VARIABILITY OF MAIN NUTRIENT-UPTAKE BY SU GAR-BEET

The aim of this work is to point out at considerable year variability in the sugar beet uptake of N, P and K in semblably homogeneous soil-c limatic conditions. The results presented in this work are achieved fr om the field experiments of development tests of sugar beet. These tes ts were realized over the years 1976 to 1992 at RBI Bucany. The field experiments were established on degraded chernozem with average conten t of P 65 mg.kg-1 of soil (the medium store) and with medium content o f K 183 mg.kg-1 of soil (good store). In the territory of our field ex periments the average annual temperature is 9.3-degrees-C and annual s um of precipitation is 560 mm. The average temperature of the vegetati on period of the sugar beet in this region is 14.9-degrees-C and sum o f precipitation is 370 mm. At least three varieties of sugar beet in f our replications were investigated annually in developmental tests, Th e manual harvest of sugar beet started on July 1 and finished on Octob er 15. The harvests were carried out in 15-day intervals. We determine d the weight of root and leaves, the content of dry matter of root and leaves and qualitative parameters of the technological line Venema th e sugar content of Na, K and alpha-amino N. In the dry matter of root and leaves after we determined mineralization with HNO3 and HClO4: the content of total N (Kjelfoss), the content of P (cololimetric method) , content of N (flame photometer). The average fertilization in the re search period was: 45 t.ha-1 of the manure, 130 kg N.ha-1, 44 kg P.ha- 1 and 150 kg K.ha-1. The medium values of the N uptake raise regularly towards the end of vegetation period. In the period 1976 to 1992 the limits of the N consumption are 157.7 (min) to 382.3 kg.ha-1 (max.). T he maximal P uptake can be used in the last third of vegetation period at the beginning of September. The uptake of P varies at the end of t he different vegetation periods from 6.9 kg P.ha-1 to 67.3 kg P.ha-1. The K values, which were taken with total biological yield, show in th e experimental years the maximal vafiability (96.3 to 472.3 kg K.ha-1) . The introduced data are valuable as a starting material for the bala nce of consumption fertilizers for supposed production of sugar beet u sed in the plans of fertilization.