POTATOES 383 



which it is believed can best be overcome by substituting grains or 

 hoe crops, such as beets or corn, in the rotation to precede the 

 potato crop rather than to plant the potatoes after alfalfa. 



Planting. On irrigated lands, after the plowing has been com- 

 pleted and the first harrowing has been given, it is necessary to 

 level the earth so as to fill in slight depressions which may occur, 

 and to take down ridges so that it will be possible to carry the 

 water and distribute it evenly over the field. The amount of level- 

 ing required to fit the land for planting will depend upon the con- 

 tour of the area. After leveling, the ground should be thoroughly 

 disked. The details of planting on irrigated areas do not differ 

 from those of planting in humid localities except that, where the 

 contour of the land will permit, the rows should be laid out in such 

 a way as to obtain a gradual, uniform slope lengthwise of the field, 

 unless the rows exceed a quarter of a mile in length, in which case 

 cross ditches must be provided. If the surface is uneven, ditches 

 must be provided along the crown of the ridge, and the planting 

 done on contour lines so as to lead the water at a uniform speed 

 through the irrigating furrows. The accuracy and care with which 

 the rows are laid out determines, to a great extent, the ease and 

 success of the irrigation. 



Planting on extensive areas is almost always done by machinery. 

 The same type of planters shown in figure 127 is used in the 

 irrigated district. 



Cultivation. As soon as the planting is completed, cultivation 

 is begun. In some instances this is simply harrowing in order to 

 loosen the surface soil which has been compacted by the tramp- 

 ling of the teams and implements during the process of preparing 

 for and planting the crop. In other cases the first cultivating is 

 done with a four-horse cultivator having narrow blades which set 

 very deep, so as to loosen the soil thoroughly and to increase slightly 

 the ridges thrown by the planter over the seed. This cultivation 

 is usually followed at once by the harrow. The number of cultiva- 

 tions necessary depends upon weather conditions and the rapidity 

 of growth of the vines and weeds. 



.The second cultivation is given when the plants are large enough 

 to make it easy to follow the rows. At that time the shovels 

 are not run so close to the row as in the first cultivation, but the 



