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Title: QUANTIFICATION OF THE NITROGEN LOSSES IN AGRICULTURAL SYSTEMS INCLUDING THE POTENTIAL USE OF A NITROGEN LEACHING INDEX TOOL TO ASSESS POTENTIAL IMPACTS TO GROUNDWATER

Author
item Delgado, Jorge
item Follett, Ronald

Submitted to: National Congress Mexican Society for Soil Science
Publication Type: Proceedings
Publication Acceptance Date: 10/19/2004
Publication Date: 11/8/2004
Citation: Delgado, J.A., Follett, R.F. 2004. Quantification of the nitrogen losses in agricultural systems including the potential use of a nitrogen leaching index tool to assess potential impacts to groundwater. National Congress Mexican Society for Soil Science. CD-ROM.

Interpretive Summary: To improve N management, we need to understand the major pathways for N losses, including ammonia volatilization, emissions of trace gases, denitrification, nitrate-N (NO3-N) leaching and off-site N transport. We need to evaluate all N inputs and how N cycling from green manures, crop residues and other organic sources will impact nitrate leaching that can potentially move N to groundwater resources. This invited paper which is to be presented at the Mexican Society of Soil Science annual meeting will cover a review of literature in the area of N management and quantification of N losses. Additionally, we are going to present some case scenarios from 15N studies. We will also present data from N cycling compost, green manures and 15N labeled crop residue. The NLEAP model was able to simulate best management practices, compost mineralization and cycling of N from several organic sources (P<0.05). NLEAP and GIS can potentially be used as a nitrate leaching tool to evaluate potential NO3-N leaching across the region. This paper discusses the importance of using best management practices (BMPs) to improve N management within the context of the N cycle by accounting for all N sources and sinks.

Technical Abstract: This invited paper, which is to be presented at the Mexican Society of Soil Science annual meeting, discusses the importance of using best management practices (BMPs) to improve N management within the context of the N cycle by accounting for all N sources and sinks. We will discuss the importance of developing BMPs that increase N use efficiency and 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. It is important that nutrient managers know the major pathways for N losses/inputs. Case scenarios of possible tools that can be used for management and site-specific field soil, climate, and hydrological factors will be discussed. Additionally, the potential to use a nitrogen Leaching Index to help identify risky crop-landscape combinations and potential hot spots for NO3-N leaching will be presented. Examples from organic and inorganic inputs will also be discussed.