74 



constituents. That one contains about the same proportion of nitro- 

 gen and phosphoric acid as the others, but has much more potash, 

 viz. : 10.16 per cent. 



The table below is of interest in considering the results of the use 

 of ''complete" fertilizer on plot 10 in our several potato experi- 

 ments. This table is designed to make possible a comparison 

 between the plant food removed by the crop and that applied. 



PLANT FOOD IN POTATOES COMPARED WITH THAT APPLIED. 



Nitrogen, 

 Phosphoric acid, 

 Potash, 



Required by 100 bushels. 



I Usual pro- 

 Tubers, lbs. I portion of .Total, lbs. 



t tops, lbs. ; 



12.4 



4. 

 17.6 



4.9 

 1.6 

 4.3 



17.3 



5.6 



21.9 



Applied in "Com- 

 plete Fertilizer" 

 per acre, lbs. 



25.3 



49.1 

 8.06 



The increase on ' ' complete " fertilizer was at the following rates per 

 acre, in the several experiments in bushels of 60 pounds : Marblehead, 

 large, 62.67 ; small, 6.33 : Concord (with double the amount of fertil- 

 izer) large, 77.28 ; small, 1.34: Shelburne, large, 21 .33 ; small, 4.16 : 

 Hadley, large, 97.33 ; small, 1.67 : Amherst, large, 44.16; small; 

 1.99. TJie average increase was at the rate of 60.6 bushels of mer- 

 chantable potatoes and .6 bushels of unmerchantable potatoes per acre. 



The above table shows that we applied much more nitrogen, phos- 

 phoric acid and potash than is contained iu one hundred bushels of 

 potatoes and the normal amount of tops for a crop of that size ; viz. 

 about one and a half times the nitrogen, nine times the phosphoric 

 acid and four times the potash. (In Concord we applied double 

 these amounts). All of these elements were applied also in soluble 

 forms, and yet we approach an increase of even 100 bushels in but 

 one of these experiments, while the average is only 61 bushels. The 

 poverty of the results in comparison with the application of plant 

 food suggests that there is something wrong. We cannot, it is tiue, 

 expect to recover in our crops all the plant food we apply to the soil, 

 but we should certainly expect to do better than we have done in 

 these experiments. I am not prepared, however, to say how this 

 can be done, even if it be possible. For the present, I can only 

 suggest either that the forms in which some or all of the various 

 elements are supplied are unsuited to the potato crop, or that the 



