Productivity of winter oilseed rape depending on its nitrogen and water use efficiency– Agnieszka Rutkowska
This paper presents the results of 11 years of field experiment concerning winter oilseed rape in Eastern Poland. The aim of the study was to characterise rape production depending on the nitrogen and water use efficiency. Oilseed rape was fertilised with increasing doses of nitrogen, i.e. 50, 100, 150, 200 and 250 kg N ha-1. It was found that rapeseed yields increased statistically significantly to 3.33 t ha-1 at a rate of 200 kg N ha-1. This dose guaranteed: nitrogen uptake of 155 kg N ha-1, nitrogen use efficiency of 78%, nitrogen surplus of 45 kg N ha-1, water use efficiency of 8.4 kg ha-1 mm-1 and nitrogen utilisation efficiency of 22 kg kg-1. Increasing the nitrogen rate in the long term to 250 kg N ha-1 proved to be unjustified because it did not cause a significant increase in the yield or water use efficiency, while it significantly increased the nitrogen uptake, its surplus in the soil and reduced the efficiency of nitrogen from fertilisers utilisation.
Keywords: Brassica napus L., nitrogen rates, Nitrogen Use Efficiency (NUE), Water Use Efficiency (WUE), nitrogen surplus