Eddie McGriff found out how important 4 inches of water in June can be for corn, cotton and soybean yields, and just how much this year’s high temperatures and drought cost some growers.

McGriff is the Alabama Cooperative Extension agent for the northeast region. He has worked for Extension and industry for decades throughout the U.S. Southeast.

Alabama, along with many locations in the Southeast, experienced high temperatures and flash-drought conditions, including the northeast region, especially in June and July. Other regions of the state had drought throughout the growing season, causing yields to suffer.

“Although yields varied in northeast Alabama — depending on location, soil type and occasional rainfall that small areas were blessed with — the monthlong drought in June and early July was especially devastating to corn and soybeans,” McGriff said.

3 crops tested

McGriff set up a trial in Fairview to test these crops on irrigated and nonirrigated plots:

All the plots were replicated three times. The location received 6 inches of rain in May and 1 inch June 1, but received only 0.58 inch between June 2 and July 5.

The irrigated plots received 1 inch of overhead irrigation on June 9, 16, 23 and 30 for a total of 4 inches. The plots received 7.39 inches of rain in July, 1.55 inches in August, 5.74 inches in September and 0.75 inch in October.

McGriff had the cotton seed weights, but not yet the gin turnouts or grades as of late November. For his analysis, he assumed 40% gin turnout. He adjusted the corn yields to 15.5% moisture and the soybean yields to 13% moisture.

Cotton is more tolerant to drought conditions than corn or soybeans. Still, nonirrigated cotton in the study suffered yield losses due to the drought.

There was 447.06-pound-per-acre difference between irrigated and nonirrigated cotton. The monthlong drought cost $312.94 per acre at 70 cents per pound.

“Nonirrigated cotton yields in northeast Alabama have ranged from 200 pounds per acre to over three bales,” McGriff said. “This trial illustrated that even nonirrigated cotton with an almost two-bales-per-acre yield would have averaged almost a bale and $300 per acre more with 4 inches of irrigation in June.”

There was a 92.66-bushel-per-acre difference between irrigated and nonirrigated corn. The June irrigations made an additional $453.11 per acre, or 92.66 bushels at $4.89 per bushel, on the corn.

The lack of rain in August also hurt soybean yields. There was 4.96-bushel-per-acre difference between irrigated and nonirrigated soybeans for an additional $53.82 per acre, or 4.96 bushels per acre at $10.85 per bushel.

McGriff plans to recreate the study next year and include subsurface irrigation.

USDA’S estimates

According to USDA’s Nov. 12 crop report, Alabama corn farmers were expected to average 100 bushels per acre, 64 bushels less than last year’s average yield.

Cotton farmers were expected to average 814 pounds per acre, 123 pounds per acre less than the average last year. Soybean’s average yield was forecast to be 28 bushels per acre, 15 bushels less than last year.

According to the 2022 Census of Agriculture released this year, Alabama has 170,537 acres under irrigation. Though the state now has 20% more irrigated acres than the previous survey, irrigated acres in Alabama remain dramatically lower than neighboring Georgia and Mississippi.

Alabama in recent years has started statewide irrigation cost-share initiatives to help farmers install holding ponds and irrigation systems.