Abstract
Biomass yield is an important factor when recommending native perennial plants and mixtures for bioenergy production. Our objective was to determine long‐term biomass yields in fertilized and unfertilized native plant monocultures and mixtures that show promise for bioenergy across diverse environments in the Upper Midwest. We measured biomass yields, species composition, and diversity annually in monocultures and mixtures ranging from 4 to 24 planted species including grasses, legumes, and other forbs; each managed with and without 67 kg N ha −1 fertilizer applied annually at nine locations for 7 yr. Without N fertilization, switchgrass ( Panicum virgatum L.) monocultures and an eight‐species mixture of grasses and legumes produced the most biomass over locations and years (5.1 Mg ha −1 ). With N fertilizer, switchgrass monocultures and a four‐species mixture of grasses produced the highest yields (6.8 and 6.4 Mg ha −1 ). Over time, biomass yields increased for switchgrass, decreased for Canada wild rye ( Elymus canadensis L.), and remained stable for the high diversity mixtures. Other mixtures had nonlinear changes in yield, likely related to changes in species composition. Although the relative abundance of individual species changed over time, Shannon diversity was constant except for the four‐species legume mixture where it decreased. Contrary to other studies, N fertilization did not decrease species diversity through time. Diversity was positively related to biomass yield following establishment, but the strength of the relationship diminished with stand age. Native plant mixtures managed with and without N fertilizer can yield similar biomass compared with highly productive monocultures in the Upper Midwest.
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Claims 15
Claim · model-written summary
Without N, switchgrass monocultures had among the highest biomass yields, 5.1 Mg ha −1.
- Taxon
- Panicum virgatum L.
Panicum virgatume0 - Treatment
- Without N fertilizatione0
- Outcome
- most biomasse0
- Value
- 5.1 Mg ha −1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Without N fertilization, switchgrass ( Panicum virgatum L.) monocultures and an eight‐species mixture of grasses and legumes produced the most biomass over locations and years (5.1 Mg ha −1 )”
Claim · model-written summary
Without N, the eight-species mixture had among the highest biomass yields, 5.1 Mg ha −1.
Not reportedTaxon
Verbatim
e0“Without N fertilization, switchgrass ( Panicum virgatum L.) monocultures and an eight‐species mixture of grasses and legumes produced the most biomass over locations and years (5.1 Mg ha −1 )”
Claim · model-written summary
With N, switchgrass monocultures yielded 6.8 Mg ha −1.
- Taxon
- switchgrassPanicum virgatume0
- Treatment
- N fertilizere0
- Outcome
- highest yieldse0
- Direction
- higheste0
- Value
- 6.8e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“With N fertilizer, switchgrass monocultures and a four‐species mixture of grasses produced the highest yields (6.8 and 6.4 Mg ha −1 )”
Claim · model-written summary
With N, four-species grass mixtures yielded 6.4 Mg ha −1.
- Material
- four‐species mixture of grassese0
- Treatment
- N fertilizere0
- Outcome
- highest yieldse0
- Direction
- higheste0
- Value
- 6.4 Mg ha −1e0
Not reportedTaxonComparator
Verbatim
e0“With N fertilizer, switchgrass monocultures and a four‐species mixture of grasses produced the highest yields (6.8 and 6.4 Mg ha −1 )”
Claim · model-written summary
Switchgrass biomass yield increased over time.
- Taxon
- switchgrassPanicum virgatume0
- Outcome
- biomass yieldse0
- Direction
- increasede0
- Setting
- Over timee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Over time, biomass yields increased for switchgrass”
Claim · model-written summary
Canada wild rye biomass yield decreased over time.
- Taxon
- Canada wild rye
Elymus canadensise0 - Outcome
- biomass yieldse1
- Direction
- decreasede0
- Qualifier
- Elymus canadensis L.e0
Not reportedSetting
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“decreased for Canada wild rye ( Elymus canadensis L.)”
e1“Over time, biomass yields increased for switchgrass”
Claim · model-written summary
High diversity mixtures maintained stable biomass yield over time.
Not reportedTaxon
Verbatim
e0“remained stable for the high diversity mixtures”
e1“Over time, biomass yields increased for switchgrass”
Claim · model-written summary
Other mixtures showed nonlinear yield changes, possibly linked to species composition changes.
Not reportedTaxonDirection
Verbatim
e0“Other mixtures had nonlinear changes in yield, likely related to changes in species composition.”
Claim · model-written summary
Individual species relative abundance changed over time.
- Outcome
- relative abundance of individual speciese0
Not reportedTaxon
Verbatim
e0“the relative abundance of individual species changed over time”
Claim · model-written summary
Shannon diversity was constant except in the four-species legume mixture.
Not reportedTaxon
Verbatim
e0“Shannon diversity was constant except for the four‐species legume mixture where it decreased”
Claim · model-written summary
Shannon diversity decreased in the four-species legume mixture.
Not reportedTaxon
Verbatim
e0“four‐species legume mixture where it decreased”
e1“Shannon diversity was constant except for the four‐species legume mixture where it decreased”
Claim · model-written summary
N fertilization did not decrease species diversity over time.
Not reportedTaxonComparator
Verbatim
e0“N fertilization did not decrease species diversity through time.”
Claim · model-written summary
Diversity was positively associated with biomass yield after establishment.
Not reportedTaxonMaterial
Verbatim
e0“Diversity was positively related to biomass yield following establishment”
Claim · model-written summary
The diversity–yield association weakened with stand age.
Not reportedTaxon
Verbatim
e0“the strength of the relationship diminished with stand age”
Claim · model-written summary
Native plant mixtures with or without N yielded similarly to highly productive monocultures.
Verbatim
e0“Native plant mixtures managed with and without N fertilizer can yield similar biomass compared with highly productive monocultures in the Upper Midwest.”
The same questions in other papers
fertilization · yield · Panicum virgatum (switchgrass)Results differ
29 papers in the same direction as this paper · 6 in the opposite direction
- no effect
- no effect
- no effect
32 papers more in this group
See all 36 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.