292 BULLETIN OF THE BUSSEY INSTITUTION. 
No. 27. — Description of an Attempt to Assay Soils by the 
Method of Sand Culture. By F. H. Srorsr, Professor 
of Agricultural Chemistry. 
Tue idea of testing the chemical power or value of a soil by 
growing plants in it directly, either with or without addition of 
chemical substances, is a very old one. It has often been acted 
upon in the laboratory * and multitudes of field experiments have 
been based upon it. So, too, processes of growing plants in sterile 
sand admixed with one or more chemical substances necessary 
for the support of plants, have for many years played an impor- 
tant part in the investigation of problems relating to the chemistry 
and physiology of vegetable growth. 
During many years I was of opinion that some combination of 
these two methods might be devised, which should be applicable 
for the practical testing or assaying of soils. I pictured to myself 
a simple, methodical, trustworthy method of research by means of 
which anyone having control of a greenhouse should be able, with- 
out much trouble, to determine the intrinsic value of a given 
soil, in so far as its value might depend upon the presence or 
absence of plant-food, and to form a just opinion as to the kinds 
of manure most neeeded by it. On being ealled to take charge of 
the Bussey laboratory, and thus finding at last opportunity to test 
this opinion, I have spent a great deal of time and labor in doing 
so, with the result that I have ‘been forced to modify my former 
conception very materially. 
The chief difficulties in carrying out the idea in question depend 
upon the extreme delicacy and sensitiveness of the method of 
research, and the unlikeness of its conditions to those which 
are found in actual farm practice. Many worthless sands, coal 
ashes, and ‘‘ exhausted” loams will, when properly watered, bear 
good crops,t provided the plants are shielded from harm and 
made comfortable in respect to heat and cold; and when these 
outward conditions are favorable, extremely little if any additional 
plant-food is needed to make an ‘‘ exhausted” loam support as 
good plants as a soil which is known, from experience in the field, 
to be fairly fertile. Under the favorable conditions of the pro- 
* Notably by Salm Horstmar, Daubeny, Bobierre, and Ville. 
+ See Bussey Bulletin, 1. 50, 252. 
