee
Supervisor
Prof. Dr. Iris Lewandowski
University of Hohenheim, Germany
Co-Supervisors
Prof. Dr. Ralf Pude
University of Bonn, Germany
Prof. Dr. Uwe Ludewig
University of Hohenheim, Germany
I | Anja Mangold
Content
List of Acronyms ...................................................................................................................... III
Abstract ...................................................................................................................................... 1
Zusammenfassung ...................................................................................................................... 3
1 General introduction ................................................................................................................ 6
1.1 Perennial biomass crops for a growing bioeconomy ........................................................ 6
1.2 Inefficiencies in miscanthus cultivation ........................................................................... 8
1.3 Aim of the study ............................................................................................................. 14
1.4 Publications .................................................................................................................... 16
1.5 References ...................................................................................................................... 18
2 Novel establishment way for miscanthus .............................................................................. 23
3 Reintegration of miscanthus fields into a crop rotation ........................................................ 38
4 Miscanthus for biogas production: The effect of genotype, harvest date and ensiling on
digestibility and methane hectare yield of miscanthus ............................................................. 53
4.1 Harvest date and leaf:stem ratio determine methane hectare yield of miscanthus biomass
.............................................................................................................................................. 53
4.2 Miscanthus for biogas production: Influence of harvest date and ensiling on digestibility
and methane hectare yield .................................................................................................... 68
5 General Discussion ................................................................................................................ 84
5.1 Efficiency of miscanthus cultivation .............................................................................. 84
Nutrient-use and environmental efficiency ....................................................................... 85
Land-use efficiency ........................................................................................................... 88
5.2 Integration of miscanthus into agricultural production systems ..................................... 92
Miscanthus utilization pathways ....................................................................................... 92
Possible land types to cultivate miscanthus on ................................................................. 96
Integrating miscanthus into the farm operation procedures .............................................. 98
Environmental services of miscanthus .............................................................................. 98
5.3 Conclusion .................................................................................................................... 100
5.4 References .................................................................................................................... 102
6 Danksagung ......................................................................................................................... 109
7 Curriculum Vitae ................................................................................................................. 111
II | Anja Mangold
III | Anja Mangold
List of Acronyms
A annum (Latin = year)
ADF acid detergent fibre
ADL acid detergent lignin
a.s.l. above sea level
C collar
C carbon
C:N ratio carbon : nitrogen ratio
CH4 methane
Cm centimetre
cm3 cubic centimetre
D depth
DM dry matter
DMC dry matter content
DMCsilage dry matter content of silage
DMY dry matter yield
EMI European Miscanthus Improvement
e.g. exempli gratia (Latin = for example)
FIA flow injection analyser
FM fresh matter
G gram
HD harvest date
GC gas chromatograph
GWel gigawatt electric
IV | Anja Mangold
Ha hectare
hPa hecto Pascal
H hour
HPLC high performance liquid chromatography
i.e. id est (Latin = that is)
K Potassium
Kg kilogramme
LAZBW Landwirtschaftliches Zentrum Baden-Württemberg
LTZ Landwirtschaftliches Technologiezentrum Augustenberg
M metre
m² square metre
m³ cubic metre
Mm millimetre
Mxg Miscanthus × giganteus
MSac Miscanthus sacchariflorus
MSin Miscanthus sinensis
MY methane hectare yield
N nitrogen
NDF neutral detergent fibre
(N)m³ (norm) cubic metre
(N)ml (norm) millilitre
Nmin soil mineral nitrogen
No number
N2O Nitrous oxide
V | Anja Mangold
NO3- nitrate
Ns non significant
oDM organic dry matter
OPM Optimisc (Optimizing Miscanthus Biomass Production)
P Phosphorus
R rhizome
Rpm rounds per minute
R+C rhizome + collar
SMY substrate-specific methane yield
T ton
VDLUFA Association of German Agricultural Analytic and Research Institutes
1 | Anja Mangold
Abstract
Abstract
The demand for biomass is increasing steadily, as fossil resources are gradually being replaced
by biomass within the context of a developing bioeconomy. Plant-based feedstocks currently
used for this replacement virtually all come from annual crops. However, perennial crops such
as miscanthus are expected to be more environmentally benign due to their generally low-input
requirements and high yield potential.
Despite these advantages, the current cultivation area of miscanthus in Europe is quite low. One
reason for this is that the cultivation and utilization of miscanthus faces several challenges. For
example, the most common propagation method via rhizomes is very labour-intensive and thus
expensive, leading to high establishment costs. Seed propagation is a promising option to
reduce costs, but is not suitable for sterile genotypes. Another challenge to be overcome is the
problem of re-integrating former miscanthus fields into crop rotations. The crop following
miscanthus needs to be highly competitive in order not to be impaired by resprouting
miscanthus shoots and thus able to achieve high yields. Additionally, there is only little
information available on the effect of miscanthus cultivation and its subsequent removal on soil
N content. This information is however crucial, for example to avoid environmental problems
being caused by a potential nitrogen leaching after a miscanthus removal. If miscanthus is to be
utilized as a biogas substrate, there are further challenges to be overcome. Firstly, the optimal
harvest date needs to be defined with regard to the methane hectare yield and resilience of the
crop to green cutting. Secondly, as a continuous supply of biomass throughout the year is
necessary, ensiling will become a relevant topic. However, information is still required on the
optimal harvest date to achieve a sufficient silage quality and the effects of ensiling on methane
hectare yield. Finally, the suitability of miscanthus for biogas production is also influenced by
biomass quality such as the proportions of leaf and stem. This has already been established for
miscanthus utilization in combustion but has not yet been sufficiently investigated for anaerobic
digestion.
In summary, there are a number of uncertainties involved in miscanthus establishment, removal
and utilization, which currently hamper its integration into agricultural production systems.
From a bioeconomic point of view,
