Abstract
Abstract In a previous study of reduced chemical cropping systems (N from legumes; chisel plow and disk tillage; cultivation for weed control) in the southeastern U.S., corn and wheat yields were less than half those obtained with recommended practices. The following practices were studied as possible ways to improve yields in the reduced chemical systems: 1) conventional tillage (chisel plowing and disking), inorganic Nat 70 or 140 kg/ha, and either cultivation or herbicides; 2) early versus late plow-down of clover green manures; 3) supplemental inorganic N fertilizer on corn and wheat in rotations relying on clover green manures for N; and 4) nicosulfuron herbicide banded on corn. Yield of soybean in the rotations was not affected by any of these practices. With herbicides and fertilizer N at 140 kg/ha, continuous corn yields with no-till and conventional tillage were equal in 1990 and 1992, but no-till yield was 30% higher in 1991. When cultivation was used for weed control in the conventional tillage treatment, corn yield was similar to that of no-till with herbicide in the one year when rain was plentiful (yield 6000 kg/ha). However, in 2 of 4 dry years, yields (<2600 kg/ha) were higher with no-till. Clover biomass consistently increased by between 700 and 3500 kg/ha when plow-down was delayed from mid-April to early or mid-May (13 to 26 days). However, biomass N content increased significantly (by between 35 and 90 kg/ha) in only 2 of 5 years. Corn yields were affected in only 2 of 12 possible comparisons. In these cases, delayed clover plow-down reduced yield by about 50%. Supplementing corn with 45 kg N/ha and banding nicosulfuron increased yields, but only to between 62 and 84% of yields with recommended practices. Supplementing wheat with 45 kg N/ha increased yields by half, but only to between 40 and 60% of the yields with 90 kg N/ha.
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Claims 12
Claim · model-written summary
Soybean yield was unaffected by the studied management practices.
- Taxon
- soybean
Glycine maxe0 - Treatment
- these practicese0
- Outcome
- Yield of soybeane0
- Direction
- not affectede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Yield of soybean in the rotations was not affected by any of these practices.”
Claim · model-written summary
No-till and conventional tillage produced equal continuous-corn yields in 1990 and 1992.
- Taxon
- corn
Zea mays subsp. mayse0 - Treatment
- no-tille0
- Outcome
- continuous corn yieldse0
- Direction
- equale0
- Qualifier
- 1990 and 1992e0
- Comparator
- conventional tillagee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“continuous corn yields with no-till and conventional tillage were equal in 1990 and 1992”
Claim · model-written summary
No-till corn yielded 30% more than conventional tillage in 1991.
- Taxon
- cornZea mays subsp. mayse1
- Treatment
- no-tille0
- Outcome
- yielde0
- Direction
- highere0
- Value
- 30%e0
- Qualifier
- in 1991e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“no-till yield was 30% higher in 1991”
e1“continuous corn yields with no-till and conventional tillage were equal in 1990 and 1992”
Claim · model-written summary
Cultivated conventional-tillage corn yielded similarly to herbicide-treated no-till corn in the plentiful-rain year.
- Taxon
- cornZea mays subsp. mayse0
- Treatment
- cultivatione0
- Outcome
- corn yielde0
- Direction
- similare0
- Value
- 6000 kg/hae0
- Qualifier
- rain was plentifule0
- Comparator
- no-till with herbicidee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“When cultivation was used for weed control in the conventional tillage treatment, corn yield was similar to that of no-till with herbicide in the one year when rain was plentiful (yield 6000 kg/ha)”
Claim · model-written summary
In two of four dry years, no-till corn yields were higher than conventional tillage yields.
- Taxon
- cornZea mays subsp. mayse1
- Treatment
- no-tille0
- Outcome
- yieldse0
- Direction
- highere0
- Value
- <2600 kg/hae0
- Qualifier
- 2 of 4 dry yearse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“in 2 of 4 dry years, yields (<2600 kg/ha) were higher with no-till.”
e1“continuous corn yields with no-till and conventional tillage were equal in 1990 and 1992”
Claim · model-written summary
Delaying clover plow-down increased clover biomass by 700 to 3500 kg/ha.
- Treatment
- plow-down was delayed from mid-April to early or mid-Maye0
- Outcome
- Clover biomasse0
- Direction
- increasede0
- Value
- between 700 and 3500 kg/hae0
TrifoliumNot reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Clover biomass consistently increased by between 700 and 3500 kg/ha when plow-down was delayed from mid-April to early or mid-May (13 to 26 days).”
Claim · model-written summary
Delayed plow-down significantly increased clover biomass nitrogen in two of five years.
- Outcome
- biomass N contente0
- Direction
- increasede0
- Value
- between 35 and 90 kg/hae0
- Qualifier
- only 2 of 5 yearse0
Not reportedTreatmentComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“biomass N content increased significantly (by between 35 and 90 kg/ha) in only 2 of 5 years.”
e1“Clover biomass consistently increased”
Claim · model-written summary
Delayed clover plow-down affected corn yield in two of twelve comparisons.
- Taxon
- CornZea mays subsp. mayse0
- Outcome
- Corn yieldse0
- Value
- 2 of 12 possible comparisonse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Corn yields were affected in only 2 of 12 possible comparisons.”
Claim · model-written summary
In the affected comparisons, delayed clover plow-down reduced corn yield by about 50%.
- Taxon
- CornZea mays subsp. mayse1
- Treatment
- delayed clover plow-downe0
- Outcome
- yielde0
- Direction
- reducede0
- Value
- about 50%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“delayed clover plow-down reduced yield by about 50%.”
e1“Corn yields were affected in only 2 of 12 possible comparisons.”
Claim · model-written summary
Supplemental nitrogen increased corn yields to 62–84% of recommended-practice yields.
- Taxon
- cornZea mays subsp. mayse0
- Treatment
- 45 kg N/hae0
- Outcome
- yieldse0
- Direction
- increasede0
- Value
- between 62 and 84%e0
- Comparator
- recommended practicese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Supplementing corn with 45 kg N/ha and banding nicosulfuron increased yields, but only to between 62 and 84% of yields with recommended practices.”
Claim · model-written summary
Banded nicosulfuron increased corn yields to 62–84% of recommended-practice yields.
- Taxon
- cornZea mays subsp. mayse0
- Treatment
- banding nicosulfurone0
- Outcome
- yieldse0
- Direction
- increasede0
- Value
- between 62 and 84%e0
- Comparator
- recommended practicese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Supplementing corn with 45 kg N/ha and banding nicosulfuron increased yields, but only to between 62 and 84% of yields with recommended practices.”
Claim · model-written summary
Supplemental nitrogen increased wheat yields by half, reaching 40–60% of yields under 90 kg N/ha.
- Taxon
- wheat
Triticum aestivume0 - Treatment
- 45 kg N/hae0
- Outcome
- yieldse0
- Direction
- increasede0
- Value
- between 40 and 60%e0
- Comparator
- 90 kg N/hae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Supplementing wheat with 45 kg N/ha increased yields by half, but only to between 40 and 60% of the yields with 90 kg N/ha.”
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