Nematodes

These are  next to protozoa and are  the abundant soil microfauna in soil.  They are also called eelworms, thread worms or roundworms.  Nematodes that feed on decaying organic matter are called saprophytic; those which feed on earthworms, other nematodes, etc, are  predatory, and those feeding on roots of higher plants are parasitic.  The saprophytic group  is abundant in soils, but those belonging to the other two groups are agriculturally important in the sense that they cause loss of vigour of the root system and make plants growing in nematode infested soil liable to diseases.  The damage to crops may be  controlled by crop rotation, ploughing, use of organic
manures, and oil cakes etc. The most successful method in controlling nematodes is soil fumigation with nematicides.