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!