THE EFFECT OF NITRATE NITROGEN IN THE SOIL PROFILE ON THE RESPONSE OF BARLEY TO FERTILIZER NITROGEN

Abstract

Barley was shown to have a variable response to fertilizer nitrogen in nine field trials on non-fallow land. A large part of this variability could be accounted for by differences in the nitrate nitrogen content of the soil profile at seeding time.It was demonstrated that nitrate nitrogen can accumulate in non-fallow soil profiles in large amounts and that this nitrogen influences the uptake of nitrogen by barley to the same extent as does nitrogen added as fertilizer.Various tests for "available" nitrogen were used and it was found that the nitrate nitrogen content of the soil to a depth of 4 feet gave the best correlation (r = 0.95**) with yield response to nitrogen.