COLLEGE STATION — New ways of predicting the natural release of nitrogen from decaying plants and animals in soils may lower fertilizer use and protect water sources, according to a new study published by the Texas Water Resources Institute.
The study, Soil Nitrogen Mineralization Potential for Improved Fertilizer Recommendations and Decreased Nitrate Contamination of Groundwater, was co-authored by Dr. Frank Hons, Texas Agricultural Experiment Station soil fertility scientist, and graduate students Richard Haney and Alan Franzluebbers.
Nitrogen mineralization, the natural release of nitrogen from decaying soil organic matter, occurs throughout the year. But the amount of nitrogen released can vary based on soil types, climate and management techniques used by farmers. The concern is that groundwater quality can decrease if too much nitrogen, converted to nitrate, is available in soils.
“Nitrogen is one of the tools farmers use most often to improve crop yields, but it can also pose threats to water quality,” Hons says. “So, it’s important to be able to specify how much nitrogen needs to be applied in forms growing crops really need. If you can accurately estimate nitrogen mineralization, there’s a much better likelihood that excess applications of nitrogen can be avoided and environmental threats can be minimized.”
The researchers evaluated different existing methods and developed new and improved techniques to measure nitrogen mineralization. This included gathering surface and subsurface agricultural soil samples from College Station, Corpus Christi, Overton and Stephenville.
They then used a variety of techniques to measure nitrogen mineralization, including short- and long-term aerobic laboratory incubations, arginine ammonification and carbon mineralization. Results suggest that measuring carbon dioxide emissions from soils that have been air-dried and later rewetted is a rapid, reliable way to measure potential nitrogen mineralization. Measuring carbon dioxide evolution was correlated to mineralization and was directly related to microbial activity in soils.
Hons says this research could have a number of practical benefits to agricultural producers.
“Widespread use of this method could provide more accurate and more rapid estimates of nitrogen and carbon mineralization in different soils. By using this information, agricultural producers can apply precisely enough nitrogen fertilizer to maximize yields, while decreasing water pollution risks,” he said.
The report is available free by contacting TWRI at (979) 845-8151 or “TWRI@tamu.edu”