Rapid determination of EUF-extractable nitrogen and boron

Summary A procedure for the rapid determination of EUF-extractable nitrogen (NH₄ ⁺, NO₃ ⁻ and easily soluble organic N compounds) is described. In this procedure the EUF-N fractions are oxidized to NO₃. The oxidation with peroxodisulfate is accelerated by ultraviolet (UV) radiation. This reduces the time of digestion to about 15 minutes. The contents of EUF-extractable N are on the average only between 2–8 mg/100 g soil. Their determination by the new procedure in the form of NO₃ is more precise than the results obtained by digestion according to Kjeldahl. The sum of EUF-extractable N fractions obtained by the new procedure allows to assess the N fertilizer requirements more precisely than is possible when using the EUF-NO₃ fractions alone. Therefore this new procedure constitutes a considerable advantage when working out fertilizer recommendations for agricultural practice.