Abstract
Abstract Switchgrass ( Panicum virgatum L.) normally is lower in forage quality by the time cool‐season forage species are less productive in early summer. The objective of this study was to determine if the major supply of switchgrass herbage could be delayed by use of partial spring defoliation and still maintain adequate herbage quality. Switchgrass plots were fertilized with 0 or 120 kg N ha −1 and defoliated at six time‐intensity combinations. Yield and quality of initial spring and 6‐wk regrowth were measured. Initial 1984 spring defoliation treatments were 1 June at 15 cm; a multiple defoliation at 15, 20, and 25 cm over 1‐wk intervals beginning on 1 June; 15 June at 6 or 20 cm; and 29 June at 6 or 20 cm. All 1985 treatments were 9 d earlier. Fertilization with N increased 6‐wk regrowth dry matter (DM) yields by 79 to 92% for 1 June treatments and by only 38 to 54% for 29 June treatments. Close defoliation on 29 June produced the greatest total seasonal DM yield of 10.5 Mg ha −1 and IVDDM yield of 5.79 Mg ha −1 , but only 30% of this was harvested in midsummer after 6 wk of regrowth. Total season DM yield and IVDDM yield were about 20 to 35% less for both 1 June treatments when compared with close defoliation on 29 June, but the 6‐wk regrowth yield accounted for about 75 to 85% of total season DM and IVDDM yields. Little or no difference in leaf or stem IVDDM of the 6‐wk regrowth was observed among defoliation treatments, so partial spring defoliation can delay the major supply of switchgrass herbage with no serious reduction in herbage quality. We conclude that a short period of moderate defoliation of switchgrass in early to mid‐June could benefit grazing programs by providing (i) some very high‐quality switchgrass herbage during early to mid‐June; (ii) a brief rest and regrowth period for the cool‐season pasture; and (iii) relatively high summer yields of quality switchgrass when it is most needed.
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Claims 11
Claim · model-written summary
Nitrogen raised 6-week regrowth DM yield 79 to 92% for June 1 treatments.
- Taxon
- Switchgrass
Panicum virgatumt0 - Treatment
- Fertilization with Ne0
- Outcome
- 6‐wk regrowth dry matter (DM) yieldse0
- Direction
- increasede0
- Value
- 79 to 92%e0
- Qualifier
- for 1 June treatmentse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Fertilization with N increased 6‐wk regrowth dry matter (DM) yields by 79 to 92% for 1 June treatments and by only 38 to 54% for 29 June treatments.”
t0“Switchgrass”
Claim · model-written summary
Nitrogen raised 6-week regrowth DM yield 38 to 54% for June 29 treatments.
- Taxon
- SwitchgrassPanicum virgatumt0
- Treatment
- Fertilization with Ne0
- Outcome
- 6‐wk regrowth dry matter (DM) yieldse0
- Direction
- increasede0
- Value
- 38 to 54%e0
- Qualifier
- for 29 June treatmentse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Fertilization with N increased 6‐wk regrowth dry matter (DM) yields by 79 to 92% for 1 June treatments and by only 38 to 54% for 29 June treatments.”
t0“Switchgrass”
Claim · model-written summary
Close June 29 defoliation gave greatest seasonal DM yield, 10.5 Mg ha−1.
- Taxon
- SwitchgrassPanicum virgatumt0
- Treatment
- Close defoliation on 29 Junee0
- Outcome
- total seasonal DM yielde0
- Direction
- greateste0
- Value
- 10.5 Mg ha −1e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Close defoliation on 29 June produced the greatest total seasonal DM yield of 10.5 Mg ha −1”
t0“Switchgrass”
Claim · model-written summary
Close June 29 defoliation gave greatest IVDDM yield, 5.79 Mg ha−1.
- Taxon
- SwitchgrassPanicum virgatumt0
- Treatment
- Close defoliation on 29 Junee0
- Outcome
- IVDDM yielde0
- Direction
- greateste0
- Value
- 5.79 Mg ha −1e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Close defoliation on 29 June produced the greatest total seasonal DM yield of 10.5 Mg ha −1 and IVDDM yield of 5.79 Mg ha −1”
t0“Switchgrass”
Claim · model-written summary
Only 30% of the June 29 treatment yield was harvested in midsummer.
- Taxon
- SwitchgrassPanicum virgatumt0
- Treatment
- Close defoliation on 29 Junee1
- Outcome
- harvested in midsummere0
- Value
- 30%e0
- Qualifier
- after 6 wk of regrowthe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“but only 30% of this was harvested in midsummer after 6 wk of regrowth.”
e1“Close defoliation on 29 June”
t0“Switchgrass”
Claim · model-written summary
June 1 treatments gave 20 to 35% less total season DM yield than close June 29 defoliation.
- Taxon
- SwitchgrassPanicum virgatumt0
- Treatment
- both 1 June treatmentse0
- Outcome
- Total season DM yielde0
- Direction
- lesse0
- Value
- 20 to 35%e0
- Comparator
- close defoliation on 29 Junee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Total season DM yield and IVDDM yield were about 20 to 35% less for both 1 June treatments when compared with close defoliation on 29 June”
t0“Switchgrass”
Claim · model-written summary
June 1 treatments gave 20 to 35% less IVDDM yield than close June 29 defoliation.
- Taxon
- SwitchgrassPanicum virgatumt0
- Treatment
- both 1 June treatmentse0
- Outcome
- IVDDM yielde0
- Direction
- lesse0
- Value
- 20 to 35%e0
- Comparator
- close defoliation on 29 Junee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Total season DM yield and IVDDM yield were about 20 to 35% less for both 1 June treatments when compared with close defoliation on 29 June”
t0“Switchgrass”
Claim · model-written summary
Regrowth made up 75 to 85% of season DM and IVDDM yield for June 1 treatments.
- Taxon
- SwitchgrassPanicum virgatumt0
- Treatment
- both 1 June treatmentse1
- Outcome
- 6‐wk regrowth yielde0
- Value
- 75 to 85%e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the 6‐wk regrowth yield accounted for about 75 to 85% of total season DM and IVDDM yields.”
e1“both 1 June treatments”
t0“Switchgrass”
Claim · model-written summary
Defoliation treatments gave little or no difference in leaf or stem IVDDM.
- Taxon
- SwitchgrassPanicum virgatumt0
- Treatment
- defoliation treatmentse0
- Outcome
- leaf or stem IVDDM of the 6‐wk regrowthe0
- Direction
- Little or no differencee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Little or no difference in leaf or stem IVDDM of the 6‐wk regrowth was observed among defoliation treatments”
t0“Switchgrass”
Claim · model-written summary
Partial spring defoliation could delay major herbage supply without serious quality loss.
- Taxon
- switchgrassPanicum virgatume0
- Outcome
- partial spring defoliation can delay the major supply of switchgrass herbage with no serious reduction in herbage qualitye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“partial spring defoliation can delay the major supply of switchgrass herbage with no serious reduction in herbage quality.”
Claim · model-written summary
Moderate early to mid-June defoliation could benefit grazing programs.
- Taxon
- switchgrassPanicum virgatume0
- Outcome
- short period of moderate defoliation of switchgrass in early to mid‐June could benefit grazing programse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“a short period of moderate defoliation of switchgrass in early to mid‐June could benefit grazing programs by providing (i) some very high‐quality switchgrass herbage during early to mid‐June; (ii) a brief rest and regrowth period for the cool‐season pasture; and (iii) relatively high summer yields of quality switchgrass when it is most needed.”
The same questions in other papers
pruning · yield · Panicum virgatum (switchgrass)Positive and negative results
2 papers in the same direction as this paper · 8 in the opposite direction
- positive
- negative
- negative
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See all 11 papers →fertilization · growth · Panicum virgatum (switchgrass)Positive and negative results
9 papers in the same direction as this paper · 2 in the opposite direction
- no effect
- negative
- positive
8 papers more in this group
See all 12 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.