Efficiency of two nitrogen fertilizers applied in different phenological stages on a winter bread wheat (Triticum aestivum L.)

Mario Mellado Z.1

A fjeld experiment was carried out during tour successive crop seasons, 1988-1991, at the Quilamapu Experiment Station (INIA), Chile, to evaluate the efficiency al nitrogen use by a winter bread wheat, when this nutrient was applied as Chilean nitrate or as urea, at different phenological stages during growth cycle.
The trials were set up under irrigation, in a split plot design. involving application date as treatments and the nitrogen fertilizars as subtreatments. Both fertilizars were broadcasted in a single application al 150 kg N/ha per subtreatment, on the soil surlace every 30 days since sowing until heading.
Evaluations were: grain yield, yield components, phytomass and nitrogen content al the grain and straw.
The most important conclusions are:
- Chilean nitrate and urea applied at different phenological stages in a winter bread wheat, had the sama performance.
- Early nitrogen applications from sowing to initial tillering, or late nitrogen application (spike emergence) negatively affect the grain production, N extraction and N recovery by the wheat plant.
- The highest values al grain yield and grain production efficiency were obtained when all the N rate was applied between tiilering and jointing.
- Total rainfall between sowing time and the fertilizer application dates related to the leaching of nitrogen, might explain the variations in the nitrogen recovery capacity by the wheat plant.

Key words: Triticum aestivum, wheat, Chilean nitrate, urea.

1 Estación Experimental Quilamapu (INIA), Casilla 426, Chillán, Chile.

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