Abstract
Increased seed cost of glyphosate tolerant (GT) compared to non‐GT alfalfa ( Medicago sativa L.) raises questions about reducing seeding rates. The objective of this study was to determine if alfalfa stand density, yield, and forage quality are compromised in the later years of the stand when reduced seeding rates, in combination with glyphosate application, were used during establishment. At seven locations in the United States, GT alfalfa was seeded into conventionally tilled seedbeds at 6.7, 11.2, 15.7, and 20.2 kg ha −1 pure live seed (PLS) in the spring of 2006. Stand density, yield, and forage quality were determined for each seeding rate under three herbicide treatments: (i) glyphosate [N‐(phosphonomethyl)glycine], (ii) non‐glyphosate herbicide, and (iii) no herbicide. For the third through fifth years of the alfalfa stand, there was no herbicide treatment × seeding rate interaction. Higher seeding rates resulted in higher plant densities. The 11.2 and 15.7 kg ha −1 seeding rates had greater alfalfa and total forage (alfalfa + weeds) yields than the 6.7 kg ha −1 seeding rate. Herbicide treatments had no effect on alfalfa plant density but produced cumulative (over the duration of the study) alfalfa yield in the following order: glyphosate > non‐glyphosate > no herbicide. Cumulative total forage yield was less when no herbicide was used compared to using a herbicide. While forage fiber content was generally unaffected by seeding rate or herbicide treatments, using glyphosate to control weeds during alfalfa establishment increased forage crude protein content of older alfalfa stands compared to no weed control.
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Claims 11
Claim · model-written summary
No herbicide treatment by seeding rate interaction was reported in the third through fifth stand years.
- Taxon
- alfalfa
Medicago sativae0 - Treatment
- herbicide treatment × seeding ratee0
- Outcome
- interactione0
- Direction
- noe0
- Qualifier
- third through fifth yearse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“For the third through fifth years of the alfalfa stand, there was no herbicide treatment × seeding rate interaction.”
Claim · model-written summary
Higher seeding rates produced higher alfalfa plant densities.
- Taxon
- AlfalfaMedicago sativat0
- Treatment
- Higher seeding ratese0
- Outcome
- plant densitiese0
- Direction
- highere0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Higher seeding rates resulted in higher plant densities.”
t0“Alfalfa”
Claim · model-written summary
The 11.2 kg ha −1 seeding rate yielded more alfalfa and total forage than 6.7 kg ha −1.
- Taxon
- alfalfaMedicago sativae0
- Treatment
- 11.2e0
- Outcome
- alfalfa and total forage (alfalfa + weeds) yieldse0
- Direction
- greatere0
- Comparator
- 6.7 kg ha −1 seeding ratee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The 11.2 and 15.7 kg ha −1 seeding rates had greater alfalfa and total forage (alfalfa + weeds) yields than the 6.7 kg ha −1 seeding rate.”
Claim · model-written summary
The 15.7 kg ha −1 seeding rate yielded more alfalfa and total forage than 6.7 kg ha −1.
- Taxon
- alfalfaMedicago sativae0
- Treatment
- 15.7 kg ha −1e0
- Outcome
- alfalfa and total forage (alfalfa + weeds) yieldse0
- Direction
- greatere0
- Comparator
- 6.7 kg ha −1 seeding ratee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The 11.2 and 15.7 kg ha −1 seeding rates had greater alfalfa and total forage (alfalfa + weeds) yields than the 6.7 kg ha −1 seeding rate.”
Claim · model-written summary
Herbicide treatments had no effect on alfalfa plant density.
- Taxon
- alfalfaMedicago sativae0
- Treatment
- Herbicide treatmentse0
- Outcome
- alfalfa plant densitye0
- Direction
- no effecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Herbicide treatments had no effect on alfalfa plant density”
Claim · model-written summary
Cumulative alfalfa yield was greater with glyphosate than with non-glyphosate herbicide.
- Taxon
- alfalfaMedicago sativae0
- Treatment
- glyphosatee0
- Outcome
- alfalfa yielde0
- Qualifier
- over the duration of the studye0
- Comparator
- non‐glyphosatee0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“produced cumulative (over the duration of the study) alfalfa yield in the following order: glyphosate > non‐glyphosate > no herbicide”
Claim · model-written summary
Cumulative alfalfa yield was greater with non-glyphosate herbicide than with no herbicide.
- Taxon
- alfalfaMedicago sativae0
- Treatment
- non‐glyphosatee0
- Outcome
- alfalfa yielde0
- Qualifier
- over the duration of the studye0
- Comparator
- no herbicidee0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“produced cumulative (over the duration of the study) alfalfa yield in the following order: glyphosate > non‐glyphosate > no herbicide”
Claim · model-written summary
Cumulative total forage yield was lower without herbicide than with herbicide.
- Taxon
- AlfalfaMedicago sativat0
- Treatment
- no herbicidee0
- Outcome
- Cumulative total forage yielde0
- Direction
- lesse0
- Comparator
- using a herbicidee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Cumulative total forage yield was less when no herbicide was used compared to using a herbicide.”
t0“Alfalfa”
Claim · model-written summary
Forage fiber content was generally unaffected by seeding rate.
- Taxon
- AlfalfaMedicago sativat0
- Treatment
- seeding ratee0
- Outcome
- forage fiber contente0
- Direction
- unaffectede0
- Qualifier
- generallye0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“While forage fiber content was generally unaffected by seeding rate or herbicide treatments”
t0“Alfalfa”
Claim · model-written summary
Forage fiber content was generally unaffected by herbicide treatments.
- Taxon
- AlfalfaMedicago sativat0
- Treatment
- herbicide treatmentse0
- Outcome
- forage fiber contente0
- Direction
- unaffectede0
- Qualifier
- generallye0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“While forage fiber content was generally unaffected by seeding rate or herbicide treatments”
t0“Alfalfa”
Claim · model-written summary
Glyphosate weed control during establishment increased crude protein content in older alfalfa stands relative to no weed control.
- Taxon
- alfalfaMedicago sativae0
- Treatment
- using glyphosate to control weeds during alfalfa establishmente0
- Interactor
- weedse0weed
- Outcome
- forage crude protein contente0
- Direction
- increasede0
- Comparator
- no weed controle0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“using glyphosate to control weeds during alfalfa establishment increased forage crude protein content of older alfalfa stands compared to no weed control”
The same questions in other papers
glyphosate · yield · Medicago sativa (alfalfa)Results differ
8 papers in the same direction as this paper · 9 in the opposite direction · 1 reporting no difference from an alternative
- no effect
- positive
- positive
15 papers more in this group
See all 19 papers →glyphosate · quality: protein · Medicago sativa (alfalfa)Results agree
2 papers in the same direction as this paper
- positive
- positive
herbicide · yield · Medicago sativa (alfalfa)Results differ
25 papers in the same direction as this paper · 26 in the opposite direction
- positive
- positive
- positive
48 papers more in this group
See all 52 papers →herbicide · quality: grain · Medicago sativa (alfalfa)Positive and negative results
5 papers in the same direction as this paper · 3 in the opposite direction
- no effect
- positive
- positive
5 papers more in this group
See all 9 papers →herbicide · organism · Medicago sativa (alfalfa)Positive and negative results
6 papers in the same direction as this paper · 12 in the opposite direction
- no effect
- positive
- positive
15 papers more in this group
See all 19 papers →density · quality: grain · Medicago sativa (alfalfa)Results agree
3 papers in the same direction as this paper
- no effect
- no effect
- no effect
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.