DECIDING WHICH FERTILIZERS ARE NEEDED 433 



with sufficient available amounts of these minerals so that 

 satisfactory tree growth and fruitfulness are produced without 

 adding them as fertilizers. Sufficient nitrogen for best growth 

 and fruiting, however, seems to be lacking in many soils and 

 on them much better growth and production results whenever 

 it is added (Fig. 170) . It is often necessary to add phosphorus, 

 potassium, and lime for the growing of farm crops on the 

 same soils where fruit trees will show no apparent improve- 



FiG. 170. The row on the left received an application of quickly available 

 nitrogen fertilizer. The row on the right received none, but was treated 

 the same otherwise. Note the differences in foliage, growth, and yield. 



ment in growth and fruiting from the addition of these fertiliz- 

 ers. A possible explanation of this may be that the roots of 

 fruit trees range wider, extend deeper, and penetrate all parts 

 of the soil more thoroughly. 



Sod orchards respond well to applications of a readily avail- 

 able nitrogen fertilizer. Cultivated orchards also, except on 

 the heavier and more fertile soils, respond well in many regions. 



Though dried blood, tankage, and fish (all organic nitrogen 

 carriers) are beneficial, still most orchards seem to respond 

 better to the more quickly available inorganic nitrogen fer- 



