The land is desolate between wheat crops in the central Great Plains. Traditionally, farmers leave the soil bare every other year because there isnt enough water for an annual crop. The average rainfall in this area is only 16.5 inches a year.
With the help of research, however, farmers are increasingly finding ways to delay fallow to every third or fourth year.
They do this by leaving crop residues in place after harvest. This reduces evaporation and stores more precipitation in the soil for the next crop.
But crops need to be rotated to minimize disease and pest problems. Sunflowers could be one of these new crops for the central Great Plains, earning farmers money while protecting soil from blowing away in spring winds that easily exceed 30 miles per hour.
David C. Nielsen, an agronomist with the Agricultural Research Service in Akron, Colorado, finds that if sunflower stalks are left about 30 inches high after harvest, they almost completely prevent soil loss. When the inevitable winter blizzards arrive, the beheaded stalks act like snow fences, trapping 3 to 10 times more snow than would normally accumulate.
"When this snow melts, it replenishes 3 to 9 inches of soil water," Nielsen says. "Depending on snowfall amounts and wind speeds, this can recharge about 30 to 95 percent of the water sunflowers use, making the practice worthwhile for farmers. They should earn more money, even when yields of wheat or other rotated crops are lower because of the water used by the sunflowers."
Nielsen says sunflowers dry a soil out down to 6 feet in the Great Plains. "But that's good because as the sunflowers use the water that is too deep to be used by other crops, they also capture nitrogen, reducing chances of groundwater pollution."
"While wheat may dry a soil down to 8 percent moisture by volume, sunflowers dry it down to 3 or 4 percent," he says.
Nielsen has found that yields are best when sunflowers are rotated in every 4 years rather than every 3. "We think that's because growing sunflowers less frequently breaks disease and pest cycles. And without disease, there's a greater chance of the sunflower stalks standing up through the entire winter and next spring."
Rotating in other crops like sunflowers also helps farmers diversify.
"They're not so tied to weather conditions in a particular year," Nielsen says. "This year's a good example. There was a drought while winter wheat was growing. Then, wouldn't you know it, it rained as soon as the wheat was harvested, and rainfall was better than average when the sunflowers were planted and grown." — By Don Comis, Agricultural Research Service Information Staff.
"Sunflowers Add Variety to the Great Plains" was published in the February 1999 issue of Agricultural Research magazine.