In worts (rye and potato) the total contents of nitrogen and carbon and their fractions were determined for fertilization purposes in agriculture. The rye wort contained more carbon and nitrogen, 442.0 and 32.0 (g.kg-1), than the potato wort; 340.3 and 28.9. 0.1 mol.dm-3 of NaOH solution was used for the extraction of humic acids from worts. The carbon extracted by alkaline extract reached 51.0% of its total content in the rye wort and 75.2% in the potato wort. The extracts were acidified to the value of pH 1.5 and got separated into precipitated solid and liquid. The content of carbon in precipitated (solid) phase accounted for 3% of the total carbon in the rye wort and for 19.5% in the potato wort. The precipitated solids were analyzed with the spectrophotometric methods and the results have shown very similar properties as the humic acids extracted from soils. The application of acid hydrolysis allowed for a separation of nitrogen compounds as the following fractions expressed as a percentage of total nitrogen in rye and potato worts were respectively: 1) in non-hydrolysable compounds 88.7 and 87.9; 2) in hydrolysable compounds 11.3 and 12.1. Taking the nitrogen determined in hydrolysable compounds as 100%, the following fractions were separated: a) easily hydrolysable compounds 30.5 and 29.5%; b) not easily hydrolysable compounds 54.0 and 5.5%; c) nitrogen in mineral compounds 15.5 and 65.0%.
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