Produkcyjność płodozmianu: burak cukrowy – pszenica jara – jęczmień ozimy uwarunkowana zróżnicowanym nawożeniem organicznym i wzrastającymi dawkami azotu mineralnego

In the years 2000–2004 a two factor field experiment on black earth soil of valuation class IIIa was conducted at Swojec Experimental Station of Agricultural University in Wrocław. The experiment was designed according to split-block method in four replications. The studies examined productivity of crop rotation: sugar beet-spring wheat-winter barley under the influence of varying types of organic fertilizers (manure – 30 t/ha, vermicompost made from manure – 10 t/ha and stubble crop growing after ploughed down barley straw with addition of 50 kg. N/ha with ploughed down sugar beet leaves and spring wheat straw) and different rates of nitrogen fertilizer – 0, 50, 100, 150 and 200 kg N/ha before sugar beet and before spring wheat, and 0, 45, 90, 135 i 180 kg N/ha before winter barley. The yield in cereal units for individual plants (mean for 3 years) was calculated from real yield and conversion rates: roots of sugar beet – 0.25; leaves of sugar beets – 0.10; grain of cereals – 1; straw of cereals – 0.13. Results of the experiment were analyzed using the analysis of variance. Mean differences were compared using Tukey’s test at = 0.05. Efficiency of crop rotation: sugar beet – spring wheat – winter barley determined by cereal units, depended on varying nitrogen fertilization only. A significant increase of yields of sugar beet roots and side yields of all cultivated plants was noticed after application of 150 or 135 kg N/ha rates. However, a significant increase of grain yield of spring wheat and winter barley was found after using 100 or 90 kg N/ha rates. Intensification of nitrogen rates was conducive to increase of cereals yields but the increase was insignificant. Application of varying organic fertilization did not significantly affect the yielding of cultivated plants. An insignificantly higher yield of sugar beet, barley and wheat was noticed after ploughing down stubble crop and side products of the yields of forecrops than after using manure or vermicompost