CHAPTER IX 

 THE PLANT AS RELATED TO THE SOIL 



65. The Welfare of Plants is dependent on the nature 

 of their surroundings. In cultivation, the effort is to 

 make and keep the environment favorable. In open- 

 field culture, little can be done to change the air, the 

 temperature, or the amount of light. While the diffi- 

 culty of changing the environment of the plant above 

 ground is great, much may be done to control the en- 

 vironment under the ground. The fertility of the soil, 

 the amount of water, the temperature, the supply of 

 air, and other conditions affecting the growth of the 

 root, may be readily changed. A knowledge, then, of 

 the habits and needs of roots, and of how to make the 

 soil conditions favorable, will be very practical infor- 

 mation. 



66. Uses of the Soil to Plants, (a) Serves as a foot- 

 hold. The roots enter the soil and act as braces to keep 

 the plant in the proper position. Plants with long stems 

 and heavy foliage must have strong roots to enable 

 them to withstand the action of the winds and other 

 forces that would displace them. 



(b) Supplies the plant with important mineral foods. 

 The amount of food which the plant takes from the soil 

 is small, as has already been seen, only about 5 per 

 cent of its dry weight; yet, small as it is, these mineral 

 foods are absolutely necessary. 



(c) The soil acts as a storehouse for water. The plant 



(40) 



