174 Peach-Growing 



than the check plats, it would still further confirm the 

 value of nitrogen under the particular conditions of the 

 experiment. In the same manner the deductions may be 

 made for all the plats and by the process of elimination 

 the plat and plant-food combinations which gave the best 

 returns can be located, and on these results the future 

 applications of fertilizers can be based. 



The inevitable question of whether it pays will arise. 

 The owner of the orchard must answer for himself. If a 

 fertilizer produces increased returns sufficient more than to 

 pay the costs of material and labor, it may be regarded as 

 a profitable procedure. If increasing the quantity applied 

 brings returns in proportion to the increased cost, or better, 

 it would appear to be a money-making proposition to apply 

 the larger amount of plant-food. 



Finally, there remains for mention some of the newer 

 views in regard to soil fertility factors, for which there seems 

 to be good support, and which have not previously been 

 taken into account. They must still be largely ignored 

 so far as peaches are concerned for lack of information. 

 The roots of plants may give rise to, or secrete, substances — 

 complicated chemical compounds — which are toxic or 

 poisonous to the roots themselves. Thus when in the past 

 a farmer has spoken of a piece of land as being "clover 

 sick" or "wheat sick" there may have been more in the 

 expression than he realized. That the roots of peach trees 

 ever develop substances in the soil which are toxic to them- 

 selves is an entirely unknown possibility. There are oc- 

 casional instances, however, when the soil is known to be 

 fertile but for some obscure reason the trees do not thrive. 

 A peach-grower rarely thinks it advisable to replant an or- 

 chard site to new trees immediately on taking out an old 



