16 



MASS. EXPERIMENT STATION BULLETIN 444 



Five pots received each treatment. 



meaning: 



No treatment 



N Nitrate of soda 



L Magnesium limestone 



The letters and figures irf this column have the following 



S Ground sulfur 



Am Ammonium sulfate 



The figures indicate grams per 17 kilos of soil 



Concluding Remarks 



The abnormal conditions brought about in the soil by the long continued 

 unusual fertilizer treatments have caused peculiar responses by the trees. There 

 is no doubt that under normal conditions nitrogen is most likely to produce 

 favorable results. In this experiment, nitrate of soda alone was injurious rather 

 than beneficial to the trees. The growth of the trees on plots that were never 

 fertilized was surprisingly good but not equal to that of a successful orchard. 

 While cover crops of rye, buckwheat, or barley were grown each year, growth, 

 especially on plots with no lime and phosphorus, was poor and added little or- 

 ganic matter to the soil. 



Lime was almost always eflective in improving growth of the trees and sulfur 

 was very injurious. Whenever the pH was depressed below 4.0 the trees grew 

 but little. This was closely correlated with soil nitrates. The addition of organic 

 nitrogen to very acid soil increased soil nitrates and improved growth but in- 

 organic sources of nitrogen were not very effective. 



The behavior of grapes was not like that of apples and peaches. Lime was 

 generally injurious and grapes grew about as well on the check plots as on the 

 fertilized plots. Only in the presence of potassium was growth better on the 

 limed plots. 



Except for the suggestion that a long-continued program of nitrogen alone is 

 not a good one, this experiment offers little in planning a practical fertilizer 

 treatment. It must be remembered that the conditions of this experiment are 

 most unusual. 



