Gras as a green resource : inventory of grass residues in Flanders

IEE/12/046/SI2.645700
Gras as a green resource : inventory of
grass residues in Flanders
Alain De Vocht
University college PXL
2013 - 2016
Hogeschool PXL – Elfde-Liniestraat 24 – B-3500 Hasselt
www.pxl.be - www.pxl.be/facebook
04/07/2014
DISCLAIMER
The sole responsibility for the content of this publication lies with the authors. It does
not necessarily reflect the opinion of the European Union. Neither the EACI nor the
European Commission are responsible for any use that may be made of the
information contained therein.
Outline
• Targets
• Vegetation types, area and yield mowed grass
residue
• Chemical composition grass residue
• Biogas yield
• Conclusions
Targets
•
•
•
•
List of stakeholders
Area mowed grass residues
Quantity per type
Composition (hemicellulosis, cellulosis, lignin,
fat, protein)
• Mapping grass residues availability
• Biogas yield and impact of conditions
VEGETATION TYPES, AREA AND
YIELD
Grassland (nature conservation)
roadsides
• 11 types of common grassland: hk, hr, hx, hf,
hp, hp*, hc, hu, hj, ha and mr
• 8 types of common roadside: 6, 14, 19, 20, 21,
25, 27 en 34
• On sand-, loam- and clay soils
type 14: meadow buttercup – red clover
scherpe boterbloem
rode klaver
Nachtegalenstraat Zonhoven, 10/05/2011
type 20: spotted medick – Colsfoot
klein hoefblad
gevlekte rupsklaver
E313 Bilzen, 11/05/2011
type 34: Common cat’s-ear – Sheep’s sorrel
gewoon biggenkruid
schapenzuring
Plant inventarisation and sampling
• 18 grasslands (ANB, Natuurpunt), 16
roadside (gemeentelijk, AWV) : PQ,
full (Tansley)
• Before mowing, mostly mowed 2/y
(start and end summer)
• Plantsociological typology (Schaminée)
andSynBioSys (Alterra, Wageningen)
Bent grassland (ha)
Oudsberg 302, Meeuwen-Gruitrode, 12/08/2010
Chalk grassland (hk)
Veursvallei Voeren, 09/05/2011
Wet grassland with meadowsweet
Area and quantity
• Based on real figures and assessments (based
on surface)
• Flanders: 66.369,42 ton DM/y (30.728,97 ha)
• Belgium 128.000 ton DM/y
Flanders
Municipal roadsides
bermmaaisel
0 - 137.55
137.55 - 457.82
457.82 - 960.16
960.16 - 2070.35
2070.35 - 5751.92
10
0
10
20
30
40 Kilometers
Municipal roadsides
2009
2010
Motorways
CHEMICAL COMPOSITION
Composition grass residues
Dry matter
Lignin
Difference first and second mowing
Composition and soil type
Ensilage
• Micro-ensilage
• 4,4 ≤ pH ≤ 6
• Gem. pH 4,97
Silage and pH
BIOGAS YIELD
Biogas
• BGP: 274,2 lN/kg oDM
• CH4: 59 %
vCH4/fresh weight
Methane volume
• i.f.o. Date mowing (month), time after last
mowing (months) en number of mowing a
year
National estimations based on 5
European regions
•
•
•
•
Belgium: 128.000 ton dm
Denmark: 1.024. 714 ton dm
Italy: 1.104.655 ton dm
Germany: 2.975.081 ton dm
Identifying of productive
regions
Data quality assessment
Manager
ANB Limburg
ANB Antwerpen
ANB Vlaams-Brabant
ANB Oost-Vlaanderen
ANB West-Vlaanderen
Natuurpunt
Other private nature org.
Airports
Harbours
Golf courses
Erosion prev. Limburg
Erosion prev.Vlaams-Brabant
Erosion prev.Oost-Vlaanderen
Erosion prev. West-Vlaanderen
Total
Grasslands
Area (ha)
340,63
315,69
520,22
61,49
408,36
2.529,06
191,68
759,68
497,24
763,25
281,02
438,24
73,79
48,62
7.228,97
Residue (ton
dm/year)
1.286,68
1.157,67
1.599,22
239,67
1.591,56
7.974,55
662,17
3.188,73
751,0
3.053,00
1.686,13
2.629,44
442,75
291,72
26.554,29
Conclusions
• ± 250.000 ton mowed yearly (fresh)
• Despite diff. vegetation types small diff. in
chem. composition
• Realistic quantities
• In the season higher cellulosis, lignin and
protein.
• hemicellulosis and fat decrease
Conclusions
• Difference do not result in sign. differences in
methane volume.
• BGP: 274,2 lN/kg oDM
• BMP: 59 % of gem. 161,5 lN/kg oDM
• 59,5 Nm3/ton VG
Conclusions
• Variability is low
– No effect of soil type, type of grassland, plant
species
– Higher lignin content -> less biogas
Met dank aan Ramon Pasmans, Anja Delief, Jan Cielen,
Katrien Achten, Sarah Descamps, Raf Dewil en vele
informatieverstrekkers en instanties
FINANCIERING LNE, PXL, EFRO, IEE

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