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Soil Organic Matter Assimilation by a Geophagous Tropical Earthworm Based on (delta)^(13)C Measurements
Author(s) -
Martin A.,
Mariotti A.,
Balesdent J.,
Lavelle P.
Publication year - 1992
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.2307/1938725
Subject(s) - organic matter , soil organic matter , earthworm , environmental chemistry , chemistry , soil biology , environmental science , agronomy , soil water , ecology , soil science , biology
Assimilation of soil organic matter and fresh plant debris by Millsonia anomala, a tropical geophagous earthworm, was investigated by measuring changes in the 1 3 C/ 1 2 C ratio of their tissues when fed on organic matter naturally labelled by 1 3 C. Individuals collected from a soil colonized by C 4 plants (C 4 soil) that were fed on C 3 soil had >50% of tissue C derived from the C 3 soil after 33 d. Assimilation of organic matter associated with different particle size fractions was investigated with individuals fed for 25 d on C 4 soil with C 4 particle size fractions substituted in turn for the equivalent C 3 soil particle fraction. A significant labelling of earthworms was observed with both the 250—2000 μm and the 0—20 μm particle size fractions. Addition of fresh C 3 plant debris to the C 4 soil also resulted in a significant change in earthworm C isotope ratio. Assimilation of fresh plant material was greater than that of soil organic matter. This shows that young M. anomala are able to assimilate young organic matter (fresh plant debris, coarse soil organic matter) as well as fine soil organic matter, both of which classically have been regarded as strongly resistant to decomposition in models of soil organic matter dynamics.