Farm drainage Part 26

This is hard work for the team and men, hard in the plowing, and hard through the whole rotation. The same field, well drained, is friable and porous, and uniform in texture. It may be well plowed and readily pulverized, if taken in hand at any reasonable season.

Land which has been puddled by the tread of cattle, or by wheels, acquires a peculiar consistency, and a singular capacity to hold water.

Certain clays are wet and beaten up into this consistency, to form the bottoms of ponds, and to tighten dams and reservoirs. A soil thus puddled, requires careful treatment to again render it permeable to water, and fit for cultivation. This puddling process is constantly going on, under the feet of cattle, under the plow and the cart-wheels, wherever land containing clay is worked upon in a wet state. Thus, by performing a day's work on wet land, we often render necessary as much additional labor as we perform, to cure the evil we have done.

_We may haul loads without injury on drained land._ On many farms, it is difficult to select a season for hauling out manure, or carting stones from place to place, when great injury is not done to some part of the land by the operation. Many farmers haul out their manure in Winter, to avoid cutting up their farms; admitting that the manure is wasted somewhat by the exposure, but, on the whole, choosing this loss as the lesser evil. In spreading manure in Spring, we are often obliged to carry half loads, because the land is soft, not only to spare our beasts, but also to spare our land the injury by treading it. Drained land is comparatively solid, especially in Spring, and will bear up heavy loads with little injury.

_Drained land is least injured by cattle in feeding._ Whether it is good husbandry to feed our mowing fields at any time, is a question upon which farmers have a right to differ. Without discussing the question, it is enough for our purpose, that most farmers feed their fields late in the Autumn. Whether we approve it, or not, when the pastures are bare and burnt up, and the second crop in the home-field is so rich and tempting, and the women are complaining that the cows give no milk, we usually bow to the necessity of the time, and "turn in" the cows. The great injury of "Fall-feeding" is not usually so much the loss of the gra.s.s-covering from the field, as the poaching of the soil and destruction of the roots by treading. A hard upland field is much less injured by feeding, than a low meadow, and the latter less in a dry than a wet season. By drainage, the surplus water is taken from the field.

None can stand upon its surface for a day after the rain ceases. The soil is compact, and the hoofs of cattle make little impression upon it, and the second or third crop may be fed off, with comparatively little damage.

_Weeds are easily destroyed on drained land._ If a weed be dug or pulled up from land that is wet and sticky, it is likely to strike root and grow again, because earth adheres to its roots; whereas, a stroke of the hoe entirely separates the weeds in friable soil from the earth, and they die at once. Every farmer knows the different effect of hoeing, or of cultivating with the horse-hoe or harrow, in a rain storm and in dry weather. In one case, the weeds are rather refreshed by the stirring, and, in the other, they are destroyed. The difference between the surface of drained land and water-soaked land is much the same as that between land in dry weather under good cultivation, and land just saturated by rain.

Again, there are many noxious weeds, such as wild gra.s.ses, which thrive only on wet land, and which are difficult to exterminate, and which give us no trouble after the land is lightened and sweetened by drainage. Among the effects of drainage, mainly of a chemical nature, on the soil, are the following:

_Drainage promotes absorption of fertilizing substances from the air._ The atmosphere bears upon its bosom, not only the oxygen essential to the vitality of plants, not only water in the form of vapor, to quench their thirst in Summer droughts, but also various substances, which rise in exhalations from the sea, from decomposing animals and vegetables, from the breathing of all living creatures, from combustion, and a thousand other causes. These would be sufficient to corrupt the very air, and render it unfit for respiration, did not Nature, with her wondrous laws of compensation, provide for its purification. It has already been stated, how the atmosphere returns to the hills, in clouds and vapor, condensed at last to rain, all the water which the rivers carry to the sea; and how the well-drained soil derives moisture, in severest time of need, from its contact with the vapor-loaded air. But the rain and dew return not their waters to the earth without treasures of fertility. Ammonia, which is one of the most valuable substances found in farm-yard manures, and which is a constant result of decomposition, is absorbed in almost incredible quant.i.ties by water.

About 780 times its own bulk of ammonia is readily absorbed by water at the common temperature and pressure of the atmosphere; and, freighted thus with treasures for the fields, the moisture of the atmosphere descends upon the earth. The rain cleanses the air of its impurities, and conveys them to the plants. The vapors of the marshes, and of the exposed manure heaps of the thriftless farmer, are gently wafted to the well-drained fields of his neighbor, and there, amidst the roots of the well-tilled crops, deposit, at the same time, their moisture and fertilizing wealth.

Of the wonderful power of the soil to absorb moisture, both from the heavens above and the earth beneath--by the deposition of dew, as well as by attraction--we shall treat more fully in another chapter. It will be found to be intimately connected with the present topic.

_Thorough drainage supplies air to the roots._ Plants, if they do not breathe like animals, require for their life almost the same constant supply of air. "All plants," says Liebig, "die in soils and water dest.i.tute of oxygen; absence of air acts exactly in the same manner as an excess of carbonic acid. Stagnant water on a marshy soil excludes air, but a renewal of water has the same effect as a renewal of air, because water contains it in solution. When the water is withdrawn from a marsh, free access is given to the air, and the marsh is changed into a fruitful meadow." Animal and vegetable matter do not decay, or decompose, so as to furnish food for plants, unless freely supplied with oxygen, which they must obtain from air. A slight quant.i.ty of air, however, is sufficient for putrefaction, which is a powerful deoxydizing process that extracts oxygen even from the roots of plants.

We are accustomed to think of the earth as a compact body of matter, vast and inert; subject, indeed, to be upheaved and rent by volcanoes and earthquakes, but as quite insensible to slight influences which operate upon living beings and upon vegetation. This, however, is a great mistake; and it may be interesting to refer to one or two facts, which ill.u.s.trate the wonderful effect of changes of the atmosphere upon the soil, and upon the subterranean currents of the earth. The following is from remarks by Mr. Denton, in a public address:

"But, as a proof of the sensibility of a soil drained four feet deep, to atmospheric changes, I may mention, that my attention has been, on more than one occasion, called to the circ.u.mstance that drains have been observed to run, after a discontinuance of that duty, without any fall of rain on the surface of the drained land; and, upon reference to the barometer, it has been found that the quicksilver has fallen whenever this has occurred. Mr. George Beaumont, jun., who first afforded tangible evidence of this extraordinary circ.u.mstance, has permitted me to read the following extracts of his letter:

"'I can verify the case of the drains running without rain, during a falling barometer, beyond all doubt.

"'The case I named to you last year of the barometer falling four days consecutively, and with rapidity, was a peculiarly favorable time for noticing it, as it occurred in a dry time, and the drains could be seen distinctly. My man, on being questioned and cautioned by me not to exaggerate, has declared the actual stream of water issuing from one particular drain to be as thick as a three-eighth-inch wire. All the drains ran--they did more than drop--and ditches, which were previously dry, became quite wet, with a perceptible stream of water; this gradually ceased with the change in the density of the atmosphere, as shown by the barometer.

"'During last harvest, 1855, the men were cutting wheat, and on getting near to a drain outlet, the ditch from the outlet downwards was observed to be wet, and the drain was dripping. No rain fell in sufficient quant.i.ty to enter the ground. The men drank of the water while they were cutting the wheat. A few days after, it was dry again. I have seen and noticed this phenomenon myself.'

"A correspondent of the _Agricultural Gazette_ has stated, that Professor Brocklesby, of Hartford, in America, had observed the same phenomena, in the case of two springs in that country; and explained, that the cause was 'the diminished atmospheric pressure which exists before a rain.'"

Dr. Lardner states many facts which support the ideas above suggested.

In his lectures on science, he says: "When storms are breaking in the heavens, and sometimes long before their commencement, and when their approach has not yet been manifested by any appearances in the firmament, phenomena are observed, apparently sympathetic, proceeding from the deep recesses of the earth, and exhibited under very various forms at its surface." Dr. Lardner cites many instances of fountains which, when a storm is approaching, burst forth with a violent flow of water, before any rain has fallen.

The cases named by Prof. Brocklesby, referred to by Mr. Denton, are those of a spring in Rutland, Vermont, and a brook in Concord, Ma.s.sachusetts. Prof. Brocklesby states, as the result of his personal observation, that the spring referred to, supplies an aqueduct; that, in several instances, when the spring had become so low, in a time of drought, that no water ran in the aqueduct, it suddenly rose so as to fill the pipes, and furnish a supply of water, before any rain had fallen in the neighborhood. This occurrence, he says, was familiar to the occupants of the premises, and they expected rain in a few days after this mysterious flow of water; which expectations were usually, if not always, realized.

The other instance is that of a brook in Concord, Ma.s.s., called Dodge's brook, which Prof. B. says, he was informed, commenced frequently to rise very perceptibly before a drop of rain had fallen.

We have inquired of our friends in Concord about this matter, and find that this opinion is entertained by many of the people who live near this brook, and it is probably well founded, though we cannot ascertain that accurate observations have been made, so as to afford any definite results.

_Thorough drainage warms the soil._ It has been stated, on high authority, that drainage raises the temperature of the soil, often as much as 15 F. Indian corn vegetates at about 55. At 45, the seed would rot in the ground, without vegetating. The writer, however, has seen rye sprouted upon ice in an ice-house, with roots two inches long, so grown to the ice that they could only be separated by thawing. Winter rye, no doubt, makes considerable growth under snow. Cultivated plants, in general, however, do not grow at all, unless the soil be raised above 45. The sun has great power to warm dry soils, and, it is said, will often raise their temperature to 90 or 100, when the air in the shade is only 60 or 70. But the sun has no such power to warm a wet soil, and for several reasons, which are as follows:

1. _The soil is rendered cold by evaporation._ If water cannot pa.s.s through the land by drainage, either natural or artificial, it must escape, if at all, at the surface, by evaporation. Now, it is a fact well known, that the heat disappears, or becomes latent, by the conversion of water into vapor. Every child knows this, practically, at least, who, in Winter, has washed his hands and gone out without drying them. The same evaporation which thus affects the hands, renders the land cold, when filled with water, every gallon of which thus carried off requires, and actually carries off, as much heat as would raise five and a half gallons of water from the freezing to the boiling point.

Morton, in his "Encyclopaedia of Agriculture," estimates that it would require an expenditure of nearly 1,200 pounds of coal per day, to evaporate artificially one half the rain which falls on an acre during the year. In other words, about 219 tons of coals annually, would be required for every acre of undrained land, so as to allow the free use of the sun's rays for the legitimate purpose of growing and maturing the crops cultivated upon it. It will not then be surprising that undrained soils are, in the language of the farmer, "cold."

2. _Heat will not pa.s.s downward in water._ If, therefore, your soil be saturated with water, the heat of the sun, in Spring, cannot warm it, and your plowing and planting must be late, and your crop a failure.

Count Rumford tried many experiments to ill.u.s.trate the mode of the propagation of heat in fluids, and his conclusion, it is presumed, is now held to be the true theory, that heat is transmitted in water only by the motion of the particles of water; so that, if you could stop the heated particles from rising, water could not be warmed except where it touches the vessel containing it. Heat applied to the bottom of a vessel of water warms the particles in contact with the vessel, and colder particles descend, and so the whole is warmed.

Heat, applied to the surface of the water, can never warm it, except so far as it is conducted downward by some other medium than the water itself. Count Rumford confined cakes of ice in the bottom of gla.s.s jars, and, covering it with one thickness of paper, poured boiling-hot water on the top of it, and there it remained for hours without melting the ice. The paper was placed over the ice, so that the hot water could not be poured on it, which would have thawed it at once. Every man who has poured hot water into a frozen pump, hoping to thaw out the ice by this means, has arrived at the fact, if not at the theory, that ice will not melt by hot water on the top of it. If, however, a piece of lead pipe be placed in the pump, resting on the ice, and hot water be poured through it, the ice will melt at once. In the first instance, the hot water in contact with the ice becomes cold; and there it remains, because cold water is heavier than warm, and there it will remain, though the top be boiling. But when hot water is poured through the pipe, the downward current drives away the cold water, and brings heated particles in succession to the ice.

Heat is propagated in water, then, only by circulation; that is, by the upward movement of the heated particles, and the downward movement of the colder ones to take their place. Anything which obstructs circulation, prevents the pa.s.sage of heat. Chocolate retains heat longer than tea, because it is thicker, and the hot particles cannot so readily rise to be cooled at the surface. Count Rumford ill.u.s.trated this fact satisfactorily, by putting eider-down into water, which was found to obstruct the circulation, and to prevent the rapid heating and cooling of it. The same is true of all viscous substances, as starch and glue; and so of oil. They retain heat much longer than water or spirits.

In a soil saturated with water, or even in water thickened with mud, there could then be but little circulation of the particles, even were the heat applied at the bottom instead of the top. Probably the soil, though saturated with water, does, to some extent, transmit heat from one particle of earth to another, but it must be but very slowly.

In the chapter upon Temperature as affected by Drainage, farther ill.u.s.trations of this point may be found.

AERATION BY DRAINS.

Among the advantages of thorough-drainage, is reckoned by all, the circulation of air through the soil. No drop of water can run from the soil into a drain without its place being supplied by air, unless there is more water to supply it; so that drainage, in this way, manifestly promotes the permeation of air through the soil.

But it is claimed that drains may be made to promote circulation of air in another way, and in dry times, when no water is flowing through them, by connecting them together by means of a header at the upper ends, and leaving an opening so that the air may pa.s.s freely through the whole system. Our friend, Prof. Mapes, is an advocate for this practice, and certainly the theory seems well supported. It is said that in dry, hot weather, when the air is most highly charged with moisture, currents thus pa.s.sing constantly through the earth, must, by contact with the cooler subsoil, part with large quant.i.ties of moisture, and tend to moisten the soil from the drains to the surface, giving off also with the moisture whatever of fertilizing elements the air may bear with it.

This point has not escaped the notice of English drainers. Mr. J. H.

Charnock, an a.s.sistant commissioner under the Drainage act, in 1843, read a paper in favor of this practice, but in 1849 he published a second article in which he suggests doubts of the advantages of such arrangements, and says he has discontinued their application. He says they add to the cost of the work, and tend to the decay of the pipes, and to promote the growth into the pipes, of any roots that may approach them.

Mr. Parkes, in a published article in 1846, speaks of this idea, but pa.s.ses it by as of very little importance. Mr. Denton quotes the authority of some of his correspondents strongly in favor of this theory. After trying some experiments himself upon clay soil, he admits the advantages of such an arrangement for such soil, in the following not very enthusiastic terms:

"It will be readily understood that as clay will always contract rapidly under the influence of a draught of air, in consequence of the rapid evaporation of moisture from its surface, one of the benefits of draining is thus very cheaply acquired; and for the denser clays it may possibly be a desirable thing to do, but in the porous soils it would appear that no advantage is gained by it."

Yet, notwithstanding this summary disposition of the question in England, it is by no means clear, that in the tropical heat of American summers, when the difference between the temperature of the air and the subsoil is so much greater than it can ever be in England, and when we suffer from severer droughts than are common there, we may not find substantial practical advantage from the pa.s.sage of these air currents through the soil.

We are not aware of experiments in America, accurate enough to be quoted as authority on the subject.

CHAPTER XIV.

DRAINAGE ADAPTS THE SOIL TO GERMINATION AND VEGETATION.

Process of Germination.--Two Cla.s.ses of Pores in Soils, ill.u.s.trated by Cuts.--Too much Water excludes Air, reduces Temperature.--How much Air the Soil Contains.--Drainage Improves the Quality of Crops.--Drainage prevents Drought.--Drained Soils hold most Water.--Allow Roots to go Deep.--Various Facts.

No apology will be necessary for the long extract which we are about to give, to any person who will read it with attention. It is from a lecture on Agricultural Science, by Dr. Madden, and we confess ourselves incompetent to condense or improve the language of the learned author.

We think we are safe in saying that it has never been before published in America:

"The first thing which occurs after the sowing of the seed is, of course, _germination_; and before we examine how this process may be influenced by the condition of the soil, we must necessarily obtain some correct idea of the process itself. The most careful examination has proved that the process of germination consists essentially of various chemical changes, which require for their development the presence of air, moisture, and a certain degree of warmth. Now it is obviously unnecessary for our present purpose that we should have the least idea of the nature of these processes: all we require to do, is to ascertain the conditions under which they take place; having detected these, we know at once what is required to make a seed grow. These, we have seen, are air, moisture, and a certain degree of warmth; and it consequently results, that wherever a seed is placed in these circ.u.mstances, germination will take place. Viewing matters in this light, it appears that soil does not act _chemically_ in the process of germination; that its sole action is confined to its being the vehicle, by means of which a supply of air and moisture and warmth can be continually kept up. With this simple statement in view, we are quite prepared to consider the various conditions of soil, for the purpose of determining how far these will influence the future prospects of the crop, and we shall accordingly at once proceed to examine carefully into the _mechanical relations of the soil_. This we propose doing by the aid of figures. Soil examined mechanically, is found to consist entirely of particles of all shapes and sizes, from stones and pebbles, down to the finest powder; and, on account of their extreme irregularity of shape, they cannot lie so close to one another as to prevent there being pa.s.sages between them, owing to which circ.u.mstance soil in the ma.s.s is always more or less _porous_. If, however, we proceed to examine one of the smallest particles of which soil is made up, we shall find that even this is not always solid, but is much more frequently porous, like soil in the ma.s.s. A considerable proportion of this finely-divided part of soil, _the impalpable matter_ as it is generally called, is found, by the aid of the microscope, to consist of _broken-down vegetable tissue_, so that when a small portion of the finest dust from a garden or field is placed under the microscope, we have exhibited to us particles of every variety of shape and structure, of which a certain part is evidently of vegetable origin. In these figures I have given a very rude representation of these particles; and I must beg you particularly to remember that they are not meant to represent by any means accurately what the microscope exhibits, but are only designed to serve as a plan by which to ill.u.s.trate the mechanical properties of the soil. On referring to Fig. 91, we perceive that there are two distinct cla.s.ses of pores; first, the large ones, which exist _between_ the particles of soil, and second, the very minute ones, which occur in the particles themselves; and you will at the same time notice, that whereas all the larger pores--those between the particles of soil--communicate most freely with each other, so that they form ca.n.a.ls, the small pores, however freely they may communicate with one another in the interior of the particle in which they occur, have no direct connection with the pores of the surrounding particles. Let us now, therefore, trace the effect of this arrangement. In Fig. 91, we perceive that these ca.n.a.ls and pores are all empty, the soil being _perfectly dry_; and the ca.n.a.ls communicating freely at the surface with the surrounding atmosphere, the whole will of course be filled with air. If in this condition, a seed be placed in the soil, as at _a_, you at once perceive that it is freely supplied with air, _but there is no moisture_; therefore, when soil is _perfectly dry_, a seed cannot grow.

[Ill.u.s.tration: Fig. 91.]

[Ill.u.s.tration: Fig. 92.]

"Let us turn our attention now to Fig. 92. Here we perceive that both the pores and ca.n.a.ls are no longer represented white, but black, this color being used to indicate water; in this instance, therefore, water has taken the place of air, or, in other words, the soil is _very wet_. If we observe our seed _a_ now, we find it abundantly supplied with water, but _no air_. Here again, therefore, germination cannot take place. It may be well to state here, that this can never occur _exactly_ in nature, because water having the power of dissolving air to a certain extent, the seed _a_ in Fig. 92 is, in fact, supplied with a _certain_ amount of this necessary substance; and, owing to this, germination does take place, although by no means under such advantageous circ.u.mstances as it would were the soil in a better condition.