Author
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Meisinger, John |
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Submitted to: Extension Service Bulletins
Publication Type: Proceedings Publication Acceptance Date: 7/25/2003 Publication Date: 8/20/2003 Citation: Meisinger, J.J. 2003. Principles for nitrogen nutrient management planning in maryland. State of the science in Maryland nutrient management. In: Proceedings of research briefing sponsored by the Maryland Department of Agriculture and University of Maryland, July 17, 2003, National Wildlife Research Visitor Center, Beltsville, Maryland. 2003 CDROM. Interpretive Summary: Developing nitrogen management plans, to maintain profitability and minimize nitrogen losses to the environment, is a challenge to nutrient managers. Nitrogen managers must develop nutrient plans that consider rate and application strategies that account for hydrology, soil properties, and crop-tillage systems of a specific site. Ammonia losses are becoming a renewed concern, which can be directly managed by soil incorporation. Nitrogen leaching is a significant loss, that occurs when soil nitrate concentrations are high and water is moving through the soil profile. The universal tools for managing nitrogen leaching include understanding the hydrologic cycle because hydrology drives nitrogen losses, avoiding excess nitrogen applications because excess nitrogen is most vulnerable to loss, and applying nitrogen in-phase with crop demand because this reduces the time that nitrogen is at risk for loss. Cropping system tools for managing leaching include use of grass cover crops, and adding a legume or deep-rooted crop to a rotation. Other approaches include use of riparian zones or conservation reserve acres that can trap nitrogen lost from agricultural fields before it enters nearby streams. Site monitoring tools, such as the pre-sidedress soil nitrate test and the leaf chlorophyll meter, are useful in identifying nitrogen sufficient sites and avoiding excess applications. Real-time monitoring techniques, combined with variable rate nitrogen applicators, offer new opportunities for improving nitrogen management. The application of the above nitrogen management tools to fields, or specific areas within a field, will improve crop nitrogen recoveries with subsequent reductions in nitrogen losses to the environment. Technical Abstract: Managing agricultural nitrogen (N) to minimize N losses is a challenge to nutrient managers who must develop nutrient management plans that consider rate and application strategies that account for hydrology, soil properties, and crop-tillage systems of a specific site. Ammonia losses are becoming a renewed concern, which can be managed by soil incorporation. Nitrogen leaching is a significant loss, with leaching events occurring when soil nitrate concentrations are high and water is moving through the soil profile. The universal tools for managing N leaching include understanding the soil-crop-hydrologic cycle because hydrology drives N losses, avoiding excess N applications because excess N is most vulnerable to loss, and applying N in-phase with crop demand because this increases crop N recoveries. Cropping system tools for managing leaching include use of grass cover crops, and adding a legume or deep-rooted crop to a rotation. Other approaches include use of riparian zones and conservation reserve program areas. Site monitoring tools such as the pre-sidedress soil nitrate test, and the leaf chlorophyll meter are useful in identifying N sufficient sites and avoiding excess N rates. Real-time monitoring techniques, combined with variable rate N applicators, offer new opportunities for improving N management. The application of the above N management tools to fields, or specific management areas within a field, will improve crop N recoveries with subsequent reductions in N losses to the environment. |
