158 HOW CROPS FEED. 
In treating of the physical characters of the soil, the 
writer employs an essay on this subject, contributed by 
him to Vol. XVI of the Transactions of the N. Y. State 
Agricultural Society, and reproduced in altered form in a 
Lecture given at the Smithsonian Institution, Dec., 1859. 
§ 1. 
THE WEIGHT OF SOILS. 
The Absolute Weight of Soils varies directly with their 
porosity, and is greater the more gravel and sand they 
contain. In the following Table is given the weight per 
cubic foot of various soils according to Schitbler, and like- 
wise (in round numbers) the weight per acre taken to the 
depth of one foot (=43,560 cubic feet). 
WEIGHT oF Sorts 
per cubic foot per acre to depth 
of one foot. . 
Dry silicious or calcareous sand......... about 110 Ibs. 4,792,000 
Half sand and half clay......... ........ te 96 4,182,000 
Common arable land*, ................4 * 80 to 90 ‘* 3,485,000 to 3,920,000 
LGAVY? C1AVE co ad dideerersaiouiveaddai actawaietestars es % 3,267,000 
Garden mold, rich in vegetable matter... “ "0 “ 3,049,000 
PURI crccewndide Ged. medeiensannsanwe 30 to 50 ‘ 1,307,000 to 2,178,000 
From the above figures we see that sandy soils, which 
are usually termed “light,” because they are worked most 
easily by the plow, are, in fact, the heaviest of all; while 
clayey land, which is called “heavy,” weighs less, bulk 
for bulk, than any other soils, save those in which vegeta- 
ble matter predominates. The resistance offered by soils 
in tillage is more the result of adhesiveness than of gravity. 
Sandy soils, though they contain in general a less percent- 
age of nutritive matters than clays, may really offer as good 
* The anthor is indebted to Prof. Seely, of Middlebury, Vt., for a sample of 
one-fourth of a cubic foot of Wheat Soil from South Onondaga, New York. The 
cubic foot of this soil, when dry, weighs 8644 lbs. The acre to depth of one foot 
weighs 3,768,000 lbs. This soil contains a large proportion of slaty gravel. A 
rich garden soil of silicious sand that had been heavily dunged, time out of 
mind, Boussingault found to weigh 81 Ibs. av. per cubic foot (1.3 kilos per liter), 
This would be per acre, one foot deep, 3,528,000 Ibs. 
