As weather patterns change, some farmers are finding they are losing more nitrogen from their fertilizers to the surrounding environment. In many cases, this is due to increased and unseasonal rainfall, followed by long dry spells and warmer winters.
"We've just come to more uncertain conditions, which is not an uncommon thing, said Elwynn Taylor, climatologist and agronomist at Iowa State University.
"If we look at the history of corn yields since we started keeping records in the 1860s, we have had four 25-year periods of highly variable corn yields because of variability in the weather, Taylor noted. "Those four periods were separated by four 18-year-long periods of consistent crop yields. I believe what we're seeing is the beginning of a period of variable yields and weather.
An increase in weather volatility means that bacteria and other microorganisms can become more active earlier than normal.
"We might get this really warm weather that we usually don't have where the soil temperature goes up into the 50s in December, Taylor said. "Microorganisms in the soil can begin to convert nitrogen to a form that can be lost. Usually if you put on nitrogen in the fall, it will remain with the crop and not be lost to microorganisms in the winter months.
Kurt Seevers, technical services manager with Verdesian Life Sciences, agrees. "Increased temperatures allow soil bacteria that contribute to nitrogen loss to be active for longer periods of time, he said. "Variability in rainfall may also play an increasing role in nitrogen loss, if we see heavy rains like we've had in some areas of the country the past couple of years. A combination of these factors could increase the likelihood of nitrogen loss.
Nitrogen loss can lead to reduced yields and increase the potential for disease pressure due to less vigorous plants. Lost nitrogen can end up in ground water if it leaches from the root zone as nitrate, or it can enter the air as ammonia which isn't good for crops.
Up to half of nitrogen applications can be lost through three main causes: leaching, volatilization and denitrification. It's important farmers do something to protect their profitability and crops from a more volatile environment. Using a nitrogen stabilizer is one effective method.
"The use of nitrogen stabilizers is a common way to address potential nitrogen loss, Seevers said. "Most work by reducing or eliminating the activity of the bacteria or enzymes responsible for metabolizing nitrogen into forms that are lost to volatilization or leaching, or are more readily tied up in the soil.
Ryan Bond, Ph.D., vice president of marketing and technical development for Verdesian, said farmers need to be aware that not all products guard against all three types of nitrogen loss.
"NutriSphere-N addresses volatilization, leaching and denitrification, Bond said. "When the product is part of a nutrient management program, it will provide the best way for growers to minimize the loss of their nitrogen investment.
Taylor agrees that due to the volatile weather conditions, nitrogen management products may be necessary. "With changing temperatures, microorganisms become more active in the soil. Nitrogen stabilizers protect your investment by giving your crop more opportunity to use those nutrients before the microorganisms do."
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