CHAPTER V 

 THE TILLAGE OP SOILS 



24. Why we till the Soil. — The question of tillage 

 of soils is so interwoven with that of air in the soil, water 

 in the soil, and the temperature of the soil that it is 

 difficult for us to set it aside as a separate lesson. There 

 are, however, some deep and fundamental objects of 

 tillage which we should fix in mind. We till the soil : 



First : to improve its texture and structure. 



Second : to cover, or to work into the soil trash, straw, 

 manure or plants by plowing or discing. 



Third : to put seed into the prepared seed bed. 



Fourth : to destroy weeds. 



Fifth : to prevent the escape of moisture from the soil by 

 making a dust mulch. 



Sixth : to enable air and water to enter the soil. 



26. Improving the Texture and Structure of the Soil. — 



If we are to study how tilling the soil will change its texture 

 and structure, we must know the meaning of these terms 

 as applied to farm lands. The size of the individual 

 particles in the soil determines its texture. The manner 

 in which these particles ^< together determines the structure. 

 The question at once arises. How does tillage change 

 the size of particles? It can not, in itself, change the 

 texture of the soil, for the particles are broken up by might- 

 ier forces than the plow, or harrow, or disc. These opera- 

 tions do, however, expose the soil particles so that the sun 

 and the water, the heat and the cold, can break them into 

 finer particles. 



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