NITRATE NITROGEN IN THE SOIL AS A MEANS OF PREDICTING THE FERTILIZER NITROGEN REQUIREMENTS OF BARLEY

Abstract

In 22 field trials, over a seven-year period, highly significant correlations were found between nitrate nitrogen to various depths in the soil profile at seeding time and the uptake of nitrogen by the above-ground portion of barley at harvest. The best correlation was found at a depth of 61 cm, where the r2 value was 0.84. Barley yields were shown to be highly significantly correlated with the uptake of nitrogen, the r2 value being 0.86. These data, combined with a factor for the efficiency of utilization of a nitrogenous fertilizer, were used to derive an equation which predicts the amount of fertilizer nitrogen required for a particular barley yield.