Resumo

PAGANI, A; ECHEVERRIA, HE; SAINZ ROZAS, HR  e  BARBIERI, PA. Economic optimal nitrogen rate for corn under no-tillage in southeast Buenos Aires Province. Cienc. suelo [online]. 2008, vol.26, n.2, pp.183-193. ISSN 1850-2067.

Nitrogen fertilization in corn under no-till is a common practice in SE Buenos Aires Province; however, there is insufficient local information to define the nitrogen (N) rate that corresponds to the maximum economic benefit. The aim of this work was to optimize the economic nitrogen rate (DOE) for corn under no-tillage using an improved mathematical model and by choosing the best moment for N fertilization. In addition, the effect of N-corn grain price and year potential was compared to the DOE. Data was obtained from 23 N fertilization experiments which took place from 1994 to 2005 and had contrasting environmental conditions (years with different potentiality). Fifteen of these experiments had N applied at planting (SI) and 8 at the six-leaf stage (V6). A statistical criterion to select the best model for defining the DOE was not found; the quadratic-plateau model presented the most conservative results from an agronomic point of view. For the quadratic-plateau model, the year potentiality effect produced variations in the DOE of 59 and 54 kg N ha^-1 for SI and V6, respectively; whereas the price relationship effect produced variations of 30 and 23 kg N ha^-1 for SI and V6, respectively. In conclusion, the year potentiality affected the DOE more than the N-corn grain price relationship and the six-leaf stage appeared to be the most appropriate moment for N fertilization taking into account economic and environmental aspects.

Palavras-chave : Corn; Nitrogen; No-tillage systems; Economic optimal rate.

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