280 Mineral Nutrition of Plants 



treatments. This product is smallest for the highest nitrogen dosage. 

 Actually the picture is not quite as simple as the table indicates because 

 there was a greater drop of fruit from the high nitrogen trees than 

 from the low nitrogen trees, average fruit color on the high nitrogen 

 trees was not as well represented by the color samples as was the color 

 from the low nitrogen trees due to the greater shade within the former 

 trees, and the average size of the fruit was considerably smaller on the 



TABLE I 



Average Yield and Percentage of Fancy Fruit from a New York Mcintosh 

 Apple Orchard under 3 Levels of Nitrogen Fertilization, 1942-1947 



Annual Total Average Percentage 

 Annual Nitrogen Yield per of Fruit Sample Column 2 



Dosage per Tree Tree Grading Fancyf X Column 3 



LD* 5% 1.1 7.6 



1% 1.4 10.2 



*Least difference for statistical significance at the odds indicated. 



f5o apples were picked at random from the outside of each tree at harvest time. Fruits having 

 half or more of their surfaces colored red were graded as fancy. The average percentage attain- 

 ing this grade for the 16 samples in each nitrogen treatment is represented in Column 3. 



low nitrogen trees than on the high; but correction for these things 

 does not change the picture greatly. Therefore, the data raise a ques- 

 tion as to the need for a dosage of nitrogen more than 0.5 pound per 

 tree in order to produce conditions satisfactory for maximum yields of 

 high quality fruit in this orchard. 



That 0.5 pound of nitrogen per tree applied annually in the spring 

 is a deficiency dose, in terms of the vegetation of these trees, is indicated 

 clearly in Table II. It is apparent that there was marked increase of 

 growth in the trees receiving the first, and again in the trees receiving 

 the second, increment of nitrogen. The first increment was associated 

 with increased total yield but the second was not. Nitrogen effects on 

 the total leaf surface of a tree and its efficiency are cumulative. On a 

 single shoot the number of leaves and their average size are directly 



