174 



THE GENESEE FARMER 



to an air saturated with moisture at a temperature of 

 62 degrees, eighteen parts; 1,000 parts of a very fer- 

 tile soil from the banks of the river Parret, in Somer- 

 setshire, under the circumstances, gained 16 parts; 

 1,000 parts of soil from Mersea, in Essex, worth 45 

 shillings [rent] per acre, gained 13 parts; 1,000 parts 

 of a fine sand from Essex, worth 288. an acre, gained 

 11 parts; 1,000 parts of a coarse sand, worth 15s. per 

 acre, gained only 8 parts; 1,000 parts of a soil of 

 bag-shot heath, gained only 8 parts." 



Other experiments, which will be quoted hereafter, 

 indicate a wide difference in the hygroscopic power 

 of dilTerent soils; and Sir H. Davy leaves no room 

 for doubt that he regards this absorbed moisture as 

 being within the control of plants to be imbibed by 

 their roots, circulated through their tissues, and 

 evaporated from their leaves. Cuthbert W. John- 

 son, and other wi'iters of distinction, express similar 

 opinions; but having recently raised the question of 

 fact, whether water drawn from the atmosphere by 

 the absorbent power of soils can be taken from these 

 soils and given back to the atmosphere again by grow- 

 ing plants, we have as yet found no experiments which 

 prove the soundness of this popular idea. 'We put 

 the question to Professor Hosford, in Cambridge 

 University, in this wise: Why should not a soil that 

 is endowed with strong absorbent powers draw mois- 

 ture from the green and watery roots of plants, as 

 well as from a dry atmosphere? Such an atmosphere 

 draws moisture rapidly from leaves of plants, as may 

 be seen when those of corn curl up in July and 

 August, from excessive evaporation beyond the sup- 

 ply of water at their roots. Does Nature operate in 

 30 limited a circle as to have the moisture that ascends 

 from a soil through the roots and stems of plants, and 

 passes out into the air through their leaves, i-e-ab- 

 gorbed from the air by the dry soil, to be again con- 

 veyed through the circulation of the plant as before? 

 We seriously doubt the truth of this theory; and 

 after stating the objections to it in a hygi'oscopic 

 point of view, Professor Hosford (who was some 

 years with Liebig) agreed with us that the annals of 

 science furnish no satisfactory evidence that plants do 

 extract hygroscopic water from the earth, and give it 

 out to the atmosphere to be again absorbed by the 

 earth for the use of the same, or other plants. If our 

 growing crops can avail themselves of water absorbed 

 from the air both night and day, as Sir H. Davy 

 teaches us to believe, the fact may be demonstrated 

 by direct experiments. Such experiments ought to 

 be made. 



Like fei-tile soils, plants have the power to imbibe 

 moisture from the atmosphere; but to what extent is 

 not known ; nor is the circulation of fluids through 

 their cells and vascular systems well understood. A 

 dry atmosphere, especially when leaves are under the 

 influence of direct rays of the sun, takes moisture 

 from plants very rapidly. But does this evaporation 

 from the surface of plants render their roots more 

 hygroscopic than the soil which surrounds them, or 

 the atmosphere that permeates such soils? 



Dr. Hales ascertained that a cabbage transmits 

 into the atmosphere about half its weight of water 

 daily by insensible vapor; and that a sunflower, three 

 feet in height, transpired in the same length of time, 

 nearly two pounds weight; but there ia no evidence 



that any of this water drawn from the earth was 

 hygroscopic. The soil not only retains water that 

 falls in showers and heavy dews with great tenacity 

 for the uses of vegetation, but it draws water from 

 the subsoil by capillary attraction fi'om a very consid- 

 eraljle depth, under favorable circumstances. Dr. 

 Woodward found that a sprig of mint, weighing 27 

 gi'ains, emitted 2.543 grains of water in 77 days; a 

 sprig of common night-shade, weighing 49 grains, 

 evolved in the same length of time 3.708 grains. M. 

 Saussure proved by direct experiment, that plants 

 may double the organized carbon in their tissues 

 without any mold to grow in, or connection with the 

 earth. Indeed, the hanging moss that grows so 

 abundantly in cypress swamps at the South, must 

 derive the whole of its carbon from the carbonic acid 

 in the atmosphere. The luxuriant growth of this 

 moss on the limbs and twigs of trees, illustrates an 

 important law of vegetable nutrition. While we 

 question the power of any soil to extract moisture 

 from what would be regarded as a moderately dry 

 atmosphere, in any quantity available to the cu'cula- 

 tion of i^lants, we see little reason to doubt the power 

 of a saturated atmosphere so to dampen a fertile soil 

 as to enable it to feed, like a damp cloth, the roots of 

 plants. When the air is cooled down to the dew 

 point, and water begins to be precipitated, it is im- 

 portant to have the soil in the utmost hygroscopic 

 condition to augment the amount of fertilizing dews 

 it may nightly condense within its cells or pores. 

 Dews are nothing more than little showers ; and so 

 far as they yield water at all, it should be husbanded 

 by the cultivator with great care. 



Intimately connected with the natural function of 

 soils to absorb water from the atmosphere, is the in- 

 qiiiry: How much water does a corn, Avheat, cotton, 

 or other agricultural plant, really need to have pass 

 through its circulating system, from the first sprouting 

 of the germ to the perfect maturity of the crop ? 

 We have devoted some attention to this inquiry, and 

 find that the poverty and richness of the soil govern 

 the amount of water needed to produce profitable 

 crops of grain, roots, cotton, tobacco and sugar cane. 

 If we mistake not, this is the law : The more fertile 

 the soil the less water it needs to yield an abundant 

 harvest. Mr. Lawes found by careful experiment, 

 that a poor soil required over three thousand grains 

 of water to pass through the stem of a single wheat 

 plant, to convey one gi-ain of the ash or minerals in 

 such plant, from the soil to its destination in the 

 plant. We will give the figures that bear upon this 

 question as they may be found in the thirteenth vol- 

 ume, second series, of the Genesee Farmer, page 79. 

 The soil in each case being alike, Wheat required 

 3111.2 grains of water to evaporate from its leavea 

 for one grain of ash deposited in the plant, from 

 March 19 to September 7. 



Barley required a smaller quantity of water to attain 



a siroilar result, viz.: - 2618.8 graiiM. 



Beans stUl less, or 2289.5 " 



Peas 2527.3 " 



Clover 1884.2 " 



It is obvious to every reasoning mind that the 

 poorer the soil the more diluted must be the food 

 which it yields to hungry plants, and the larger the 

 amount of water that must enter their roots and 

 evaporate from their leaves to supply the needful all- 



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