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Nitrogen Use Efficiency in Maize as Affected by Nitrogen Availability and Row Spacing

Est. Exp. Agropecuaria INTA Balcarce and Fac. Ciencias Agrarias (U.N.M.P.), Unidad Integrada Balcarce, C.C. 276 (7620) Balcarce, Buenos Aires, Argentina

^* Corresponding author (pbarbieri{at}balcarce.inta.gov.ar).

Efficient use of N in plant production is an essential goal in crop management. An experiment was performed at INTA Balcarce, Argentina during 3-yr to evaluate the effect of row spacing and N level on nitrogen use efficiency (NUE) in no-till (NT) irrigated maize (Zea mays L.). Treatments consisted of a factorial combination of row width (70, 52 and 35 cm) and N rates (0 to 180 kg N ha^–1). Nitrogen rate and narrow rows increased total dry matter (DM), grain yield, and N accumulation. Relative responses to narrow rows decreased as N availability increased. The NUE decreased with N rate and increased with narrow row spacing. Narrow rows increased NUE by 12 and 15% expressed as DM or grain yield per unit of available N, respectively. Physiological efficiency decreased with N rate and was not affected by row spacing. Recovery efficiency (RE) decreased with increasing N rate, and increased for the narrow row spacings. The effect of narrow rows on RE decreased as N availability increased. Narrow rows increased NUE largely as a result of increased RE. These increments in RE could contribute to increase the profitability of maize production and to diminish the risk of environmental pollution.

Abbreviations: CET, crop evapotranspiration • DM, dry matter • ETO, evapotranspiration • GPN, grain yield (0% moisture) per unit N in grain • NGE, N in grain per unit of available N • NT, no-till • NUE, nitrogen use efficiency • PAR, photosynthetically active radiation • PE, physiological efficiency • RE, recovery efficiency

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Received for publication February 22, 2006.