Nitrous Oxide Emissions from Bermudagrass Turf Fertilized with Slow Release and Soluble Nitrogen Sources

Nitrous Oxide Emissions from Bermudagrass Turf Fertilized with Slow Release and Soluble Nitrogen Sources

Project Leader: Dale Bremer, Kansas State University, Department of Horticulture, Forestry & Recreation Resources, 2021 Throckmorton Plant Sciences Center, Manhattan, KS 66506. Telephone: 785-532-1429.
E-mail: bremer@ksu.edu

Project Cooperators: Jack Fry and Jason Lewis

Nitrous oxide (N₂O) is an important greenhouse gas (GHG) and the majority of emissions in the USA are from agriculture. Most of this comes from the soil and is linked to soil management and nutrient use. Although most attention given this issue has been focused on production agriculture, an important component that is often overlooked relates to the contributions from turfgrass areas. One estimate indicates that there are about 40 to 50 million acres of urbanized land covered with turfgrasses (e.g., golf courses, lawns, parks, sport fields). Because turfgrasses often receive fertilizer N, these areas have the potential for significant contribution to overall N₂O emissions. One best management practice (BMP) that may help achieve the goal of reduced GHG emissions from turf is the use of controlled release N fertilizers. The objective of this work is to quantify N₂O emissions from bermudagrass turf fertilized with a conventional soluble N fertilizer (urea), a slow-release polymer coated N fertilizer, and an organic (manure) source of N.

Emissions of N₂O increased after application of each of the N fertilizer sources in 2007. Emissions from urea, however, were sometimes higher than either of the slow-release sources. In general, N₂O emissions returned to pre-fertilization levels among treatments after 7 to 10 days. Cumulative emissions of N₂O during the first year were statistically similar among N sources. However, numerically, emissions were highest from urea and lowest from the organic source. Emissions also tended to increase after irrigation or precipitation. The relationship between soil temperature and N₂O emissions was weaker than between soil moisture and emissions, although emissions were lower during winter when soils were colder. There were no significant correlations between N₂O emissions and soil ammonium and nitrate levels.

Strict interpretation of the first year data indicates that fertilizer source did not affect overall N₂O emissions from turfgrass. But, variability is high in this type of data collection and thus complicates statistical detection of differences among treatments. Additionally, emissions of N₂O from turfgrass are complex, and likely are affected partially by all factors including fertilizer type, soil moisture level, temperature, and N level. KS-37F