174 



THE STUDY OP SOILS. 



It ia only by very minute researches into the con- 

 dition and chemical constituents of arable fields that 

 one is able to understand the causes of barrenness 

 and of fruitfulness. The unwillingness of farmers to 

 foster the study of Bones in the Soil, although most 

 intimately connected with their success in stock-grow- 

 ing, dairy-husbandry, and grain-culture, is one of the 

 marvels of the nineteenth century. While science 

 teaches them that one kind of limestone and one 

 kind of earth has twenty times more of the raw ma- 

 terial for making bones than another, experience in 

 tillage informs them that the soil that possesses 

 the least bone earth is least productive. Differ- 

 ent strata of rocks, from the abrasion and commin- 

 ution of which soils are formed, contain very une- 

 qual quantities of fossil animals and fossil dung, and 

 of course give existence to land of very unequal 

 fertility. Rocks rich in the remains of moUusks, like 

 the shells of oysters and clams, may abound in the 

 carbonate of lime, but lack the phosphate ; while 

 strata rich in the remains of testacea and crocodiles, 

 having boney skeletons, yield soils that abound in the 

 phosphate of lime. The earthy substance, called co- 

 prolites, which is the fossilized dung of ancient and 

 extinct reptiles, mingled, perhaps, with that of other 

 animals, is now somewhat extensively manufactured 

 into superphosphate iu England, being ground and 

 treated with sulphuric acid for that purpose. Bones 

 are too much neglected in this country. 



THE STUDY OF SOttS. 

 It most farmers were asked how many pounds of 

 water a cubic foot of well tilled loam or clay ought 

 to absorb, and will hold without dripping, they would 

 be unable to give a satisfactory answer — never hav- 

 ing made the capacity of soils to hold water the sub- 

 ject of special inquiry. Such an investigation, how- 

 ever, is desirable, because a soil which has a small 

 capacity for imbibing moisture and retaining it, lacks 

 one of the most essential elements of productiveness. 

 According to the trust-worthy experiments of Prof. 

 ScHUBLER, a cubic foot of fair, arable soil, being a 

 mixture of sand, clay, and vegetable mold, will take 

 np 40.8 pounds of water; silicious sand absorbs only 

 27.3 pounds; sand derived from limestone rock has 

 a somewhat larger power of holding water, namely, 

 that of retaining 31.8 pounds. Stiff clay, suitable 

 for making brick, imbibes over 41 pounds to the cu- 

 bic foot. Fine lime takes up still more water, or 

 47.5 pounds; and fine magnesia a still larger quantity, 

 or 62.6 pounds, which is within a fraction of the full 

 weight of a cubic foot of water. Magnesia in a fine 



powder, is very light, and displaces very little water. 

 Rich vegetable mold is exceedingly hygroscopic, 

 whicli tends to increase its fertilizing power. An- 

 other important feature iu such mold is the quantity 

 of organized nitrogen, or of ammonia contained 

 therein. Dr. Anderson, chemist to the Highland 

 Agricultural Society of Scotland, has published in 

 its journal some interesting analyses of the organic 

 elements in soils. 100 parts of an excellent wheat 

 soil from Midlothian gave 6.787 parts of combusti- 

 ble matter, which had the following composition : 



Carbon 4.500 



HjiJrogen 0.213 



Oxygen 1.806 



0.268 



The above figures are interesting, as showing the 

 amount of oxygen and hydrogen given off by the 

 decay of the leaves and plants from which the mold 

 was, doubtless, derived. Before they began to rot, 

 or eremacausis commenced, they contained about as 

 much of the elements of water in an organized con- 

 dition as of carbon; while in the mold analyzed, the 

 o.xygen and hydrogen taken together make but Uttle 

 over one-fourth of the mass. All vegetable and an- 

 imal substances that slowly decay to form mold in 

 the soil, part with the elements of water (o.xygen and 

 hydrogen) in the process, and turn dark colored, or 

 black, from the excess of carbon, or eoal, that re- 

 mains. An acre of soil, estimated to the depth of 

 ten inches, weighs not far from one thousand tons; 

 and as a thousand parts of the above soil contain 

 two and si-^c-teuths parts of ammonia, an acre would 

 possess over two and a half tons of ammonia within 

 ten inches, provided the organic matter extended 

 equally to that depth. Dr. A. treated the first ten 

 inches as " surface soil," and all below he regarded 

 as "subsoil." 



The quantity of carbon and ammonia in cultivated 

 land has been very little studied ; and yet, ammonia 

 is universally recognized as the most valuable sub- 

 stance in stable manure; while carbon which imparts 

 a dark, rich color to loam, plays an important part 

 in the economy of vegetation. Good soils contain 

 from twenty to sixty tons of carbon to the acre. It 

 will be seen that two-thirds of the mold analysed by 

 Dr. Anderson is carbon. This is derived exclusively 

 from plants and animals, in a solid form. 



The incombustible elements of sells are mostly 

 flint or silicious sand, alumina, (the basis of clay,) 

 and iron. To these should be added the alkaUne 

 earths, lime, and magnesia, the alkalies potash and 

 soda, and the mineral acids formed of phosphorus, 



