Does a highly intensive plant production induce changes in the algal soil flora?
1994
Sauthoff, W. (Biologische Bundesanstalt fuer Land- und Forstwirtschaft, Berlin (Germany). Inst. fuer Mikrobiologie) | Oesterreicher, W.
Besides other microorganisms in arable soils blue-green algae (Cyanobacteria) as well as eukaryotic algae can be found. Unlike decomposers such as soil fungi and most of the soil bacteria, algae as photoautotrophic organisms are able to form organic matter. Many blue-green algae can fix atmospheric nitrogen. The present study should elucidate, whether a long-term intensive crop production with its high usage of pesticides will influence the algal soil flora. From a long-term project of the Federal Biological Research Centre for Agriculture and Forestry in Ahlum near Braunschweig two experimental plots were selected: one of low cropping intensity without any application of pesticides and a small amount of fertilizers (IO); the other with the highest meaningful amount of pesticides and fertilizers (I3) for maximum crop yield. From May 1987 till December 1989 soil samples were taken in eight-week intervals from the upper layer (0-5 cm) of the soil. The crop rotation consisted of winter wheat, winter barley, yellow mustard (catch crop) and sugar beet. The total amount of blue-green algae makes up about one tenth of all algal species being found in I0 in total. In I3 the number of bluegreen algae was by 75.4 %, the number of eukaryotic algae by 35.8 %, the total number of both groups together by 39.6 % lower than in IO. In the soil of the experimental area in Ahlum 102 algal taxa were found. 24 taxa were significantly more abundant in I0, two in I3. There was no evidence that any algal taxon vanished as a consequence of the high production intensity. It can not be excluded, that the application of herbicides might be responsible for the suppression of soil algae. However, we do not see much probability for that. The strong suppression of blue-green algae is probably a result of the high level of nitrogen fertilizer in I3
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