The production of soft red winter wheat is mainly concentrated in the northern Alabama (the Northern Valley and the northeastern region of the Appalachian Mountains in Alabama) followed by the southern part (the Coastal Plain and Gulf Coast), although wheat fields are spread out throughout the state. Limestone, Madison, Lauderdale, Morgan, Lawrence, Jackson, DeKalb, Marshall, and Colbert are the leading counties in the northern region, and Baldwin, Escambia, Geneva, Houston, Henry, Dale, Coffee, and Covington are the leading counties in the southern region.

The climate variability 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.

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

Seasonal Climate Variability Affecting Wheat Production in Alabama

• The ocean-atmospheric phenomenon associated with unusually warm water that occasionally forms across the tropical 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 region.
• 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 (El Niño-Southern Oscillation). In Alabama, ENSO affects rainfall and temperature mainly during fall, winter, and spring
• In El Niño phase years, the southern part of Alabama is wetter and cooler than average condition during winter, whereas the northern part is drier and The conditions are just opposite in a La Niña phase year.
• Among the ENSO phases, La Niña results in the highest wheat yields in the northern part of the state, whereas El Niño tends to produce most in the mid-southern part (Figure 1). Of all phases, the neutral phase yields are the largest in the southern and mid-northern parts. La Niña produces more yields than El Niño in the northern part, whereas El Niño produces more yields than La Niña in the central and southern locations.
• Yield losses associated with delayed planting are high in La Niña phase years, moderate in Neutral phase years, and low in El Niño phase
• In a wetter season, the anaerobic condition in soil due to water logging may reduce root growth and result in nitrogen and phosphorus deficiency.
• Temperature and precipitation are key weather variables determining growth, development, and yield of Due to lower temperatures during growing season, El Niño phase years generally result in larger yields. La Niña phase years, in contrast, have smaller yields due to higher temperatures during the season. Higher temperatures lead to shorter growing season, shorter grain-filling period, lack of vernalization, and increased leaf senescence. Higher temperatures in February, however, are beneficial due to an enhancement of early development, following vernalization.

Figure 1. Wheat yield differences among ENSO phases for four locations in Alabama.