September 5, 2017 at 3:32 p.m.
Oats finicky, doesn't like too much nitrogen
Yet, they harvested just 170,000 acres, according to the Wisconsin Agricultural Statistics Service. The discrepancy in numbers is due to the widespread use of oats as a nurse crop, to help another crop - such as alfalfa - to become established.
Farmers growing oats need to pay particular attention to the amount of nitrogen they apply to oats, according to Matt Ruark, a University of Wisconsin-Madison soils scientist. He spoke at a recent soil fertility and nutrient management meeting at Sparta, Wis.
Too much nitrogen makes oats more prone to lodging, which can complicate harvesting, Ruark said. And, in fields where soil nitrogen is already high, oats doesn't need more nitrogen.
Here's what Ruark recommends for nitrogen for oats. If a soil contains two to 10 percent organic matter, 40 pounds per acre will do. A sandier soil - one that has less than two percent organic matter in it - can use 60 pounds of nitrogen per acre, when oats are being grown.
If soybeans were grown in a field just before oats, be sure to credit 40 pounds of nitrogen.
"This credit reflects the fact that yields of small grains following soybeans are optimized with 40 pounds less of nitrogen compared to when they're following corn or other grain crops," Ruark said. "This nitrogen credit does not mean that growing soybeans results in an extra 40 pounds of nitrogen in the soil at the end of the season. In fact, the net nitrogen balance during a soybean crop is often zero and can become negative with greater yields."
Researchers - Ruark among them - conducted a study in 2010 and 2011 at the Lancaster Agricultural Research Station, in southwest Wisconsin's Grant County. They looked at the impact of three rates of nitrogen - in the form of ammonium nitrate.
The fertilizer was applied at 40, 80 and 120 pounds per acre, when the oats were 2 inches tall. As a control, some plots did not receive any ammonium nitrate.
Pre-plant nitrate tests showed 85 parts per million in 2010, and 87 parts per million following corn. In 2011, the nitrate amounts were 67 parts per million after soybeans, and 81 parts per million after corn.
So what happened? During 2010, the highest oats yield was achieved after soybeans. That yield was a bit more than 80 bushels per acre, with no nitrogen applied.
But in 2011, oats after corn yielded the most. That yield was approximately 115 bushels, some 25 bushels higher than the yield for oats after soybeans.
Lots of lodging occurred during 2010. Ruark called the amount of lodging in all the plots at Lancaster "severe." But it was lowest where no nitrogen was applied, and when oats were grown after soybeans.
Moving to 2011, the soils scientist said the amount of lodging increased. It was measured at more than 80 percent when 80 pounds of nitrogen were applied per acre. By contrast, the amount of lodging fell to less than 30 percent when the oats received no nitrogen.
Summing up, Ruark said, "Small grains are excellent to grow to increase the length of your crop rotation. But it's important to select your nitrogen rates wisely."[[In-content Ad]]
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