Effects of a tropical geophagous earthworm, Millsonia anomala, on some soil characteristics, on maize-residue decomposition and on maize production in Ivory Coast
Maize was grown under field conditions in the presence and absence of the tropical endogenic 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/m2 during the cultivation period (90 days). Activity of #M. anomalasignificantlymodifiedthestructureofthesoilbyincreasingtheproportionoflargeaggregates(over2mmindiameter).Maizeproductionwasincreasedby12. 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. (Résumé d'auteur