Materials which cannot be broken down or decomposed into the soil by micro-organisms and natural agents are said to be as
Substances which can be broken down into non-poisonous substances by the action of microorganisms are said to be
Which of the following is not a use of micro-organisms ?
(a) preparation of medicines (or drugas)
(b) preparation of food by photosynthesis
(c) recycling of materials in nature
(d) increasing the fertility of soil