Abstract
Core Ideas Diversification of established no‐till, rain‐fed crop rotations was examined. Mean daily N 2 O fluxes were 24% lower in 4‐yr vs. 2‐yr rotation. Both no‐till rotations (2‐yr and 4‐yr) accrued soil C over this time span. 4‐yr rotation accrued soil C earlier and deeper than 2‐yr rotation. Soybean yields were 22% higher in 4‐yr vs. 2‐yr rotation. The effect of crop rotational diversity on greenhouse gas (GHG) emissions has been explored in several studies, although rarely have measurements been made on whole rotations consisting of two or more crops. We evaluated the impact of crop rotational diversity on GHG emissions, soil organic carbon (SOC), and crop yields over a 4‐yr period in eastern South Dakota, USA. Under no‐till, rain‐fed conditions, a 2‐yr (corn [ Zea mays L.]–soybean [ Glycine max (L.) Merr.]) rotation and a 4‐yr rotation (corn‐field peas [ Pisum sativum L.]–winter wheat [ Triticum aestivum L.]–soybean) were established in a randomized, complete block design (each crop present each year) 8 yr prior to the current study. Average daily N 2 O fluxes were 24% lower ( P = 0.0313) for the 4‐yr rotation (2.34 ± 0.56 g N 2 O‐N ha –1 d –1 ) compared with the 2‐yr rotation (3.06 ± 0.59 g N 2 O‐N ha –1 d –1 ). Significantly elevated N 2 O flux peaks were observed in June of every year and every phase of the 2‐yr rotation, but only in one of 4 yr (corn phase) in the 4‐yr rotation. There was no significant difference in average daily CH 4 flux between the two rotations. Over this 4‐yr period, SOC increased in the 0‐ to 15‐cm depth interval for the 2‐yr rotation, but increased in both the 0‐ to 15‐ and 15‐ to 30‐cm depth intervals for the 4‐yr rotation. Corn yields (6.75 Mg ha –1 ) did not differ between the two rotations. However, the yield of soybean in the 4‐yr rotation (2.87 Mg ha –1 ) was 22% greater ( P = 0.0001) than soybean within the 2‐yr rotation (2.35 Mg ha –1 ). Diversified rotations can decrease N 2 O emissions, increase or accelerate SOC gains, distribute soil C gains deeper in the soil profile, and boost soybean yield.
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Claims 7
Claim · model-written summary
Four-year rotation had 24% lower N2O flux than two-year rotation.
Not reportedTaxonComparator
Verbatim
e0“Average daily N 2 O fluxes were 24% lower ( P = 0.0313) for the 4‐yr rotation”
Claim · model-written summary
Nitrous oxide flux peaks occurred each June in two-year rotation, but only one year in the four-year rotation.
- Taxon
- corn
Zea mays subsp. mayse0 - Outcome
- N 2 O flux peakse0
- Direction
- elevatede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Significantly elevated N 2 O flux peaks were observed in June of every year and every phase of the 2‐yr rotation, but only in one of 4 yr (corn phase) in the 4‐yr rotation”
Claim · model-written summary
Mean daily methane flux did not differ significantly between rotations.
- Treatment
- two rotationse0
- Outcome
- average daily CH 4 fluxe0
- Direction
- no significant differencee0
- Comparator
- two rotationse0
Not reportedTaxon
Verbatim
e0“There was no significant difference in average daily CH 4 flux between the two rotations”
Claim · model-written summary
Soil carbon increased at 0 to 15 cm under two-year rotation.
Not reportedTaxon
Verbatim
e0“SOC increased in the 0‐ to 15‐cm depth interval for the 2‐yr rotation”
Claim · model-written summary
Soil carbon increased at both 0 to 15 and 15 to 30 cm under four-year rotation.
Not reportedTaxon
Verbatim
e0“SOC increased in the 0‐ to 15‐cm depth interval for the 2‐yr rotation, but increased in both the 0‐ to 15‐ and 15‐ to 30‐cm depth intervals for the 4‐yr rotation”
Claim · model-written summary
Corn yield was 6.75 Mg per hectare and did not differ by rotation.
- Taxon
- CornZea mays subsp. mayse0
- Treatment
- two rotationse0
- Outcome
- Corn yieldse0
- Direction
- did not differe0
- Value
- 6.75 Mg ha –1e0
- Comparator
- two rotationse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Corn yields (6.75 Mg ha –1 ) did not differ between the two rotations”
Claim · model-written summary
Soybean yield was 22% greater in the four-year rotation.
- Taxon
- soybean
Glycine maxe0 - Treatment
- 4‐yr rotatione0
- Outcome
- yield of soybeane0
- Direction
- greatere0
- Value
- 22%e0
- Comparator
- 2‐yr rotatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the yield of soybean in the 4‐yr rotation (2.87 Mg ha –1 ) was 22% greater ( P = 0.0001) than soybean within the 2‐yr rotation”
The same questions in other papers
rotation · yield · Glycine max (soybean)Positive and negative results
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- negative
- positive
- positive
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See all 144 papers →rotation · yield · Zea mays (maize)Positive and negative results
67 papers in the same direction as this paper · 254 reporting no difference from an alternative
- positive
- positive
- positive
318 papers more in this group
See all 322 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.