Paper · 2019 · Iowa State University Digital Repository (Iowa State University)

Characterizing climate change in the Midwest: Magnitude of warming and plausibility of adaptation strategies for maize-based systems

Lori Abendroth

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citations
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Open access

Abstract

Maize-based agricultural systems dominate the U.S. Midwest landscape and maintaining productive systems in the short- and long-term are high priorities for the agricultural sector. Climate change has and will continue to alter the environment in which farmers produce their crops. Information and recommendations are necessary for understanding the magnitude of warming and adaptation strategies that can mitigate intensified precipitation events, moisture shortages, and increased temperatures. The multi-faceted changes in temperature were aggregated using thermal time as an agro-climate index to describe the warming relevant for producing maize. Across 1054 counties, the change in thermal time since 1950 was disproportionally warming for northern and eastern counties. Counties in the central and western regions have not warmed substantially. A future adaptation strategy may be the use of longer-season maize hybrids that have thermal requirements more closely aligned with the environmental thermal availability of an area. The feasibility of this adaptation strategy was assessed based on current hybrid choices. Pioneer brand hybrid sales were provided from Corteva Agriscience for 650 counties from 2000 to 2016. The difference between hybrid thermal requirements and environmental thermal availability varied with northern counties having a difference near zero Growing Degree Days (GDDs) while southern counties had up to 800 GDDs available following crop maturation. Over the 17-year period, hybrid maturities changed in 345 of 650 counties with an increase in 64 and decrease in 281; 305 were unchanged. An inverse relationship was identified for the majority of counties between long-term climate trend and hybrid choice such that as seasonal thermal time lengthened, hybrid maturity shortened. Finally, climate adaptation strategies for farmers often focus on mitigation of intensified precipitation events and increased temperatures through conservation and diversification practices that build system “resilience”. Twenty-three experiments located across eight Midwest states were used to assess maize yield response to “improved” management practices relative to a “standard”. Climate adaptation practices included: differing intensity of tillage, diversity of cropping systems, and management of drainage water. Research sites were binned relative to yield environment or soil organic carbon; the latter was most helpful as a characterization variable in separating treatment response.

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Claims 9

Observationobservedoriginal resultmeasured

Claim · model-written summary

Thermal time warmed disproportionately in northern and eastern counties since 1950.

Taxon
maize-based systemst0
Outcome
thermal timee0
Direction
warminge0
Setting
northern and eastern countiese0

Verbatim

t0

“maize-based systems”

✓ located verbatim in the source · title, characters 113–132 · show in text ↑
e0

“Across 1054 counties, the change in thermal time since 1950 was disproportionally warming for northern and eastern counties”

✓ located verbatim in the source · abstract, characters 651–774 · show in text ↑
Observationobservedoriginal resultno effectmeasured

Claim · model-written summary

Central and western counties did not warm substantially.

Taxon
maize-based systemst0
Outcome
warmede0
Direction
not warmed substantiallye0
Setting
central and western regionse0

Verbatim

t0

“maize-based systems”

✓ located verbatim in the source · title, characters 113–132 · show in text ↑
e0

“Counties in the central and western regions have not warmed substantially”

✓ located verbatim in the source · abstract, characters 776–849 · show in text ↑
Observationobservedoriginal resultmeasured

Claim · model-written summary

Northern counties had a near-zero difference between hybrid requirements and environmental thermal availability.

Taxon
maize-based systemst0
Outcome
differencee0
Value
near zero Growing Degree Days (GDDs)e0
Setting
northern countiese0

Verbatim

t0

“maize-based systems”

✓ located verbatim in the source · title, characters 113–132 · show in text ↑
e0

“northern counties having a difference near zero Growing Degree Days (GDDs) while southern counties had up to 800 GDDs available following crop maturation”

✓ located verbatim in the source · abstract, characters 1328–1481 · show in text ↑
Observationobservedoriginal resultmeasured

Claim · model-written summary

Southern counties had up to 800 GDDs remaining after crop maturation.

Taxon
maize-based systemst0
Outcome
GDDs available following crop maturatione0
Value
800 GDDse0
Setting
southern countiese0

Verbatim

t0

“maize-based systems”

✓ located verbatim in the source · title, characters 113–132 · show in text ↑
e0

“northern counties having a difference near zero Growing Degree Days (GDDs) while southern counties had up to 800 GDDs available following crop maturation”

✓ located verbatim in the source · abstract, characters 1328–1481 · show in text ↑
Observationobservedoriginal resultmeasured

Claim · model-written summary

Hybrid maturity increased in 64 counties.

Taxon
maize-based systemst0
Outcome
hybrid maturitiese0
Direction
increasee0
Value
64e0

Verbatim

t0

“maize-based systems”

✓ located verbatim in the source · title, characters 113–132 · show in text ↑
e0

“hybrid maturities changed in 345 of 650 counties with an increase in 64 and decrease in 281; 305 were unchanged”

✓ located verbatim in the source · abstract, characters 1508–1619 · show in text ↑
Observationobservedoriginal resultmeasured

Claim · model-written summary

Hybrid maturity decreased in 281 counties.

Taxon
maize-based systemst0
Outcome
hybrid maturitiese0
Direction
decreasee0
Value
281e0

Verbatim

t0

“maize-based systems”

✓ located verbatim in the source · title, characters 113–132 · show in text ↑
e0

“hybrid maturities changed in 345 of 650 counties with an increase in 64 and decrease in 281; 305 were unchanged”

✓ located verbatim in the source · abstract, characters 1508–1619 · show in text ↑
Observationobservedoriginal resultno effectmeasured

Claim · model-written summary

Hybrid maturity was unchanged in 305 counties.

Taxon
maize-based systemst0
Outcome
hybrid maturitiese0
Direction
unchangede0
Value
305e0

Verbatim

t0

“maize-based systems”

✓ located verbatim in the source · title, characters 113–132 · show in text ↑
e0

“hybrid maturities changed in 345 of 650 counties with an increase in 64 and decrease in 281; 305 were unchanged”

✓ located verbatim in the source · abstract, characters 1508–1619 · show in text ↑
Associationobservedoriginal resultmeasured

Claim · model-written summary

For most counties, hybrid maturity shortened as seasonal thermal time lengthened.

Taxon
maize-based systemst0
Outcome
hybrid maturitye0
Direction
shortenede0
Qualifier
seasonal thermal time lengthenede0

Not reportedSetting

Verbatim

t0

“maize-based systems”

✓ located verbatim in the source · title, characters 113–132 · show in text ↑
e0

“as seasonal thermal time lengthened, hybrid maturity shortened”

✓ located verbatim in the source · abstract, characters 1749–1811 · show in text ↑
Method / resourceobservedoriginal resultmeasured

Claim · model-written summary

Soil organic carbon best separated management treatment responses.

Taxon
maize-based systemst0
Outcome
separating treatment responsee0
Comparator
characterization variablee0

Verbatim

t0

“maize-based systems”

✓ located verbatim in the source · title, characters 113–132 · show in text ↑
e0

“soil organic carbon; the latter was most helpful as a characterization variable in separating treatment response”

✓ located verbatim in the source · abstract, characters 2395–2507 · show in text ↑