Abstract
Abstract Double-cropping winter rye cover crops (CC) with soybean in the North Central US could help with the global effort to sustainably intensify agriculture. Studies addressing the management of these systems are limited. Therefore, a field study was conducted from 2017 to 2019 in Central Iowa, US to evaluate winter rye CC biomass production, aboveground N accumulation, estimated economics, estimated within-field energy balance and estimated greenhouse gas (GHG) emissions under three N application rates (0, 60, 120 kg N ha −1 ) and three planting methods (pre- and post-harvest broadcast and post-harvest drilling). Averaged over N rates, all planting methods resulted in >5.0 Mg ha −1 year −1 rye aboveground biomass dry matter. Averaged over the 2-year study and compared with unfertilized treatments, applying 60 kg N ha −1 produced 1.1 Mg ha −1 more aboveground biomass (6.1 vs 5.0 Mg ha −1 ), accumulated 30 kg ha −1 more N in aboveground biomass (88 vs 58 kg N ha −1 ), and led to 20 GJ ha −1 more net energy. Biomass production was not significantly higher with 120 kg N ha −1 compared with the 60 kg N ha −1 rate. Even when accounting for an estimated 0.75 Mg ha −1 of above ground rye biomass left in the field after harvesting, more N was removed than applied at the 60 kg N ha −1 rate. The minimum rye prices over the 2-year study needed for double-cropping winter rye CC to be profitable (breakeven prices) averaged $117 and $104 Mg −1 for the 0 and 60 kg N ha −1 rates, which factors in estimated soybean yield reductions in 2019 compared with local averages but not off-site transportation. GHG emissions were estimated to increase approximately threefold between the unfertilized and 60 kg N ha −1 rates without considering bioenergy offsets. While environmental tradeoffs need further study, results suggest harvesting fertilized rye CC biomass before planting soybean is a promising practice for the North Central US to maximize total crop and net energy production.
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Claims 9
Claim · model-written summary
All planting methods produced more than 5.0 Mg ha −1 year −1 of winter rye aboveground biomass dry matter in Central Iowa.
- Taxon
- winter rye
Secale cerealee0 - Outcome
- aboveground biomass dry mattere5
- Value
- >5.0 Mg ha −1 year −1e5
- Setting
- Central Iowa, USe2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Double-cropping winter rye cover crops (CC) with soybean in the North Central US”
e5“all planting methods resulted in >5.0 Mg ha −1 year −1 rye aboveground biomass dry matter”
e2“a field study was conducted from 2017 to 2019 in Central Iowa, US”
Claim · model-written summary
Applying 60 kg N ha −1 increased rye aboveground biomass by 1.1 Mg ha −1 compared with unfertilized treatments.
- Taxon
- winter ryeSecale cerealee0
- Treatment
- 60 kg N ha −1e1
- Outcome
- aboveground biomasse1
- Direction
- moree1
- Value
- 1.1 Mg ha −1e1
- Comparator
- unfertilized treatmentse1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Double-cropping winter rye cover crops (CC) with soybean in the North Central US”
e1“compared with unfertilized treatments, applying 60 kg N ha −1 produced 1.1 Mg ha −1 more aboveground biomass (6.1 vs 5.0 Mg ha −1 )”
Claim · model-written summary
Applying 60 kg N ha −1 increased N accumulated in rye aboveground biomass by 30 kg ha −1 compared with unfertilized treatments.
- Taxon
- winter ryeSecale cerealee0
- Treatment
- 60 kg N ha −1e1
- Outcome
- N in aboveground biomasse2
- Direction
- moree2
- Value
- 30 kg ha −1e2
- Comparator
- unfertilized treatmentse1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Double-cropping winter rye cover crops (CC) with soybean in the North Central US”
e1“compared with unfertilized treatments, applying 60 kg N ha −1 produced 1.1 Mg ha −1 more aboveground biomass (6.1 vs 5.0 Mg ha −1 )”
e2“accumulated 30 kg ha −1 more N in aboveground biomass (88 vs 58 kg N ha −1 )”
Claim · model-written summary
Applying 60 kg N ha −1 increased net energy by 20 GJ ha −1 compared with unfertilized treatments.
- Taxon
- winter ryeSecale cerealee0
- Treatment
- 60 kg N ha −1e1
- Outcome
- net energye3
- Direction
- moree3
- Value
- 20 GJ ha −1e3
- Comparator
- unfertilized treatmentse1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Double-cropping winter rye cover crops (CC) with soybean in the North Central US”
e1“compared with unfertilized treatments, applying 60 kg N ha −1 produced 1.1 Mg ha −1 more aboveground biomass (6.1 vs 5.0 Mg ha −1 )”
e3“led to 20 GJ ha −1 more net energy”
Claim · model-written summary
Biomass production with 120 kg N ha −1 was not significantly higher than with 60 kg N ha −1.
- Taxon
- winter ryeSecale cerealee0
- Treatment
- 120 kg N ha −1e4
- Outcome
- Biomass productione4
- Direction
- not significantly highere4
- Comparator
- 60 kg N ha −1e4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Double-cropping winter rye cover crops (CC) with soybean in the North Central US”
e4“Biomass production was not significantly higher with 120 kg N ha −1 compared with the 60 kg N ha −1 rate”
Claim · model-written summary
At 60 kg N ha −1 more N was removed in rye harvest than was applied.
- Taxon
- ryeSecale cerealee6
- Treatment
- 60 kg N ha −1e6
- Outcome
- N was removede6
- Direction
- moree6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e6“Even when accounting for an estimated 0.75 Mg ha −1 of above ground rye biomass left in the field after harvesting, more N was removed than applied at the 60 kg N ha −1 rate”
Claim · model-written summary
Breakeven rye prices for double-cropped winter rye were $117 and $104 Mg −1 at the 0 and 60 kg N ha −1 rates.
- Taxon
- winter ryeSecale cerealee7
- Outcome
- minimum rye pricese7
- Value
- $117 and $104 Mg −1e7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Double-cropping winter rye cover crops (CC) with soybean in the North Central US”
e7“The minimum rye prices over the 2-year study needed for double-cropping winter rye CC to be profitable (breakeven prices) averaged $117 and $104 Mg −1 for the 0 and 60 kg N ha −1 rates”
Claim · model-written summary
GHG emissions were estimated to increase about threefold from unfertilized to 60 kg N ha −1.
- Taxon
- winter ryeSecale cerealee0
- Treatment
- 60 kg N ha −1e1
- Outcome
- GHG emissionse1
- Direction
- increasee1
- Value
- approximately threefolde1
- Comparator
- unfertilizede1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Double-cropping winter rye cover crops (CC) with soybean in the North Central US”
e1“GHG emissions were estimated to increase approximately threefold between the unfertilized and 60 kg N ha −1 rates without considering bioenergy offsets”
Claim · model-written summary
Harvesting fertilized rye cover-crop biomass before planting soybean is a promising practice to maximize total crop and net energy production.
- Taxon
- ryeSecale cerealee1
- Outcome
- total crop and net energy productione1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“results suggest harvesting fertilized rye CC biomass before planting soybean is a promising practice for the North Central US to maximize total crop and net energy production”
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See all 28 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.