216 POMOLOGY 



the variety. Thinning has a greater effect on increasing 

 size on a heavily ladened tree than any other practice. 



187. Summary.^ — The following statements summarize 

 the general conclusions which may be drawn from the fore^ 

 going discussion: 



1. The most fundamental difficulty in interpreting the 

 experiments in orchard fertilization is due to failure to 

 recognize whether or not an orchard is tilled. 



2. Apple orchards in sod or grass mulch usually require 

 fertilization to maintain the growth and yield of the trees. 



3. Orchards which are being well cultivated, involving 

 the use of some cover-crop, are likely to respond rather 

 slowly to the use of chemical fertilizers, and when such bene- 

 fit appears it is usually first seen in growth rather than 

 in yield. 



4. The length of time which an orchard under cultiva- 

 tion can be operated without supplying additional fertility 

 will depend on the initial fertility of the soil. 



5. Nitrogen is likely to be the first limiting factor so far 

 as soil fertility is concerned. This one element is likely to 

 give as good results for a few years as a complete fertilizer, 

 although on some soils the latter would be more desirable 

 in the end. 



6. This element (nitrogen) then may be supplied in either 

 of two ways, by the use of the plow and harrow or from the 

 fertilizer bag. 



7. A peach orchard (which should always be cultivated) 

 will respond generously to the use of fertilizers unless it is 

 for the first two or three years after planting. 



8. Red color of fruit is apparently not affected except 

 adversely by fertilizing. 



9. Size of fruit is variously affected by fertilizing. A 



1 Author's statement. Proc. N. Y. State Hort. Soc, 2nd Ann. Meet- 

 ing. 1920. pp. 92-93. 



