5382 AGRICULTURAL REPORT. 
time the crop is gathered; the supply of nitrates thus keeps pace with the wants of 
the plant. In the case of green crops, the functions of the foliage decline as the seed 
begins to develop, and the plant’s means of providing itself with assimilable nitrogen 
fail, although the need for it still exists. Furthermore, the clover cut for hay leaves 
behind much more roots and stubble per acre than green crops, and the clover stubble 
is twice as rich in nitrogen as the stubble of ripened grain. This is a result of the 
fact that the clover is cut when in active growth, while the grain is harvested after the 
roots, stems, and leaves have been exhausted of their own juices to meet the demands 
ofthe seed. * * * The fact is not to be denied that the soil is enriched in nitrogen 
by the culture of large-leaved plants, which are harvested while in active growth, and 
leave a considerable proportion of roots, leaves, or stubble on the field. On the other 
hand, the field is impoverished in nitrogen when grain crops are raised upon it. 
In the conversion of rocks into soil, the action of freezing water is 
remarkable. Water, in the act of conversion into ice, expands one- 
fifteenth of its bulk, and the force thus exerted is sufficient to burst 
vessels of the strongest materials, and, in cold latitudes or altitudes, 
accomplishes stupendous results. 
Along the base of the vertical trap cliffs of New Haven and the Hudson River lie 
immense masses of broken rock, reaching to more than half the height of the bluffs 
themselves, rent off by this means. The same cause operates in a less conspicuous but 
not less important way on the surface of the stone, loosening the minute grains, as in 
the above instances it rends off enormous blocks. A smooth, clean pebble of the very 
compact Jura limestone, of such kind, for example, as abounds in the rivers of South 
Bavaria, if moistened with water and exposed over night to sharp frost, on the thaw- 
ing is muddy with the detached particles. 
Many interesting illustrations are given of the absorbent power of 
soils. Liquid manure is deodorized, decolorized, and rendered nearly 
tasteless by filtration through garden earth. It is a matter of common 
experience that a few feet or yards of soil intervening between a cess- 
pool or dung-pit and a well, preserves the latter against contamination 
for a longer or shorter period. The foul water of the Seine, at Paris, 
becomes potable after filtering through sandstone. These effects are 
not strikingly manifested by pure sand, but appear when clay is used. 
Solutions of coloring matters, such as logwood, sandal-wood, cochineal, 
litmus, &c., when shaken up with a portion of clay, are entirely de- 
prived of color. 
Garments which have been rendered disgusting by the fetid secretions of the skunk, 
may be “sweetened,” i. e., deprived of odors by burying them for a few days in the 
earth. The Indians of this country are said to sweeten the carcass of the skunk by 
the same process, when needful, to fit it for their food. Dogs and foxes bury bones and 
ineat in the ground, and afterward exhume them in a siate of comparative freedom 
from offensive odor. 
When human excrements are covered with fine dry earth, as in the earth-closet sys- 
tem, all cdor is at once suppressed and never reappears. At the most, besides an 
“earthy” smell, an odor of ammonia appears, resulting from decomposition, which 
seems to proceed at once to its ultimate results without admitting the formation of any 
intermediate offensive compounds. * * * These examples sufficiently prove that 
the soil, even sand, possesses the property of attracting and fully absorbing the ex- 
tractive matters, so that the water which subsequently passes is not able to remove 
them; even the soluble salts are absorbed, and are washed out only to a small extent 
by new quantities of water. 
Professor Johnson concludes this volume with remarks on the signifi- 
cance of the absorptive quality, in which he remarks that disintegration 
and nitrification would lead to a waste of the resources of fertility, were 
it not for the conserving effect of those physical absorptions and chemi- 
cal combinations and replacements which have been described. 
The great beneficent law regulating these absorptions appears to admit of the fol- 
lowing expression, viz: Those bodies which are most rare and precious to the growing 
plant are by the soil converted into, and retained in, a condition not of absolute, but 
of relative insolubility, and are kept available to the plant by the continual circulation 
in the soil of the more abundant saline matters. 
The soil, speaking in the widest sense, is then not only the ultimate exhausiless 
source of mineral (fixed) food to yegetation, but it is the storehouse and conservatory 
