COLOR 441 



phosphoric acid in growing apple trees, nor that the lime accom- 

 paniment could in any way nullify or obscure the action of these 

 nutrients as to the yield or color of apples. In this connection it 

 is worth noting that some of the best apple regions in the United 

 States have limestone soils. Many fruit-growers use lime in mod- 

 erate quantities as a fertilizer for apples. From these consider- 

 ations it may be assumed that lime in the quantities added did 

 not have a deleterious effect on the yield or color of the apple 

 in this experiment ; on the contrary it might be suspected that 

 the lime was in part responsible for such beneficial effects as 

 were noted. 



While no tests to determine the acidity of the soil were made, 

 it may be inferred, since all leguminous cover crops grew readily 

 in the untreated plats, that the soil of the orchard is not strongly 

 acid, for the clovers in particular do not thrive in an acid soil. 



Acid phosphate was applied to the treated plats at the rate of 

 8.1 pounds per tree during the last seven years of the experiment. 

 With 48 trees per acre there were, therefore, 408 pounds of the 

 acid phosphate applied to each acre. The fertilizer was guaranteed 

 to contain 14 per cent of phosphoric acid (analysis proved it to 

 contain approximately that much), and the amount of available 

 phosphoric acid per tree each season was 1.19 pounds, or 8.33 

 pounds per tree in the seven years. This is equivalent to 399.84 

 pounds per acre, an average of 57 pounds per acre annually. The 

 amount of phosphoric acid recommended for apples ranges from 

 30 to 60 pounds per acre. Adding to the above amount the phos- 

 phoric acid to be found in the wood ashes, approximately 72 pounds 

 per acre, the total quantity is about 1 29 pounds per acre — a great 

 abundance. 



In the Station orchard apples did not color well, and it was 

 thought that if the addition of these fertilizers would heighten 

 color, their use might be desirable, even though there was no 

 great gain in yield. As a rule apples take on their brightest colors 

 on sandy soils, while on clay they run to duller hues. Because 

 of their influence on color, potash and phosphoric acid are thought 

 to be especially valuable on clay soils. The clay soil of the Station 

 orchard was therefore a very favorable one on which to try these 

 substances to influence color. 



