Abstract
Abstract Switchgrass ( Panicum virgatum L.) has a relatively high N requirement for high yields of quality forage. It is not clear what role legumes can play in supplying this N and in improving herbage yield when grown in association with switchgrass. To evaluate cool‐season legume renovation vs. N fertilization of established switchgrass, 10 forage legumes and a legume mixture were compared with 0, 60, 120, and 240 kg N ha −1 . Forage yield and botanical composition of basal (<20 cm) and upper (>20 cm) canopy were compared at Ames, IA, on a Webster silty clay loam (mesic Typic Haplaquoll). Legumes were no‐till interseeded in early April; N was applied before mid‐May. Legume renovation did not affect June yield during the establishment year (Yl), but produced 9% greater yields than 0‐N grass in July. N fertilization increased uppercanopy grass yield 2.4‐fold compared with 0 N and legume renovation during Yl. During the second year (Y2) of 1991 seedings, all legume treatments except crownvetch ( Coronilla varia L.) produced more totalseason upper‐canopy yield than grass fertilized with 240 kg N. For 1992 seedings, birdsfoot trefoil ( Lotus corniculatus L.), Mammoth red clover ( Trifolium pratense L.), and trefoil‐red clover mixture had Y2 yields that equaled or exceeded yield for 240 kg N. Mean legume composition of Y2 upper canopy for June, July, and August was 84, 70, and 51%, respectively, in 1991 seedings and 53, 28, and 27% in weather‐damaged stands of 1992 seedings. Y2 yields for interseeded legumes provided significant improvement over 120 or 240 kg ha −1 N, so cool‐season legumes can substitute for N fertilization after the seeding year. Adequate defoliation in early June is important to minimize legume competition to established switchgrass. Livestock producers should renovate only a portion of switchgrass pastures in a single year, because of a shortfall in forage supply during legume establishment compared with that of N‐fertilized grass.
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Claims 9
Claim · model-written summary
Legume renovation did not affect June yield in the establishment year.
- Taxon
- Switchgrass
Panicum virgatumt0 - Organ / stage
- establishment yeare0
- Treatment
- Legume renovatione0
- Outcome
- June yielde0
- Direction
- did not affecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Legume renovation did not affect June yield during the establishment year (Yl)”
t0“Switchgrass”
Claim · model-written summary
Legume renovation yielded 9% more than unfertilized grass in July.
Not reportedTreatment
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“produced 9% greater yields than 0‐N grass in July”
t0“Switchgrass”
Claim · model-written summary
Nitrogen fertilization raised upper-canopy grass yield 2.4-fold.
- Taxon
- SwitchgrassPanicum virgatumt0
- Treatment
- N fertilizatione0
- Outcome
- uppercanopy grass yielde0
- Direction
- increasede0
- Value
- 2.4‐folde0
- Comparator
- 0 N and legume renovatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“N fertilization increased uppercanopy grass yield 2.4‐fold compared with 0 N and legume renovation during Yl”
t0“Switchgrass”
Claim · model-written summary
Most legume treatments exceeded the 240 kg N treatment for second-year upper-canopy yield.
- Taxon
- SwitchgrassPanicum virgatumt0
- Treatment
- all legume treatments except crownvetche0
- Outcome
- totalseason upper‐canopy yielde0
- Direction
- moree0
- Comparator
- grass fertilized with 240 kg Ne0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“all legume treatments except crownvetch ( Coronilla varia L.) produced more totalseason upper‐canopy yield than grass fertilized with 240 kg N”
t0“Switchgrass”
Claim · model-written summary
Second-year yields of birdsfoot trefoil equaled or exceeded 240 kg N.
- Taxon
- SwitchgrassPanicum virgatumt0
- Treatment
- birdsfoot trefoile0
- Outcome
- Y2 yieldse0
- Direction
- equaled or exceedede0
- Comparator
- 240 kg Ne0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“birdsfoot trefoil ( Lotus corniculatus L.), Mammoth red clover ( Trifolium pratense L.), and trefoil‐red clover mixture had Y2 yields that equaled or exceeded yield for 240 kg N”
t0“Switchgrass”
Claim · model-written summary
Second-year yields of Mammoth red clover equaled or exceeded 240 kg N.
- Taxon
- SwitchgrassPanicum virgatumt0
- Treatment
- Mammoth red clovere0
- Outcome
- Y2 yieldse0
- Direction
- equaled or exceedede0
- Comparator
- 240 kg Ne0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Mammoth red clover ( Trifolium pratense L.), and trefoil‐red clover mixture had Y2 yields that equaled or exceeded yield for 240 kg N”
t0“Switchgrass”
Claim · model-written summary
Second-year yields of the trefoil and red clover mixture equaled or exceeded 240 kg N.
- Taxon
- SwitchgrassPanicum virgatumt0
- Treatment
- trefoil‐red clover mixturee0
- Outcome
- Y2 yieldse0
- Direction
- equaled or exceedede0
- Comparator
- 240 kg Ne0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“trefoil‐red clover mixture had Y2 yields that equaled or exceeded yield for 240 kg N”
t0“Switchgrass”
Claim · model-written summary
Legume share of the second-year upper canopy declined across summer.
- Taxon
- SwitchgrassPanicum virgatumt0
- Outcome
- Mean legume compositione0
- Value
- 84, 70, and 51%e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Mean legume composition of Y2 upper canopy for June, July, and August was 84, 70, and 51%, respectively, in 1991 seedings and 53, 28, and 27% in weather‐damaged stands of 1992 seedings”
t0“Switchgrass”
Claim · model-written summary
Second-year interseeded-legume yields significantly improved on nitrogen fertilization.
- Taxon
- SwitchgrassPanicum virgatumt0
- Treatment
- interseeded legumese0
- Outcome
- Y2 yieldse0
- Direction
- improvemente0
- Comparator
- 120 or 240 kg ha −1 Ne0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Y2 yields for interseeded legumes provided significant improvement over 120 or 240 kg ha −1 N”
t0“Switchgrass”
The same questions in other papers
Trifolium pratense · yield · Panicum virgatum (switchgrass)Positive and negative results
2 reporting no difference from an alternative
- no effect
- no effect
fertilization · yield · Panicum virgatum (switchgrass)Results differ
29 papers in the same direction as this paper · 6 in the opposite direction
- positive
- 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.