FERTILIZERS AND MANURES FOR THE ORCHARD 211 



It is possible that the difference in results is due largely 

 to the organic matter in the soil. In a climate where the 

 season is long and the suramer heat intense, cultivation 

 would "bum out" the organic matter or source of nitrogen 

 much more quickly than where the opposite conditions 

 obtain. Also a soil already devoid of organic material 

 would probably produce the same results. It is at least 

 worthy of notice that three of the experiments here consid- 

 ered in which fertilizers in a cultivated apple orchard were 

 very slow in producing results were in the North (Maine, 

 New Hampshire, and New York). 



OTHER RESULTS OF FERTILIZING 



182. Color of fruit. — In general, it may be stated that no 

 fertilizer combination yet tried will increase the color of 

 fruit appreciably. In some apple experiments there seemed 

 to be a slight advantage to color from potash but not suffi- 

 cient to warrant its use for this purpose. Alderman ^ gave 

 double and triple applications of potash to plots of peaches 

 and reports that there is "absolutely no effect upon color 

 of fruit, a fact which indicates the worthlessness of this 

 material as a coloring agent." In the case of a number of 

 crops, phosphoric acid will hasten maturity, but this has 

 not been observed with the apple. 



It has not infrequently been stated that iron salts will 

 heighten the red color of fruits, and several well-planned 

 experiments have been prosecuted to determine this point. 

 At the Woburn Experimental Fruit Farm ^ where such a 

 test was made, it was concluded after twenty-two years' 

 work that where 2.8 grains of iron sulfate to a square meter 

 or a similar amount of manganese sulfate was used, no ef- 

 fect had been noticed on fruit color with the exception of 



1 W. Va. Asr. Exp. Sta. Bull. 150. 1915. 



2 Woburn Exp. Fruit Farm. 16th Rept. 1917. 



