106 THE POTATO 



tions will vary with each year and the class of soil. 

 The Ohio Experiment Station 1 found that thorough 

 culture encouraged vigorous growth and aided the 

 plants to resist fungous troubles. 

 The objects of tillage, then, are : 



1. To increase the crop-producing power, presum- 

 ably by : 



O) Liberating plant-food. 



() Maintaining good texture. 



(/) Conserving moisture by the aid of a soil mulch. 



(cf) Pulverizing the ground, so that every shower 

 of rain can enter the soil and not flow off, 

 transporting the fine soil particles. 



2. To keep weeds in check. 



System of Culture. Hills. Generally hills that 

 is, where potatoes are planted in checks are unprofit- 

 able because there are not enough plants per acre and 

 the yield is too low; hence the system is little used un- 

 less a piece of land is very weedy. 



Drills. By "drills" it is understood that the soil is 

 thrown toward the potatoes, leaving a depression or 

 furrow between the rows. This system is used for 

 irrigation, when the water flows between the rows. It 

 is also practiced in humid climates, where the tempera- 

 ture does not go high as, Northern England, Scot- 

 land, etc. and on wet soils and in wet seasons. Often 

 the "furrowing" injures roots and reduces the yield, 

 but many growers claim that the ease with which the 

 potatoes can be dug from drills compensates for any 

 loss in yield. The objection to level culture is that 



Ohio Bui. 76, p. 47. 



