Ammonium Nitrate Fertilization Increases the Crude Protein Content and Wheat Grain Yield in Subtropical Conditions

The objective was to evaluate the relationship between yield components, quality and estimated grain yield of wheat under ammoniacal and nitric nitrogen fertilization in mild winter conditions. The treatments consisted factorial 2 × 3 + 1 at local 1 (L1), where two nitrogen (N) sources, urea and ammonium nitrate (AN), and three rates of N, in two crop seasons 2021 and 2022, and the a factorial 2 × 4 + 1 at local 2 (L2) with a 2022 crop season. The parameters assessed were tillers per plant (TP), plant height (PH), spike insertion height (SIH), spike size (SS), spikelet per spike (SkS), grain per spike (GS), estimated yield, dry matter accumulation (DMY), hectoliter weight (HLW) and crude protein content (CPC). It was observed that the yield components increased with increasing N rates, with some increasing significantly when AN was used compared to urea. In relation to grain yield, it increases with the use of N, showing superiority when using AN in relation 17.6% urea in L1-Y2022 at a rate of 160 kg ha^− 1 and 21 and 16.6%, respectively at rate of 40 and 80 kg ha^− 1 in L2-Y2022. The CPC present an average superiority of 12.1% when using AN in the early cultivar, and increases with the increase in N rates. Grain yield is increased by N supplementation and is rate dependent. Yield response to ammonium nitrate is greater than to urea. Crude protein content is increased as N rate increases. The rate with the highest dry matter accumulation is 160 kg N ha^− 1.