E. W. Hilgard— Objects and Interpretation of Soil Analyses. 191 
less; and yet it will not only not produce a smaller crop, but 
it is more likely to produce the maximum crop every year, on 
account of improved physical conditions. If we compare the 
root system of the plants grown in the original, and in the di- 
luted soil, we will find the roots in the latter more fully dif- 
fused, longer, and better developed ; not confined to the crevices 
of a hard “clay, permeating the entire mass, and evidently hay- 
ing fully as extensive a surface-contact with the fertile soil 
particles, as was the case in the undiluted soil 
How far may this dilution be carried Fi 80 detriment ?—T he 
answer to this question must largely be experimental and must 
vary with different plants; whic his preoleels what the farmers’ 
experience has shown, long since. A plant capable of devel- 
oping a very large root- surface, ean obviously make up by 
greater spread, for a far greater dilution than one whose 
root surface i is in any case but small. The former flourishes 
even on “poor, sandy” soils, while the latter succeeds, and is 
naturally found on “rich, heavy” ones only ; although the ab- 
solute amount - plant- food taken from the soil may be the 
same in either ¢ 
Now the pocdieanes here splat are ik ae 3 fulfilled in 
soils about equally esteemed for the production of cotton, both 
equally durable, so far as experience has gone, and yet differing 
so in their percentages of mineral plant-food, to the extent of 
from three to five times. 
In cases like these, which are not at all infrequent, the mere 
percentage of plant- food in the soil show wing the low figures, 
would lead to a most erroneous estimate of its agricultural 
value. But when, in addition to these, we know the fact that 
a! cultivation, they will rarely reach to a greater depth than 
ria ve or fifteen inches, the equal productiveness becomes 
Cie Ne intelligible. 
must ass be eervccanbeeccey oon the subsoil in which these 
processes are but feebly developed, and where the store of 
plant-food—in which it is generally richer than the surface ee 
—Is comparatively inert. ence the obvious importane 
specimens correctly taken, and the necessity of intelligent ni 
accurate observations on the s spot. 
