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 N 2 O 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 N 2 O emissions in turf soils. The objectives of this study were (i) to quantify the magnitude and patterns of N 2 O emissions in turfgrass, and (ii) to determine how irrigation and N fertilization may be managed to reduce N 2 O 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, N 2 O 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 N 2 O 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 N 2 O emissions in turfgrass.