Abstract
Abstract Potential benefits associated with establishing cover crops, such as reduced NO 3 leaching risk and lower fertilizer N requirements for succeeding crops, will be fully realized only when the cover crop N contribution is accurately accounted for and availability is synchronous with succeeding crop N demands. The objectives of this study were to evaluate spring soil NO 3 −N accumulation patterns and N availability to corn ( Zea mays L.) following annual ryegrass ( Lolium multiflorum L.), oilseed radish [ Raphanus sativus (L.) var. oleiferus (Stokes) Metzg.], red clover ( Trifolium pratense L.), and no cover crop established after either winter wheat ( Triticum aestivum L.) or barley ( Hordeum vulgare L.). The wheat and barley were produced with 0.5, 1.0, and 2.0 times the amount of recommended N fertilizer. Six field trials were conducted on well‐drained Typic Hapludalf soils in southwestern Ontario intermittently from 1989 to 1995. Corn was produced using a spring mulch‐till system with only 10 kg ha −1 of fertilizer N, which was applied as part of the P starter fertilizer. Applying more fertilizer N to the previous year's small‐grain crop rarely increased spring soil NO 3 −N concentrations or corn yields. Soil NO 3 −N concentration increases between the May and June sample dates following annual ryegrass and oilseed radish did not differ substantially from where a cover crop had not been established; following red clover, however, NO 3 −N increases were always at least 2.8 times greater than after no cover crop. Average aboveground corn biomass N at anthesis following annual ryegrass was 25.6 kg ha −1 less than when no cover crop was grown, whereas following red clover it was 40.4 kg ha −1 greater than with no cover crop. Corn yields were consistently the highest following red clover and often the lowest following annual ryegrass; yield response was positively correlated with June soil NO 3 −N concentrations ( r = 0.61‐0.93). These results suggest that N availability to succeeding corn differs among the cover crop treatments evaluated in the order red clover > oilseed radish ≥ no cover crop > annual ryegrass.
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Claims 9
Claim · model-written summary
More N fertilizer on the previous small-grain crop rarely increased spring soil nitrate or corn yield.
- Treatment
- more fertilizer Ne0
- Outcome
- spring soil NO 3 −N concentrations or corn yieldse0
- Direction
- rarely increasede0
Zea maysNot reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Applying more fertilizer N to the previous year's small‐grain crop rarely increased spring soil NO 3 −N concentrations or corn yields”
e1“corn ( Zea mays L.)”
Claim · model-written summary
Spring soil nitrate increases after annual ryegrass did not differ substantially from no cover crop.
- Treatment
- annual ryegrasse0
- Outcome
- Soil NO 3 −N concentration increasese0
- Direction
- did not differ substantiallye0
- Comparator
- a cover crop had not been establishede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Soil NO 3 −N concentration increases between the May and June sample dates following annual ryegrass and oilseed radish did not differ substantially from where a cover crop had not been established”
e1“corn ( Zea mays L.)”
Claim · model-written summary
Spring soil nitrate increases after oilseed radish did not differ substantially from no cover crop.
- Treatment
- oilseed radishe0
- Outcome
- Soil NO 3 −N concentration increasese0
- Direction
- did not differ substantiallye0
- Comparator
- a cover crop had not been establishede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Soil NO 3 −N concentration increases between the May and June sample dates following annual ryegrass and oilseed radish did not differ substantially from where a cover crop had not been established”
e1“corn ( Zea mays L.)”
Claim · model-written summary
Red clover produced at least 2.8 times greater spring soil nitrate increases than no cover crop.
- Treatment
- red clovere0
- Outcome
- NO 3 −N increasese0
- Direction
- greatere0
- Value
- at least 2.8 timese0
- Comparator
- no cover crope0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“following red clover, however, NO 3 −N increases were always at least 2.8 times greater than after no cover crop”
e1“corn ( Zea mays L.)”
Claim · model-written summary
Corn biomass N at anthesis after annual ryegrass was 25.6 kg ha −1 less than without cover crop.
- Taxon
- corn
Zea mays subsp. mayse0 - Treatment
- annual ryegrasse0
- Outcome
- aboveground corn biomass N at anthesise0
- Direction
- lesse0
- Value
- 25.6 kg ha −1e0
- Comparator
- no cover crope0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Average aboveground corn biomass N at anthesis following annual ryegrass was 25.6 kg ha −1 less than when no cover crop was grown”
Claim · model-written summary
Corn biomass N at anthesis after red clover was 40.4 kg ha −1 greater than without cover crop.
- Taxon
- cornZea mays subsp. mayse1
- Treatment
- red clovere0
- Outcome
- aboveground corn biomass N at anthesise1
- Direction
- greatere0
- Value
- 40.4 kg ha −1e0
- Comparator
- no cover crope0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“whereas following red clover it was 40.4 kg ha −1 greater than with no cover crop”
e1“aboveground corn biomass N at anthesis”
Claim · model-written summary
Corn yields were consistently highest after red clover.
- Taxon
- CornZea mays subsp. mayse0
- Treatment
- red clovere0
- Outcome
- Corn yieldse0
- Direction
- higheste0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Corn yields were consistently the highest following red clover”
Claim · model-written summary
Corn yields were often lowest after annual ryegrass.
- Taxon
- CornZea mays subsp. mayse1
- Treatment
- annual ryegrasse0
- Outcome
- Corn yieldse1
- Direction
- loweste0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“often the lowest following annual ryegrass”
e1“Corn yields”
Claim · model-written summary
Corn yield response correlated positively with June soil nitrate concentration.
- Taxon
- CornZea mays subsp. mayse1
- Compound
- NO 3 −Ne0
- Outcome
- yield responsee0
- Direction
- positively correlatede0
- Value
- r = 0.61‐0.93e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“yield response was positively correlated with June soil NO 3 −N concentrations ( r = 0.61‐0.93)”
e1“Corn yields”
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