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 

 Axricultural 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 Schiibler, and like- 

 wise (in round numbers) the weight per acre taken to the 

 depth of one foot (=43,560 cubic feet). 



Weight op Soils 



per cubic foot per acre to depth 

 of one foot. 



Dry silicious or calcareous sand about 110 lbs. 4,792,000 



Half sand and half clay " 96" 4,182,000 



Common arable land * " SO to 90 " 3,485,000 to 3,920,000 



Heavy clay " 75 " 3,207,000 



Garden mold, rich in vegetable matter. . . " 70 " 3,049,000 



Peat soil " 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 author 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 86'/^ lbs. The acre to depth of one foot 

 weighs 3,708,000 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 

 jnind. Boussingault found to weigh 81 lbs. av. per cubic foot (1.3 kilos per liter). 

 This would be per acre, cue foot deep, 3,528,000 lbs. 



