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WMT FERTILIZER ELEt.ffiNT DOES THE CULTIVATED BLUEBERRY NEED MOST? 



The question of the how and what in fertilizing cultivated blueberries has 

 been discussed on several occasions in Fruit Notes, Rec5ntly, in the Nov. -Dec, 

 1955j and the March, 1956, issues reference was made to a nutritional survey in 

 fields of cultivated blueberries throughout the state. The purpose of the survey 

 ■'ras to find out how several of the most important chemical elements vary in the 

 leaves under actual grovfing conditions . The field work for this survey was conduct- 

 ed in the summer of 1955 and the chemical analysis of leaves made in the winter of 

 1955-56. 



Thirty-three blueberry plantings " situated all over the state were visited. 

 These fields represent a Yd.de range in bush vigor, soil-type, soil management, 

 cultural practices, fertilization, soil moisture, and climatic ccnditions. Ten 

 bushes which were considered representative- were selected in each field. The 

 growth made in 1955 of ten shoots on each of the ten bushes was measured and aver- 

 aged. Forty leaves were picked from each bush, made into a composite sample, 

 dried and analysed for nitrogen (N), phosphorous (P), potassium (k), calcium (Ca), 

 and magnesium (Ugo). 



The results are given in the following table s 



Average shoot Percent in leaveq (dry weight basis) 

 Growth in inches "1 P K Mg Ca 



5 cultivated fields 13.7 1.81 ,10 .U8 .16 .U8 

 5 sod fields JhJx 1.71 .09 .U2 .17 .U5 



The highest values for the several elements were not all from the same field. 

 Neither were the lowest values. These values do not necessarily represent the 

 maximum range but are probably somewhere near it. Nor should the averages be taken 

 as the most desirable values. They are merely a handy point of reference. 



To get a better idea on the effects of vigor of growth on leaf element content, 

 five of the best and most vigorously growing fields T/ere selected and compared 

 \Tith five of the poorest. It is interesting that, although the average shoot 

 growth of the bushes in the five best fields was nearly twice that in the poor 

 fields,., nitrogen Yfas the only element which varied enough to appear significant, 



■ When five cultivated fields were compared vrith five sod fields, the differ- 

 ence in growth was slight and again the only element in the leaves which varied 

 to any extent was nitrogen. 



From these data it appears that leaf nitrogen is the element most likely to 

 change significantly under different grovdng conditions. Experimenters in lifichigan 



