Controlled-release shows positive N2O effect

Ft. Collins, Colo.-USDA’s Agricultural Research Service (ARS) is testing at least three controlled-release or stabilized specialty fertilizer brands to determine the effects of nitrogen sources on nitrous oxide emissions, Green Markets has learned. According to ARS at Ft. Collins, researchers at eight laboratories are using Agrium Inc.’s ESN and Agrotain International’s SuperU and UAN plus AgrotainPlus in their N2O analyses. The labs are located at Pullman, Wash.; Ames, Iowa; St. Paul, Minn.; Auburn, Ala.; Bowling Green, Ky.; University Park, Penn.; and Ft. Collins, Colo. “Our efforts are directed at determining if climates, precipitation differences, soil types, and cropping systems influence nitrous oxide emissions from these enhanced efficiency fertilizers,” explained Ardell Halvorson with the Soil Plant Nutrient Research Unit at Ft. Collins. “Use of controlled release and stabilized N sources reduced N2O emissions under no-till when compared to urea and UAN fertilizer sources. Results of this work indicate that there are crop and fertilizer N management alternatives to reduce N2O emissions from irrigated systems.” Summarizing one of his tests, Halverson wrote that granular urea had the greatest growing season N2O emission, followed by UAN, Duration III, and ESN, with the SuperU and UAN+AP treatments having the lowest N2O emissions. When compared to urea, the controlled release ESN and stabilized N (SuperU) sources reduced N2O emissions 33 and 48 percent, respectively, in this irrigated NT-CC production system. Addition of AgrotainPlus to the UAN solution reduced N2O emissions 35 percent when compared to UAN alone. Application of SuperU resulted in a 29 percent reduction in N2O emissions compared with UAN alone. The check (no N applied) treatment had the lowest level of N2O emissions during the growing season. These data indicate that selection of N source can have an impact on N2O emissions from irrigated, no-till production systems. Producers managing their cropping systems to reduce N2O emissions need to consider using the controlled release and stabilized N sources along with no-till. No-till has been shown to reduce carbon dioxide emissions and increase soil organic matter.