356 



THE SOUTHERN PLANTER. 



phere where the proportion is much reduced. 

 It is rapidly absorbed by forests, as well as 

 growing crops. Quick growing plants, such 

 as grape vines, melons, Indian corn, &c, when 

 in full growth, will absorb as it passes, nearly 

 all the carbonic acid from quite a swift current 

 of air, so that only slight traces of it can after- 

 wards be found. — [Norton's Elements, p. 31.] 

 Crops are more nourishing when the uniform 

 proportion, existing in the atmosphere under 

 ordinary circumstances, is in that body of air 

 immediately surrounding their leaves. They 

 can no more feed upon the carbonic acid in 

 the air above, than they can derive benefit 

 from the manure which has never been hauled 

 from the farm-pen. Hence they thrive better 

 in air that is in motion, and frequently re- 

 newed, than in calms.— [Boussingault, 42.] 

 The free access of carbonic acid to their leaves 

 promotes their growth, increases their vigor, 

 and enriches their secretions.— [Farmers' En- 

 cyclopedia, 522.] Whatever impedes the free 

 circulation of the atmosphere, or exhausts its 

 carbonic acid in its progress to Ajb growing 

 crops, always produces injuriousTrfects upon 

 the cultivated plants. 



It has been observed in Europe, that the 

 crops always yield an inferior produce when 

 surrounded by thick plantations of timber trees, 

 not from the effects of shading, but from their 

 exhausting power upon the carbonic acid of 

 the air— [Farmers' Encyclopaedia, Cuthbert 

 Johnson.] This is the observed effect, even 

 when so large a proportion of the country is 

 open, and when the same density of forests 

 does not occur as prevails with us. Upon 

 many farms there is inexcusable carelessness 

 and neglect in the dense growth of old field 

 pines in the arable fields, neglected hedge 

 rows, ditch and creek banks, sometimes a few 

 acres of native forest and irregular outlines 

 in the clearings. These must not be regarded 

 as merely negligent, but as positively inju- 

 rious — not only as presenting a slovenly ap- 

 pearance, rendering the cultivation and enclo- 

 sure of the fields more expensive and labo- 

 rious, but as diminishing the products of the 

 cultivated surface. The old field pine is par- 

 ticularly liable to this objection. The rapidity 

 of its growth, even upon the poorest soils, 

 the number of its leaves show its exhausting 

 powers upon the atmosphere. The farmer 

 should remember that his crop can thrive no 

 better in an atmosphere deprived of its car- 

 bonic acid, than in a soil exhausted of its fer- 

 tility. If he wishes a striking illustration, let 

 him sow alternate strips of cjover with plas- 

 ter; or of wheat with guano, and leave narrow 

 strips for trial. The plastered clover and the 

 guanoed wheat will soon overtop the unaided 

 portions, exhaust the air of its carbonic acid 

 in passing, and by its greater, luxuriance ac- 

 tually injure the unaided strips. The experi- 

 ment will not present simply a striking con- 

 trast—nor injury from shading— but a dimi- 

 nished crop, from mere proximity to a more 

 uxuriant growth. 



The injurious effects of these patches of 

 pines may be impressed by another statement. 

 In four thousand pounds of the atmosphere, 

 only four pounds of carbonic acid are inter- 

 mixed—or rather more than one pound of car- 

 bon — sufficient to form about two pounds of 

 dry pine. If, then, we assume the correctness 

 of that theory, which asserts the assimilation 

 of the entire carbon through the leaves of the 

 plants, near four thousand pounds of air must 

 have been entirely deprived of its carbonic 

 acid to form two pounds of dry pine— or a 

 still larger quantity of air partially exhausted. 

 Under such circumstances, a gentle current of 

 air reaches the borders of the cultivated crops, 

 after passing through these patches, of dense 

 pines, to supply that food to the growing crop 

 which is to make near one-half of its weight. 

 It is true that the inequalities of the earth's 

 surface, the varying currents of air, and the 

 known property of these gases to intermingle 

 and pervade each other will again restore the 

 equilibrium, but extensive injury may first en- 

 sue. One of the first objects to which the at- 

 tention of the farmer should be turned, is the 

 removal of all such nuisances in his culti- 

 vated fields — leaving nothing but the neces- 

 sary shade trees for ornament, or for protec- 

 tion to his cattle. 



The next organic element of plants is nitro- 

 gen. Of this substance the cultivated plants 

 contain small and variable proportions, seldom 

 reaching as high as four per cent. One hun- 

 dred pounds in the dry state will generally 

 contain about fifty pounds of carbon and about 

 two pounds of nitrogen. The proportions are 

 used merely for illustration, and not for spe- 

 cific information. Small as the relative quan- 

 tity of nitrogen is, it forms a most important 

 element in plants and manures. It constitutes 

 the nutritious principle of plants— that ingre- 

 dient which imparts flesh and muscle to ani- 

 mals. An eminent author asserts, as the re- 

 sult of analysis and observation, that the nu- 

 tritious powers of plants are in proportion to 

 the quantity of nitrogen they contain.— [Bous- 

 singault, 387.] This quantity is increased by 

 the supply furnished through the soil on which 

 they grow; hence it becomes a most important 

 subject for our examination. 



Whilst it plays so prominent a part in the 

 nutritious principle of food, it is at the same 

 time the eminently enriching quality of all or- 

 ganic manures, % 270. — [Boussingault.] It forms 

 the chief fertilizing substance in the guanos, 

 nitrates and compounds of ammonia; in fact, 

 it is the proportion of nitrogen which fixes the 

 comparative value of different manures. It 

 forms four-fifths of the entire atmosphere, con- 

 stantly surrounding the plants, and presenting 

 an inexhaustible supply— but generally una- 

 vailing in its simple form. 



Plants receive their nitrogen through their 

 roots, sometimes from the nitrates, but chiefly 

 in the form of ammonia; (Liebig, 70,) the for- 

 mation of these compounds then becomes the 

 subject of inquiry, as the enriching quality of 



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