Vol. 123, No. 3 * Pages 265–408 * July - September 2019

The effect of the amount and application date of nitrogen fertilizer on maize productivity and profitability was examined in a field experiment established on calcareous chernozem soil at the University of Debrecen in Hungary (47^o 33’ N, 21^o 26’ E, 111 m) under different environmental conditions in the wet crop year of 2016 and the average crop year of 2017. In addition to the non-fertilized treatment, N fertilizer doses were applied in the form of basal and top dressing. The 60 and 120 kg N ha^-1 treatments applied as spring basal dressing were followed by two occasions of 30 kg N ha^-1 top dressing at the V6 and V12 phenophases each. The longer maturity hybrid Armagnac (FAO 490) had a better conversion ratio concerning the precipitation during the growing season of 2016 (which was higher than the 30-year average), as well as the basal and top dressing (averaged over the different treatments) in comparison with the shorter maturity hybrid Renfor (FAO 320). In the wet crop year, the yield of Armagnac was 21.7% higher, while that of Renfor was 10.4% higher. The 60 kg N ha^-1 basal dressing and the +30 kg N ha^-1 top dressing at the V6 phenophase (V6₉₀) resulted in more efficient uptake and better conversion rate in the rainy crop year (2016) in the case of both examined hybrids. In the average crop year (2017), a difference was observed in the successfulness of top dressing. In the case of the Armagnac hybrid (FAO 490), top dressing did not cause any significant yield surplus and the 120 kg N ha^-1 basal dressing was shown to be successful. In the case of the Renfor hybrid (FAO 320), the early top dressing (V6₁₅₀) applied on the basal dressing of 120 kg N ha^-1 was favorable. The most favorable income of nutrient management (N) was provided by the basal dressing of 120 kg N ha^-1 and the +30 kg N ha^-1 (V6₁₅₀) top dressing applied at the early V6 phenophase, averaged over the examined hybrids and years. In the case of the Renfor hybrid (FAO 320), the highest profitability was reached with the V6₁₅₀ treatment, independently of the prevailing environmental factors. However, as regards the Armagnac (FAO 490) hybrid, the top dressing applied at the V12 phenophase provided the highest profitability, which could be achieved with the lowest dose of V12₁₂₀ treatment in the wet year (2016) and the highest dose of V12₁₈₀ in the average crop year (2017). Altogether, based on the results of yield and marginal revenue analysis, the recommended fertilization technology is basal dressing of 120 kg N ha^-1 and basal dressing of +30 kg N ha^-1 (V6₁₅₀) applied at the early V6 phenophase. The obtained findings also show that the effect of N is greatly affected by crop year, genotype, and other elements of the applied technology. Also, marginal efficiency has to be defined for each hybrid, considering the given crop year, too.