Evaluation of effect of autumn nitrogen dose and nitrogen nutrition status on oilseed rape yield

The aim of the experiment was to investigate the effect of nitrogen on oilseed rape (Brassica napus L.) yield as well as evaluate the level of nitrogen nutrition based on the value N.N.I. (nitrogen nutrition index). The plot-scale experiment was based in years 2013/2014 and 2014/2015 in terms of agricultural cooperative in Mojmirovce. Hybrid Artoga was seeded. There were three treatments of fertilization and the block method of experimental plot size of 600 m(2) in triplicate was used in this experiment. The first treatment was unfertilized control treatment. Other treatments were fertilized by the same dose of nitrogen 240 kg*ha(-1). Treatment 3 was fertilized three times during spring and treatment 2 was fertilized except 3 spring doses also in autumn. Results showed that yield of rapeseed was greatly influenced by weather conditions. Both experimental years were not equable in precipitation and temperatures. The highest average yield (at 12% moisture) 3.69 t*ha(-1) was reached at treatment 3, where any autumn dose of nitrogen was not applied. It means an increase by 55.04% and 24.66% compared to unfertilized control treatment and treatment 2. Autumn dose of nitrogen did not influence significantly yield of seeds. Values of N.N.I. ranged from 0.71% to 1.25% and there were not observed any significant differences among treatments as well as between experimental years.