Comparative investigations of soil-mite populations in agricultural soils with different intensities of cultivation
1994
Kampmann, T. (Biologische Bundesanstalt fuer Land- und Forstwirtschaft, Braunschweig (Germany). Inst. fuer Pflanzenschutz im Gartenbau) | Koellner, V.
The coenoses of mites in agricultural soils and their influence by different crops and intensities of cultivation were investigated. Soil samples were taken in 100 qm large areas in each of four intensities in all of the three crops (winter-wheat, winter-barley, sugar beet) in intervalls of four weeks. In each of the intensities seven samples were taken two sample parts. Each sample was in a diameter of 5 cm. The samples were taken in the horizontal line separated into the parts 'in the seed-row' and 'between the seed-row'.And in the vertical line they were divided into two horizons of 0-5 and 5-10 cm. The 49 taxa (species to families) of 23 families found in the field the ones in the sugar beet were clearly less than in both of the cereals. Four taxa (Alliphis siculus, Bakerdania blumentritti, Tectocepheus velatus, Tydeidae) were very dominant and also four taxa (Arctoseius cetratus, Bakerdania sellnicki, Histiostoma strenzkei, Tarsonemus sp.) were dominant. All the other 37 taxa were less than dominant. The distribution into the depth of the soil showed 75-85 % of all mites living in the upper soil layer. Divided into horizontal lines there were found twice the density of individuals in the seed-rows than between the seed-rows. The density of individuals/qm was 10000-20000 in average and changing the crops from winter-barley, to catch crop they increased to 100000 individuals/qm in average. The influence of cultivation was very different: - no effect was found on the number of taxa in the different intensities. - No or only little influence was found in most of the very dominant or dominant taxa. - To a few of the subdominant taxa a strong influence was observed: Tyrophagus infestans. Tectocepheus velatus, Siteroptes graminum and Dendroaelaps foveolatus.
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