Physical control of soil biological activity due to endogeic earthworm behaviour
1992
Kretzschmar, A. | Monestiez, P.
Clitellate adults of Aporrectodea trapezoides were maintained for 11 weeks in soil columns (h = 60 cm, diameter = 7.5 cm) under the following conditions: (i) the columns were packed with top soil, sieved to include particle sizes between 1 and 4 mm; (ii) water content was maintained at 31% on a volume basis (pF = 0.3); (iii) the soil was compacted at three levels: 200, 400 and 600 kPa; (iv) Aporrectodea trapezoides was introduced at densities of 0, 4 or 7 per column. (v) 1 g (dry wt) of 14C-labelled organic material (clover leaves) was added to the soil column either spread on the surface, or mixed with the top 5 cm of soil, or mixed with the soil at half the depth of the column; (iv) columns without 14C-labelled material were maintained as control. CO2 release (distinguishing CO2 from the soil and CO2 from the added plant material) was measured throughout the experiment. At the end of the experiment, the relative gas diffusivity of the highly compacted columns was measured at different depths. It was demonstrated that the decomposition of labelled plant material can be controlled by the presence of a burrow system when the gas diffusivity in the soil limits the gas exchange from the soil to the surface.
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