SOILS 291 



Plant food must be in the form of solutions. Since the 

 water touches more surface in a given volume of soil when 

 the particles are small than when they are large, it will 

 be able to dissolve and furnish plant food more readily in 

 the finer soils. On thepther hand, the coarser soils will be 

 better aerated, due to the fact that the spaces between the 

 particles are larger so that the air moves more freely. 



All of these things affect the crops that grow in the soils. 

 Sandy soils which are well adapted for corn, potatoes, and 

 market gardening are not well adapted for wheat, which 

 may be grown to advantage on the heavier clay soil. The 

 successful farmer will soon learn what crops are suited 

 to his land and cease cultivating those that are not. 



Conservation of the Soil. - - The study of the soil and 

 its products will soon convince us that it is quite important 

 to care properly for this great gift to man. It has required 

 ages for the soils to be formed and reach a certain produc- 

 tive stage, but it requires but a few years of careless farm- 

 ing to reduce them to a non-paying productive basis. 

 The population of the United States is increasing rapidly, 

 and this means that the demands on the soil are increasing 

 proportionately. It is not possible to harvest crops year 

 after year and put nothing back on the land without 

 decreasing its fertility. Certain crops take certain kinds 

 of food from the soil with the inevitable result that the 

 amount of this particular food in the soil is lessened. 



Measure of Soil Values. A soil from the agricultural 

 standpoint is measured by the abundance of its scarcest 

 element. There are five substances in which our soils 

 are likely to be deficient : water, nitrogen, phosphoric acid, 

 potash, and lime. These foods are needed by different 

 crops in varying quantities. If the soil is deficient in 

 phosphoric acid, the addition of phosphoric acid will 



