Submitted to: National Conservation Tillage Cotton and Rice Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 10/30/2015
Publication Date: 1/12/2016
Citation: Torbert III, H.A., Watts, D.B., Runion, G.B. 2016. Enhanced efficiency fertilizer’s effect on cotton yield and greenhouse gas emissions. National Conservation Tillage Cotton and Rice Conference Proceedings. CDROM.
Technical Abstract: Interest in the use of enhanced-efficiency nitrogen fertilizer (EENFs) sources has increased in recent years due to the potential of these new EENF sources to increase crop yield, while at the same time decreasing N loss from agricultural fields. Nitrogen is the most essential nutrient needed to optimized crop yield and economic return. However, N use efficiency of most fertilizer is just 30 to 50%. Recent development of EENFs to reduce excessive N loss are presently being marketed for agricultural production. The efficacy of these fertilizer sources on cotton (Gossypium hirsutum L.) production in southeastern U.S. upland soils has not been well documented. Thus, a field study was conducted on a Coastal Plain soil (Marvyn loamy sand; fine-loamy, kaolinitic, thermic Typic Kanhapludult) in Central Alabama from 2009 to 2011 to compare EENFs to traditional N sources in a high-residue conservation cotton production system. The nitrogen fertilizer sources evaluated included urea (U), ammonium sulfate (AS), urea ammonium sulfate (UAS), Environmentally Smart Nitrogen (ESN) (Agrium Advanced Technologies, Loveland, CO), stabilized urea (SuperU [SU] [Agrotain International, St. Louis, MO]), poultry litter (PL), poultry litter + AgrotainPlus (PLA) (KOCH Agronomic Services LLC, Wichita, KS), and an unfertilized control (C). This study is the first to demonstrate the impact of using EENF sources for top-dressing in a cotton production system in the Coastal Plain Region of the United States. Generally, EENF use did not show an advantage or disadvantage to traditional fertilizers in this study. While differences in lint fiber yield and quality among N sources were observed in this study, they was a lot of variability among years, most likely due to weather. Furthermore, lint quality for all of the fertilizer sources generally were not in the discounted range for cotton fibers, suggesting that these differences will not likely influence net return. From a monetary standpoint, EENF use may not be economically advantageous. However, if EENFs can reduce N loss from agricultural fields they could be environmentally important. Agricultural soil can contribute to GHG emissions, particularly N2O following N fertilization. But, the effect of EENFs on greenhouse gas (GHG) emissions from different agricultural systems is not well understood. This study also evaluated EENF efficacy for reducing GHG emissions in a Coastal Plains soil under cotton production. Greenhouse gas emissions increased following rainfall. Poultry litter additions tended to increase daily and cumulative seasonal CO2 fluxes compared with other N sources regardless of whether PL or PLA was applied. Differences in cumulative N2O flux among N sources were minimal as a result of high temporal and spatial variability among treatments. Methane fluxes were higher in 2009, the wettest year, however, N treatments minimally impacted CH4 flux. Evaluating GWP showed that CO2 was the primary driver, which resulted in PL and PLA having the highest impact with the control, UAS, ESN, and SU being lowest. Results suggest that PL application to cotton increases GHG flux, but GHG flux reductions from EENFs were infrequently different from standard inorganic fertilizers, suggesting their higher cost may render them impractical. These results show that EENFs may not provide any environmental advantage over standard inorganic fertilizer sources when applied to cotton in humid southeastern US regions. More research is needed to evaluate the effects of EENF in cropping systems such as corn or wheat that use higher N rates to determine their effectiveness in reducing GHG emissions.