Abstract: Effects of Nitrapyrin, N Rates and N Timing On N2O Emissions in Maize Fertilized with UAN. (ASA, CSSA and SSSA Annual Meetings (Cincinnati, OH- Oct. 21

291-8 Effects of Nitrapyrin, N Rates and N Timing On N2O Emissions in Maize Fertilized with UAN.

See more from this Division: S06 Soil & Water Management & Conservation
See more from this Session: Nitrogen-Use Efficiency, Nitrogen Leaching, and Nitrous Oxide Emissions As Influenced by Management Practices: I

Tuesday, October 23, 2012: 10:05 AM

Duke Energy Convention Center, Room 202, Level 2

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Juan Burzaco¹, Douglas Smith² and Tony Vyn¹, (1)Purdue University, West Lafayette, IN
(2)National Soil Erosion Research Laboratory, West Lafayette, IN

Agricultural soil management has been identified as the largest single source of N₂O emissions in the US. The use of nitrification inhibitors is one of several management practices that show potential to reduce the amount of N₂O released from agricultural fields. Since 2010, a reformulation of nitrapyrin (Instinct^TM), optimized to be used with liquid fertilizers and manure, has been made available to farmers. Our objectives were to assess: i) the impact of N management practices (timing, rate and nitrification inhibitor) and environmental variables on N₂O fluxes, and ii) which combination of treatments presents the best alternative to both reduce N₂O emissions and increase maize productivity. Field experiments in 2010 and 2011 included three N rates (0, 90 and 180 kg N ha^-1), two timings (pre-plant and side-dress), and with or without nitrapyrin (Instinct^TM,Dow Agrosciences LLC, Indianapolis, IN). The experiment was conducted on a dark prairie soil at Purdue University Agronomy Center for Research and Education (ACRE) (40°28'07'' N, 87°00'25'' W) near West Lafayette, Indiana. Gas samples were collected on a 7-10 day intervals, following planting. To avoid over-estimation of cumulative N₂O-N emissions, the observations were corrected by the daily mean soil temperature by estimating a Q10 factor.

Daily N₂O-N fluxes were increased by each N rate increment, while nitrification inhibitor use reduced N₂O-N emissions significantly. The cumulative N₂O-N emissions were significantly affected by the N rate, timing of N application and nitrapyrin presence. The mean cumulative emissions 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; 1.49 and 2.06 kg N₂O-N ha^-1 for the pre-emergence and side-dress timings, respectively; and 2.05 and 1.50 kg N₂O-N ha^-1 for without and with nitrapyrin, respectively. Average grain yields increased ca. 40% in response to the 90 kg/ha rate, and a further 23 % in response to the 180 kg/ha N rate. Yield-scaled N₂O-N emissions were significantly affected by the N rate, timing of application, and nitrapyrin. The emissions for the 0, 90, and 180 kg N ha^-1 rates were 135, 149, and 234 g N₂O-N Mg grain^-1. Overall N rates and inhibitor treatments, side-dress timing resulted in 27% higher yield-scaled N₂O-N emissions than the pre-emergence timing even though grain yields with sidedress N applications were at least as high as those pre-emergence N applications . Yield-scaled N₂O-N emissions were 25% lower with nitrapyrin than without the inhibitor.