In the years [2001][2002][2003] in field trials we studied the effects of the conditions of year, fore-crops (winter wheat, sugarbeet, grain maize) and optimalization of the nutritional status on the yield and crude protein content in the grain of spring barley. From the analysis of the plants we can see that dry ma�er production and nutrient concentration in the plants were influenced by the conditions of the year and the fore-crop. A�er sugar beet, the growth of the dry ma�er was intensive and the concentrations of nutrients per one plant were higher as early as in the initial stages of vegetation. The yields in the years 2001 and 2002 corresponded with these results while the highest yields were seen a�er the sugar beet. Due to the extreme lack of precipitation, the best fore-crop in 2003 was maize. While the dose of 50 kg N/ha increased the yields a�er maize, a�er wheat it reduced the yields and increased the crude protein content in the grain.

HŘIVNA, L., RICHTER, R., RYANT, P., PŘÍKOPA, M.: The eff ect of the previous crop and diff erentiated fertilisation on yields and content of N-substances in spring barley grain. Acta univ. agric. et silvic. Mendel. Brun., 2009, LVII, No. 5, pp. 141-148 In small-plot experiments established in 2001-2004 we studied the eff ect of the chemical composition of the plant dry matter of spring barley, varieties Kompakt and Jersey, on grain yields. A re la tive ly strong correlation was confi rmed between the chemical composition of the plant dry matter and yields. The correlation was most intensive in the case of nitrogen (r = 0.536), phosphorus (r = 0.503), magnesium (r = 0.464) and sulphur (r = 0.431) at the beginning of shooting (DC 30); in the case of potassium (r = 0.557) at the beginning of tillering (DC 23) and calcium (r = 0.530) during ear formation (DC 55). A relatively strong correlation remained from the beginning of tillering to the beginning of ear formation and later decreased. The weather conditions of the year and variety signifi cantly affected grain yields and also the previous crop was important. Grain yields of the variety Kompakt were statistically signifi cantly lower than of the variety Jersey (6.02 t . ha −1 and 6.45 t . ha −1, respectively). The yields of barley grown a er sugar-beet were the highest (6.30-6.79 t . ha −1 ); the grain yields of barley a er maize decreased by 9.1-9.7 %. Higher grain yields of the Jersey variety resulted in levels of N-substances (11.35 %) lower than in the Kompakt variety (11.35 % and 11.60 %, resp.). No correlation was discovered between the nitrogen level in the plant dry matter during vegetation and the content of N-substances in barley grain.