Recovery, Residual Effects, and Fate of Nitrogen Fertilizer Sources in a Semiarid Region1

Abstract

AbstractInformation on recovery and eventual fate of fertilizer N applied to dryland crops in the northern Great Plains is needed to optimize economic returns and to minimize pollution hazards. In a field experiment at Mandan, N. Dak., four fertilizer N sources were applied to separate areas of corn (Zea mays L.) and bromegrass (Bromus inermis L.) for 4 years. From the fifth through seventh years, the two areas were uniformly seeded to barley (Hordeum vulgare L.) without additional N fertilization, until residual effects were no longer significant. Sources of N used were ammonium sulfate, ammonium nitrate, calcium nitrate, and urea, applied at either 55 or 110 kg/ha to Parshall fine sandy loam. Recovery of fertilizer N in corn plant tops was greatest for ammonium nitrate. Over 35% of the calcium nitrate and urea applied at 110 kg/ha of N to corn was leached below the root zone. Leaching of fertilizer N applied to bromegrass was insignificant. Except for urea, fertilizer N recovery by bromegrass from the other N sources was nearly equal and usually higher at 55 kg/ha. Residual growth responses were smaller from N applied to bromegrass than to corn. About 70 to 95% of the fertilizer N applied was accounted for by the end of the residual period, except for lower values for several of the urea treatments. Gaseous losses were probably high for urea surface broadcast on bromegrass at 110 kg/ha of N because only 47% could be accounted for and no residual effects were observed.