Nitrous Oxide Emissions from Turfgrass Receiving Different Irrigation Amounts and Nitrogen Fertilizer Forms

Nitrous oxide is an important greenhouse gas associated with global climate change. Turfgrasses emit N2O when fertilized with N and irrigated. The development of management practices such as use of controlled-release N fertilizers and/or deficit irrigation may reduce N2O emissions in turf soils. The objectives of this study were (i) to quantify the magnitude and patterns of N2O emissions in turfgrass, and (ii) to determine how irrigation and N fertilization may be managed to reduce N2O fluxes. Nitrous oxide emissions were measured for 2 yr in 'Meyer' zoysiagrass (Zoysia japonica Steud.) under an automated rainout shelter in Manhattan, KS, using static chambers. Two irrigation levels (66 [medium] and 33% [low] reference evapotranspiration replacement), and three N fertilization treatments (urea and polymer-coated urea [PCU], both applied at a rate of 98 kg N ha(-1) yr(-1), and an unfertilized plot) were included. During two summers, N2O emissions were reduced by 6% with low (2.71 kg ha(-1)) vs. medium irrigation (2.88 kg ha-1) (P <= 0.001). Over the 2 yr, cumulative N2O emissions averaged 4.06 kg ha(-1) in unfertilized turf and 4.5 kg ha(-1) in PCU-treated turf, which represent reductions of 28 and 20%, respectively, from urea-treated turf (5.62 kg ha(-1)) (P <= 0.01). Results from this study indicate that the use of a controlled-release fertilizer, such as PCU, and/or lower irrigation reduces N2O emissions in turfgrass.