64 AGRICULTURE OF MAINE. 



In plats II and 12, and in similarly treated plats of our 

 other experiments, we see the apparent futility of attempting 

 to improve yields materially by applying phosphates alone. 

 The present slight gains on these plats have only been secured 

 by the addition of nitrogen and potash to "complete" their 

 fertilization during the past two seasons. This failure of the 

 phosphates when applied alone is not due to the fact that phos- 

 phorus is not needed, nor can it be largely attributable to the 

 absence of cultivation, as may be seen by comparing the results 

 in plats 9 and 2. Nitrogen by itself in No. 9 shows an annual 

 gain of 64.3 per cent or 120 bushels ger acre, but when phos- 

 phorus is added in plat 2 these benefits are more than doubled. 

 Phosphorus, as usual, therefore, appears to be next in impor- 

 tance after nitrogen in improving yields. 



The Permanence of Fertilizer Influence. — It is another fairly 

 common impression that the influence of fertilizers is transient 

 and that, even where their effect is favorable at first, this effect 

 soon wears out and may leave the soil worse than before. This 

 evidently depends very largely on the character of the ferti- 

 lization, and in this respect apples are not dift'erent from other 

 crops. ^If the gains are induced by some caustic action of such 

 materials as gypsum or lime when used alone, this may actually 

 be the final result. 



On the other hand, it should be noted that in plats 2, 3 and 

 8, where definite plant foods are being supplied, the effects of 

 fertilization were greater in 1912, the sixth year of the experi- 

 ment, than ever before. The steadiness and regularity of the 

 increases also are especially notable in plat 8, which shows a 

 distinct gain in every year except 1909, and in that year the 

 yield would have been fully 1,000 pounds greater had there 

 been sufficient moisture available to properly develop the fruits 

 that were actually present. In 19 13, all the yields were reduced 

 here also by the unusually late and severe frosts in May. 



In plats 2 and 3, only two fertilizer elements have been ap- 

 plied, and also the yields have been so large in the evenly num- 

 bered years that it was impossible to prevent some alternation 

 with lighter crops in the odd years. This same general condi- 

 tion is evident to a considerable extent in the Johnston orchard. 

 In other experiments, however, and especially in one primarily 



