63 



Fertilizer. Manure. Plaster. Lime. 



Value of net increment due to $38.84 $37.08 $1.71 $0.32 

 Financial result, 14.84 gain 12.92 loss 0.27 gain 1.60 loss 



A study of these comparisons reveals the fact that this soil is be- 

 coming generally exhausted, but to a far greater extent of potash 

 than of either of the other elements. Neither of these produces an 

 increase sufficient to pay for itself either alone or in combination the 

 one with the other ; but each when used alone with potash produces 

 a profitable increase in the crop. The fact that each produces its 

 maximum effect when used with both the others shows that all were 

 to some extent required. Potash appears to have been the element 

 "in minimo". Even when used alone it produces a profitable 

 increase ; but its beneficial effect is greater with either of the other 

 elements than alone, and greatest with both the others. For 'potatoes 

 on this soil a fertilizer similar to that recommended for Marblehead 

 {p. 59) should give a profitable increase. 



It may be doubted, however, whether the materials used in these 

 soil tests are those which are best suited for this crop. Sulphate of 

 potash is admitted to be superior to the muriate, and it is not unlikely 

 that the nitrogen should, in part at least, be supplied in a less soluble 

 form. Neither lime nor plastei' appears to have been especially 

 beneficial. 



