Nitrous oxide emissions in Midwest US maize production vary widely with band-injected liquid N fertilizer rates, timing and nitrapyrin presence

Authors: BURZACO, J - Purdue University; Smith, Douglas; VYN, T - Purdue University

Submitted to: Environmental Research Letters
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/7/2013
Publication Date: 8/27/2013
Publication URL: https://handle.nal.usda.gov/10113/59011
Citation: Burzaco, J.P., Smith, D.R., Vyn, T.J. 2013. Nitrous oxide emissions in Midwest US maize production vary widely with band-injected liquid N fertilizer rates, timing and nitrapyrin presence. Environmental Research Letters. 8(2013)035031(11pp). DOI:10.1088/1748-9326/8/3/035031.

Interpretive Summary: Agriculture has been identified as the number one contributor of nitrous oxide emissions, primarily as a result of nitrogen fertilizer applications. Nitrification inhibitors, such as nitrapyrin, theoretically decrease the amount of nitrogen fertilizers lost through nitrification/denitrification processes, which is how nitrous oxide is released from fertilizers. The objective of this research was to determine how fertilizer management (time of application, rate of application and with or without nitrification inhibitor) on nitrous oxide emissions. Field experiments were conducted near West Lafayette, IN. The experiment used three rates of nitrogen fertilizer application, two nitrogen fertilizer timings, and fertilizer with and without nitrapyrin. Increasing the rate of fertilizer increased the nitrous oxide released to the atmosphere. Applying fertilizer before the plants emerged from the soil resulted in 25% lower nitrous oxide releases compared to when fertilizer was applied after the crop was up. The co-application of nitrapyrin resulted in decreases in nitrous oxide losses of about 25% compared to the normal nitrogen fertilizer without the nitrapyrin. These results may provide farmers with practices that may help them decrease the amount of nitrogen lost to the atmosphere, thereby potentially improving the amount of nitrogen available to the crop.

Technical Abstract: Nitrification inhibitors have potential to reduce N2O emissions from maize fields. A new micro-encapsulated formulation of nitrapyrin, optimized to be used with liquid fertilizers became available to US farmers in 2010. Our objectives were to: i) 15assess the impacts of urea-ammonium nitrate (UAN) management practices (timing, rate and nitrification inhibitor) and environmental variables on growing-season N2O fluxes during the maize growing season, and ii) identify UAN treatment combinations that both reduce N2O emissions and optimize maize productivity. Field experiments near West Lafayette, Indiana in 2010 and 2011 examined three N rates (0, 90 and 180 kg N ha-1), two timings (pre-emergence and side-dress), and presence or absence of nitrapyrin. Mean cumulative N2O-N emissions (Q10 corrected) were 0.8, 1.57, and 2.96 kg N2O-N ha-1 for the rates of 0, 90, and 180 kg N ha-1, respectively; 1.49 and 2.06 kg N2O-N ha-1 for pre-emergence and side-dress timings, respectively; and 1.50 versus 2.05 kg N2O-N ha-1 for with and without nitrapyrin, respectively. Yield-scaled N2O-N emissions were significantly affected by the N rate, timing of application, and nitrapyrin treatments. Mean emissions for the 0, 90, and 180 kg N ha-1 rates were 135, 149, and 234 g N2O-N Mg grain-1. Side-dress timing resulted in 27% greater yield-scaled N2O-N emissions than the pre-emergence timing (when averaged across N rates and inhibitor treatments) because environmental conditions were conducive to higher N2O-N emissions after side-dress applications. Yield-scaled N2O-N emissions were also 25% lower with nitrapyrin than without the inhibitor.