CONTEXTEffective nitrogen (N) management is an essential aspect of productivity and sustainability of corn silage (Zea mays L.) production in New York (NY) dairy systems. Implementing end-of-season evaluations for N use can help farms identify opportunities to refine N management over time, and support field experimentation through the NY adaptive N management process. OBJECTIVESThe objectives of this study were to (1) define operational or feasible outcome values for end-of-season field N use efficiency (NUE) indicators in NY corn silage production, (2) characterize NUE indicators across a dataset of field observations, and (3) delineate complementary graphical tools and numerical indicators to identify opportunities for N management refinement over time. METHODSData were collected for 994 corn silage field*year observations (10,048ha) across eight NY dairies. For each observation, N balances (N supply - N removal) and N removal/N supply were calculated based on land-grant university (LGU) guidelines and farm management data. A green operational outcomes domain (GOOD) was defined, and a series of complementary graphical tools and numerical indicators were created to identify opportunities for N management refinement over time. RESULTS AND CONCLUSIONSFeasible outcome values for NUE indicators in the GOOD framework were established at a 50% minimum N removal/N supply and a 159kgN ha-1 maximum tolerable available N balance. Feasible values were in partial agreement with previous literature, did not constrain P-based manure applications, and identified fields with large N balances and low efficiencies in the context of adaptive N management. Considerable farm-to-farm differences existed, with 66% of field*year observations meeting the GOOD feasible values and 34% displaying opportunities for refinement. The strategies with largest potential for enhancing N management included reducing N inputs and evaluating non-N yield barriers (e.g. drainage, pests) for fields with low yields and high balances, increasing manure N utilization efficiency (with spring injection or incorporation), and crediting N contributions from sod. SIGNIFICANCEThe current work proposes a practical end-of-season evaluation framework for N management in corn silage that is easy to scale across NY dairies to facilitate implementation of the NY adaptive N management process. The framework also allows farmers to assess current practices and identify opportunities for management refinement over time. Enhancing NUE in corn silage should result in financial benefits for farms and reduced N losses to prevent water quality impairment and/or direct or indirect nitrous oxide emissions that contribute to global warming.
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