HOW PLANT FOOD IS PRESERVED 69 



day ; it is for the morrow. It is the inside material that 

 is being prepared and manufactured slowly, that it may 

 be made a part of the soil's labor and commerce, and 

 that it may be available at some future day when it will 

 be called into use. 



Making this kind of food available. To help in this 

 work you can do these things : 



Till the soil frequently and well. 



Cultivate when needed, using judgment and fore- 

 thought. 



Keep vegetable matter in the soil. 



Tillage will admit air and water to lower depths in 

 the soil. These agents, in themselves, will do wonders in 

 changing this heretofore unavailable plant food into avail- 

 able forms. 



Correct culture will do the same : for it allows these 

 same busy bodies to carry on their weathering processes 

 even though the soil be dry or moist or cold or hot. 



The tightly-secured plant food. The third class, or 

 that form in which plant food is tightly secured, occupies 

 the greater part of the storehouse of the soil. Here are 

 the rocks and the boulders ; the many materials that 

 plants never use find rest and shelter within this clothing 

 of the earth : and not a bit of it is available plant food, 

 not a bit of it will be plant food for ages and ages and 

 ages to come. 



Use the strongest acids known and they will act but 

 slowly on many of the materials herein sheltered or hid 

 away from water and air. What headway may plants 

 be expected to make against these giant forms? Not 

 much, truly. But still remember this : In the beginning 

 the earth was rock nothing but rock, and yet plants 

 did conquer. And so in time, aided by other good soil 

 makers, they will conquer every stubborn rock that finds 



