Abstract
In order to assess the effects of future elevated atmospheric CO 2 concentrations on yield, mineral content and the nutritive value of mixed swards of perennial ryegrass ( Lolium perenne L.) and white clover ( Trifolium repens L.), both species were grown as monocultures and as different mixtures and were exposed season‐long to ambient (380 p.p.m.) and elevated (670 p.p.m.) CO 2 concentrations in open‐top chambers. Mini‐swards were cut four times at about monthly intervals at a height of 5 cm, dry‐matter yields were determined and content of macroelements (N, P, K, S, Mg, Ca, Na) and crude fibre, crude protein and ash content were measured. The CO 2 ‐related increase in seasonal yield amounted to 16–38% for white clover monocultures, 12–29% for mixed swards and 5–9% for ryegrass monocultures. The white clover content of all swards was significantly enhanced by elevated CO 2 . The K and Na content of total yield was decreased by high CO 2 but did not fall below the minimum requirements for ruminants. As the Ca content of total yield was increased by elevated CO 2 and the P content was not changed, the Ca/P ratio of total yield was increased and exceeded values required for animal nutrition. The crude protein content of total yield was reduced by high CO 2 at the beginning of the growing season only and was increased by elevated CO 2 in the course of the experiment, whereas crude fibre content was decreased throughout the season, sometimes falling below the minimum requirement for ruminants. Removal of N, P, S, Mg and Ca by cutting was significantly enhanced because of CO 2 enrichment. The results show that, besides the positive effect of rising atmospheric CO 2 on dry‐matter yield of white clover/ryegrass swards, impacts on the nutritive value should be expected. Possible changes in species composition and implications for grassland management are briefly discussed.
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Claims 12
Claim · model-written summary
Elevated CO2 increased white clover monoculture seasonal yield by 16–38%.
- Taxon
- white clover
Trifolium repense0 - Treatment
- CO 2e0
- Outcome
- seasonal yielde0
- Direction
- increasee0
- Value
- 16–38%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The CO 2 ‐related increase in seasonal yield amounted to 16–38% for white clover monocultures”
Claim · model-written summary
Elevated CO2 increased mixed-sward seasonal yield by 12–29%.
- Taxon
- perennial ryegrass/white cloverTrifolium repens
Lolium perennet0 - Outcome
- swardse0
- Direction
- increaseinferrede0
- Value
- 12–29%e0
Not reportedTreatmentComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“12–29% for mixed swards”
t0“perennial ryegrass/white clover”
Claim · model-written summary
Elevated CO2 increased ryegrass monoculture seasonal yield by 5–9%.
LoliumNot reportedTreatmentComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“5–9% for ryegrass monocultures”
Claim · model-written summary
Elevated CO2 significantly increased the white clover share of all swards.
- Taxon
- white cloverTrifolium repense0
- Treatment
- elevated CO 2e0
- Outcome
- white clover contente0
- Direction
- enhancede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The white clover content of all swards was significantly enhanced by elevated CO 2”
Claim · model-written summary
High CO2 decreased K and Na content of total yield without falling below ruminant minima.
- Taxon
- perennial ryegrass/white cloverTrifolium repensLolium perennet0
- Treatment
- high CO 2e0
- Outcome
- K and Na content of total yielde0
- Direction
- decreasede0
- Qualifier
- did not fall below the minimum requirements for ruminantse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The K and Na content of total yield was decreased by high CO 2 but did not fall below the minimum requirements for ruminants”
t0“perennial ryegrass/white clover”
Claim · model-written summary
Elevated CO2 increased calcium content of total yield.
- Taxon
- perennial ryegrass/white cloverTrifolium repensLolium perennet0
- Treatment
- elevated CO 2e0
- Outcome
- Ca content of total yielde0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the Ca content of total yield was increased by elevated CO 2”
t0“perennial ryegrass/white clover”
Claim · model-written summary
Elevated CO2 left phosphorus content unchanged.
- Taxon
- perennial ryegrass/white cloverTrifolium repensLolium perennet0
- Outcome
- P contente0
- Direction
- not changede0
Not reportedTreatmentComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the P content was not changed”
t0“perennial ryegrass/white clover”
Claim · model-written summary
Elevated CO2 increased the Ca/P ratio beyond the level required for animal nutrition.
- Taxon
- perennial ryegrass/white cloverTrifolium repensLolium perennet0
- Outcome
- Ca/P ratio of total yielde0
- Direction
- increasede0
- Qualifier
- exceeded values required for animal nutritione0
Not reportedTreatmentComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the Ca/P ratio of total yield was increased and exceeded values required for animal nutrition”
t0“perennial ryegrass/white clover”
Claim · model-written summary
High CO2 reduced crude protein content early in the growing season.
- Taxon
- perennial ryegrass/white cloverTrifolium repensLolium perennet0
- Treatment
- high CO 2e0
- Outcome
- crude protein content of total yielde0
- Direction
- reducede0
- Qualifier
- at the beginning of the growing season onlye0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The crude protein content of total yield was reduced by high CO 2 at the beginning of the growing season only”
t0“perennial ryegrass/white clover”
Claim · model-written summary
Elevated CO2 increased crude protein content later in the experiment.
- Taxon
- perennial ryegrass/white cloverTrifolium repensLolium perennet0
- Treatment
- elevated CO 2e0
- Outcome
- crude protein contente0
- Direction
- increasede0
- Qualifier
- in the course of the experimente0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The crude protein content of total yield was reduced by high CO 2 at the beginning of the growing season only and was increased by elevated CO 2 in the course of the experiment”
t0“perennial ryegrass/white clover”
Claim · model-written summary
Elevated CO2 decreased crude fibre content throughout the season, sometimes below ruminant requirements.
- Taxon
- perennial ryegrass/white cloverTrifolium repensLolium perennet0
- Outcome
- crude fibre contente0
- Direction
- decreasede0
- Qualifier
- throughout the seasone0
Not reportedTreatmentComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“crude fibre content was decreased throughout the season, sometimes falling below the minimum requirement for ruminants”
t0“perennial ryegrass/white clover”
Claim · model-written summary
CO2 enrichment significantly enhanced removal of N, P and S by cutting.
- Taxon
- perennial ryegrass/white cloverTrifolium repensLolium perennet0
- Treatment
- CO 2 enrichmente0
- Outcome
- Removal of N, P, S, Mg and Ca by cuttinge0
- Direction
- enhancede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Removal of N, P, S, Mg and Ca by cutting was significantly enhanced because of CO 2 enrichment”
t0“perennial ryegrass/white clover”
The same questions in other papers
co2 · molecular: metabolites · Trifolium repens (white clover)Positive and negative results
1 in the opposite direction
- no effect
co2 · yield · Trifolium repens (white clover)Positive and negative results
4 papers in the same direction as this paper · 1 in the opposite direction
- positive
- no effect
- positive
2 papers more in this group
See all 6 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.