BULLETIN OF THE BUSSEY INSTITUTION. 293 
posed assay a poor soil will give good, and a mediocre soil excel- 
lent crops; and I have found it extremely difficult if not impossible 
to discriminate between several samples of cultivable earths, un- 
less indeed they were very different in reality. 
A striking illustration of the power of a loam of poor quality to 
supply plants with food, provided it be kept continually moistened, 
was afforded by an experiment in which Indian corn was grown in 
two contiguous jars, one filled with loam from Mr. F. H. Apple- 
ton’s farm, at Lynnfield, Mass., and the other with Berkshire 
County sand. ‘Two kernels of common yellow maize were planted 
in each jar, January 18, 1873, and after the young plants had 
appeared, the jar which contained the loam was watered with 
nothing but rain-water, while the sand jar was watered with a 
mixed solution of the nitrates of lime and potash, phosphate of 
potash and sulphate of magnesia. The plants prospered in both 
jars ; all of them were healthy and vigorous, and they grew as well 
as could be expected in so cool a house.* When the experiment 
was interrupted on the 29th of April, each of the loam-grown 
plants was seven inches high, while the sand-grown plants were 
seven and fifteen inches high, respectively. But on being dried 
and weighed it appeared that, while the crops grown in mere 
loam watered with rain-water weighed 3.42 grms., the sand crop, 
which had received an abundant supply of a complete mixture of 
plant-foods, weighed no more than 3.51 grms. | 
In discussing any method of testing soils upon this plan, it is 
always to be remembered that the so-called fertility of a given 
field depends upon many other circumstances beside the -propor- 
tion of chemical constituents which are contained in the soil. In 
actual farm practice the difference between a fresh and an ‘ ex- 
hausted ” soil depends often enough upon some purely physical 
dissimilarity. For example, the particles of the exhausted soil 
may haye passed into such a condition of aggregation that they 
can no longer lift or hold enough capillary water for the needs of 
the crop, and in thi: case the plant would naturally suffer from 
lack of food in default of the vehicle by which the food is trans- 
ported. But in the carefully watered jars of the experimental 
assay this difficulty, though of the gravest practical importance in 
the field, might be wholly eliminated. So, too, in respect to the 
* In all my experiments the temperature of the glass house has been kept, 
as nearly as might be, at 48° to 50° F. by night and 68° to 70° by day. 
