Arizona Agricultural Expkriment Station. 162 



to that of Early Rose. Tubers form on this former variety very 

 early in its growth. As early as April i8, the yield of a measured 

 area was at the rate of 3440 pounds per acre, against a yield of 

 1650 pounds for Early Rose. May 5 Burpee's gave a yield of 

 3840 pounds per acre, and Early Rose 2670 pounds. Seed of the 

 former variety sprouted so freely early in the winter that it was 

 not deemed best to hold any of it for the later planting. 



Of the February 7 planting, Triumph gave the best results. 

 It matured as early as Ohio and gave a much higher yield. It 

 also forms tubers early in its growth. April 18 it gave a yield of 

 2550 pounds per acre, against 660 pounds for Early Rose planted 

 at the same time. Mays the yield was 3180 pounds, against 

 2275 pounds for Early Rose. Burpee's Early and Triumph are 

 promising varieties for the region. At present, however, there is 

 no available supply of seed. Raising seed in the vicinity of 

 Phoenix is impracticable. An attempt is being made to get the 

 varieties introduced into the cooler valleys along the railroad to 

 the north of Phoenix. To this end, seed from those grown at the 

 farm was sent early in June to a grower near Kirkland, upon con- 

 dition that he save for seed the tubers grown from it. It would 

 be a distinct advantage to the valley if a source of supply of seed 

 potatoes could be established in the cooler valleys to the north. 



Part of the Early Rose plat was treated with Chili saltpetre 

 (sodium nitrate) at the rate of 500 pounds per acre. The unfer- 

 tilized portion gave a yield of 3025 pounds per acre, and the fertil- 

 ized portion a yield of 3695 pounds per acre, a gain of 670 

 pounds, worth about $12. The nitrate applied per acre was 

 worth nearly this amount. 



A test of the effect of dropping seed different distances apart 

 in the rows gave the following results: 18 inches apart, 2810 

 pounds per acre; 15 inches apart, 3280 pounds per acre; 9 inches 

 apart, 4370 pounds per acre, a gain of over 1500 pounds, worth 

 about $30, over the plat planted 18 inches apart. The difference 

 in cost of seed would be $10 to $12. 



WINTER IRRIGATION OF ORCHARDS. 



The test of the effectiveness of the thorough irrigation of or- 



