Again, much of the mineral matter in the soil is combined within particles, and is therefore out of the reach of roots. Lime, among other thing, has the effect of causing these particles to crumble and expose their constituents to the demand of roots. Therefore, lime has for one of its offices the development of the fertilizing ingredients of the soil.

3d. Those manures which improve the mechanical condition of the soil.

The alkalies, in combining with sand, commence their action on the surfaces of the particles, and roughen them—rust them as it were. This roughening of particles of the soil prevents them from moving among each other as easily as they do when they are smooth, and thus keeps the soil from being compacted by heavy rains, as it is liable to be in its natural condition. In this way, the mechanical texture of the soil is improved.

It has just been said that lime causes the pulverization of the particles of the soil; and thus, by making it finer, improves its mechanical condition.

Some mineral manures, as plaster and salt, have the power of absorbing moisture from the atmosphere; and this is a mechanical improvement to dry soils.

[Name some mineral manures which absorb ammonia?]

4th. Those mineral manures which have the power of absorbing ammonia.

Plaster, chloride of lime, alumina (clay), etc., are large absorbents of ammonia, whether arising from the fermentation of animal manures or washed down from the atmosphere by rains. The ammonia thus absorbed is of course very important in the vegetation of crops.

Having now explained the reasons why mineral manures are necessary, and the manner in which they produce their effects, we will proceed to examine the various deficiencies of soils and the character of many kinds of this class of fertilizers.



CHAPTER IX.

DEFICIENCIES OF SOILS, MEANS OF RESTORATION, ETC.

As will be seen by referring to the analyses of soils on p. 72, they may be deficient in certain ingredients, which it is the object of mineral manures to supply. These we will take up in order, and endeavor to show in a simple manner the best means of managing them in practical farming.

ALKALIES.

POTASH.

[Do all soils contain a sufficient amount of potash?

How may its deficiency have been caused?

How may its absence be detected?

Does barn-yard manure contain sufficient potash to supply its deficiency in worn-out soils?]

Potash is often deficient in the soil. Its deficiency may have been caused in two ways. Either it may not have existed largely in the rock from which the soil was formed, and consequently is equally absent from the soil itself, or it may have once been present in sufficient quantities, and been carried away in crops, without being returned to the soil in the form of manure until too little remains for the requirements of fertility.

In either case, its absence may be accurately detected by a skilful chemist, and it may be supplied by the farmer in various ways. Potash, as well as all of the other mineral manures, is contained in the excrements of animals, but not (as is also the case with the others) in sufficient quantities to restore the proper balance to soils where it is largely deficient, nor even to make up for what is yearly removed with each crop, except that crop (or its equivalent) has been fed to such animals as return all of the fertilizing constituents of their food in the form of manure, and this be all carefully preserved and applied to the soil. In all other cases, it is necessary to apply more potash than is contained in the excrements of animals.

[What is generally the most available source from which to obtain this alkali?

Will leached ashes answer the same purpose?

How may ashes be used?]

Unleached wood ashes is generally the most available source from which to obtain this alkali. The ashes of all kinds of wood contain potash (more or less according to the kind—see analysis section V.) If the ashes are leached, the potash is removed; and, hence for the purpose of supplying it, they are worthless; but unleached ashes are an excellent source from which to obtain it. They may be made into compost with muck, as directed in a previous chapter, or applied directly to the soil. In either case the potash is available directly to the plant, or is capable of uniting with the silica in the soil to form silicate of potash. Neither potash nor any other alkali should ever be applied to animal manures unless in compost with an absorbent, as they cause the ammonia to be thrown off and lost.

[From what other sources may potash be obtained?

How may we obtain soda?

In what quantities should pure salt be applied to the soil?]

Potash sparlings, or the refuse of potash warehouses, is an excellent manure for lands deficient in this constituent.

Potash marl, such as is found in New Jersey, contains a large proportion of potash, and is an excellent application to soils requiring it.

Feldspar, kaolin, and other minerals containing potash, are, in some localities, to be obtained in sufficient quantities to be used for manurial purposes.

Granite contains potash, and if it can be crushed (as is the case with some of the softer kinds,) it serves a very good purpose.

SODA.

[If applied in large quantities will it produce permanent injury?

In what quantities should salt be applied to composts? To asparagus?]

Soda, the requirement of which is occasioned by the same causes as create a deficiency of potash, and all of the other ingredients of vegetable ashes, may be very readily supplied by the use of common salt (chloride of sodium), which consists of about one half sodium (the base of soda). The best way to use salt is in the lime and salt mixture, previously described, or as a direct application to the soil. If too much salt be given to the soil it will kill any plant. In small quantities, however, it is highly beneficial, and if six bushels per acre be sown broadcast over the land, to be carried in by rains and dews, it will not only destroy many insects (grubs, worms, etc.), but will, after decomposing and becoming chlorine and soda, prove an excellent manure. Salt, even in quantities large enough to denude the soil of all vegetation, is never permanently injurious. After the first year, it becomes resolved into its constituents, and furnishes chlorine and soda to plants, without injuring them. One bushel of salt in each cord of compost will not only hasten the decomposition of the manures, but will kill all seeds and grubs—a very desirable effect. While small quantities of salt in a compost heap are beneficial, too much (as when applied to the soil) is positively injurious, as it arrests decomposition; fairly pickles the manures, and prevents them from rotting.

[What is generally the best way to use salt?

What is nitrate of soda?

What plants contain lime?]

For asparagus, which is a marine plant, salt is an excellent manure, and may be applied in almost unlimited quantities, while the plants are growing, if used after they have gone to top, it is injurious. Salt has been applied to asparagus beds in such quantities as to completely cover them, and with apparent benefit to the plants. Of course large doses of salt kill all weeds, and thus save labor and the injury to the asparagus roots, which would result from their removal by hoeing. Salt may be used advantageously in any of the foregoing manners, but should always be applied with care. For ordinary farm purposes, it is undoubtedly most profitable to use the salt with lime, and make it perform the double duty of assisting in the decomposition of vegetable matter, and fertilizing the soil.

Soda unites with the silica in the soil, and forms the valuable silicate of soda.

Nitrate of soda, or cubical nitre, which is found in South America, consists of soda and nitric acid. It furnishes both soda and nitrogen to plants, and is an excellent manure.

LIME.

The subject of lime is one of most vital importance to the farmer; indeed, so varied are its modes of action and its effects, that some writers have given it credit for every thing good in the way of farming, and have gone so far as to say that all permanent improvement of agriculture must depend on the use of lime. Although this is far in excess of the truth (as lime cannot plow, nor drain, nor supply any thing but lime to the soil), its many beneficial effects demand for it the closest attention.

[Do all soils contain enough lime for the use of plants?

What amount is needed for this purpose?

What is its first-named effect on the soil?

Its second? Third? Fourth? Fifth?

How are acids produced in the soil?]

As food for plants, lime is of considerable importance. All plants contain lime—some of them in large quantities. It is an important constituent of straw, meadow hay, leaves of fruit trees, peas, beans, and turnips. It constitutes more than one third of the ash of red clover. Many soils contain lime enough for the use of plants, in others it is deficient, and must be supplied artificially before they can produce good crops of those plants of which lime is an important ingredient. The only way in which the exact quantity of lime in the soil can be ascertained is by chemical analysis. However, the amount required for the mere feeding plants is not large, (much less than one per cent.), but lime is often necessary for other purposes; and setting aside, for the present, its feeding action, we will examine its various effects on the mechanical and chemical condition of the soil.

1. It corrects acidity (sourness).

2. It hastens the decomposition of the organic matter in the soil.

3. It causes the mineral particles of the soil to crumble.

4. By producing the above effects, it prepares the constituents of the soil for assimilation by plants.

5. It is said to exhaust the soil, but it does so in a very desirable manner, the injurious effects of which may be easily avoided.

[How does lime correct them?

How does it affect animal manures in the soil?]

1. The decomposition of organic matter in the soil, often produces acids which makes the land sour, and cause it to produce sorrel and other weeds, which interfere with the healthy growth of crops. Lime is an alkali, and if applied to soils suffering from sourness, it will unite with the acids, and neutralize them, so that they will no longer be injurious.

2. We have before stated that lime is a decomposing agent, and hastens the rotting of muck and other organic matter. It has the same effect on the organic parts of the soil, and causes them to be resolved into the gases and minerals of which they are formed. It has this effect, especially, on organic matters containing nitrogen, causing them to throw off ammonia; consequently, it liberates this gas from the animal manures in the soil.

3. Various inorganic compounds in the soil are so affected by lime, that they lose their power of holding together, and crumble, or are reduced to finer particles, while some of their constituents are rendered soluble. One way in which this is accomplished is by the action of the lime on the silica contained in these compounds, forming the silicate of lime. This crumbling effect improves the mechanical as well as the chemical condition of the soil.

4. We are now enabled to see how lime prepares the constituents of the soil for the use of plants.

[Inorganic compounds?

How does lime prepare the constituents of the soil for use?

What can you say of the remark that lime exhausts the organic matter in the soil?]

By its action on the roots, buried stubble, and other organic matter in the soil, it causes them to be decomposed, and to give up many of their gaseous and inorganic constituents for the use of roots. In this manner the organic matter is prepared for use more rapidly than would be the case, if there were no lime present to hasten its decomposition.

By the decomposing action of lime on the mineral parts of the soil (3), they also are placed more rapidly in a useful condition than would be the case, if their preparation depended on the slow action of atmospheric influences.

Thus, we see that lime, aside from its use directly as food for plants, exerts a beneficial influence on both the organic and inorganic parts of the soil.

5. Many contend that lime exhausts the soil.

If we examine the manner in which it does so, we shall see that this is no argument against its use.

[How can lime exhaust the mineral parts of the soil?

Must the matter taken away be returned to the soil?]

It exhausts the organic parts of the soil, by decomposing them, and resolving them into the gases and minerals of which they are composed. If the soil do not contain a sufficient quantity of absorbent matter, such as clay or charcoal, the gases arising from the organic matter are liable to escape; but when there is a sufficient amount of these substances present (as there always should be), these gases are all retained until required by the roots of plants. Hence, although the organic matter of manure and vegetable substances may be altered in form, by the use of lime, it can escape (except in very poor soils) only as it is taken up by roots to feed the crop, and such exhaustion is certainly profitable; still, in order that the fertility of the soil may be maintained, enough of organic manure should be applied, to make up for the amount taken from the soil by the crop, after liberation for its use by the action of the lime. This will be but a small proportion of the organic matter contained in the crop, as it obtains the larger part from the atmosphere.

The only way in which lime can exhaust the inorganic part of the soil is, by altering its condition, so that plants can use it more readily. That is, it exposes it for solution in water. We have seen that fertilizing matter cannot be leached out of a good soil, in any material quantity, but can only be carried down to a depth of about thirty-four inches. Hence, we see that there can be no loss in this direction; and, as inorganic matter cannot evaporate from the soil, the only way in which it can escape is through the structure of plants.

[If this course be pursued, will the soil suffer from the use of lime?

Is it the lime, or its crop, that exhausts the soil?

Is lime containing magnesia better than pure lime?

What is the best kind of lime?]

If lime is applied to the soil, and increases the amount of crops grown by furnishing a larger supply of inorganic matter, of course, the removal of inorganic substances from the soil will be more rapid than when only a small amount of crop is grown, and the soil will be sooner exhausted—not by the lime, but by the plants. In order to make up for this exhaustion, it is necessary that a sufficient amount of inorganic matter be supplied to compensate for the increased quantity taken away by plants.

Thus we see, that it is hardly fair to accuse the lime of exhausting the soil, when it only improves its character, and increases the amount of its yield. It is the crop that takes away the fertility of the soil (the same as would be the case if no lime were used, only faster as the crop is larger), and in all judicious cultivation, this loss will be fully compensated by the application of manures, thereby preventing the exhaustion of the soil.

[Is the purchase of marl to be recommended?

How is lime prepared for use? (Note.)

Describe the burning and slaking of lime.]

Kind of lime to be used. The first consideration in procuring lime for manuring land, is to select that which contains but little, if any magnesia. Nearly all stone lime contains more or less of this, but some kinds contain more than others. When magnesia is applied to the soil, in too large quantities, it is positively injurious to plants, and great care is necessary in making selection. As a general rule, it may be stated, that the best plastering lime makes the best manure. Such kinds only should be used as are known from experiment not to be injurious.

Shell lime is undoubtedly the best of all, for it contains no magnesia, and it does contain a small quantity of phosphate of lime. In the vicinity of the sea-coast, and near the lines of railroads, oyster shells, clam shells, etc., can be cheaply procured. These may be prepared for use in the same manner as stone lime.[AG]

The preparation of the lime is done by first burning and then slaking, or by putting it directly on the land, in an unslaked condition, after its having been burned. Shells are sometimes ground, and used without burning; this is hardly advisable, as they cannot be made so fine as by burning and slaking. As was stated in the first section of this book, lime usually exists in nature, in the form of carbonate of lime, as limestone, chalk, or marble (being lime and carbonic acid combined), and when this is burned, the carbonic acid is thrown off, leaving the lime in a pure or caustic form. This is called burned lime, quick-lime, lime shells, hot lime, etc. If the proper quantity of water be poured on it, it is immediately taken up by the lime, which falls into a dry powder, called slaked lime. If quick-lime were left exposed to the weather, it would absorb moisture from the atmosphere, and become what is termed air slaked.

[What is air slaking?

If slaked lime be exposed to the air, what change does it undergo?

What is the object of slaking lime?

How much carbonic acid is contained in a ton of carbonate of lime?

How much lime does a ton of slaked lime contain?

What is the most economical form for transportation?]

When slaked lime (consisting of lime and water) is exposed to the atmosphere, it absorbs carbonic acid, and becomes carbonate of lime again; but it is now in the form of a very fine powder, and is much more useful than when in the stone.

If quick-lime is applied directly to the soil, it absorbs first moisture, and then carbonic acid, becoming finally a powdered carbonate of lime.

One ton of carbonate of lime contains 11-1/4 cwt. of lime; the remainder is carbonic acid. One ton of slaked lime contains about 15 cwt. of lime; the remainder is water.

Hence we see that lime should be burned, and not slaked, before being transported, as it would be unprofitable to transport the large quantity of carbonic acid and water contained in carbonate of lime and slaked lime. The quick-lime may be slaked, and carbonated after reaching its destination, either before or after being applied to the land.

[What is the best form for immediate action on the inorganic matter in the soil?

For most other purposes?]

As has been before stated, much is gained by slaking lime with salt water, thus imitating the lime and salt mixture. Indeed in many cases, it will be found profitable to use all lime in this way. Where a direct action on the inorganic matters contained in the soil is desired, it may be well to apply the lime directly in the form of quick-lime; but, where the decomposition of the vegetable and animal constituents of the soil is desired, the correction of sourness, or the supplying of lime to the crop, the mixture with salt would be advisable.

The amount of lime required by plants is, as was before observed, usually small compared with the whole amount contained in the soil; still it is not unimportant.

OF LIME. 25 bus. of wheat contain about 13 lbs. 25 " barley " 10-1/2 " 25 " oats " 11 " 2 tons of turnips " 12 " 2 " potatoes " 5 " 2 " red clover " 77 " 2 " rye grass " 30 "[AH]

[What is the best guide concerning the quantity of lime to be applied?

What is said of the sinking of lime in the soil?

What is plaster of Paris composed of?

Why is it called plaster of Paris?]

The amount of lime required at each application, and the frequency of those applications, must depend on the chemical and mechanical condition of the soil. No exact rule can be given, but probably the custom of each district—regulated by long experience—is the best guide.

Lime sinks in the soil; and therefore, when used alone, should always be applied as a top dressing to be carried into the soil by rains. The tendency of lime to settle is so great that, when cutting drains, it may often be observed in a whitish streak on the top of the subsoil. After heavy doses of lime have been given to the soil, and have settled so as to have apparently ceased from their action, they may be brought up and mixed with the soil by deeper plowing.

Lime should never be mixed with animal manures, unless in compost with muck, or some other good absorbent, as it is liable to cause the escape of their ammonia.

PLASTER OF PARIS.

Plaster of Paris or Gypsum (sulphate of lime) is composed of sulphuric acid and lime in combination. It is called 'plaster of Paris,' because it constitutes the rock underlying the city of Paris.

[Is it a constituent of plants?

What else does it furnish them?

How does it affect manure?

How does it produce sorrel in the soil?

How may the acidity be overcome?]

It is a constituent of many plants. It also furnishes them with sulphur—a constituent of the sulphuric acid which it contains.

It is an excellent absorbent of ammonia, and is very useful to sprinkle around stables, poultry houses, pig-styes, and privies, where it absorbs the escaping gases, saving them for the use of plants, and purifying the air, thus rendering stables, etc., more healthy than when not so supplied.

It has been observed that the extravagant use of plaster sometimes induces the growth of sorrel. This is probably the case only where the soil is deficient in lime. In such instances, the lime required by plants is obtained by the decomposition of the plaster. The lime enters into the construction of the plant, and the sulphuric acid remains free, rendering the soil sour, and therefore in condition to produce sorrel. In such a case, an application of lime will correct the acid by uniting with it and converting it into plaster.

CHLORIDE OF LIME.

[What does chloride of lime supply to plants?

How does it affect manures?

How may it be used?

How may magnesia be supplied, when wanting?

What care is necessary concerning the use of magnesia?]

Chloride of lime is a compound of lime and chlorine. It furnishes both of these constituents to plants, and it is an excellent absorbent of ammonia and other gases arising from decomposition—hence its usefulness in destroying bad odors, and in preserving fertilizing matters for the use of crops.

It may be used like plaster, or in the decomposition of organic matters, where it not only hastens decay, but absorbs and retains the escaping gases. It will be recollected that chloride of lime is one of the products of the lime and salt mixture.

Lime in combination with phosphoric acid forms the valuable phosphate of lime, of which so large a portion of the ash of grain, and the bones of animals, is formed. This will be spoken of more at length under the head of 'phosphoric acid.'

MAGNESIA.

Magnesia is a constituent of vegetable ashes, and is almost always present in the soil in sufficient quantities. When analysis indicates that it is needed, it may be applied in the form of magnesian lime, or refuse epsom salts, which are composed of sulphuric acid and magnesia (sulphate of magnesia).

The great care necessary concerning the use of magnesia is, not to apply too much of it, it being, when in excess, as has been previously remarked, injurious to the fertility of the soil. Some soils are hopelessly barren from the fact that they contain too much magnesia.

ACIDS.

SULPHURIC ACID.

[What is sulphuric acid commonly called?

How may it be used?

How does it prevent the escape of ammonia?]

Sulphuric acid is a very important constituent of vegetable ashes, especially of oats and the root-crops.

It is often deficient in the soil, particularly where potatoes have been long cultivated. One of the reasons why plaster (sulphate of lime) is so beneficial to the potato crop is undoubtedly that it supplies it with sulphuric acid.

Sulphuric acid is commonly known by the name of oil vitriol, and may be purchased for agricultural purposes at a low price. It may be used in a very dilute form (weakened by mixing it with a large quantity of water) to the compost heap, where it will change the ammonia to a sulphate as soon as formed, and thus prevent its loss, as the sulphate of ammonia is not volatile; and, being soluble in water, is useful to plants. Some idea of the value of this compound may be formed from the fact that manufacturers of manures are willing to pay seven cents per lb., or even more, for sulphate of ammonia, to insure the success of their fertilizers. Notwithstanding this, many farmers persist in throwing away hundreds of pounds of ammonia every year, as a tax for their ignorance (or indolence), while a small tax in money—not more valuable, nor more necessary to their success—for the support of common schools, and the better education of the young, is too often unwillingly paid.

[What is the effect of using too much sulphuric acid?]

If a tumbler full of sulphuric acid (costing a few cents), be thrown into the tank of the compost heap once a month, the benefit to the manure would be very great.

Where a deficiency of sulphuric acid in the soil is indicated by analysis, it may be supplied in this way, or by the use of plaster or refuse epsom salts.

Care is necessary that too much sulphuric acid be not used, as it would prevent the proper decomposition of manures, and would induce a growth of sorrel in the soil by making it sour.

In many instances, it will be found profitable to use sulphuric acid in the manufacture of super-phosphate of lime (as directed under the head of 'phosphoric acid,') thus making it perform the double purpose of preparing an available form of phosphate, and of supplying sulphur and sulphuric acid to the plant.

PHOSPHORIC ACID.

[How large a part of the ashes of grain consists of phosphoric acid?

Of what other substances does it form a leading ingredient?

How many pounds of sulphuric acid are contained in one hundred bushels of wheat?]

We come now to the consideration of one of the most important of all subjects connected with agriculture, that is, phosphoric acid.

Phosphoric acid, forming about one half of the ashes of wheat, rye, corn, buckwheat, and oats; nearly the same proportion of those of barley, peas, beans and linseed; an important ingredient of the ashes of potatoes and turnips; one quarter of the ash of milk and a large proportion of the bones of animals, often exists in the soil in the proportion of only about one or two pounds in a thousand. The cultivation of our whole country has been such, as to take away the phosphoric acid from the soil without returning it, except in very minute quantities. Every hundred bushels of wheat sold contains (and removes permanently from the soil) about sixty pounds of phosphoric acid. Other grains, as well as the root crops and grasses, remove likewise a large quantity of it. It has been said by a contemporary writer, that for each cow kept on a pasture through the summer, there is carried off in veal, butter and cheese, not less than fifty lbs. of phosphate of lime (bone-earth) on an average. This would be one thousand lbs. for twenty cows; and it shows clearly why old dairy pastures become so exhausted of this substance, that they will no longer produce those nutritious grasses, which are favorable to butter and cheese-making.

[How much phosphate of lime will twenty cows remove from a pasture during a summer?

What has this removal of phosphate of lime occasioned?

How have the Genesee and Mohawk valleys been affected by this removal of phosphoric acid?]

That this removal of the most valuable constituent of the soil, has been the cause of more exhaustion of farms, and more emigration, in search of fertile districts, than any other single effect of injudicious farming, is a fact which multiplied instances most clearly prove.

It is stated that the Genesee and Mohawk valleys, which once produced an average of thirty-five or forty bushels of wheat, per acre, have since been reduced in their average production to twelve and a half bushels. Hundreds of similar cases might be stated; and in a large majority of these, could the cause of the impoverishment be ascertained, it would be found to be the removal of the phosphoric acid from the soil.

[How may this devastation be arrested?

Is any soil inexhaustible?

What is usually the best source from which to obtain phosphoric acid?]

The evident tendency of cultivation being to continue this murderous system, and to prey upon the vital strength of the country, it is necessary to take such measures as will arrest the outflow of this valuable material. This can never be fully accomplished until laws shall be made preventing the wastes of cities and towns. Such laws have existed for a long time in China, and have doubtlessly been the secret of the long subsistence and present prosperity of the millions of people inhabiting that country.

We have, nevertheless, a means of restoring to fertility many of our worn-out lands, and preserving our fertile fields from so rapid impoverishment as they are now suffering. Many suppose that soils which produce good crops, year after year, are inexhaustible, but time will prove to the contrary. They may possess a sufficiently large stock of phosphoric acid, and other constituents of plants, to last a long time, but when that stock becomes so reduced, that there is not enough left for the uses of full crops, the productive power of the soil will yearly decrease, until it becomes worthless. It may last a long time, a century, or even more, but as long as the system is—to remove every thing, and return nothing,—the fate of the most fertile soil is evident.

The source mentioned, from which to obtain phosphoric acid, is the bones of animals. These contain large quantities of phosphate of lime. They are the receptacles which collect nearly all of the phosphates in crops, which are fed to animals, and are not returned in their excrements. For the grain, etc., sent out of the country, there is no way to be repaid except by the importation of this material; but, all that is fed to animals, or to human beings, may, if a proper use be made of their excrement, and of their bones after death, be returned to the soil. With the treatment of animal excrements we are already familiar, and we will now turn our attention to the subject of

BONES.

[Of what do dried bones consist?

What is the organic matter of bones?

The inorganic?

What can you say of the use of whole bones?]

Bones consist, when dried, of about one third organic matter, and two thirds inorganic matter.

The organic matter consists chiefly of gelatine—a compound containing nitrogen.

The inorganic part is chiefly phosphate of lime.

Hence, we see that bones are excellent, as both organic and mineral manure. The organic part, containing nitrogen, forms ammonia, and the inorganic part supplies the much needed phosphoric acid to the soil.

Liebig says that, as a producer of ammonia, 100 lbs. of dry bones are equivalent to 250 lbs. of human urine.

[How does the value of bone dust compare with that of broken bones?

What is the reason of the superiority of bone dust?

How is bone-black made?

Of what does it consist?]

Bones are applied to the soil in almost every conceivable form. Whole bones are often used in very large quantities; their action, however, is extremely slow, and it is never advisable to use bones in this form.

Ten bushels of bones, finely ground, will produce larger results, during the current ten years after application, than would ensue from the use of one hundred bushels merely broken, not because the dust contains more fertilizing matter than the whole bones, but because that which it does contain is in a much more available condition. It ferments readily, and produces ammonia, while the ashy parts are exposed to the action of roots.

[Should farmers burn bones before using them?

How would you compost bones with ashes?

In what way would you prevent the escape of ammonia?]

Bone-black. If bones are burned in retorts, or otherwise protected from the atmosphere, their organic matter will all be driven off, except the carbon, which not being supplied with oxygen cannot escape. In this form bones are called ivory black, or bone-black. It consists of the inorganic matter, and the carbon of the bones. The nitrogen having been expelled it can make no ammonia, and thus far the original value of bones is reduced by burning; that is, one ton of bones contains more fertilizing matter before, than after burning; but one ton of bone black is more valuable than one ton of raw bones, as the carbon is retained in a good form to act as an absorbent in the soil, while the whole may be crushed or ground much more easily than before being burned. This means of pulverizing bones is adopted by manufacturers, who replace the ammonia in the form of guano, or otherwise; but it is not to be recommended for the use of farmers, who should not lose the ammonia, forming a part of bones, more than that of other manure.

Composting bones with ashes is a good means of securing their decomposition. They should be placed in a water-tight vessel (such as a cask); first, three or four inches of bones, then the same quantity of strong unleached wood ashes, continuing these alternate layers until the cask is full, and keeping them always wet. If they become too dry they will throw off an offensive odor, accompanied by the escape of ammonia, and consequent loss of value. In about one year, the whole mass of bones (except, perhaps, those at the top) will be softened, so that they may be easily crushed, and they are in a good condition for manuring. The ashes are, in themselves, valuable, and this compost is excellent for many crops, particularly for Indian corn. A little dilute sulphuric acid, occasionally sprinkled on the upper part of the matter in the cask, will prevent the escape of the ammonia.

[What is the effect of boiling bones under pressure?

How is super-phosphate of lime made?

Describe the composition of phosphate of lime, and the chemical changes which take place in altering it to super-phosphate of lime.]

Boiling bones under pressure, whereby their gelatine is dissolved away, and the inorganic matter left in an available condition, from its softness, is a very good way of rendering them useful; but, as it requires, among other things, a steam boiler, it is hardly probable that it will be largely adopted by farmers of limited means.

Any or all of these methods are good, but bones cannot be used with true economy, except by changing their inorganic matter into

SUPER-PHOSPHATE OF LIME.

Super-phosphate of lime is made by treating phosphate of lime, or the ashes of bones, with sulphuric acid.

Phosphate of lime, as it exists in bones, consists of one atom of phosphoric acid and three atoms of lime. It may be represented as

{ Lime Phosphoric acid { Lime { Lime

By adding a proper quantity of sulphuric acid with this, it becomes super-phosphate of lime; that is, the same amount of phosphoric acid, with a smaller proportion of lime (or a super-abundance of phosphoric acid), the sulphuric acid, taking two atoms of lime away from the compound, combined with it making sulphate of lime (plaster). The changes may be thus represented.

{Phosphoric acid} Super-phosphate Phosphate of lime {Lime } of lime. {Lime} {Lime} Sulphate of lime. Sulphuric acid}

Super-phosphate of lime may be made from whole bones, bone dust, bone-black, or from the pure ashes of bones.

[How should sulphuric acid be applied to whole bones?

What is the necessity for so large an amount of water?]

The process of making it from whole bones is slow and troublesome, as it requires a long time for the effect to diffuse itself through the whole mass of a large bone. When it is made in this way, the bones should be dry, and the acid should be diluted in many times its bulk of water, and should be applied to the bones (which may be placed in a suitable cask, with a spiggot at the bottom), in quantities sufficient to cover them, about once in ten days; and at the end of that time, one half of the liquid should be drawn off by the spiggot. This liquid is a solution of super-phosphate of lime, containing sulphate of lime, and may be applied to the soil in a liquid form, or through the medium of a compost heap. The object of using so much water is to prevent an incrustation of sulphate of lime on the surfaces of the bones, this must be removed by stirring the mass, which allows the next application of acid to act directly on the phosphate remaining. The amount of acid required is about 50 or 60 lbs. to each 100 lbs. of bones. The gelatine will remain after the phosphate is all dissolved, and may be composted with muck, or plowed under the soil, where it will form ammonia.

[May less water be employed in making super-phosphate from bone dust or crushed bones?]

Bone dust, or crushed bones, may be much more easily changed to the desired condition, as the surface exposed is much greater, and the acid can act more generally throughout the whole mass. The amount of acid required is the same as in the other case, but it may be used stronger, two or three times its bulk of water being sufficient, if the bones are finely ground or crushed—more or less water should be used according to the fineness of the bones. The time occupied will also be much less, and the result of the operation will be in better condition for manure.

Bones may be made fine enough for this operation, either by grinding, etc., or by boiling under pressure, as previously described; indeed, by whatever method bones are pulverized, they should always be treated with sulphuric acid before being applied to the soil, as this will more than double their value for immediate use.

Bone-black is chiefly used by manufacturers of super-phosphate of lime, who treat it with acid the same as has been directed above, only that they grind the black very finely before applying the acid.

[What other forms of bones may be used in making super-phosphate of lime?

Why is super-phosphate of lime a better fertilizer than phosphate of lime?

What can you say of the lasting manures?]

Bone ashes, or bones burned to whiteness, may be similarly treated. Indeed, in all of the forms of bones here described, the phosphate of lime remains unaltered, as it is indestructible by heat; the differences of composition are only in the admixture of organic constituents.

The reason why super-phosphate of lime is so much better than phosphate, may be easily explained. The phosphate is very slowly soluble in water, and consequently furnishes food to plants slowly. A piece of bone as large as a pea may lie in the soil for years without being all consumed; consequently, it will be years before its value is returned, and it pays no interest on its cost while lying there. The super-phosphate dissolves very rapidly and furnishes food for plants with equal facility; hence its much greater value as a manure.

It is true that the phosphate is the most lasting manure; but, once for all, let us caution farmers against considering this a virtue in mineral manures, or in organic manures either, when used on soils containing the proper absorbents of ammonia. They are lasting, only in proportion as they are lazy. Manures are worthless unless they are in condition to be immediately used. The farmer who wishes his manures to last in the soil, and to lose their use, may be justly compared with the miser, who buries his gold and silver in the ground for the satisfaction of knowing that he owns it. It is an old and a true saying that "a nimble sixpence is better than a slow shilling."

IMPROVED SUPER-PHOSPHATE OF LIME.

[What are the ingredients of the improved super-phosphate of lime?]

To show the manner in which super-phosphate of lime is perfected, and rendered the best manure for general uses, which has yet been made, containing large quantities of phosphoric acid and a good supply of ammonia,—hereby covering the two leading deficiencies in a majority of soils, it may be well to explain the composition of the improved super-phosphate of lime invented by Prof. Mapes.

This manure consists of the following ingredients in the proportions named:—

100 lbs. bone-black (phosphate of lime and carbon). 56 " sulphuric acid. 36 " guano. 20 " sulphate of ammonia.

[Explain the uses of these different constituents.

What is nitrogenized phosphate?]

The sulphuric acid has the before-mentioned effect on the bone-black, and fixes the ammonia of the guano by changing it to a sulphate. The twenty pounds of sulphate of ammonia added increase the amount, so as to furnish nitrogen to plants in sufficient quantities to give them energy, and induce them to take up the super-phosphate of lime in the manure more readily than would be done, were there not a sufficient supply of ammonia in the soil.

The addition of the guano, which contains all of the elements of fertility, and many of them in considerable quantities, renders the manure of a more general character, and enables it to produce very large crops of almost any kind, while it assists in fortifying the soil in what is usually its weakest point—phosphoric acid.

Prof. Mapes has more recently invented a new fertilizer called nitrogenized super-phosphate of lime, composed of the improved super-phosphate of lime and blood, dried and ground before mixture, in equal proportions. This manure, from its highly nitrogenous character, theoretically surpasses all others, and probably will be found in practice to have great value; its cost will be rather greater than guano.

We understand its manufacture will shortly be commenced by a company now forming for that purpose.

[What should be learned before purchasing amendments for the soil?

What do you know of silica?]

Many farmers will find it expedient to purchase bones, or bone dust, and manufacture their own super-phosphate of lime; others will prefer to purchase the prepared manure. In doing so, it should be obtained of men of known respectability, as manures are easily adulterated with worthless matters; and, as their price is so high, that such deception may occasion great loss.

We would not recommend the application of any artificial manure, without first obtaining an analysis of the soil, and knowing to a certainty that the manure is needed; still, when no analysis has been procured, it may be profitable to apply such manures as most generally produce good results—such as stable manure, night soil, the improved super-phosphate of lime; or, if this cannot be procured, guano.

NEUTRALS.

SILICA.

Silica (or sand) always exists in the soil in sufficient quantities for the supply of food for plants; but, as has been often stated in the preceding pages, not always in the proper condition. This subject has been so often explained to the student of this book, that it is only necessary to repeat here, that when the weakness of the straw or stalk of plants grown on any soil indicates an inability in that soil to supply the silicates required for strength, not more sand should be added, but alkalies, to combine with the sand already contained in it, and make soluble silicates which are available to roots.

Sand is often necessary to stiff clays, as a mechanical manure, to loosen their texture and render them easier of cultivation, and more favorable to the distribution of roots, and to the circulation of air and water.

CHLORINE.

[How may chlorine be applied?]

Chlorine, a necessary constituent of plants, and often deficient in the soil (as indicated by analysis), may be applied in the form of salt (chloride of sodium), or chloride of lime. The former may be dissolved in the water used to slake lime, and the latter may, with much advantage, be sprinkled around stables and other places where fertilizing gases are escaping, and, after being saturated with ammonia, applied to the soil, thus serving a double purpose.

OXIDE OF IRON.

[How may the protoxide of iron be changed to peroxide?]

Nearly all soils contain sufficient quantities of oxide of iron, or iron rust, so that this substance can hardly be required as a manure.

Some soils, however, contain the protoxide of iron in such quantities as to be injurious to plants,—see page 86. When this is the case, it is necessary to plow the soil thoroughly, and use such other mechanical means as shall render it open to the admission of air. The protoxide of iron will then take up more oxygen, and become the peroxide—which is not only inoffensive, but is absolutely necessary to fertility.

OXIDE OF MANGANESE.

This can hardly be called an essential constituent of plants, and is never taken into consideration in manuring lands.

VARIOUS OTHER MINERAL MANURES.

LEACHED ASHES.

[Why are leached ashes inferior to those that have not been leached?

On what do the benefits of leached ashes depend?

Can these ingredients be more cheaply obtained in another form?

Why do unleached ashes, applied in the spring, sometimes cause grain to lodge?]

Among the mineral manures which have not yet been mentioned—not coming strictly under any of the preceding heads, is the one known as leached ashes.

These are not without their benefits, though worth much less than unleached ashes, which, besides the constituents of those which have been leached, contain much potash, soda, etc.

Farmers have generally overrated the value of leached ashes, because they contain small quantities of available phosphate of lime, and soluble silicates, in which most old soils are deficient. While we witness the good results ensuing from their application, we should not forget that the fertilizing ingredients of thirty bushels of these ashes may be bought in a more convenient form for ten or fifteen cents, or for less than the cost of spreading the ashes on the soil. In many parts of Long Island farmers pay as much as eight or ten cents per bushel for this manure, and thousands of loads of leached ashes are taken to this locality from the river counties of New York, and even from the State of Maine, and are sold for many times their value, producing an effect which could be as well and much more cheaply obtained by the use of small quantities of super-phosphate of lime and potash.

These ashes often contain a little charcoal (resulting from the imperfect combustion of the wood), which acts as an absorbent of ammonia.

It is sometimes observed that unleached ashes, when applied in the spring, cause grain to lodge. When this is the case, as it seldom is, it may be inferred that the potash which they contain causes so rapid a growth, that the soil is not able to supply silicates as fast as they are required by the plants, but after the first year, the potash will have united with the silica in the soil, and overcome the difficulty.

OLD MORTAR.

[What are the most fertilizing ingredients of old mortar?]

Old mortar is a valuable manure, because it contains nitrate of potash and other compounds of nitric acid with alkalies.

These are slowly formed in the mortar by the changing of the nitrogen of the hair (in the mortar) into nitric acid, and the union of this with the small quantities of potash, or with the lime of the plaster. Nitrogen, presented in other forms, as ammonia, for instance, may be transformed into nitric acid, by uniting with the oxygen of the air, and this nitric acid combines immediately with the alkalies of the mortar.[AI]

The lime contained in the mortar may be useful in the soil for the many purposes accomplished by other lime.

GAS HOUSE LIME.

[How may gas-house lime be prepared for use?

Why should it not be used fresh, from the gas house?

On what do its fertilizing properties depend?

What use may be made of its offensive odor?]

The refuse lime of gas works, where it can be cheaply obtained, may be advantageously used as a manure. It consists, chiefly, of various compounds of sulphur and lime. It should be composted with earth or refuse matter, so as to expose it to the action of air. It should never be used fresh from the gas house. In a few months the sulphur will have united with the oxygen of the air, and become sulphuric acid, which unites with the lime and makes sulphate of lime (plaster), which form it must assume, before it is of much value. Having been used to purify gas made from coal, it contains a small quantity of ammonia, which adds to its value. It is considered a profitable manure in England, at the price there paid for it (forty cents a cartload), and, if of good quality, it may be worth double that sum, especially for soils deficient in plaster, or for such crops as are much benefited by plaster. Its price must, of course, be regulated somewhat by the price of lime, which constitutes a large proportion of its fertilizing parts. The offensive odor of this compound renders it a good protection against many insects.

The refuse liquor of gas works contains enough ammonia to make it a valuable manure.

SOAPERS' LEY AND BLEACHERS' LEY.

[What use may be made of the refuse ley of soap-makers and bleachers?

What peculiar qualities does soapers' ley possess?]

The refuse ley of soap factories and bleaching establishments contains greater or less quantities of soluble silicates and alkalies (especially soda and potash), and is a good addition to the tank of the compost heap, or it may be used directly as a liquid application to the soil. The soapers' ley, especially, will be found a good manure for lands on which grain lodges.

Much of the benefit of this manure arises from the soluble silicates it contains, while its nitrogenous matter,[AJ] obtained from those parts of the fatty matters which cannot be converted into soap, and consequently remains in this solution, forms a valuable addition. Heaps of soil saturated with this liquid in autumn, and subjected to the freezings of winter, form an admirable manure for spring use. Mr. Crane, near Newark (N. J.), has long used a mixture of spent ley and stable manure, applied in the fall to trenches plowed in the soil, and has been most successful in obtaining large crops.

IRRIGATION.

[On what does the benefit arising from irrigation chiefly depend?

What kind of water is best for irrigation?

How do under-drains increase the benefits of irrigation?]

Irrigation does not come strictly under the head of inorganic manures, as it often supplies ammonia to the soil. Its chief value, however, in most cases, must depend on the amount of mineral matter which it furnishes.

The word "irrigation" means simply watering. In many districts water is in various ways made to overflow the land, and is removed when necessary for the purposes of cultivation. All river and spring water contains some impurities, many of which are beneficial to vegetation. These are derived from the earth over, or through which, the water has passed, and ammonia absorbed from the atmosphere. When water is made to cover the earth, especially if its rapid motion be arrested, much of this fertilizing matter settles, and is deposited on the soil. The water which sinks into the soil carries its impurities to be retained for the uses of plants. When, by the aid of under-drains, or in open soils, the water passes through the soil, its impurities are arrested, and become available in vegetable growth. It is, of course, impossible to say exactly what kind of mineral matter is supplied by water, as that depends on the kind of rock or soil from which the impurities are derived; but, whatever it may be, it is generally soluble and ready for immediate use by plants.

[What is the difference between water which only runs over the surface of the earth, and that which runs out of the earth?

Why should strong currents of water not be allowed to traverse the soil?]

Water which has run over the surface of the earth contains both ammonia and mineral matter, while that which has arisen out of the earth, contains usually only mineral matter. The direct use of the water of irrigation as a solvent for the mineral ingredients of the soil, is one of its main benefits.

To describe the many modes of irrigation would be too long a task for our limited space. It may be applied in any way in which it is possible to cover the land with water, at stated times. Care is necessary, however, that it do not wash more fertilizing matter from the soil than it deposits on it, as would often be the case, if a strong current of water were run over it. Brooks may be dammed up, and thus made to cover a large quantity of land. In such a case the rapid current would be destroyed, and the fertilizing matter would settle; but, if the course of the brook were turned, so that it would run in a current over any part of the soil, it might carry away more than it deposited, and thus prove injurious. Small streams turned on to land, from the washing of roads, or from elevated springs, are good means of irrigation, and produce increased fertility, except where the soil is of such a character as to prevent the water from passing away, in which case it should be under-drained.

Irrigation was one of the oldest means of fertility ever used by man, and still continues in great favor wherever its effects have been witnessed.

MIXING SOILS.

[How are soils improved by mixing?]

The mixing of soils is often all that is necessary to render them fertile, and to improve their mechanical condition. For instance, soils deficient in potash, or any other constituent, may have that deficiency supplied, by mixing with them soil containing this constituent in excess.

It is very frequently the case, that such means of improvement are easily availed of. While these chemical effects are being produced, there may be an equal improvement in the mechanical character of the soil. Thus stiff clay soils are rendered lighter, and more easily workable, by an admixture of sand, while light blowy sands are compacted, and made more retentive of manure, by a dressing of clay or of muck.

[Why may the same effect sometimes be produced by deep plowing?

What is absolutely necessary to economical manuring?]

Of course, this cannot be depended on as a sure means of chemical improvement, unless the soils are previously analyzed, so as to know their requirements; but, in a majority of cases, the soil will be benefited, by mixing with it soil of a different character. It is not always necessary to go to other locations to procure the soil to be applied, as the subsoil is often very different from the surface soil, and simple deep plowing will suffice, in such cases, to produce the required admixture, by bringing up the earth from below to mingle it with that of a different character at the surface.

* * * * *

In the foregoing remarks on the subject of mineral manures, the writer has endeavored to point out such a course as would produce the "greatest good to the greatest number," and, consequently, has neglected much which might discourage the farmer with the idea, that the whole system of scientific agriculture is too expensive for his adoption. Still, while he has confined his remarks to the more simple improvements on the present system of management, he would say, briefly, that no manuring can be strictly economical that is not based on an analysis of the soil, and a knowledge of the best means of overcoming the deficiencies indicated, together with the most scrupulous care of every ounce of evaporating or soluble manure.

FOOTNOTES:

[AG] Marl is earth containing lime, but its use is not to be recommended in this country, except where it can be obtained at little cost, as the expenses of carting the earth would often be more than the value of the lime.

[AH] The straw producing the grain and the turnip and potato tops contain more lime than the grain and roots.

[AI] See Working Farmer, vol. 2, p. 278.

[AJ] Glycerine, etc.



CHAPTER X.

ATMOSPHERIC FERTILIZERS.

[Are the gases in the atmosphere manures?

What would be the result if they were not so?]

It is not common to look on the gases in the atmosphere in the light of manures, but they are decidedly so. Indeed, they are almost the only organic manure ever received by the uncultivated parts of the earth, as well as a large portion of that which is occupied in the production of food for man.

If these gases were not manures; if there were no means by which they could be used by plants, the fertility of the soil would long since have ceased, and the earth would now be in an unfertile condition. That this must be true, will be proved by a few moments' reflection on the facts stated in the first part of this book. The fertilizing gases in the atmosphere being composed of the constituents of decayed plants and animals, it is as necessary that they should be again returned to the form of organized matter, as it is that constituents taken from the soil should not be put out of existence.

AMMONIA.

[How is ammonia used by plants?

How may it be carried to the soil?

How may the value of organic manures be estimated?

What effects has ammonia beside supplying food to plants?]

The ammonia in the atmosphere probably cannot be appropriated by the leaves of plants, and must, therefore, enter the soil to be assimilated by roots. It reaches the soil in two ways. It is either arrested from the air circulating through the soil, or it is absorbed by rains in the atmosphere, and thus carried to the earth, where it is retained by clay and carbon, for the uses of plants. In the soil, ammonia is the most important of all organic manures. In fact, the value of organic manure may be estimated, either by the amount of ammonia which it will yield, or by its power of absorbing ammonia from other sources.

The most important action of ammonia in the soil is the supply of nitrogen to plants; but it has other offices which are of consequence. It assists in some of the chemical changes necessary to prepare the matters in the soil for assimilation. Some argue that ammonia stimulates the roots of plants, and causes them to take up increased quantities of inorganic matter. The discussion of this question would be out of place here, and we will simply say, that it gives them such vigor that they require increased amounts of ashy matter, and enables them to take this from the soil.

[To how great a degree can the farmer control atmospheric fertilizers?

What should be the condition of the soil?

What substances are good absorbents in the soil?

How may sandy soils be made retentive of ammonia?]

Although, in the course of nature, the atmospheric fertilizers are plentifully supplied to the soil, without the immediate attention of the farmer, it is not beyond his power to manage them in such a manner as to arrest a greater quantity. The precautions necessary have been repeatedly given in the preceding pages, but it may be well to name them again in this chapter.

The condition of the soil is the main point to be considered. It must be such as to absorb and retain ammonia—to allow water to pass through it, and be discharged below the point to which the roots of crops are searching for food—and to admit of a free circulation of air.

The power of absorbing and retaining ammonia is not possessed by sand, but it is a prominent property of clay, charcoal, and some other matters named as absorbents. Hence, if the soil consists of nearly pure sand, it will not make use of the ammonia brought to it from the atmosphere, but will allow it to evaporate immediately after a shower. Soils in this condition require additions of absorbent matters, to enable them to use the ammonia received from the atmosphere. Soils already containing a sufficient amount of clay or charcoal, are thus far prepared to receive benefit from this source.

[Why does under-draining increase the absorptive power of the soil?

How do plants obtain their carbonic acid?

How does carbonic acid affect caustic lime in the soil?]

The next point is to cause the water of rains to pass through the soil. If it lies on the surface, or runs off without entering the soil, or even if it only enters to a slight depth, and comes in contact with but a small quantity of the absorbents, it is not probable that the fertilizing matters which it contains will all be abstracted. Some of them will undoubtedly return to the atmosphere on the evaporation of the water; but, if the soil contains a sufficient supply of absorbents, and will allow all rain water to pass through it, the fertilizing gases will all be retained. They will be filtered (or raked) out of the water.

This subject will be more fully treated in Section IV. in connection with under-draining.

Besides the properties just described, the soil must possess the power of admitting a free circulation of air. To effect this, it is necessary that the soil should be well pulverized to a great depth. If, in addition to this, the soil be such as to admit water to pass through, it will allow that circulation of air necessary to the greatest supply of ammonia.

CARBONIC ACID.

[What power does it give to water?

What condition of the soil is necessary for the reception of the largest quantity of carbonic acid?

May oxygen be considered a manure?

What is the effect of the oxidation of the constituents of the soil?]

Carbonic acid is received from the atmosphere, both by the leaves and roots of plants.

If there is caustic lime in the soil, it unites with it, and makes it milder and finer. It is absorbed by the water in the soil, and gives it the power of dissolving many more substances than it would do without the carbonic acid. This use is one of very great importance, as it is equivalent to making the minerals themselves more soluble. Water dissolves carbonate of lime, etc., exactly in proportion to the amount of carbonic acid which it contains. We should, therefore, strive to have as much carbonic acid as possible in the water in the soil; and one way, in which to effect this, is to admit to the soil the largest possible quantity of atmospheric air which contains this gas.

The condition of soil necessary for this, is the same as is required for the deposit of ammonia by the same circulation of air.

OXYGEN.

[How does it affect the protoxide of iron?

How does it neutralize the acids in the soil?

How does it affect its organic parts?

How does it form nitric acid?

How may it affect excrementitious matter of plants?

What effect has it on the mechanical condition of the soil?]

Oxygen, though not taken up by plants in its pure form, may justly be classed among manures, if we consider its effects both chemical and mechanical in the soil.

1. By oxidizing or rusting some of the constituents of the soil, it prepares them for the uses of plants.

2. It unites with the protoxide of iron, and changes it to the peroxide.

3. If there are acids in the soil, which make it sour and unfertile, it may be opened to the circulation of the air, and the oxygen will prepare some of the mineral matters contained in the soil to unite with the acids and neutralize them.

4. Oxygen combines with the carbon of organic matters in the soil, and causes them to decay. The combination produces carbonic acid.

5. It combines with the nitrogen of decaying substances and forms nitric acid, which is serviceable as food for plants.

6. It undoubtedly affects in some way the matter which is thrown out from the roots of plants. This, if allowed to accumulate, and remain unchanged, is often very injurious to plants; but, probably, the oxygen and carbonic acid of the air in the soil change it to a form to be inoffensive, or even make it again useful to the plant.

7. It may also improve the mechanical condition of the soil, as it causes its particles to crumble, thus making it finer; and it roughens the surfaces of particles, making them less easy to move among each other.

These properties of oxygen claim for it a high place among the atmospheric fertilizers.

WATER.

[Why may water be considered an atmospheric manure?

What classes of action have manures?

What are chemical manures? Mechanical?]

Water may be considered an atmospheric manure, as its chief supply to vegetation is received from the air in the form of rain or dew. Its many effects are already too well known to need farther comment.

The means of supplying water to the soil by the deposit of dew will be fully explained in Section IV.



CHAPTER XI.

RECAPITULATION.

Manures have two distinct classes of action in the soil, namely, chemical and mechanical.

Chemical manures are those which enter into the construction of plants, or produce such chemical effects on matters in the soil as shall prepare them for use.

Mechanical manures are those which improve the mechanical condition of the soil, such as loosening stiff clays, compacting light sands, pulverizing large particles, etc.

[What are the three kinds of manures?

What are organic manures, and what are their uses? Mineral? Atmospheric?]

Manures are of three distinct kinds, namely, Organic, mineral, and atmospheric.

Organic manures comprise all vegetable and animal matters (except ashes) which are used to fertilize the soil. Vegetable manures supply carbonic acid, and inorganic matter to plants. Animal manures supply the same substances and ammonia.

Mineral manures comprise ashes, salt, phosphate of lime, plaster, etc. They supply plants with inorganic matter. Their usefulness depends on their solubility.

Many of the organic and mineral manures have the power of absorbing ammonia arising from the decomposition of animal manures, as well as that which is brought to the soil by rains—these are called absorbents.

Atmospheric manures consist of ammonia, carbonic acid, oxygen and water. Their greatest usefulness requires the soil to allow the water of rains to pass through it, to admit of a free circulation of air among its particles, and to contain a sufficient amount of absorbent matter to arrest and retain all ammonia and carbonic acid presented to it.

[What rule should regulate the application of manures?

How must organic manures be managed? Atmospheric?]

Manures should never be applied to the soil without regard to its requirements.

Ammonia and carbon are almost always useful, but mineral manures become mere dirt when applied to soils not deficient of them.

The only true guide to the exact requirements of the soil is chemical analysis; and this must always be obtained before farming can be carried on with true economy.

Organic manures must be protected against the escape of their ammonia and the leaching out of their soluble parts. One cord of stable manure properly preserved, is worth ten cords which have lost all of their ammonia by evaporation, and their soluble parts by leaching—as is the case with much of the manure kept exposed in open barn-yards.

Atmospheric manures cost nothing, and are of great value when properly employed. In consequence of this, the soil which is enabled to make the largest appropriation of the atmospheric fertilizers, is worth many times as much as that which allows them to escape.



SECTION FOURTH.

MECHANICAL CULTIVATION.



CHAPTER I.

THE MECHANICAL CHARACTER OF SOILS.

[What is the first office of the soil?

How does it hold water for the uses of the plant?

How does it obtain a part of its moisture?]

The mechanical character of the soil is well understood from preceding remarks, and the learner knows that there are many offices to be performed by the soil aside from the feeding of plants.

1. It admits the roots of plants, and holds them in their position.

2. By a sponge-like action, it holds water for the uses of the plant.

3. It absorbs moisture from the atmosphere to supply the demands of plants.

[How may it obtain heat?

What is the use of the air circulating among its particles?

Could most soils be brought to the highest state of fertility?

What is the first thing to be done?

Should its color be darkened?]

4. It absorbs heat from the sun's rays to assist in the process of growth.

5. It admits air to circulate among roots, and supply them with a part of their food, while the oxygen of that air renders available the minerals of the soil; and its carbonic acid, being absorbed by the water in the soil, gives it the power of dissolving, and carrying into roots more inorganic matter than would be contained in purer water.

6. It allows the excrementitious matter thrown out by roots to be carried out of their reach.

All of these actions the soil must be capable of performing, before it can be in its highest state of fertility. There are comparatively few soils now in this condition, but there are also few which could not be profitably rendered so, by a judicious application of the modes of cultivation to be described in the following chapters.

The three great objects to be accomplished are:—

1. To adopt such a system of drainage as will cause all of the water of rains to pass through the soil, instead of evaporating from the surface.

2. To pulverize the soil to a considerable depth.

3. To darken its color, and render it capable of absorbing atmospheric fertilizers.

[Name some of the means used to secure these effects.

Why are under-drains superior to open drains?]

The means used to secure these effects are under-draining, sub-soil and surface-plowing, digging, applying muck, etc.



CHAPTER II.

UNDER-DRAINING.

The advantages of under-drains over open drains are very great.

When open drains are used, much water passes into them immediately from the surface, and carries with it fertilizing parts of the soil, while their beds are often compacted by the running water and the heat of the sun, so that they become water-tight, and do not admit water from the lower parts of the soil.

The sides of these drains are often covered with weeds, which spread their seeds throughout the whole field. Open drains are not only a great obstruction to the proper cultivation of the land, but they cause much waste of room, as we can rarely plow nearer than within six or eight feet of them.

There are none of these objections to the use of under-drains, as these are completely covered, and do not at all interfere with the cultivation of the surface.

[With what materials may under-drains be constructed?

Describe the tile.]

Under drains may be made with brush, stones, or tiles. Brush is a very poor material, and its use is hardly to be recommended. Small stones are better, and if these be placed in the bottoms of the trenches, to a depth of eight or ten inches, and covered with sods turned upside down, having the earth packed well down on to them, they make very good drains.

TILE DRAINING.

The best under-drains are those made with tiles, or burnt clay pipes. The first form of these used was that called the horse-shoe tile, which was in two distinct pieces; this was superseded by a round pipe, and we have now what is called the sole tile, which is much better than either of the others.



[Why is the sole tile superior to those of previous construction?

How are these tiles laid?

How may the trenches be dug?]

This tile is made (like the horse-shoe and pipe tile) of common brick clay, and is burned the same as bricks. It is about one half or three quarters of an inch thick, and is so porous that water passes directly through it. It has a flat bottom on which to stand, and this enables it to retain its position, while making the drain, better than would be done by the round pipe. The orifice through which the water passes is egg-shaped, having its smallest curve at the bottom. This shape is the one most easily kept clear, as any particles of dirt which get into the drain must fall immediately to the point where even the smallest stream of water runs, and are thus removed. An orifice of about two inches is sufficient for the smaller drains, while the main drains require larger tiles.

These tiles are laid, so that their ends will touch each other, on the bottoms of the trenches, and are kept in position by having the earth tightly packed around them. Care must be taken that no space is left between the ends of the tiles, as dirt would be liable to get in and choke the drain. It is advisable to place a sod—grass side down—over each joint, before filling the trench, as this more effectually protects them against the entrance of dirt. There is no danger of keeping the water out by this operation, as it will readily pass through any part of the tiles.

In digging the trenches it is not necessary (except in very stony ground) to dig out a place wide enough for a man to stand in, as there are tools made expressly for the purpose, by which a trench may be dug six or seven inches wide, and to any required depth. One set of these implements consists of a long narrow spade and a hoe to correspond, such as are represented in the accompanying figure.



With these tools, and a long light crowbar, for hard soils, trenches may be dug much more cheaply than with the common spade and pickaxe. Where there are large boulders in the soil, these draining tools may dig under them so that they will not have to be removed.

When the trenches are dug to a sufficient depth, the bottoms must be made perfectly smooth, with the required descent (from six inches to a few feet in one hundred feet). Then the tiles may be laid in, so that their ends will correspond, be packed down, and the trenches filled up. Such a drain, if properly constructed, may last for ages. Unlike the stone drain, it is not liable to be frequented by rats, nor choked up by the soil working into it.

The position of the tile may be best represented by a figure, also the mode of constructing stone drains.

[Why are small stones better than large stones in the construction of drains?

On what must the depth of under-drains depend?]

It will be seen that the tile drain is made with much less labor than the stone drain, as it requires less digging, while the breaking up of the stone for the stone drain will be nearly, or quite as expensive as the tiles. Drains made with large stones are not nearly so good as with small ones, because they are more liable to be choked up by animals working in them.[AK]



[Describe the principle which regulates these relative depths and distances. (Blackboard.)

Which is usually the cheaper plan of constructing drains?]

The depth of the drains must depend on the distances at which they are placed. If but twenty feet apart, they need be but three feet deep; while, if they are eighty feet apart, they must be five feet deep, to produce the same effect. The reason for this is, that the water in the drained soil is not level, but is higher midway between the drains, than at any other point. It is necessary that this highest point should be sufficiently far from the surface not to interfere with the roots of plants, consequently, as the water line between two drains is curved, the most distant drains must be the deepest. This will be understood by referring to the following diagram.



The curved line represents the position of the water.

In most soils it will be easier to dig one trench five feet deep, than four trenches three feet deep, and the deep trenches will be equally beneficial; but where the soil is very hard below a depth of three feet, the shallow trenches will be the cheapest, and in such soils they will often be better, as the hard mass might not allow the water to pass down to enter the deeper drains.

By following out these instructions, land may be cheaply, thoroughly, and permanently drained.

FOOTNOTES:

[AK] It is probable that a composition of hydraulic cement and some soluble material will be invented, by which a continuous pipe may be laid in the bottoms of trenches, becoming porous as the soluble material is removed by water.



CHAPTER III.

ADVANTAGES OF UNDER-DRAINING.

The advantages of under-draining are many and important.

1. It entirely prevents drought.

2. It furnishes an increased supply of atmospheric fertilizers.

3. It warms the lower portions of the soil.

4. It hastens the decomposition of roots and other organic matter.

5. It accelerates the disintegration of the mineral matters in the soil.

6. It causes a more even distribution of nutritious matters among those parts of soil traversed by roots.

7. It improves the mechanical texture of the soil.

8. It causes the poisonous excrementitious matter of plants to be carried out of the reach of their roots.

9. It prevents grasses from running out.

10. It enables us to deepen the surface soil.

By removing excess of water—

11. It renders soils earlier in the spring.

12. It prevents the throwing out of grain in winter.

13. It allows us to work sooner after rains.

14. It keeps off the effects of cold weather longer in the fall.

15. It prevents the formation of acetic and other organic acids, which induce the growth of sorrel and similar weeds.

16. It hastens the decay of vegetable matter, and the finer comminution of the earthy parts of the soil.

17. It prevents, in a great measure, the evaporation of water, and the consequent abstraction of heat from the soil.

18. It admits fresh quantities of water from rains, etc., which are always more or less imbued with the fertilizing gases of the atmosphere, to be deposited among the absorbent parts of soil, and given up to the necessities of plants.

19. It prevents the formation of so hard a crust on the surface of the soil as is customary on heavy lands.

* * * * *

[How does under-draining prevent drought?]

1. Under-draining prevents drought, because it gives a better circulation of air in the soil; (it does so by making it more open). There is always the same amount of water in and about the surface of the earth. In winter, there is more in the soil than in summer, while in summer, that which has been dried out of the soil exists in the atmosphere in the form of a vapor. It is held in the vapory form by heat, which acts as braces to keep it distended. When vapor comes in contact with substances sufficiently colder than itself, it gives up its heat—thus losing its braces—contracts, and becomes liquid water.

This may be observed in hundreds of common operations.

[Why is there less water in the soil in summer than in winter, and where does it exist?

What holds it in its vapory form?

How is it affected by cold substances?

Describe the deposit of moisture on the outside of a pitcher in summer.

What other instances of the same action can be named?]

It is well known that a cold pitcher in summer robs the vapor in the atmosphere of its heat, and causes it to be deposited on its own surface. It looks as though the pitcher were sweating, but the water all comes from the atmosphere, not, of course, through the sides of the pitcher.

If we breathe on a knife-blade, it condenses in the same manner the moisture of the breath, and becomes covered with a film of water.

Stone houses are damp in summer, because the inner surfaces of the walls, being cooler than the atmosphere, cause its moisture to be deposited in the manner described. By leaving a space, however, between the walls and the plaster, this moisture is prevented from being troublesome.

[How does this principle affect the soil?

Explain the experiment with the two boxes of soil.]

Nearly every night in the summer season, the cold earth receives moisture from the atmosphere in the form of dew.

A cabbage, which at night is very cold, condenses water to the amount of a gill or more.

The same operation takes place in the soil. When the air is allowed to circulate among its lower and cooler particles, they receive moisture from the same process of condensation. Therefore, when, by the aid of under-drains, the lower soil becomes sufficiently open to admit of a circulation of air, the deposit of atmospheric moisture will keep the soil supplied with water at a point easily accessible to the roots of plants.

If we wish to satisfy ourselves that this is practically correct, we have only to prepare two boxes of finely pulverized soil, one, five or six inches deep, and the other fifteen or twenty inches deep, and place them in the sun at mid-day in summer. The thinner soil will be completely dried, while the deeper one, though it may have been perfectly dry at first, will soon accumulate a large amount of water on those particles which, being lower and more sheltered from the sun's heat than the particles of the thin soil, are made cooler.

With an open condition of subsoil, then, such as may be secured by under-draining, we entirely overcome drought.

[How does under-draining supply to the soil an increased amount of atmospheric fertilizers?

How does it warm the lower parts of the soil?]

2. Under-draining furnishes an increased supply of atmospheric fertilizers, because it secures a change of air in the soil. This change is produced whenever the soil becomes filled with water, and then dried; when the air above the earth is in rapid motion, and when the comparative temperature of the upper and lower soils changes. It causes new quantities of the ammonia and carbonic acid which it contains to be presented to the absorbent parts of the soil.

3. Under-draining warms the lower parts of the soil, because the deposit of moisture (1) is necessarily accompanied by an abstraction of heat from the atmospheric vapor, and because heat is withdrawn from the whole amount of air circulating through the cooler soil.

When rain falls on the parched surface soil, it robs it of a portion of its heat, which is carried down to equalize the temperature for the whole depth. The heat of the rain-water itself is given up to the soil, leaving the water from one to ten degrees cooler, when it passes out of the drains, than when received by the earth.

There is always a current of air passing from the lower to the upper end of a well constructed drain; and this air is always cooler in warm weather, when it issues from, than when it enters the drain. Its lost heat is imparted to the soil.

[How does it hasten the decomposition of roots and other organic matter in the soil?

How does it accelerate the disintegration of its mineral parts?

Why is this disintegration necessary to fertility?]

This heating of the lower soil renders it more favorable to vegetation, partially by expanding the spongioles at the end of the roots, thus enabling them to absorb larger quantities of nutritious matters.

4. Under-draining hastens the decomposition of roots and other organic matters in the soil, by admitting increased quantities of air, thus supplying oxygen, which is as essential in decay as it is in combustion. It also allows the resultant gases of decomposition to pass away, leaving the air around the decaying substances in a condition to continue the process.

This organic decay, besides its other benefits, produces an amount of heat perfectly perceptible to the smaller roots of plants, though not so to us.

5. Draining accelerates the disintegration of the mineral matters in the soil, by admitting water and oxygen to keep up the process. This disintegration is necessary to fertility, because the roots of plants can feed only on matters dissolved from surfaces; and the more finely we pulverize the soil, the more surface we expose. For instance, the interior of a stone can furnish no food for plants; while, if it were finely crushed, it might make a fertile soil.

Any thing, tending to open the soil to exposure, facilitates the disintegration of its particles, and thereby increases its fertility.

[How does under-draining equalize the distribution of the fertilizing parts of the soil?

Why does this distribution lessen the impoverishment of the soil?

How does under-draining improve the mechanical texture of the soil?

How do drains affect the excrementitious matter of plants?]

6. Draining causes a more even distribution of nutritious matters among those parts of soil traversed by roots, because it increases the ease with which water travels around, descending by its own weight, moving sideways by a desire to find its level, or carried upward by attraction to supply the evaporation at the surface. By this continued motion of the water, soluble matter of one part of the soil may be carried to some other part; and another constituent from this latter position may be carried back to the former. Thus the food of vegetables is continually circulating around among their roots, ready for absorption at any point where it is needed, while the more open character of the soil enables roots to occupy larger portions, making a more even drain on the whole, and preventing the undue impoverishment of any part.

7. Under-drains improve the mechanical texture of the soil; because, by the decomposition of its parts, as previously described (4 and 5), it is rendered of a character to be more easily worked; while smooth round particles, which have a tendency to pack, are roughened by the oxidation of their surfaces, and move less easily among each other.

8. Drains cause the excrementitious matter of plants to be carried out of the reach of their roots. Nearly all plants return to the soil those parts of their food, which are not adapted to their necessities, and usually in a form that is poisonous to plants of the same kind. In an open soil, this matter may be carried by rains to a point where roots cannot reach it, and where it may undergo such changes as will fit it to be again taken up.

[Why do they prevent grasses from running out?]

9. By under-draining, grasses are prevented from running out, partly by preventing the accumulation of the poisonous excrementitious matter, and partly because these grasses usually consist of tillering plants.

These plants continually reproduce themselves in sprouts from the upper parts of their roots. These sprouts become independent plants, and continue to tiller (thus keeping the land supplied with a full growth), until the roots of the stools (or clumps of tillers), come in contact with an uncongenial part of the soil, when the tillering ceases; the stools become extinct on the death of their plants, and the grasses run out.

The open and healthy condition of soil produced by draining prevents the tillering from being stopped, and thus keeps up a full growth of grass until the nutriment of the soil is exhausted.

10. Draining enables us to deepen the surface-soil, because the admission of air and the decay of roots render the condition of the subsoil such that it may be brought up and mixed with the surface-soil, without injuring its quality.

The second class of advantages of under-draining, arising in the removal of the excess of water in the soil, are quite as important as those just described.

[How does the removal of water render soils earlier in spring?

Why does it prevent the throwing out of grain in winter?

Why does it enable us to work sooner after rains?

Why does it keep off the effects of cold weather longer in the fall?]

11. Soils are, thereby, rendered earlier in spring, because the water, which rendered them cold, heavy, and untillable, is earlier removed, leaving them earlier in a growing condition.

12. The throwing out of grain in winter is prevented, because the water falling on the earth is immediately removed instead of remaining to throw up the soil by freezing, as it always does from the upright position taken by the particles of ice.

13. We are enabled to work sooner after rains, because the water descends, and is immediately removed instead of lying to be taken off by the slow process of evaporation, and sinking through a heavy soil.

14. The effects of cold weather are kept off longer in the fall, because the excess of water is removed, which would produce an unfertile condition on the first appearance of cold weather.

The drains also, from causes already named (3), keep the soil warmer than before being drained, thus actually lengthening the season, by making the soil warm enough for vegetable growth earlier in spring, and later in autumn.

[How does it prevent lands from becoming sour?

Why does it hasten the decay of roots, and the comminution of mineral matters?

How does it prevent the abstraction of heat from the soil?]

15. Lands are prevented from becoming sour by the formation of acetic acid, etc., because these acids are produced in the soil only when the decomposition of organic matter is arrested by the antiseptic (preserving) powers of water. If the water is removed, the decomposition of the organic matter assumes a healthy form, while the acids already produced are neutralized by atmospheric influences, and the soil is restored from sorrel to a condition in which it is fitted for the growth of more valuable plants.

16. The decay of roots, etc., is allowed to proceed, because the preservative influence of too much water is removed. Wood, leaves, or other vegetable matter kept continually under water, will last for ages; while, if exposed to the action of the weather, as in under-drained soils, they soon decay.

The presence of too much water, by excluding the oxygen of the air, prevents the comminution of matters necessary to fertility.

[How much heat does water take up in becoming vapor?

Why does water sprinkled on a floor render it cooler?

Why is not a cubic inch of vapor warmer than a cubic inch of water?

Why does a wet cloth on the head make it cooler when fanned?

How does this principle apply to the soil?]

17. The evaporation of water, and the consequent abstraction of heat from the soil, is in a great measure prevented by draining the water out at the bottom of the soil, instead of leaving it to be dried off from the surface.

When water assumes the gaseous (or vapory) form, it takes up 1723 times as much heat as it contained while a liquid. A large part of this heat is derived from surrounding substances. When water is sprinkled on the floor, it cools the room; because, as it becomes a vapor, it takes heat from the room. The reason why vapor does not feel hotter than liquid water is, that, while it contains 1723 times as much heat, it is 1723 as large. Hence, a cubic inch of vapor, into which we place the bulb of a thermometer, contains no more heat than a cubic inch of water. The principle is the same in some other cases. A sponge containing a table-spoonful of water is just as wet as one twice as large and containing two spoonsful.

If a wet cloth be placed on the head, and the evaporation of its water assisted by fanning, the head becomes cooler—a portion of its heat being taken to sustain the vapory condition of the water.

The same principle holds true with the soil. When the evaporation of water is rapidly going on, by the assistance of the sun, wind, etc., a large quantity of heat is abstracted, and the soil becomes cold.

When there is no evaporation taking place, except of water which has been deposited on the lower portions of soil, and carried to the surface by capillary attraction (as is nearly true on under-drained soils), the loss of heat is compensated by that taken from the moisture in the atmosphere by the soil, in the above-named manner.

This cooling of the soil by the evaporation of water, is of very great injury to its powers of producing crops, and the fact that under-drains avoid it, is one of the best arguments in favor of their use. Some idea may, perhaps, be formed of the amount of heat taken from the soil in this way, from the fact that, in midsummer, 25 hogsheads of water may be evaporated from a single acre in twelve hours.

[When rains are allowed to enter the soil, how do they benefit it?

How do under-drains prevent the formation of a crust on the surface of a soil?]

18. When not saturated with water the soil admits the water of rains, etc., which bring with them fertilizing gases from the atmosphere, to be deposited among the absorbent parts of soil, and given up to the necessities of the plant. When this rain falls on lands already saturated, it cannot enter the soil, but must run off from the surface, or be removed by evaporation, either of which is injurious. The first, because fertilizing matter is washed away. The second, because the soil is deprived of necessary heat.

19. The formation of crust on the surface of the soil is due to the evaporation of water, which is drawn up from below by capillary attraction. It arises from the fact that the water in the soil is saturated with mineral substances, which it leaves at its point of evaporation at the surface. This soluble matter from below, often forms a very hard crust, which is a complete shield to prevent the admission of air with its ameliorating effects, and should, as far as possible, be avoided. Under-draining is the best means of doing this, as it is the best means of lessening the evaporation.

The foregoing are some of the more important reasons why under-draining is always beneficial. Thorough experiments have amply proved the truth of the theory.

[What kinds of soil are benefited by under-draining?]

The kinds of soil benefited by under-draining are nearly as unlimited as the kinds of soil in existence. It is a common opinion, among farmers, that the only soils which require draining are those which are at times covered with water, such as swamps and other low lands; but the facts stated in the early part of this chapter, show us that every kind of soil—wet, dry, compact, or light—receives benefit from the treatment. The fact that land is too dry, is as much a reason why it should be drained, as that it is too wet, as it overcomes drought as effectually as it removes the injurious effects of too much water.

All soils in which the water of heavy rains does not immediately pass down to a depth of at least thirty inches, should be under-drained, and the operation, if carried on with judgment, would invariably result in profit.