Growth of earthworms (Perionyx excavatus) on cattle or buffalo manure with or without water hyacinth.

The growth of earthworms (Perionyx excavates) was studied in a 2*2 factorial experiment with 4 replicates, in which the treatments were: source of manure (cow or buffalo) and supplementation with water hyacinth at 25% of the weight of manure (DM basis) or none. Adding chopped water hyacinth to buffalo or cattle manure led a decrease in worm numbers and in productivity per kg DM and crude protein of added substrate. Relative growth in numbers and in weight of the worms was similar on manure derived from buffaloes and cattle. The negative effect of water hyacinth was greater with buffalo than with cattle manure. Residual compost from cattle manure was richer in N and poorer in ash than compost derived from buffalo manure. Water hyacinth added to the substrate resulted in compost with less N but more ash