People constantly wonder why they need to apply nitrogen fertilizer each year. Scientists at Cornell University have been researching this using recent technological advances in measuring gaseous nitrogen emissions in home lawns.
High soil moisture, low soil oxygen and sufficient nitrogen (a very common situation in carefully managed turf areas in NC) lead to the process of denitrification, which occurs in small areas during brief times. The Cornell researchers used this sophisticated technology to determine that denitrification is an important pathway for removing excess nitrogen from lawns. Annual loss was about 15% of the total applied. They determined that while small amounts of nitrogen were transported to groundwater and streams, the majority of fertilizer nitrogen inputs were retained in lawn soils.
Source: November/December issue of Journal of Environmental Quality