Abstract
The adoption of conservation tillage systems has been challenged by concerns potential weed species shifts. A 9-yr study from 1988 to 1996 was conducted Delhi, Ontario, on a loamy sand soil to evaluate the effect of tillage systems (conventional [CT] and no-till [NT]), cover crop Secale cereale , and nitrogen (N) rate (0, 50, 100, 125, 150, and 200 kg N ha −1 ) on monocrop Zea mays L. (corn) yield and changes in the composition of the weed flora. CT consisted of spring moldboard plowing followed by cultivation with a tooth cultivator. Weed counts were taken in the last 3 yr of the study (1994, 1995, and 1996) prior to postemergence herbicide application and then again 2 to 3 wk after herbicide treatment. Composition or the weed flora was analyzed by canonical discriminant analysis (CDA). The relationship between weed density and tillage system was not consistent. Weed species composition differed between CT and NT systems. Chenopodium album and Amaranthus retroflexus were associated with CT and Digitaria sanguinalis with NT. N rate and cover crop did not affect weed density or species composition. Proper management of weeds with herbicides appeared to minimize any long-term effect on the weed flora resulting from varying N rates. Zea mays yields did not differ between CT and NT systems but were greater in both systems with a cover crop at the higher N rates. Disturbance caused by tillage was more important than N rate and cover crop as a mechanism influencing composition of the weed flora.
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Claims 8
Claim · model-written summary
Weed density response to tillage was inconsistent.
Zea maysNot reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The relationship between weed density and tillage system was not consistent”
t0“monocrop Zea mays L. (corn) yield”
Claim · model-written summary
Weed species composition differed between conventional and no-till systems.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Weed species composition differed between CT and NT systems”
t0“monocrop Zea mays L. (corn) yield”
Claim · model-written summary
Chenopodium album and Amaranthus retroflexus were associated with conventional tillage.
- Treatment
- CTe0
- Interactor
- Chenopodium album
Chenopodium albume0weed - Second interactor
- Amaranthus retroflexus
Amaranthus retroflexuse0weed - Outcome
- associated with CTe0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Chenopodium album and Amaranthus retroflexus were associated with CT”
t0“monocrop Zea mays L. (corn) yield”
Claim · model-written summary
Digitaria sanguinalis was associated with no-till.
- Treatment
- NTe0
- Interactor
- Digitaria sanguinalis
.jpg?width=60)
Digitaria sanguinalise0weed - Outcome
- Digitaria sanguinalis with NTe0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)
Verbatim
e0“Digitaria sanguinalis with NT”
t0“monocrop Zea mays L. (corn) yield”
Claim · model-written summary
Nitrogen rate and cover crop did not affect weed density or composition.
- Treatment
- N rate and cover crope0
- Outcome
- weed density or species compositione0
- Direction
- did not affecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“N rate and cover crop did not affect weed density or species composition”
t0“monocrop Zea mays L. (corn) yield”
Claim · model-written summary
Corn yields did not differ between conventional and no-till systems.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Zea mays yields did not differ between CT and NT systems”
Claim · model-written summary
Cover crops increased corn yields at higher nitrogen rates in both tillage systems.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Zea mays yields did not differ between CT and NT systems but were greater in both systems with a cover crop at the higher N rates”
Claim · model-written summary
The authors infer that tillage disturbance influenced weed composition more than nitrogen or cover crops.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Disturbance caused by tillage was more important than N rate and cover crop as a mechanism influencing composition of the weed flora”
t0“monocrop Zea mays L. (corn) yield”
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