The comparative use of nitrate, ammonium and urea fertilizers by oats and wheat as determined by 15N‐techniques

Abstract

Abstract The efficiency of nitrate, ammonium and urea fertilizers were compared by growing oats (Avena sativa L.) and wheat (Triticum (aestivum L.) sp.) as test crops on four widely different soils in a greenhouse experiment. No differences in oats or wheat yields were found among the N‐fertilizers on the mineral soils. On the organic soil, however, nitrate fertilization produced higher oat yields than the ammonium chloride treatment and it produced higher wheat yields than either the ammonium chloride or the urea treatments. Oat and wheat yields were increased with N‐fertilization on two and three soils, respectively. Wheat was found to have a higher N‐requirement than oats, but no proportional relationship was found between tissue‐N concentration and yields. The lowest tissue‐N concentration at which maximum yields were observed were 1.3% N in oats and 1.7% in wheat. A priming effect was observed on two soils severely deficient in N (but the proportion of soil‐N absorbed by oats and wheat decreased on a...