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Submitted to: Nitrogen Workshop Proceedings
Publication Type: Proceedings Publication Acceptance Date: 2/3/2004 Publication Date: 3/3/2004 Citation: Delgado, J.A. 2004. Use of best management practices and a nitrogen leaching index to maximize n recovery and protect ground water for high risk cropping systems - landscape conbinations systems. Ontario Nitrogen Forum. CD-ROM. Interpretive Summary: Nitrogen (N) inputs are needed to maintain the sustainability, viability and economical returns of agricultural systems. Average nitrogen use efficiencies (NUE) are reported to be about fifty percent, in part because N management is difficult since this is the most mobile and dynamic essential element. We need to continue the development of best management practices (BMP) that link soil, crop, weather and hydrologic factors with cultural, irrigation, soil and water conservation practices to maximize yields and economical returns while reducing off-site transport of nutrients. This paper discusses the importance of using BMPs to improve N management within the context of the N cycle by accounting for all N sources and sinks. The manuscript also discusses the previous works in the Nitrogen Leaching Index (NLI). If we are going to use an NLI to help us identify risky crop-landscape combinations and potential hot spots for NO3-N leaching, we need a new generation NLI that can integrate management within the N cycle, site-specific and off-site factors and impacts on the pathways for N losses. As recommended by Shaffer and Delgado (2002) this new NLI should be framed into tier approach with the first tier capable of quickly screening and identifying the sensitive areas from those areas that are not so sensitive to NO3-N leaching. Higher tiers of the NLI should be based on mechanistic and complex modeling evaluations that can be applied to those sensitive and potential hot spot areas. Finally, a NLI must include a complete evaluation for the whole cropping system. Technical Abstract: Nitrogen (N) inputs are needed to maintain the sustainability, viability and economical returns of agricultural systems. Average nitrogen use efficiencies (NUE) are reported to be about fifty percent, in part because N management is difficult since this is the most mobile and dynamic essential element. We need to continue the development of best management practices (BMP) that link soil, crop, weather and hydrologic factors with cultural, irrigation, soil and water conservation practices to maximize yields and economical returns while reducing off-site transport of nutrients. This paper discusses the importance of using BMPs to improve N management within the context of the N cycle by accounting for all N sources and sinks. The manuscript also discusses the previous works in the Nitrogen Leaching Index (NLI). If we are going to use an NLI to help us identify risky crop-landscape combinations and potential hot spots for NO3-N leaching, we need a new generation NLI that can integrate management within the N cycle, site-specific and off-site factors and impacts on the pathways for N losses. As recommended by Shaffer and Delgado (2002) this new NLI should be framed into tier approach with the first tier capable of quickly screening and identifying the sensitive areas from those areas that are not so sensitive to NO3-N leaching. Higher tiers of the NLI should be based on mechanistic and complex modeling evaluations that can be applied to those sensitive and potential hot spot areas. Finally, a NLI must include a complete evaluation for the whole cropping system. |
