Fertilizers for Peach Orchards 151 



On the other hand, a soil may analyze low in plant-food 

 elements yet prove to be very productive. 



The whole difficulty here rests in the fact that the methods 

 of analysis known to the chemists do not approximate those 

 used by the roots of the trees in abstracting the food material 

 from the soil. Thus, a soil that analyzes very rich in plant- 

 food elements may hold them in such chemical combina- 

 tions that the roots can obtain them only in minute quanti- 

 ties or not at all; while in a soil that appears poor in 

 comparison when analyzed the plant-food elements may be 

 in such chemical combinations that the roots can obtain 

 them in the degree necessary for optimum results. 



The real problem, then, is not whether this fertilizer, 

 or that one, is good for peaches, but to determine whether 

 nitrogen, potash (potassium), and phosphoric acid (phos- 

 phorus) are contained in the soil in sufficient abundance 

 and in available forms for the needs of the trees. 



The reader should here recall the very close bearing 

 which tillage and the use of suitable cover- and green-manure 

 crops have on the fertility of the soils, as presented in the 

 preceding chapters. Not infrequently when an orchard 

 has been neglected or improperly managed with respect to 

 tillage and cover-crops and the trees are lacking in thrift 

 and vigor with the attending signs of starvation, their con- 

 dition is entirely and speedily changed for the better on the 

 adoption of suitable methods of orchard management, the 

 trees soon giving evidence that all needed plant-food is 

 being supplied. The reader will recall in this connection 

 the influence of the physical condition of the soil as affected 

 by tillage and humus on the bacterial and other organisms 

 in the soil and their relation to soil fertility. 



It follows in logical sequence that questions relating to 



