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Multispecies grassland for crop productivity and carbon storage
Jørgen Eriksen, Tine Bloch Søe, Karen Søegaard Department of Agroecology
Aarhus University
Potential benefits of multispecies grasslands
• Yield • Feed quality • Appetite • Animal health • Mineral availability • Conditions for pollinators • Carbon storage • Product quality • Marketing
Experimental
Objective Inclusion of herb mixture in grass-clover leys Hypotheses 1. Increased persistence of swards 2. Increased potential for carbon storage through
increased and deeper root growth
Seed mixtures 100% herbs Salad burnet, fenugreek, chicory, caraway, birdsfoot trefoil,
chervil, lucerne, melilot and English plantain
50% herbs 50% herb mixture + 50% grass-clover mixture
5% herbs 5% herb mixture + 95% grass-clover mixture
Cutting frequency 4 vs. 6 cuts per growing season
Slurry application 0 vs. 200 kg total N ha-1
Experimental
1. Harvest yield and botanical composition in three years
2. Root biomass
3. Simulated ploughing (CO2 evolution over 226 days)
Experimental
Year
1 2 3
Yiel
d (t
ha-1
)
0
5
10
15
Year
1 2 3Yi
eld
(t ha
-1)
0
5
10
15
5% herbs 50% herbs 100% herbs
Unfertilized Fertilized
Aboveground biomass 4 cuts per year
Year
1 2 3Yi
eld
(t ha
-1)
0
5
10
15
Year
1 2 3
Yiel
d (t
ha-1
)
0
5
10
15
5% herbs 50% herbs 100% herbs
Unfertilized Fertilized
Aboveground biomass 6 cuts per year
Competitiveness of species
Herbs in mixture 5% 50% 100%
Dominant Perennial ryegrass 42 29 White clover 53 31 Lucerne 1.0 20 42 Chicory 2 10 19 Caraway 0.7 3 13
Intermediate English plantain 1.1 5 8 Birdsfoot trefoil 0.1 0.9 7 Salad burnet 0.1 0.5 3
Weak Melilot 0 0.2 0.7 Chervil 0 0 0 Fenugreek 0 0 0
Chicory (Chicorium intybus L.)
05
10152025
1-yr 2-yr 3-yr
Prop
ortio
n of
DM
Chicory
Caraway (Carum carvi L.)
05
1015202530
May Aug May Aug May Aug
1-yr 2-yr 3-yr
Prop
ortio
n of
DM Caraway
5% 50%100%5% 50%100%5% 50%100%Salad BurnetChicoryCarawayLucernePlantain
t DM
ha-1
0
1
2
3
4
5
5% 50%100%5% 50%100%5% 50%100%Salad BurnetChicoryCarawayLucernePlantain
0
1
2
3
4
5Small roots (<8 mm) Large roots (>8 mm)
4-cut200N
6-cut0N
4-cut0N
4-cut200N
6-cut0N
4-cut0N
0-10 cm10-20 cm20-50 cm
Belowground biomass
5% 50%100%5% 50%100%5% 50%100%Salad BurnetChicoryCarawayLucernePlantain
mg
CO
2-C
kg-1
soi
l
0
500
1000
1500
2000
4-cut200N
6-cut0N
4-cut0N
CO2 evolution following ”ploughing”
0.5 1.0 1.5 2.0
Root biomass (t/ha)
0.0 0.2 0.4 0.6
mg
CO
2-C
kg-1
soi
l
0
200
400
600
800
1000
12000-10 cm10-20 cm
Small roots Large roots
CO2 evolution following ”ploughing”
Multispecies mixtures • Increases yield stability (management dependent) • Potential to increase belowground biomass and C
storage • Dependency on few driver species
Conclusions
Multi-functionality
• Dairy farming systems: Productivity, C storage, pollinators, product quality, marketing
• Stockless organic farming: Low input – high yield perennial crops for bioenergy, protein or
quality feed. Weed control, nutrient input, sales products
Perspectives
Thanks for your attention!