148 FOOD FOR PLANTS 



Results of Investigation on the Fertilization of 

 Apple Trees at State Agricultural Experiment 

 Stations. 



That nitrogen is the limiting element of plant-food 

 in many apple orchards is indicated by the results of 

 investigations on the fertilization of apple trees, con- 

 ducted for a number of years past at several state 

 Agricultural Experiment Stations. 



Studies over a period of five years at the Maine 

 Agricultural Experiment Station are summarized in 

 their Bulletin 322 as follows : 



"Annual applications of a complete 5-8-7 fertilizer 

 to mature Ben Davis apple trees under cultivation, at 

 the rate of 7 and 14 lbs. per tree, over a period of five 

 years did not increase the yield as compared with 

 check trees which received no fertilizer. 



*'Two annual applications of Nitrate of Soda to 

 mature Ben Davis apple trees in sod, at the rate of 

 6 and 12 lbs. per tree, more than doubled the yield 

 of fruit. The use of 20 cents worth of Nitrate of 

 Soda per tree resulted in an increased yield of more 

 than one barrel of fruit per tree. Six pounds of Ni- 

 trate was as effective as 12 pounds in this experiment. 



"These results are in accord with most fertilizer 

 experiments throughout the country. Applications 

 of phosphoric acid and potash seldom, if ever, cause 

 increased yields of apple trees. 



"Nitrogen may not increase the yield of apple trees 

 grown on fertile soil under a system of cultivation 

 and cover crop. Apple trees grown on a poor soil, or 

 under the sod-m^ulch system of culture, will usually 

 respond to applications of nitrogenous fertilizers. 



