274 LESSONS IN AGRICULTURE 



and holds larger quantities of rainfall than no plowing 

 or shallow plowing, it becomes the part of good tillage 

 to save as much of this ground water as possible by 

 preventing its evaporation from the surface. We know 

 that if we cover a vessel of water it keeps the sun from 

 drying it up. In the same way a cover spread over the 

 soil will check the evaporation of the capillary water. 

 The simplest way to get this cover spread over the 

 soil is to cultivate it. The layer of cultivated soil dries 

 out rapidly, but it keeps the air from getting at the 

 moist soil underneath and drying it out, and it also 

 breaks the rise of capillary water and prevents its com- 

 ing to the surface. The surface cultivation should be 

 shallow to prevent injury to the plant roots, and it 

 should be frequent to provide the dust mulch. 



Constant cultivation. When the writer was a boy, 

 living in the corn belt of Illinois, it used to seem a 

 terrible hardship when the father announced, after just 

 finishing the cultivation of a large field of corn, that we 

 must now go back to the beginning and go over it all 

 again. Fishing and swimming never seemed more in- 

 viting to the boy, but the father knew what was best 

 for the corn. He knew that constant cultivation was 

 the price to pay for a good crop. He paid the price 

 and got the reward. 



Summary. To summarize, we may give four chief 

 reasons for tillage: (1) To pulverize the soil, so that 

 plant roots can easily penetrate in every direction 

 and get at the store of plant food the soil contains. 

 (2) To increase the water-holding capacity of the 



