70 CULTIVATION AND IRRIGATION 



farther away from the rows and towards the center a har- 

 row-tooth cultivator or one that will serve the purpose of 

 mellowing the soil. If it is necessary to irrigate more than 

 once, deepen the center furrow again and cultivate after the 

 irrigation. When using the harrow-tooth cultivator it is 

 well to narrow it so it will not tear down the loose soil that 

 has been thrown up against the potatoes. It should be just 

 wide enough to stir the wet soil in the center of the rows. 



Never allow the soil to become too dry. It should be in 

 a mellow, fine and moist state always, but not wet. When 

 the soil becomes too dry, after the tubers are a certain size, 

 and is then irrigated, a new growth starts, and the result is 

 knotty tubers, and they are of a poor quality. Never allow 

 the water to soak around the potatoes, but allow the mois- 

 ture to be drawn up by capillary attraction. The best way 

 to determine the need of irrigation is to dig in the subsoil 

 beside the large vine, one that is forming tubers, as they use 

 up the moisture more readily than the smaller vines. If the 

 soil around the hills becomes too wet the leaves turn pale, 

 and when too dry, they become a bright, dark green shade. 



When the tubers have begun to ripen they should be 

 allowed to mature in comparatively dry soil, so the skin may 

 toughen before digging. 



In planting where hill culture is practiced, it is a wise 

 plan to grade the land. If graded to a gradual slope, when 

 irrigated or when rain comes the water will not stand in any 

 one place. If it stands in one place long it causes the soil to 

 become water soaked and soggy. When such poor condi- 

 tions exist the result will be very unsatisfactory, generally 

 making the tubers scabby and of a poor quality. On the 

 other hand, if the slope is too great, the water will make 

 deep ditches or washes, causing the grower severe losses. 



