van Kessel, CClough, Timothyvan Groenigen, J-W2010-04-232009-032009van Kessel, C., Clough, T., & van Groenigen, J. W. (2009). Dissolved organic nitrogen: An overlooked pathway of nitrogen loss from agricultural systems? Journal of Environmental Quality, 38(2), 393-401.0047-242519202010 (pubmed)https://hdl.handle.net/10182/1736Conventional wisdom postulates that leaching losses of N from agriculture systems are dominated by NO₃⁻. Although the export of dissolved organic nitrogen (DON) into the groundwater has been recognized for more than 100 yr, it is often ignored when total N budgets are constructed. Leaching of DON into stream and drinking water reservoirs leads to eutrophication and acidification, and can pose a potential risk to human health. The main objective of this review was to determine whether DON losses from agricultural systems are significant, and to what extent they pose a risk to human health and the environment. Dissolved organic N losses across agricultural systems varied widely with minimum losses of 0.3 kg DON ha⁻¹yr⁻¹ in a pasture to a maximum loss of 127 kg DON ha⁻¹yr⁻¹ in a grassland following the application of urine. The mean and median values for DON leaching losses were found to be 12.7 and 4.0 kg N ha⁻¹yr⁻¹, respectively. On average, DON losses accounted for 26% of the total soluble N (NO₃⁻ plus DON) losses, with a median value of 19%. With a few exceptions, DON concentrations exceeded the criteria recommendations for drinking water quality. The extent of DON losses increased with increasing precipitation/irrigation, higher total inputs of N, and increasing sand content. It is concluded that DON leaching can be an important N loss pathway from agricultural systems. Models used to simulate and predict N losses from agricultural systems should include DON losses.pp.393-401Electronic-PrintenCopyright © 2009 American Society of Agronomy, Crop Science Society of America, and Soil Science Society of Americanitrogenleachingdissolved organic nitrogengroundwaterHumansNitratesNitrogenSoilWater Pollutants, ChemicalWater Pollution, ChemicalAgricultureTerminology as TopicJournal ArticleMarsden::300103 Soil chemistry10.2134/jeq2008.02771537-2537ANZSRC::31 Biological sciencesANZSRC::37 Earth sciencesANZSRC::41 Environmental scienceshttps://creativecommons.org/licenses/by-nc-nd/4.0/Attribution-NonCommercial-NoDerivatives