PRINCIPLES OF FARM PRACTICE 



CHAPTER I 



WHAT WE NEED TO KNOW ABOUT PLANTS TO HELP 

 THEM GROW 



Plants, the basis of agriculture. Plants are the founda- 

 tion of all agriculture either directly when they supply food, 

 clothing, or some other human need, or indirectly when they 

 furnish feed for domestic animals. Since plants are really 

 the basis of agricultural production, we must, first of all, in a 

 study of agriculture consider some of the main facts about 

 how plants live. 



Plants are living beings. That plants have life is a 

 fact that needs to be repeated though it may be known to all 

 who read these lines. It seems necessary to emphasize this 

 because we habitually think of the word " living " as mean- 

 ing to move around and behave like animals. As a matter 

 of fact, plants are as much alive as animals. In order to live, 

 they require essentially the same things as animals do; but 

 they get these things in an entirely different way. The most 

 important of these requirements are food, water, and air. 



How plants get food. The green plants make their own 

 food from raw materials obtained from air, soil, and water. 

 The basic food material made by the plant is starch or a 

 starch-like substance. Starch is composed of three elements: 

 carbon, oxygen, and hydrogen. The carbon and oxygen come 



