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Fluid Journal : Late Spring 2013
10 The Fluid Journal Late Spring 2013 Summary: Nitrogen (N) application to crops generally results in increased nitrous oxide (N2O) emissions. Commercially available enhanced-efficiency N fertilizers were evaluated for their potential to reduce N2O emissions from a clay loam soil compared with conventionally used granular urea and urea-ammonium nitrate (UAN) fertilizers in an irrigated strip-till (ST) corn production system. All other N sources had significantly lower growing season N2O emissions than granular urea, with UAN + AgrotainPlus and UAN + Nfusion having lower emissions than UAN. Similar trends were observed when expressing N2O emissions on a grain yield and N uptake basis. Loss of N2O-N per kilogram of N applied was <0.8% for urea and <0.5% for all other N sources. Corn grain yields were not different among N sources but greater than treatments with no N applied. N selection can be a mitigation practice for reducing N2O emissions in irrigated corn. The Fluid Journal • Official Journal of the Fluid Fertilizer Foundation • Late Spring 2013 • Vol. 21, No. 3, Issue # 81 Drs. Ardell Halvorson, Stephen Del Grosso, and Claudia Jantalia Nitrous oxide has a global warming potential (GWP) approximately 298 times greater than that of CO2, thus the importance of developing methods to reduce N2O emissions in agricultural systems. Nitrogen fertilization has been essential for optimizing crop yield and economic returns in irrigated cropping system in the U.S . Central Great Plains. Data available for analyzing impacts of N2O emissions on net GWP in irrigated crop production systems are limited, however. More research on enhanced- efficiency N fertilizers is needed to thoroughly evaluate their agronomic impact and effects on N2O losses. The main objectives of this study were: • Study the effects of the following enhanced-efficiency N fertilizers (1) controlled release polymer- coated urea (ESN), (2) stabilized granular urea (SuperU), (3) stabilized UAN (UAN + AgrotainPlus), and (4) slow-release UAN (UAN + Nfusion) on growing season N2O emissions compared with those from conventionally-used granular urea and liquid UAN applications within an irrigated strip-till (ST) continuous corn production system • Evaluate the possible agronomic benefits of the enhanced-efficiency N fertilizers on grain yield and N uptake, and relate N2O emissions from each N source on a grain yield and N uptake basis. Results/Discussion Environmental. Air and soil temperatures at each greenhouse gas emission (GHG) sampling date in 2009 and 2010 are shown in Figure 1. Both years, soil temperatures were cooler Nitrogen Source Effects on Soil Nitrous Oxide Emissions during May and early June (DOY 121 – 160) than the main part of the growing season, with cooler soil temperatures during May 2010 than during May 2009, but warmer temperatures, starting in June through most of the growing season, in 2010 than in 2009. With crop canopy closure in late June, soil temperature rose to ~20o C and then declined starting in September. Soil temperatures, during the December 2009 through February 2010 sampling period, were generally <0oC, with an increase in soil temperature starting in early March. Air temperatures in early May were generally cooler in 2010 than in 2009. Precipitation and irrigation amounts in 2009 and 2010 are shown in Figure 2. Total 2009 yearly precipitation was 341 mm, with the May through October corn growing season totaling 259 mm. In 2009, 397 mm of irrigation water was DOWNLOAD PDF
Early Spring 2013