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field corn. shutterstock.com/ Zeljko Radojko

Corn is one of Alabama’s most important row crops. Alabama farmers usually harvest more than half a million acres of corn each year. Corn is grown as a part of crop rotation systems that include cotton and peanuts. Although corn is planted throughout Alabama, the majority of production is located in the northern region (Lawrence, Madison, Limestone, Jackson, Lauderdale, and Colbert Counties) providing more than 50 percent of total corn acreage. Central and southern counties such as Talladega, Baldwin, Coffee, Escambia, and Houston provide 12 percent of corn acreage.

The climate variability in Alabama is mainly linked to ENSO, which is an oscillation that occurs every 3 to 7 years between warm and cold phases of sea surface temperature in the Equatorial Pacific. The El Niño phase of ENSO results in lower winter temperatures and higher winter-spring rainfall. The La Niña phase of ENSO causes warmer and drier conditions from fall to spring. Summers are drier and hotter than normal in El Niño years in northern and southern parts, but wetter and cooler in La Niña years in northern and central parts of the state.

Crop yield is affected by the variability in rainfall and temperature in Alabama through the influence in plant growth and development rates and pest and disease dynamics. Climate forecasting can be a valuable tool in increasing yields and securing a more profitable crop.

Here is how you can use this climate information to enhance yields and secure higher levels of profitability.

Key Climate Impacts and Management Strategies

Drier/Warmer Spring

Insect Pests
Increased population of stinkbugsAdditional scouting is needed.
Increased lesser cornstalk borer damage on corn grown on lighter soils, especially if planted lateAvoid light soils if possible. Plant early.
Increased chinch bugs, mainly on the crops with reduced tillage following grassy winter crops or weedsAdditional scouting is needed.
Increased risk to charcoal rotPlant no-till or strip till corn early.
More outbreak of southern corn rustScout and treat as needed with a fungicide.

Wetter/Cooler Spring

About 20% less than average yield due to more floods, less germination, less sunshine, and freeze injuryDelay planting until soil temperature reaches 55 ?F.
Insect Pests
Greater risks of true armyworms.Increased scouting is needed.
More cutworms damaging seedlings in conservation tillageSupplement seed treatments with a broadcast insecti- cide spray at planting
Fewer chinch bugs and stinkbugs
More risk to seedling blightDelay planting to promote germination and seedling growth.
Increased outbreak of southern and northern corn leaf blight and southern rustScout and treat as needed with a fungicide.
More leaching losses of nitrogen and potassiumSplit applications to increase efficiency.
Reduction in phosphate uptakeBand starter fertilizer 2 inches to the side and 2 inches below the seed.

Drier/Warmer Summer

Low yield due to water stress and excessive heat during pollination and grain-fillingPlant corn early to avoid low rainfall and high heat periods during the summer. Apply irrigation.
High risk to aflatoxin contaminationPlant corn early, fertilize according to soil test recom- mendations, use recommended seeding rate of adapted corn variety, irrigate, and apply Afla-Guard.

Wetter/Cooler Summer

Larger yields due to more rainfall at silking and tasseling, the critical stages of water requirementIncrease planting density and nitrogen dose to take advantage of more favorable moisture.
Insect Pests
Fewer chinch bugs and fall armyworms
Increased risk to southern rust, southern corn rust, and northern corn leaf blight.Scout and apply fungicides as needed.

Drier/Warmer Winter

Insect Pests
Increased survival of stink bugs and chinch bugsAdditional scouting is needed.
Southern root-knot nematode may remain active for longer periods in late fall/winter, thus increasing in number and becoming active earlier in the following yearCollect a soil sample for a nematode assay from fields going into corn in fall to early winter. Treat with nematicide based on the results of nematode soil assay.

Seasonal Climate Variability Affecting Corn Production in Alabama

  • The ocean-atmospheric phenomenon associated with unusually warm water forming occasionally across the eastern and central Pacific is referred to as the El Niño
  • The La Niña phase is characterized by cooler than average sea surface temperatures across the same
  • The phenomenon associated with close-to-average sea surface temperature in this region is referred to as the Neutral
  • El Niño, La Niña, and Neutral are the three phases of ENSO, the El Niño-Southern In Alabama, the ENSO phenomena affect rainfall and temperature during winter, spring and summer months.
  • In an El Niño phase year, the southern part of Alabama is wetter and cooler than average condition during winter, whereas the northern part is drier and In a La Niña phase year, the conditions are just opposite.
  • Summers are drier and hotter than normal in El Niño years in northern and southern parts, but wetter and cooler in La Niña years in northern and central
  • The effect of ENSO on corn yield is more pronounced closer to the Gulf Coast (south) than in the northern parts of the
  • El Niño produces larger yields than does La Niña in the southern part of the state, whereas La Niña results in larger yields than El Niño in the central and northern parts.
  • Throughout Alabama, the Neutral phase has the largest yields of all ENSO
  • Corn is most susceptible to water stress at tasseling which occurs during the Low precipitation especially in July, the warmest month of the year, reduces corn yield substantially. La Niña phase years have larger yields than El Niño phase years. Thisis mainly due to summer rainfall which tends to be higher in La Niña phase years. For the same reason, El Niño phase years have lower yields.
  • High maximum temperatures during tasseling and grain filling periods also reduce corn yield Higher temperatures shorten grain filling period. La Niña phase years have larger yields than neutral or El Niño phase years because La Niña phase years tend to be cooler during summer.


AgroClimate Tools:


Climate Risk Tool:


Climate Impacts:


ENSO overview:

http://www.cpc.ncep.noaa.gov/products/ precip/CWlink/MJO/enso.shtml


Download a PDF of Adapting Corn Production to Climate in Alabama, ANR-2090.


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