6o STATE POMOLOGICAL SOCIETY. 



ditions for any crop cannot be determined by the external 

 appearance of the soil nor with absolute accuracy by the behavior 

 of other crops upon the land before the test crop was planted. 

 Plants vary greatly in their requirements and the limiters for 

 one crop may not be the limiters for another. The fact that a 

 field yields a uniform number of bushels of oats per acre over its 

 entire acreage is no sign that it will yield a uniform number of 

 bushels of potatoes or barrels of apples per acre. 



The most comprehensive set of orchard fertilizer experiments 

 in existence are probably those inaugurated by the Pennsylvania 

 Experiment Station in 1907. It is too soon, however, to draw 

 any fundamental conclusions from the results so far published, 

 although some of their results are very suggestive. 



The Delaware Experiment Station has had under way a fer- 

 tilizer experiment on apples covering the last six years. This 

 is on a young orchard that just came into bearing this past sea- 

 son and it would be folly to attempt to draw any conclusions 

 from the behavior of these trees. A vast difference in growth 

 and appearance of the trees can be seen, but six years more 

 growth may change the relative prosperity of some of these 

 blocks. In this experiment it has been our aim to determine as 

 far as possible the physiological offtce of nitrogen potash, and 

 phosphoric acid in growing apples. So far many facts con- 

 cerning the physiological function of various plant foods are 

 surmised, but few facts are absolutely known. 



Nitrogen is generally considered the element most concerned 

 with the growth functions of a plant. It, together with phos- 

 phorus and sulphur, is concerned chiefly in the formation of 

 protein. The general effect of heavy applications of nitrogen is 

 to produce a heavy growth of the vegetative parts. It retards 

 maturity of both wood and fruit in most plants. In regions sub- 

 ject to long, cold and severe winters, too heavy an application of 

 nitrogen, late in the growing season, will tend to produce a soft, 

 sappy, and perhaps immature wood that will be particularly sub- 

 ject to injury from cold. On the other hand, I have observed 

 ih the peach that where heavy applications of quickly available 

 nitrogen were applied early in the spring the fruit buds were as 

 cold resistant as any in the orchard. Properly handled, I be- 

 lieve that there is but little danger of winter-killing buds as 

 the result of heavy applications of nitrogenous fertilizers. In 



