| Abstract: | Fractions of Nitrogen in various types of slurry and their effects in vegetation trials Total Nitrogen in slurry of different animal species was separated by fractionating methods, and effectiveness of the organic N was then tested in pot trials. Total N content of cattle slurry was 0.44% based on 10% dry matter; pig and chicken slurry almost reached values twice as high. Ammonium-N amounted (in the same order) to 45–70% of total N. The C/N-ratio was 8–10 in cattle slurry, and about 4 in pig and chicken slurry which are richer in ammonium. The biggest part of the residual organic N is, “6 n HCl – hydrolyzable N”, mainly microorganism nitrogen, half of which could be analyzed as amino acid N. After fractionating of humus, 28 to 37% of organic N appeared as fulvic acid N, 32 to 44% as humic acid N, and 19–32% humine N. Mineralization of organic N (largely free of ammonium) in an incubation trial under controlled conditions was only 17% (pig slurry) resp. 22% (chicken slurry) resp. 27% (cattle slurry) within 40 weeks, in spite of a relatively small C/N-ratio (13). In short term vegetation trials with green maize and green oats in Neubauer- resp. rye grass in Mitscherlich experiments with a very intensive utilization (3 cuttings), all types of slurry gave only very small raises (max. 5–10 %) in yields and N removals as compared to the control on the basis of organic N. In one set of experiments with “aerated” cattle slurry, a somewhat better mineralization and utilization of organic N in vegetation trials could be observed. |
