82 AGRICULTURE 



Nature's Processes. How is a soil made fertile ? We have 

 observed the processes of Nature. We have seen how they build 

 up soil from rock. Left to themselves, they usually improve it and 

 make it fertile. Frost fines and mellows it, rain brings plant food 

 from the atmosphere, and chemical changes make available some 

 elements in the soil. Roots drink in food from the surface and 

 pump it up from the subsoil; decaying plants give to the soil the 

 elements thus gathered and others derived from the air. Year 

 after year the barren land, improves; slowly but surely it becomes 

 fertile. 



Farm Methods. But the farmer cannot wait on the slow 

 processes of Nature, nor restore to the land all the fertility of its 

 products. His business is to take from it once a year, or oftener, 

 the richest of these products. Can he do this and not impoverish 

 it? He can, if he. will imitate and aid Nature. The plow can fine 

 and mellow the soil more quickly than the frost; green and stable 

 manures can improve texture and supply humus, and these manures 

 and commercial fertilizers can add plant food more rapidly than 

 do the methods of Nature. 



The farmer can take the place of Nature's reclaiming processes 

 and protect his land against her destroying ones. By drainage 

 and irrigation and tillage he can largely regulate the supply of 

 moisture, and improve the texture of the soil and its relations to 

 heat and air. By proper rotation he can lessen the drain of crop- 

 ping. To do all this he must work and work intelligently. 



The Ideal Soil. The best soil for agricultural purposes is a 

 loam containing sand, clay, humus, and lime. The sand admits 

 air and water, the clay holds moisture and plant food, the humus 

 absorbs and retains moisture, and the lime assists the decay of 

 vegetable matter. This soil is ideal if it be rich in available plant 

 food and has a well-drained subsoil. Most farm soils have not this 



