62 Gardening 



FIG. 40. Spreading manure over the garden. The coarse lumps should be 

 broken up and the material spread evenly. Many gardeners prefer putting the 

 manure into the trench direct and spading it under, instead of scattering it over 

 the surface of the soil. 



SOIL FERTILITY 



The soil is more than a place for the roots of plants to 

 grow. It supplies water and raw food materials on 

 which the plant lives. // is itself raw food material 

 for plants, as plants actually take into themselves certain 

 compounds contained in the soil and change these mate- 

 rials into substances which build the plants up. A rich 

 soil is one that supplies in large amounts the materials 

 that the plant needs. Of these, aside from water, the 

 ones that are most often lacking in sufficient amounts 

 are nitrogen, potassium, phosphorus, and lime. 



The food materials are constantly being removed 

 from a cultivated soil in the crops harvested, and are 

 also being lost in the drainage water. Therefore it is 

 often necessary to furnish new supplies of these materials 

 to keep a soil from becoming poorer and less productive. 

 They may be added to the soil as manures, compost, 



