Verbesserungsvorschlag zur gefahrlosen Beheizung brennbarer Lösungsmittel zur Fettextraktion (Kurzmitteilung)

A crop rotation field study with manure application was established at Tartu in 1985. Biological and chemical properties were evaluated on fine sandy loam Podzoluvisol in May 1989. The treatments included unmanured (N_o and N₈₀) controls, two peat based composts and five manures of different origin. The procedures of the most probable number (MPN) and spread plate counts were used for microbiological investigation, but also enzymatic activities, nitrogen forms, total‐C and pH were simultaneously estimated in plough layer soil. The most variable i.e. the most clearly differentiated physiological groups within manures were cellulolytic and ammonifying bacteria followed by Azotobacter spp. together with actinomycetes. Abundance of aerobic cellulolytic and ammonifying bacteria correlated positively with the number of soil algae and fungi, and negatively with nitrate‐ and nitrite‐reductase. The number of actinomycetes correlated positively with urease and catalase activity. Soil enzymatic activity was mainly modified by nitrite‐reductase. Peat composts had the highest C‐content and highest pH value compared with other soils. Pig slurry and NH₄NO₃ (N80) treatment had the highest level of fixed NH⁺ ₄ ‐ions in soil. Nine months after manure application no differences were found in the unstable NO^– ₃content of soil. Variation in the number of the studied microbial physiological groups between treatments remained insignificant.