13 



the state that do not need these fertilizers. 



The practical application of the results obtained 

 is that fruit growers should not apply manures in quantity 

 until good evidence has been obtained as to what food 

 elements, If any, are wanted in the soil. As long as the 

 trees are making good growth and producing average crops of 

 well colored fruit, it may be taken for granted that they 

 need no additional food from fertilizers. If the contrary 

 be true, the fruit grower should put in operation tests 

 with fertilizers to ascertain what plant foods his soil needs. 



If the above be true of an orchard that has stood 

 for fifty- three years in sod, then in view of the fact that 

 perhaps fev/ orchards older than that are worth renovating, 

 it would seem that fertilization should be carried on only 

 very cautiously, for although the fertilizers applied w^ould 

 not be detrimental to the trees, yet they would not benefit 

 them materially and their application v/ould only result in 

 financial loss. 



If, however, after careful observation it is found 

 that the soil is distinctly lacking in some essential 

 element of plant food, it might be well to apply the defl© 

 cient element alone. There would perhaps never be a case 

 where a complete comiaercial fertilizer would be necessary. 



For the purposes of the above the pi'^incipal source 

 of the three essentials are here briefly discussed. 



Nitrogen, 



The sources of nitrogen in the soil are many 

 and it would seem unnecessary to add nitrogenous fertilizers 

 in the chemical form, when natural agencies are so rapidly 



