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.

Keywords: Triticum aestivum, wheat, Chilean nitrate, urea.
1 Estación Experimental Quilamapu (INIA), Casilla 426, Chillán, Chile.