Explain in detail about the Viruses

Viruses are the ultramicroscopic parasites which always require a living h ost for their multiplication. Since they are much smaller than bacteria they can be observed only through an electron microscope. Chemically, the viruses are nucleic acids contained within a shell of protein. The viruses in the soil are known as parasitised bacteria and are named  bacteriophages. When they destroy the bacteria of agricultural importance like rhizobium, they attain economic importance. Clay and organic matter in the soil adsorb bacteriophages and thus cause their retention and spread in the soil.