N2O Emissions From Cotton Treated With Nutrisphere-N.

The effects of increasing atmospheric greenhouse gases (GHGs) on potential climate change are being widely debated. Of the three biogenic GHGs (i.e., carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (N₂O)), N₂O is considered to be the most potent. It has been estimated that in California, agricultural soils accounts for 64% of the total N₂O emissions. California’s San Joaquin Valley (SJV) is among the major producers of cotton in the United States. The objective of this study was to determine N₂O fluxes for cotton fertilized with Urea Ammonium Nitrate applied with and without Nutrisphere-N nitrification inhibitor. Nutrisphere-N inhibits nitrification and urease activity by complexing with soil copper ions and nickel ions within the urease enzyme respectively. Flux chamber measurements were conducted using an Environmental Protection Agency approved methodology to collect air samples which were ultimately analyzed using a Gas Chromatograph. In 2011, N₂O emissions were influenced by Nitrogen fertilizer rates and irrigation events. For example, field measurements of N₂O fluxes ranged from less than 240 to 960 µg N/m²/d for plots receiving 50 to 100lbs N/acre, respectively. After an irrigation event, these fluxes ranged from 480 to 1920 ugN/m²/d. Nutrisphere – N reduced N₂O fluxes as much as 50% during fertilizer application and irrigation events. In 2012, it was evident that in addition to the soil and crop management practices, N₂O fluxes were influenced by the crop growth stages. However, there was no significant difference in crop yield between plants treated with and without Nutrisphere-N. Nonetheless, the potential for this nitrification inhibitor to mitigate N₂O emissions needs to be investigated further during various physiological growth stages for cotton cropping systems in SJV.