474 



THE SOUTHERN PLANTER. 



[August 



through a soil, the phosphate of lime is 

 removed from solution, and the same result 

 takes place with the phosphate of magnesia 

 and ammonia. This is a fact of great agri- 

 cultural importance, from the constant occur- 

 rence of those substances in organic ma- 

 nures. 



The complete absorption of potash, am- 

 monia, and phosphoric acid by the soil, and 

 thus entering into combination and forming 

 insoluble compounds, would appear to mili- 

 tate against the received opinion, viz: that 

 plant- food must necessarily be in a soluble 

 state for assimilation. This is contradicted 

 by the above facts. It is, besides, well known 

 that plant vitality has the power, as it were, 

 of corroding insoluble substances, and ab- 

 sorbing them by the roots. Varieties of 

 plants growing upon rocks contain large 

 quantities of the substance of which the 

 rocks is composed. Such is known to be the 

 case with lichens growing on calcareous 

 rocks. Again, the roots of the grape- vine 

 have been , found surrounding, and its root- 

 lets insinuated in every manner, through, 

 around, and enveloping a piece of bone, 

 which finally disappears. Nor does it seem 

 that assimilable food should necessarily be 

 soluble_, provided it be in a state of atomic 

 division. 



It has been stated that the constituents 

 of plants are divided into two classes, or- 

 ganic and inorganic. The first named are 

 derived from water, carbonic acid, nitric 

 acid, and ammonia, and may come from 

 the air through the leaves, or from the soil 

 through the roots. The inorganic constitu- 

 ents are of a difibrent character, and can 

 only be received from the soil and through 

 the roots. It then becomes important that 

 there should he deep preparation of the soil, 

 in order to commingle the surface with that 

 which underlies, that the roots in their search 

 for food, (for it is proved that it does not 

 circulate in the soil as it becomes fixed by 

 combination,) may more readily come in 

 contact with all the substances the plant 

 requires to form the wonderful compound 

 necessary to its growth and development. 

 Deep preparation insures aeration, and the 

 decomposition of the constituents of the 

 soil is thus attained by the action of the 

 atmospheric agents. Both carbonic and ni- 

 tric acid, which are known to exist in the 

 air and water, have a powerful action upon 

 the soil, but unfortunately our knowledge 

 upon that subject leaves much to be desired. 



The importance of minute division of the 

 soil, and the manures which may be added, 

 must, on reflection, be evident to every one. 

 Plants assimilate food in a state of atomic 

 division, and the nearer we approach that 

 point" the better; beside which, they will 

 more readily undergo those chemical changes 

 which are ever taking place in Nature's 

 great laboratory, the earth. By breaking 

 the clods mechanically, by exposure to the 

 air, and the freezing effects of water, the 

 mass is pulverized, and thus food, before 

 locked up, is approached and used by the 

 tender roots of the plant. 



" Plants cannot obtain from the soil more 

 food than it contains. Further, its fertility 

 is not to be measured by the whole quantity 

 present in it, but only by that portion of the 

 whole quantity which exists in the smallest 

 particles of soil, for it is with such portions 

 alone that the rootlets can come into close 

 contact. 



" A piece of bone weighing one ounce, 

 in a cubic foot of earth, produces no mark- 

 ed effect on its fertility. But if this one 

 ounce of phosphate of lime be rniformly 

 distributed through eut the earth, it will suf- 

 fice for the nourishment of one hundred 

 and twenty wheat plants. 



^' Of two fields with the same amount of 

 food, one may be very fertile, and the other 

 very unfruitful, if the food is more uniformly 

 distributed throughout the former than the 

 latter. The common plough breaks and 

 turns up the soil without mixing it. It only 

 displaces, to a certain extent, the spots on 

 which plants have already grown, but the 

 spade breaks, turns, and mixes it thorough- 

 ly." (Liebig's Letters on Modern Agricul- 

 ture, p. 108.) 



Those plants which reach maturity in a 

 short time are materially affected by the 

 preparation of the soil. Their powers of 

 absorption are much greater in the spring 

 than in the summer, when the leaves are 

 being formed, and when the plant is in the 

 full vigor of growth, than when it has roacli- 

 ed its maturity. We have a familiar in- 

 stance of the importance of preparation in 

 our corn crop, and the stimulus that is im- 

 parted to it by constant working, by which 

 food is continually renewed and brought into 

 close contact with the roots, and the soil 

 kept in a well pulverized state, thus increas- 

 ing its absorbing powers. The descent of 

 water through the soil, and its escape up- 

 ward as vapor, tend to the same end, and 



