Timing of fertilizer application can impact the release of nitrous oxide

Although less abundant than carbon dioxide (CO2) in the atmosphere, nitrous oxide (N2O) has a potential 300 times greater than that as a greenhouse gas. Its effect on global warming, via agriculture, in the off-season, is beginning to be studied in depth by the universities of Illinois and Minnesota in the Midwest of the United States. Everything indicates that the process is linked to the application of fertilizers. Previously all measurements were taken in the growing season.

The first conclusions, now released, show that in seasons without cultivation, the release of nitrous oxide into the atmosphere accounts for 70% to 90% of annual emissions in the so-called American Corn Belt. It remains unclear how accurate the assessment is for the entire Midwest and what management processes and practices contribute to the increase. Using a computer simulation model, researchers are determining the geographic points and climatic factors at times of the most intense emissions. In particular, they analyze the effects of the application time of fertilizers and nitrification inhibitors.

Kaiyu Guan, a professor at the University of Illinois, says the assessment study can simulate the contributions of environmental variations and the timing of nitrogen application to the release of the gas into the atmosphere. If the greatest effect occurs during the off-season, it is already known that it is the result of microbial processes that convert nitrogen from one form to another. Environmental conditions, the amount of moisture and nitrogen in the soil, and its temperature affect the speed at which microbes can metabolize nitrogen, as well as the ability of gaseous nitrogen products to be released.

The researchers say the model can be used to evaluate additional management strategies such as cover cropping and no-till on N2O emissions. "We already have a highly accurate method for estimating emissions in the Corn Belt. We underestimated the non-growing season, which in the end ends up being a very significant portion of the process," Guan explained.

The material above refers to a study by researchers Yufeng Yang; Licheng Liu; Wang Zhou; Kaiyu Guan; Jinyun Tang; Taegon Kim; Robert F. Grant; Bin Peng; Peng Zhu; Ziyi Li; Timothy J. Griffis; and Zhenong Jin. Your article can be obtained from full here.