The effect of 3 rates, 2 sources, and application dates of nitrogen was evaluated on yield, grain quality, and malting quality on two barley cultivars. The study was conducted in an Andisol with the cv. Granifén and in an Ultisol with the cv. Libra in the IX Region, Chile, during the 1988/89 growing season.
Treatments were arranged in a split plot design for both soils, with N sources and application dates as a main plot, and N rates as subplots. Main plot treatments in the Andisol were as follows: urea applied 37 and 21 days before planting and sodium nitrate at planting time. Subplot treatments were 0, 50, 100, and 150 kg/ha of N.
In the Ultisol the main plot treatments were as follows: urea and sodium nitrate applied at planting time; urea applied 20 days before planting; and 50% of N rate applied before planting and the other 50% applied as sodium nitrate at planting time. The subplot treatments were 0, 50, and 100 kg/ha of N.
N rate significantly increased (P < 0.01) yield in both experiments. N rates aboye 50 kgjha caused an increase in grain protein content and a reduction in grain plumpness, negatively affecting friability pe(centage, malt extract, and Kolbach index.
In the Andisol, both N sources and application dates did not have any effect (P < 0.05) on the evaluated parameters. In contrast, in the Ultisol both N sources and application dates showed a statistically significant effect (P < 0.01) on yield, grain protein content, and grain plumpness.
The different responses obtained with N sources and application dates in both soils are attributed to some soil characteristics as organic matter content, which affects the urea hydrolysis; and to the rainfall distribution throughout the growing season, as well as to the genotypic diffences between cultivars.
|Keywords: barley, fertilizer, sodium nitrate, urea, urease, commercial yield, plumpness, hydrolisis, friability, malt extract, Kolbach Index.|