Abstract
Switchgrass ( Panicum virgatum L.) was identified as a “model” bioenergy crop by the USDOE in 1991. Since then, there has been little research to understand changes in switchgrass quality during the growing season or the effect that drought may have on these quality characteristics. This study determined changes in total N, P, K, S, Ca, Mg, moisture concentration, and dry weight yield through intensive sampling during the growing season. Subsamples from a one‐cut system were harvested on 13 different dates in 2011 and eight different dates in 2012 between late May and early November. Low rainfall in late spring and early summer 2012 created drought conditions that led to some differences between years. In general, the measured variables decreased with time, but dry weight yield increased in both years and peaked around late August. In 2011, a significant rise in N between late July and mid‐August may have been caused by reproductive growth and/or organic matter mineralization, although this has not been documented elsewhere. Differences between normal (2011) and drought (2012) conditions included lower biomass production, reduced N concentrations, increased S and P concentrations in late August, and increased plant moisture in late August and October under drought conditions. Years with drought conditions may allow more staggered harvesting because nutrient ranges are smaller. This will allow a more continuous supply of feedstock to the biorefinery. These data and future economic analyses will allow better decision‐making opportunities for producers.
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Claims 8
Claim · model-written summary
Most measured switchgrass nutrient and moisture variables declined during the growing season.
- Taxon
- Switchgrass
Panicum virgatumt0 - Outcome
- measured variablese0
- Direction
- decreasede0
Not reportedSetting
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In general, the measured variables decreased with time”
t0“Changes in Nutrient Characteristics of Switchgrass for Bioenergy”
Claim · model-written summary
Switchgrass dry weight yield rose through late August in both years.
- Taxon
- SwitchgrassPanicum virgatumt0
- Outcome
- dry weight yielde0
- Direction
- increasede0
- Qualifier
- both years and peaked around late Auguste0
Not reportedOrgan / stage
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“dry weight yield increased in both years and peaked around late August.”
t0“Changes in Nutrient Characteristics of Switchgrass for Bioenergy”
Claim · model-written summary
Nitrogen rose significantly from late July to mid August 2011.
- Taxon
- SwitchgrassPanicum virgatumt0
- Outcome
- Ne0
- Direction
- risee0
Not reportedSetting
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In 2011, a significant rise in N between late July and mid‐August”
t0“Changes in Nutrient Characteristics of Switchgrass for Bioenergy”
Claim · model-written summary
Drought reduced biomass production relative to normal conditions.
- Taxon
- SwitchgrassPanicum virgatumt0
- Treatment
- drought (2012)e0
- Outcome
- biomass productione0
- Direction
- lowere0
- Comparator
- normal (2011)e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Differences between normal (2011) and drought (2012) conditions included lower biomass production”
t0“Changes in Nutrient Characteristics of Switchgrass for Bioenergy”
Claim · model-written summary
Drought reduced switchgrass nitrogen concentration.
- Taxon
- SwitchgrassPanicum virgatumt0
- Treatment
- drought (2012)e0
- Outcome
- N concentrationse0
- Direction
- reducede0
- Comparator
- normal (2011)e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Differences between normal (2011) and drought (2012) conditions included lower biomass production, reduced N concentrations”
t0“Changes in Nutrient Characteristics of Switchgrass for Bioenergy”
Claim · model-written summary
Drought raised sulfur and phosphorus concentrations in late August.
- Taxon
- SwitchgrassPanicum virgatumt0
- Outcome
- S and P concentrationse0
- Direction
- increasede0
- Qualifier
- late Auguste0
Not reportedSetting
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“increased S and P concentrations in late August”
t0“Changes in Nutrient Characteristics of Switchgrass for Bioenergy”
Claim · model-written summary
Drought raised plant moisture in late August and October.
- Taxon
- SwitchgrassPanicum virgatumt0
- Treatment
- drought conditionse0
- Outcome
- plant moisturee0
- Direction
- increasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“increased plant moisture in late August and October under drought conditions.”
t0“Changes in Nutrient Characteristics of Switchgrass for Bioenergy”
Claim · model-written summary
Drought years may permit more staggered harvesting because nutrient ranges are narrower.
- Taxon
- SwitchgrassPanicum virgatumt0
- Outcome
- more staggered harvestinge0
- Qualifier
- nutrient ranges are smallere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Years with drought conditions may allow more staggered harvesting because nutrient ranges are smaller.”
t0“Changes in Nutrient Characteristics of Switchgrass for Bioenergy”
The same questions in other papers
drought · yield · Panicum virgatum (switchgrass)Results differ
3 papers in the same direction as this paper · 1 in the opposite direction
- positive
- negative
- negative
1 paper more in this group
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