Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: February 24, 2011
Publication Date: February 24, 2011
Citation: Venterea, R.T. 2011. The leaking soil nitrogen cycle and rising atmospheric N2O: Is there anything we can do to cap the well?[abstract]. University of California Sustainable Agriculture Research and Education Program, Nitrogen Speaker Series, February 24, 2011. Abstract No. 022411. Technical Abstract: Nutrient management refers to the addition and management of synthetic or organic fertilizers to soils primarily for purposes of increasing the supply of nutrients and efficiency of crop nutrient uptake in order to improve yields while minimizing environmental impact. Nitrogen (N) is generally the most important nutrient from an agronomic standpoint because it is usually the primary nutrient limiting crop yields and usually must be added more often and in greater amounts than other nutrients such as phosphorus (P) and potassium (K). Nitrogen is also the primary nutrient of concern with regard to GHG emissions because once fertilizer N enters the soil it can be directly converted to N2O by soil biological processes and, in some cases, chemical reactions. Emissions of N2O are generally a large component of the total GHG budget of croplands because N2O is 300 times better than CO2 at absorbing long-wave radiation. Other forms of N originating from N fertilizers may also be lost to the environment, including ammonia (NH3), nitric oxide (NO), and nitrate (NO3-). Once transported to downwind or downstream ecosystems, these other N forms can be subsequently converted to N2O; such emissions are referred to as “indirect” N2O emissions. Fertilizer rate, timing, placement, and formulation have impacts on N2O fluxes. In general, any practice that increases crop N use efficiency (NUE) would be expected to reduce N2O emissions, because applied N that is taken up by crops or cover crops is not available to soil processes that lead to N2O emissions, at least in the short term. Additionally, specific practices can also reduce N2O emissions independent of NUE impacts. This section provides of summary of the most important factors related to nutrient management that need to be considered in efforts to develop entity-scale estimates of GHG emissions. This information will be useful to agricultural producers and regulatory agencies involved in GHG estimation activities.