There is plenty of life below the soil surface. The function of most of the organisms found there is to eat and multiply as fast as possible. In doing this, the organisms combat disease-causing nematodes and fungi. Here are three examples:
- There’s a benevolent fungus which preys on root knot nematodes. It has snare-type appendages, which exude a pheromone. The pheromone attracts nematodes searching for new succulent roots to feed upon. In this way the nematode is tricked into entering the snare, which closes and traps the nematode. Once it is caught, the fungus will feed on the nematode, ensuring that it will never damage another crop.
- Another fungus is more like a spider’s web, but has adhesive knobs scattered around at strategic places. Root-feeding nematodes are attracted to the web and then caught and devoured.
- Protozoa from the Vampyrellid family prey on fungi, especially Gaeumannomyces graminis, which causes a serious disease in wheat called ‘take all disease’. The protozoa make tiny holes in the stems of the fungi and feed on it, minimising its disease-ausing ability.
These are only three of many thousands of examples where a healthy food web is more than able to deal with pests or diseases which may challenge our crops. When we use chemicals we eliminate these pests, but all the beneficial organisms too.
Foundations for Farming (FFF) is a Zimbabwe-based NGO that teaches conservation agriculture practices to farmers, based on Christian principles. FFF provided the information for this article. Visit www.foundationsforfarming.com.