Effects of a tropical geophagous earthworm, Millsonia anomala, on some soil characteristics, on maize-residue decomposition and on maize production in Ivory Coast

• Published in: Applied soil ecology : a section of Agriculture, ecosystems & environment ecosystems & environment, 1996-11, Vol.4 (3), p.201-211
• Main Authors: Gilot-Villenave, C., Lavelle, P., Ganry, F.
• Format: Article
• Language: English
• Subjects: 15N; Earthworms; Maize; Soil physical characteristics; Tropics
• ISSN: 0929-1393; 1873-0272
• DOI: 10.1016/S0929-1393(96)00119-9

Maize was grown under field conditions in the presence and absence of the tropical endogeic earthworm Millsonia anomala (Omodeo and Vaillaud, 1967) in soil of a secondary forest of central Ivory Coast. Experimental units were isolated by PVC sheets to limit earthworm movements. Decomposition and redistribution of nitrogen from maize crop residues incorporated in the soil were monitored using 15N-labelled residues. The density of M. anomala decreased from 50 to 15.9 m −2 during the cultivation period (90 days). Activity of M. anomala significantly modified the structure of the soil by increasing the proportion of large aggregates (over 2 mm in diameter). Maize production was increased by 12% for stalks and 18% for grains in the presence of earthworms. Nitrogen contained in the maize residue was more efficiently used by plants grown in the presence of earthworms; the real coefficient of utilisation of the organic residue increased from 9 to 11% in the presence of M. anomala. Nonetheless, total nitrogen exportation was not significantly different between the two treatments. Furthermore, N from the organic residues left after the cultivation period was less easily assimilated by plants in treatments with earthworms.