Der Einfluß von Rinderkotmehl, Bodenbakterien und Streptomyces sp. auf die Naßsieb‐ und Druckstabilität künstlicher Bodenaggregate

Abstract

The influence of cow manure, soil bacteria, and Streptomyces sp. on the wet sieving stability and the mechanical strength of artificial soil aggregates.. The wet sieving stability of fresh and the mechanical strength of artificially dried aggregates from a Parabraunerde rich in coarse silt, with and without addition of 0,5% of cow manure, was determined during colonization with natural flora (unsterilized, re‐moistened) and with pure cultures of 11 soil bacteria and a Streptomyces sp. (after sterilization with ethylene oxide) during a 21 day incubation period. The mechanical strength of dried aggregates was chosen as a direct measure for comparison with the wet sieving stability. The differences showed however, that these two parameters of stability were only weakly correlated. The wet sieving stability was initially low. After addition of manure this stability was markedly increased during colonization with mixed flora and with Pseudomonas fluorescens, whereas the mechanical strength increased only slightly. In unamended soil the wet sieving stability of small aggregates was increased significantly only by Streptomyces sp. The mechanical strength was higher than in amended soil and was highest in unsterilized soil and in soil colonized by Arthrobacter sp. The mechanical strength decreased strongly after prolonged incubation. Die Verfasser danken Frau H. Karnapp und Fräulein D. Eggelsmann für ihre zuverlässige technische Assistenz.