TILLAGE. 73 



That proper tillage or cultivation of the soil often 

 increases its productive power is undoubtedly true. 

 The ability of a soil to produce crops is often as di- 

 rectly increased by tillage as by the application of 

 manures. The saying that "tillage is manui'e" as un- 

 derstood by Jethro Tull and by an occasional writer 

 of modern times — that is, that good tillage makes ma- 

 nuring unnecessary — may lead to bad practice. Good 

 tillage, liberal manuring, and good drainage combined 

 are much more likely to continue to give satisfactory 

 crops than if one places chief reliance on either op- 

 eration. 



Some of the reasons why cultivation makes soils 

 more productive are easily seen. Stirring and pul- 

 verizing a hard, compact soil enables the roots of 

 plants to penetrate it more easily and greatly increases 

 the quantity of plant food reached by the roots. These 

 operations also permit air and water to enter the soil 

 more freely and thus increase the supply of available 

 plant food. Autumn cultivation exposes the loosened 

 surface to the action of the frost. Prof. Wrightson 

 says: "No implement is so effective in pulverizing 

 the ground as frost." 



Sometimes tillage greaftly improves very open, coarse 

 textured soils by making them more compact, increas- 

 ing the number and reducing the size of the pores. 

 This increases the capillary power of the soil. 



Surface cultivation, keeping the surface soil loose 

 and dry, causes it to act as a mulch, retarding evapora- 

 tion. 



The destruction of weeds prevents their robbing the 

 crop of food and water. 



Plowing. — The plow is the typical farm imple- 



