144 BULLETIN OF THE BUSSEY INSTITUTION. 
have indicated the lack of potash. Iam at present unable to say 
whether the generality of the drift soils of New England are equally 
well provided for in respect to phosphoric acid. Of course, the remark 
made above applies in its full force only to the soil of this particular 
experimental field. As will be shown directly, phosphoric acid seems 
to be less needed, on the whole, by New England soils, than potash ; 
but there are undoubtedly some soils in the country in which phos- 
phoric acid is lacking, and it is uncertain whether there may not be 
many soils that contain very much less of it in proportion to the » 
potash than has been found to be the case here. 
An interesting illustration of the necessity of restricting the conclu- 
sions drawn from field experiments to soils similar to that upon which 
the experiments were made, and to like conditions, was afforded by 
the fact that in an old garden at the base of the ridge upon which the 
Plain-field is situated, and distant some thirty rods from Section C, 
the yield of beans, peas, and potatoes was decidedly increased in 1872 
by the .application of one of the mixtures of soluble and insoluble 
phosphate of lime and fish-scrap, similar to those used in my experi- 
ment, which are sold in the Boston market for superphosphate of 
lime. The soil of this garden is a deep loam that has long been under 
cultivation, and is very favorably situated with regard to the ground- 
water. 
In the following tables the amounts of each crop obtained by the 
use of the several fertilizers are given, in the order of excellence, as 
in the previous reports : — 
