Umsatz von 15N-Harnstoff und 15N-Ammonsulfatsalpeter mit Zusatz von Dicyandiamid unter aeroben Bedingungen im Boden

Turnover of ¹⁵N-urea and ¹⁵N-ammonium sulfa-nitrate with addition of dicyandiamide under aerobic conditions in the soil In aerobic incubation trials, the turnover of ¹⁵N-labelled urea (UR) and ammonium sulfa-nitrate (ASN) was investigated in the soil (silty loam, pH 6.5) under addition of the nitrification inhibitor dicyandiamide (DCD).

• 1 Nitrification of urea at 7°C was markedly inhibited by addition of 10 ppm DCD-N (in relation to soil); at 14°C, a concentration of 20 ppm DCD-N was required for a sufficient inhibition; nitrification of ASN was more inhibited by DCD than nitrification of UR.
• 2 By use of dicyandiamide, up to 14% (as compared with 10% without DCD) of the supplied N was transformed into a non-extractable N-Form from which only a slight release of nitrogen could be observed after 147 days. Also, the proportion of fixed ammoniuum was higher in the treatments with DCD as compared without DCD.
• 3 In all experiments, the recovery was 100% ± max. 2.6%, that means that no essential (gaseous) losses of N occurred under the aerobic conditions of these trials.