TUB SOUTIIEKN PLANTER. 



G75 



The knowledge of the physical condi- 

 tions which determine the fertility or bar- 

 renness of soils is an indispensable prepa- 

 ration to the study of the value and action 

 of manures, and it is utterly impossible in 

 practice, to derive adequate return from 

 fertilizers, unless the soil either originally 

 possesses, or has been brought into a pro- 

 per physical state. 



These reasons have induced the writer 

 to attempt presenting the subject anew, in 

 the light of the latest and fullest investi- 

 gations, and he is confident that it is pos- 

 sible thus to write one of the most practi- 

 cally useful chapters of agricultural sci- 

 ence. 



I. The fineness of the Particles of a soil 

 greatly influences its fertility. On the sur- 

 face of a block of granite only a few lich- 

 ens and mosses can exist; crush the block 

 to a coarse powder and a more abundant 

 vegetation can be supported on it ; if it is 

 reduced to a very fine dust and dul}- water- 

 ed, even the cereal grains will grow and 

 perfect fruit on it. Thus two soils may 

 h^ve the same chemical composition, and 

 yet one be almost inexhaustibly fertile, 

 and the other almost hopelessly barren. 

 There are sandy soils in the Eastern states, 

 which without manure yield onl}' the most 

 meagie crops of rye or buckwheat; and 

 there are sandy soils ia Ohio which with- 

 out manure, j^ield on an average 80 bush- 

 els of Indian corn per acre, and have yield- 

 ed this for twenty to fifty years in unbro- 

 ken succession. According to David A. 

 * Wells, (Am. Jour, of Science, July, 1852,) 

 these two kinds of soil yield very similar, 

 practically identical results on chemical 

 analysis, so far as their inorganic ingredi- 

 ents are concerned. What is the cause of 

 the difference of fertility ? Our present 

 knowledge can point to no other explana- 

 tion than is furnished by the different fine- 

 ness of the particles. The barren sandy 

 soils consist in great part of coarse grains, 

 while the Ohio soil is an exceedingly fine 

 powder. 



It is true as a general rule, that all fer- 

 tile soils contain a large proportion of very 

 fine or impalpable matter. How the ex- 

 treme division of the particles of the soil 

 is connected with its fertility is not difti- 

 cult to understand. The food of the plant 

 must enter it in a state of solution, or if 

 undissolved, the particles must be smaller 

 than we can discover with the best optical 



aids, because the pores of the roots of 

 plants are not discernible by any micro- 

 scope. The mineral matters of the soil 

 must be dissolved or diffused in water. 

 The rapidity of their solution is in direct 

 proportion to the extent of their surface. 

 The finer the particles, the more abundant- 

 ly will the plant be supplied with its ne- 

 cessary nourishment. In the Scioto Val- 

 ley soils, the water which is transpired by 

 the crops, comes in contact with such an 

 extent of surface that it is able to dissolve 

 the soil-ingredients in as large quantity 

 and as rapidly as the crop requires, lu 

 the coarse grained soils, this is not the 

 case. Soluble matters, (manures) must be 

 applied to them by the farmer, or his crops 

 refuse to yield handsomely. 



Again, it is obvious that the finer the 

 particles of the soil, the more space the 

 growing roots have in which to expand 

 themselves, and the more numerously are 

 they able to present their absorbent sur- 

 faces to the supplies which the soil con- 

 tains. 



Other advantages of fine soils will ap- 

 pear in the progress of this essay. 



II, We will discuss the power of the soil 

 to absorb or condense gases or vapors. With 

 regard to this subject we have no actual 

 observations on soils, of any great value. 

 Those we do possess were made forty years 

 ago by Schiibler, then a teacher in Fellen- 

 berg's school at Hotwyl in Switzerland, 

 and will be presently adduced. 



In the first place may be considered 

 those facts of science which bear upon the 

 question before us. It is found that many 

 solid bodies are able to condense gases 

 upon their surface, or within their pores. 

 Freshly burned box-wood charcoal thus' 

 absorbs ninety times its volume of ammo- 

 nia gas, thirty -five' of carbonic acid and 

 nine of oxygen. Copper, iron, lead,, pla- 

 tinum, and probably the other metals-, also 

 condense gases upon their surfaces. This 

 condensation is scarcely perceptible in 

 plates of solid metal; but when by chemi- 

 cal means these metals are produaed in a 

 very finely divided state, as fine powder 

 or sponge, their surface attraciica becomes 

 manifested to an extraordinaisy degree. 

 There is then, a physical attractive (adhe- 

 sive) force which is exhibited with greater 

 intensity, the greater the surface of the 

 body posses.^ing it. It is manifested by 

 diflerent bodies in very uulike degree, and 



