ABSTRACT
Fertilizing consists in the physical application to the soil of elements which are immediately or mediately available for plant food, or which aid in changing from unavailable to available forms of plant food any elements existing in the soil. The degree to which intensive cultivation had developed, the natural fertility of the soil and the incidental occurrence of materials that could be used as fertilizers have been the factors determining the extent of the practice. To understand the effect and value of fertilizers, a knowledge of the chemical and physical composition of soils, and of the relation of their composition to plant growth is essential. Fertilizers applied in the spring can be traced from the place of application down through the different depths of the soil which they invade. Efforts were made to inoculate soils with artificial pure cultures of the third class and thus increase the nitrogen content without the aid of manure or mineral fertilizer.
