Abstract
Concerns about energy security and climate change have increased biofuel demand, particularly ethanol produced from cellulosic feedstocks (e.g., food crop residues). A central challenge to cropping for cellulosic ethanol is the potential environmental damage from increased fertilizer use. Previous analyses have assumed that cropping for carbohydrate in residue will require the same amount of fertilizer as cropping for grain. Using (13)C nuclear magnetic resonance, we show that increases in biomass in response to fertilization are not uniform across biochemical classes (carbohydrate, protein, lipid, lignin) or tissues (leaf and stem, grain, reproductive support). Although corn grain responds vigorously and nonlinearly, corn residue shows only modest increases in carbohydrate yields in response to high levels of fertilization (25% increase with 202 kg N ha(-1)). Lignin yields in the residue increased almost twice as much as carbohydrate yields in response to nitrogen, implying that residue feedstock quality declines as more fertilizer is applied. Fertilization also increases the decomposability of corn residue, implying that soil carbon sequestration becomes less efficient with increased fertilizer. Our results suggest that even when corn is grown for grain, benefits of fertilization decline rapidly after the ecosystem's N demands are met. Heavy application of fertilizer yields minimal grain benefits and almost no benefits in residue carbohydrates, while degrading the cellulosic ethanol feedstock quality and soil carbon sequestration capacity.
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Claims 7
Claim · model-written summary
Biomass responses to fertilization differed across biochemical classes and tissues.
- Taxon
- corn
Zea mays subsp. mayse1 - Treatment
- fertilizatione0
- Outcome
- increases in biomasse0
- Direction
- increasese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“increases in biomass in response to fertilization are not uniform across biochemical classes (carbohydrate, protein, lipid, lignin) or tissues (leaf and stem, grain, reproductive support)”
e1“corn grain”
Claim · model-written summary
Corn grain responded vigorously and nonlinearly to fertilization.
- Taxon
- cornZea mays subsp. mayse0
- Treatment
- fertilizatione1
- Outcome
- corn graine0
- Direction
- vigorouslye0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“corn grain responds vigorously and nonlinearly”
e1“in response to fertilization”
Claim · model-written summary
Corn residue carbohydrate yield increased 25% at 202 kg N ha(-1).
- Taxon
- cornZea mays subsp. mayse0
- Treatment
- 202 kg N ha(-1)e0
- Outcome
- carbohydrate yieldse0
- Direction
- increasese0
- Value
- 25%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“corn residue shows only modest increases in carbohydrate yields in response to high levels of fertilization (25% increase with 202 kg N ha(-1))”
Claim · model-written summary
Residue lignin yield increased almost twice as much as carbohydrate yield with nitrogen.
- Taxon
- cornZea mays subsp. mayse1
- Treatment
- nitrogene0
- Outcome
- Lignin yields in the residuee0
- Direction
- increasede0
- Value
- almost twice as muche0
- Comparator
- carbohydrate yieldse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Lignin yields in the residue increased almost twice as much as carbohydrate yields in response to nitrogen”
e1“Although corn grain responds vigorously and nonlinearly, corn residue”
Claim · model-written summary
Fertilization increased corn residue decomposability.
- Taxon
- cornZea mays subsp. mayse0
- Treatment
- Fertilizatione0
- Outcome
- decomposability of corn residuee0
- Direction
- increasese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Fertilization also increases the decomposability of corn residue”
Claim · model-written summary
Authors conclude fertilization benefits decline after ecosystem nitrogen demand is met.
- Taxon
- cornZea mays subsp. mayse1
- Outcome
- benefits of fertilization decline rapidlye0
- Qualifier
- after the ecosystem's N demands are mete0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“benefits of fertilization decline rapidly after the ecosystem's N demands are met”
e1“corn is grown for grain”
Claim · model-written summary
Heavy fertilizer gives minimal grain benefit and almost no residue carbohydrate benefit while degrading feedstock quality and soil carbon capacity.
- Taxon
- cornZea mays subsp. mayse1
- Outcome
- minimal grain benefits and almost no benefits in residue carbohydratese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Heavy application of fertilizer yields minimal grain benefits and almost no benefits in residue carbohydrates, while degrading the cellulosic ethanol feedstock quality and soil carbon sequestration capacity”
e1“even when corn is grown for grain”
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See all 2,185 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.