Soil Drainage Effects on N2O Emissions from a Colorado Golf Course Using Controlled Released Fertilizers.

Due to high potency, recent rapid accumulation in atmospheric concentrations and lack of significant surface sinks, N2O is one of the most important GHGs of the 21st Century. Turfgrass systems have been quantified as a source of N2O however fertilizer technologies that use different mechanisms to control the release of N substrate may reduce N2O emissions. Yet further investigations are needed to test the effectiveness of these products under a variety of conditions. Two fertilizers that use two different mechanisms to control the release of N, UMaxx ® and Polyon ®, were applied at a rate of 150 kg ha-1 yr-1 to a golf course fairway and rough in three seasonal applications (50 kg ha-1 each) at a poorly-drained (PD16) and well-drained (WD5) field site. Soil drainage characteristics were based on soil bulk density and water filled pore space (WFPS). Soil WFPS at PD16 fairway and rough often exceeded 60% during the summer producing peak fluxes from UMaxx treatments of 2025 and 995 g N2O–N g ha-1 day-1, with emissions totaling 20.1 and 14.9 kg N2O-N ha-1 yr-1, respectively. Annual emissions from WD5 fairway and rough UMaxx treatments totaled 8.9 and 2.3 kg N2O-N ha-1 yr-1, respectively. Polyon treatments were more resistant to N2O fluxes across drainage sites and emissions did not exceed 2.8 kg N2O-N ha-1 yr-1. Polyon uses a temperature controlled barrier to diffusion that was more resistant to N2O losses during conditions that favored denitrification, whereas the nitrification and urease inhibitors formulated for UMaxx were less effective.