Nitrous Oxide Emissions and Nitrate Leaching From Non-Irrigated Turf Managed With Synthetic and Organic Nitrogen Sources.

Identifying best management practices for turfgrasses while achieving environmental sustainability is imperative. It remains unclear if the use of organic fertilizers poses less environmental concern than synthetic fertilizers. Research is needed in order to determine the environmental fate of the products.  The objectives of our study were to compare the contribution to NO₃^- leaching, and N₂O emissions of five turfgrass management programs that include synthetic and organic products.  Stands of turfgrass composed of either of a seed mixture of Poa pratensis L., Lolium perenne L., and Festuca rubra L. spp. rubra or a transplanted mature P. pratensis sod were established during August of 2010 in Madison, WI, on a silt loam soil in a randomized complete block design with four replications.  Nitrous oxide emissions from fertilized treatments were not significantly different than the unfertilized control on 64 of the 89 total dates of observation.  On three sampling dates the synthetic fertilizer program resulted in less nitrous oxide emissions than the treatments managed with an organic fertilizer.  The treatment that utilized an organic fertilizer did not result in less N₂O emissions than the synthetic fertilizer on any single date during the two years of observations.  There was a significant difference in mean flow-weighted nitrate leaching between years but not among management programs, establishment methods, or any of the interactions.  In the absence of an irrigation program the use of an organic product did not reduce environmental concerns, while the majority of the N₂O emissions and nitrate leaching appear to be a result of natural nitrogen cycling from sources other than fertilization.