Justus von Liebig proposed the use of chemical fertilisers beneficial for plant growth, so that abundant food could be produced. But, about ten per cent of ground water samples showed the presence of noxious chemicals, apparently from fertilisers, more than the permissible limit prescribed by the World Health Organisation (WHO). This paved the need for organic farming, wherein bio-fertilisers are used instead of synthetic chemical fertilisers. Sir Howard introduced the concept of organic farming; hence he is regarded as the father of organic farming.
Bio-fertilisers are substances containing living organisms such as bacteria, cyanobacteria and fungi that promote plant growth by increasing soil fertility. Moreover, they sometimes form symbiotic associations with plants and aid in inorganic nutrient uptake by the plants.
Biofertilisers contain nitrogen fixing bacteria which include:symbiotic bacteria in root nodules of legume plants such as Rhizobium, free living bacteria in soil such as Azospirillum , Azotobacter or cyanobacteria such as Anabaena, Nostoc and Oscillatoria or symbiotic fungal mycorrhizea such as glomus in the roots of vascular plants. In all these associations, bacteria or fungi provide nutrients to the plants, and in turn derive food from the plants. As bio-fertilisers contain living organisms, they safely convert the complex nutrients including remnant chemical fertilisers into simple absorbable form, thereby making them eco-friendly.