Summary:

The influence of sprinkler irrigation and four nitrogen fertilization doses on the height of true millet cv. ‘Gierczyckie’ was determined in a field experiment carried out in the years 2005–2006 on a very light soil at Kruszyn Krajeński near Bydgoszcz. The soil in horizon 0–50 cm was characterized by field water capacity 57 mm, useful retention 43 mm and effective useful retention 30 mm only. The experiments were run in a split-plot system with three replications. Two different factors were compared. The first row factor – irrigation, was used in the two following treatments: Wo – without irrigation (control), W1 – sprinkler irrigation according to tensiometer indications (-0,03 MPa). The second row factor – differentiated nitrogen fertilization, was used in the four following variants (doses): N₀ = 0 kg N ha ^-1, N₁ = 40 kg N ha ^-1, N₂ = 80 kg N ha ^-1, N₃ = 120 kg N ha ^-1. Water requirements of true millet were estimated as optimal rainfall amounts for this crop, according to Klatt and Press proposals. Mean - for two seasons - water needs of true millet (since May 1 to August 31) amounted 278 and 294 mm, for Klatt and Press proposals, respectively; but they ranged in particular years from 264 to 307 mm. Yields of non-irrigated true millet dependent on rainfall amounts. Lower yield (1,87 t ha^-1) was noted in case of lower rainfall in the period May 1- August 31 (161 mm), and the higher yield was harvested when rainfall in this period amounted 229 mm. It was found that the sprinkler irrigation significantly increased grain yield by 1,79 t ha^-1 (85 %). Production results of sprinkler irrigation were inversely correlated with rainfall amount in the vegetation period. Higher yield increases due to irrigation were obtained in drier year (2,32 t ha^-1 i.e. 124 %), and the lower results – in a more wet season (1,28 t ha^-1 i.e. 55 %). Increased nitrogen fertilization doses (from 0 to 120 kg N ha ^-1) - under conditions of sprinkler irrigation – caused a significant grain increase of true millet to the amount 4,42 t ha^-1.