ARS | Publication request: A NEW NITROGEN INDEX: An Adaptive Management Tool for Reducing Nitrogen Losses to the Environment from Mexican Forage Production Systems

Submitted to: Soil and Water Conservation Society
Publication Type: Abstract Only
Publication Acceptance Date: May 7, 2009
Publication Date: July 11, 2009
Citation: Figueroa, V.U., Delgado, J.A., Cueto-Wong, J., Nunez, H.G., Reta, D.G., Fry, R., Barbarick, K., Gagliardi, P., Gross, C. 2009. A NEW NITROGEN INDEX: An Adaptive Management Tool for Reducing Nitrogen Losses to the Environment from Mexican Forage Production Systems. Soil and Water Conservation Society.

Technical Abstract: Mexico has about 2 million ha planted in forage, which is used to feed 2.2 million dairy cows. It is estimated that up to 70% of the ingested nitrogen (N) is cycled back into the system via manure and urea depositions. This contributes to an undesirably high ratio of manure N to land available to use N across milk producing regions in Mexico, even at the highest agronomic rates. We propose that the New Mexican Nitrogen Index for Forage Systems can be used as an Adaptive Management Tool for evaluating fertilizer and manure management scenarios in forage crop systems and ultimately reduce N application rates and N losses. This new N-Index (available in both English and Spanish versions) was developed by the USDA-ARS-SPNR in Fort Collins, CO, with support from cooperators and a grant from the USDA Foreign Agriculture Service. It is simple and easy to use. For example, several scenarios can be evaluated side-by-side, and each can be conducted in an average of five minutes or less per scenario. Our results showed that the N Index accurately evaluated residual soil nitrates (NO3-N) (r2=0.96) and crop N uptake (r2=0.78) in Mexican forage systems. Because the N-Index can simulate scenarios with inorganic fertilizer and manure rates, users can identify the most efficient management with the minimum environmental impacts. The N-Index can serve as a quick and effective Adaptive N Management Tool and its use in research and practical applications is expanding across Mexico.