Bio-fertilizers are defined as biologically active products or microbial inoculants consist bacteria, algae, fungi or biological compound which may help to benefit of the soil and plants. These fertilizers are not harmful to the environment unlike the chemical fertilizers. It’s originated from plant or animal wastes along with the microbial mixtures. Microorganisms are used to increase the level of nutrients uptake by the plants and restore biodiversity of the soil. Bio-fertilizers let the plants grow in a healthy environment where it is doing not cause the pollution of any sort.

Bio-fertilizer often refers to microbial fertilizers that utilize active microorganisms to increase the nutrients or their availability in soils, enhance absorption, or protect the roots. It is usually called microbial fertilizer or microbial inoculants, because of the most frequent use of microorganism. The products of bio-fertilizer are modern fertilizer with new science and technology, and the classification varies a lot. It is mainly classified according to the function of microorganism.

For example, the application of nitrogen fixing microorganisms can increase the source of nitrogen in soil. Nitrogen fixing microorganisms can also be classified into symbiotic nitrogen fixing microorganisms (such as Azosperilum). Mycorrhizal fungi can mainly help plants to dissolve phosphorus fertilizer. There are various phosphate-solubilizing microorganisms, and the insoluble phosphate can be dissolved into soluble phosphate.

The biofertilizers have a low environmental impact. Nutrients in the soil environment are limited, and microbial fertilizers will not destroy the ecosystem after applied to soil; therefore, microbial application should not be the concerns about the contamination.

It is reported that in the diseases of human beings, almost half of the diseases are directly or indirectly caused by insufficient or inappropriate nutrient.