Abstract

REUSSI CALVO, Nahuel Ignacio  and  ECHEVERRIA, Hernán Eduardo. Wheat nitrogen fertilization strategy: water balance for the south of Buenos Aires province. Cienc. suelo [online]. 2006, vol.24, n.2, pp.115-122. ISSN 1850-2067.

Wheat nitrogen fertilization at planting or tillering allows the achievement of high yields, but it does not necessarily considerate grain quality. Under adequate water availability, complementary nitrogen fertilization at booting stage is a promissory strategy to increase grain quality. The aim of this work was to determinate the probability of water excess or stress during initial stages (sowing or tillering) or reproductive stages (booting) for wheat crop in the south of Buenos Aires province. Wheat Ceres model was utilized to determine average dates to emergence, late tillering and booting stages in Balcarce, Tres Arroyos and Puán. It was determined an annual soil water balance using a climatic series of 30 years (1971-2001), and it was estimated the probability of water stress or excess for these stages. Average date to emergence, late tillering and booting was the second decade of July, first and third decade of October, respectively. Water stress happened at some moment during the growing season in the 33, 68 and 70% of the years in Balcarce, Tres Arroyos and Puán, respectively. However, in Balcarce and Tres Arroyos water availability was adequate from sowing in the third decade of October for 97 and 74% of the years, respectively. At emergence stage, water excess greater than 10 mm was estimated in the 33, 35 and 12% of the years in Balcarce, Tres Arroyos and Puán, respectively. In Tres Arroyos and Puán, water stress for the first decade of October was estimated in the 23 and 50% of the years, respectively. For these counties, water stress in the third decade of October was estimated in the 17 and 50% of the years, respectively, but it was only 3% for Balcarce. These results would indicate that in Balcarce exist a high probability of achieve response for nitrogen fertilization at sowing, late tillering and booting, however nitrogen fertilization at sowing would not be an efficient practice to achieve high nitrogen use efficiency. In Puán, nitrogen fertilization at sowing would be the most efficiency strategy. In Tres Arroyos, nitrogen could be apply at sowing, late tillering and boot stage, although nitrogen fertilization at booting would have a lower probability of response than Balcarce.

Keywords : Triticum aestivum; Nitrogen; Water balance; Timing of nitrogen fertilization.

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