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A New Nitrogen Index for Assessment of Nitrogen Management of Andean Mountain Cropping Systems of Ecuador

Escudero, Luis1; Delgado, Jorge A.2; Monar, Carlos3; Valverde, Franklin1; Barrera, Víctor1; Alwang, Jeffrey4

doi: 10.1097/SS.0000000000000052
Technical Article

Corn (Zea mays L.) is important for food security in much of Ecuador. Small-scale farmers are using nitrogen (N) fertilizer without technical advice based on soil, crop, and climatologic data. The literature lacks studies where tools that can quickly assess management practices’ effects on N uptake, N use efficiency, and risk of N losses to the environment in high-altitude mountain systems are validated. We tested corn response to fertilizer application and the capability of the Nitrogen Index to assess N dynamics within a conservation agriculture production system in a mountainous area of Ecuador. Responses to fertilizer were tested across six sites in the Bolivar province. Steep slopes and declining soil productivity make conservation agriculture a promising option in this area. However, N availability is limiting for corn production and better information is needed to optimize the system. Corn responded to fertilizer application with an average increase of 30 kg ha−1 corn grain per every 1 kg of N ha−1 applied (P < 0.001). The data suggest that N leaching increased with fertilizer application for areas with precipitation greater than 900 mm. The Nitrogen Index for Ecuador was able to quickly assess management practices’ effects on N uptake (P < 0.001), N use efficiency (P < 0.001), and risk of N losses. It could be used to increase use of best management practices in these systems.

1Instituto Nacional Autónomo de Investigaciones Agropecuarias (INIAP), Quito, Ecuador.

2US Department of Agriculture–Agricultural Research Service, Soil Plant Nutrient Research (USDA-ARS-SPNR) Unit, Fort Collins, CO.

3Universidad Estatal de Bolívar, Guaranda, Ecuador.

4Virginia Polytechnic Institute and State University, Blacksburg, VA.

L.E. and C.M. were visiting scientists at USDA-ARS-SPNR, Fort Collins, CO.

Address for correspondence: Jorge A. Delgado, USDA-ARS, Soil Plant Nutrient Research Unit, 2150 Centre Ave, Building D, Suite 100, Fort Collins, CO 80526; E-mail:

Received November 11, 2013.

Accepted for publication April 24, 2014.

Financial Disclosures/Conflicts of Interest: None reported.

Trade and manufacturers’ names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by USDA implies no approval of the product, to the exclusion of others that may also be suitable.

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