1. Productivity, nitrogen use efficiency and water use efficiency of maize for grain in long term field experiments – Agnieszka Rutkowska
Maize, one of the most important cereals species grown in Poland, use large quantities of nitrogen, but water deficit through the vegetation period might lead to yield reduction and diminish nitrogen uptake. The aim of the study was to characterize the productivity of the crop, depending on its nitrogen and water use efficiency. In two locations, in Western and Eastern Poland, eleven-year field experiments with maize grown for grain were conducted. Maize was fertilized with increasing rates of nitrogen: 50, 100, 150, 200 i 250 kg N ha-1. It was found, that grain yields of maize raised statistically significant up to 8.03 t ha-1 under 150 kg N ha-1. Such a dose guaranteed: nitrogen uptake 182 kg N ha-1, nitrogen use efficiency 121%, nitrogen surplus-32 kg N ha-1, water use efficiency 14,5 kg ha-1 mm-1, and nitrogen utilization efficiency 43 kg kg-1. Increasing nitrogen doses over the years was not justified because maize productivity was limited by water availability under higher nitrogen rates.
Keywords: Zea mays, nitrogen rates, Nitrogen Use Efficiency (NUE), Water Use Efficiency (WUE), nitrogen surplus