Send in the nutrient scavengers
Research confirms that more than 50% of nitrogen (N) applied to wheat crops is not recovered in plants at harvest. Research also shows the remaining N in many soils across the U.S. washes below the root zone before next year’s crop is planted.
This data applies to regions where farmers traditionally plant one crop per year. This leaves the fields fallow over winter, exposed directly to the elements.
Leaving fertilizer behind has serious financial and environmental consequences. That’s why researchers are exploring ways to more fully utilize the inputs they apply.
“There does not appear to be a single silver bullet on the horizon,” says Lucas Patzek, a Washington State University (WSU) agricultural Extension faculty member who has been studying N use in wheat production. “Instead, we see that the real solution to this problem lies in approaching it from two directions.”
In the short-term, this means developing and promoting cropping systems that integrate a nutrient-scavenging component in their rotation.
Long-term, it means identifying wheat varieties that use N more efficiently. These would function as foundation stock for breeding programs that focus on varieties with improved uptake and lower N requirements.
Double Cropping For Nutrient Recovery
Ken Miller operates a 2,000-acre wheat and cattle ranch in central North Dakota near Fort Rice. In recent years, he has experimented with cropping systems that help him recover unused N left in the soil after wheat and corn harvest.
“With the cost of inputs going up, it just makes good sense to reduce them as much as possible,” says Miller. “Planting a second crop right after my grain harvest has worked particularly well for me.”
He cites a stand of spring wheat he planted under irrigation in 2011. He applied the recommended 100 pounds per acre of N. After harvest at the end of August, Miller direct-seeded a second crop of cool-season annuals that included field peas, lentils, hairy vetch, clover, turnips, radishes, and Italian ryegrass.
“In most years, my wheat comes off in the beginning of August,” he says. “That puts the blend in the ground 30 days earlier.”
Miller says that under normal circumstances this second crop would be intensively grazed in October.
“When it goes in at the beginning of August, it is waist-high at the end of September,” says Miller. “That’s when I really get a tremendous amount of forage.”
He says the gain he usually sees in animal-production units equals his production costs, plus a nice profit. “But because of my late start and the fact that I had a surplus of quality grazing ground last year, I didn’t bother running the cattle through that field,” says Miller.
In the spring of 2012, Miller planted corn. Normally, he broadcasts 100 pounds of N per acre at seeding on top of 300 to 350 pounds per acre of broadcast fertilizer. Last year, though, he sliced the broadcast rate to 100 pounds.