Nitrapyrin Reduced Nitrous Oxide Emissions from Beef Cattle Urine Patches on a Semiarid Tame Pasture

Abstract

Core Ideas Limited data are available about mitigating N2O emissions from urine patches on semiarid pasture. Nitrapyrin reduced cumulative N2O emissions by 39% in a dry season. Nitrapyrin reduced cumulative N2O emissions by 58% in normal precipitation season. NBPT and NBPT plus DCD did not limit N2O emissions compared with untreated urine patches. N2O emission factors ranged from 0.03 to 0.21% over two grazing seasons Urease and/or nitrification inhibitors applied to urine patches or pastures may increase N retention in the soil–plant system, but how N2O emissions respond to these N stabilizers in semiarid regions is poorly understood. The objectives of this research were (i) to quantify N2O emissions and the associated emission factors, based on the percentage of applied urine‐N emitted as N2O–N, from beef cattle urine patches (urine) and (ii) to test the N2O reduction potential of three N stabilizers [2‐chloro‐6(trichloromethyl) pyridine (nitrapyrin), N‐(n‐butyl)‐thiophosphoric triamide (NBPT), and NBPT plus dicyandiamide (DCD)] on a semiarid tame pasture over two grazing seasons in western Canada. A deionized water control was also included. Nitrapyrin reduced cumulative N2O emissions by 39% and the N2O emission factor by 50% compared with untreated urine in a dry grazing season and reduced cumulative N2O emissions by 58% and the N2O emission factor by 68% compared with untreated urine in a grazing season with normal precipitation. The NBPT and NBPT + DCD had similar cumulative N2O emissions compared with untreated urine patches. The N2O emission factors ranged from 0.03 to 0.08% over 103 d in 2015 and from 0.06 to 0.21% over 119 d in 2016, all lower than the 2% Intergovernmental Panel on Climate Change default 365‐d value. Extrapolating over 1‐yr periods, N2O emission factors ranged from 0.11 to 0.64%. Based on the N stabilizers tested, nitrapyrin most effectively reduced N2O emissions from beef cattle urine patches on a tame pasture in a nonirrigated semiarid region of Canada.