The Story of the Soil Part 13

"Marry rich," he replied. "Don't make such a blunder as your sister did."

"I fear that Mr. Johnston will suggest that we sell some more land,"

remarked Mrs. Thornton.

"All right," replied her sister; "and we will sell it to him. If he won't take the whole farm as a gift, we'll cut it to any length he wishes. Do you consider 'Ten Acres Enough,' Mr. Johnston; or would you prefer 'Three Acres and Liberty?' We'll do our best to enable you to enjoy 'The Fat of the Land.' Just tell us how large a farm you want, I know already that you do not want nine hundred acres."

"My dear Miss Russell," said Percy. "This is so sudden"; whereupon Mr. Thornton nearly fell from his chair and Mrs. Thornton laughed heartily at the sister's expense who blushed as she might have done twenty years before.

"However," Percy resumed, "if you should decide to dispose of about half of that seven hundred acres which you use only as a safety bank for most of your two hundred dollars in taxes, please consider me a prospective taker."

"Take her," said Mr. Thornton, and again confusion reigned.

"Tom is so anxious to get rid of his sister-in-law that he reminds me of the man whose mother-in-law died," said Miss Russell. "He was too far from home to return to the usual funeral, and they telegraphed him the sad news and asked if they should embalm, cremate, or bury the remains. He wired back: 'Embalm, cremate, and bury'"

"That matter of outside capital is by no means so substantial as it might seem," said Percy. "It is worth while to consider how little real wealth there would be in America if the remaining rich lands should become impoverished. The railroads would at once cease to pay dividends, and those who are now millionaires in railroad stock would find themselves on the rapid road to poverty. The manufacturer of finished products from the raw materials raised on the farm, the manufacturer of agricultural implements, and the great urban population whose income is from the trade in raw materials and manufactured goods would soon see their wealth shrivel. The great sky sc.r.a.pers of the cities would be left for the owls and bats to harbor in, if our agricultural lands ceased to yield their great harvests. Meanwhile the farming people would continue to live upon the meager products still produced from the impoverished soil, even though they had no surplus food to s.h.i.+p into the cities. Human labor would replace that of domestic animals on the farm, just as it has done in China and India, in part because man's labor is worth more than that of the beast, when measured only by the amount of food consumed, and in part because a thousand bushels of grain will support five times as many people can be supported for the same time upon the animal products that could be produced by feeding the grain."

"Oh, that is such a gloomy view to take of it," said Miss Russell.

"And all the world loves an optimist," replied Percy laughingly.

"Soils do not wear out; there is no poor land; the farms are better and the crops larger than ever before; and we are the people of the world's greatest nation, with an a.s.sured future glory which surposses all conception."

"As soon as we get the ca.n.a.l dug," suggested Mr. Thornton.

"Yes, we will surely be able to dig that Panama ditch," said Percy; "and probably our resources will last to cut a gash or two in our own interior, if we don't build too many battle s.h.i.+ps. You know Egypt built three great pyramids before her resources became reduced to such an extent that the people required all their energies to secure a living."

CHAPTER XVII

MORE PROBLEMS

"NOW let us give Mr. Johnston a chance to tell us about the nitrogen problem," said Mr. Thornton. "I'm pretty well satisfied with the natural circulation of carbon, oxygen, and hydrogen; but I want to understand all I can of the practical methods of securing and utilizing nitrogen; and we have heard almost nothing about the other six essential elements which the soil must furnish. Let me see.--I think you said that iron, calcium, magnesium and pota.s.sium are usually abundant in the soil, while phosphorus and sulfur are very limited."

"Yes, that is the rule under general or average conditions, but it should be stated that the amount of sulfur required by plants is very small as compared with phosphorus, a difference which places a great distinction between them. Besides considerable quant.i.ties of sulfur are returned to the air in the combustion of coal and organic matter, and this returns to the soil in rain. The information thus far secured shows that sulfur rarely if ever limits the crop yields under field conditions; and the same may be said of iron, which is required by plants in very small amount and is contained in practically all soils in enormous quant.i.ties.

"While normal soils contain abundance of pota.s.sium, with about half as much calcium and one-fourth as much magnesium; yet, when measured by crop requirements for plant food, the supplies of these three elements are not markedly different. On the other hand, about 300 pounds of calcium are lost per acre per annum by leaching from good soils in humid climates, compared with about 10 pounds of pota.s.ssium and intermediate amounts of magnesium; so that, of these three elements, calcium requires by far the most consideration and pota.s.sium the least, even aside from the use of limestone to correct or prevent soil acidity.

"Among the conditions essential for nitrification may be mentioned the presence of free oxygen and limestone; and of course all bacteria require certain food materials, resembling other plants in this respect."

"Are they plants?" asked Mrs. Thornton. "I thought they were tiny little animals."

"No, they are cla.s.sified as plants," replied Percy; "but the scientists have difficulty with some of the lower organism to decide whether they are plants or animals. The college boys used to say that some animals were plants in the botanical department and animals again when they studied zoology. Orton says it is easy to tell a cow from a cabbage, but impossible to a.s.sign any absolute, distinctive character which will divide animal life from plant life.

"The oxygen is essential for nitrification, because that is an oxidation process. That is, it is a kind of combustion, so to speak.

The organic matter is oxidized or converted into substances containing more oxygen than in the original form. In ammonification the carbon is separated or divorced from the nitrogen and united with oxygen. Some of the hydrogen of the organic matter remains temporarily with the carbon, and some is held temporarily with the nitrogen in the form of ammonia.

"The nitrite bacteria replace two of the hydrogen atoms in ammonia with one of oxygen, and insert another oxygen atom between the nitrogen and the remaining hydrogen, thus forming nitrous acid; H-O-N=O, or HNO2.

"The nitrate bacteria then cause the direct addition of another oxygen atom, which is held by the two extra bonds of the nitrogen atom, which you will remember is a five-handed atom.

"Thus you will see the absolute need of free oxygen in the nitrification process; and we can control the rate of nitrification to a considerable extent by our methods of tillage. In soils deficient in organic matter, excessive cultivation may still liberate sufficient nitrogen for a fairly satisfactory crop; and the benefits of such excessive cultivation for potatoes and other vegetables is more often due to increased nitrification than to the conservation of moisture, to which it is frequently ascribed by agricultural writers.

"Thus the more we cultivate, the more we hasten the nitrification, oxidation, or destruction of the organic matter or humus of the soil. Where the soil is well supplied with decaying organic matter, we rarely need to cultivate in a humid section like this, except for the purpose of killing weeds.

"The presence of carbonates in the soil is essential for nitrification, because the bacteria will not continue the process in the presence of their own product. Nitrification ceases if the nitrous or nitric acid remains as such; but, in the presence of carbonates such as calcium carbonate (ordinary limestone) or the double carbonate of magnesium and calcium (magnesian limestone, or dolomite), the nitrous acid or nitric acid is converted into a neutral salt of calcium or magnesium, one of these atoms taking the place of two hydrogen atoms and forming, say, calcium nitrate: Ca(NO3)2. At the same time the hydrogen atoms take the place of the calcium in limestone ( CaC03), and form carbonic acid (H2CO3), which at once decomposes into water (H2O) and carbon dioxid (CO2), which thus escapes as a gas into the air or remains in the pores of the soil.

"The fact that nitrification will not proceed in the presence of acid reminds us that only a certain degree of acidity can be developed in sour milk. Here the lactic acid bacteria produce the acid from milk sugar, but the process stops when about seven-tenths of one per cent. of lactic acid has developed. If some basic substance, such as lime, is then added, the acid is neutralized and the fermentation again proceeds.

"In the general process of decay and oxidation of the organic matter of the soil, the nitrogen thus pa.s.ses through the forms of ammonia, nitrous acid, and nitric acid, and at the same time the carbon pa.s.ses into various acid compounds, including the complex humic and ulmic acids, and smaller amounts of acetic acid (found in vinegar), lactic acid, oxalic acid (found in oxalic), and tartaric acid (found in grapes). The final oxidation products of the carbon and hydrogen are carbon dioxid and water, which result from the decomposition of the carbonic acid.

"Now the various acids of carbon and nitrogen const.i.tute one of the most important factors in soil fertility. They are the means by which the farmer can dissolve and make available for the growing crops the otherwise insoluble mineral elements, such as iron, calcium, magnesium, and pota.s.sium, all of which are contained in most soils in great abundance. These elements exist in the soil chiefly in the form of insoluble silicates. Silicon itself is a four-handed element which bears somewhat the same relation to the mineral matter of the soil as carbon bears to the organic matter.

Quartz sand is silicon dioxid (SiO2). Oxygen, which is present in nearly all substances, including air, water, and most solids, const.i.tutes about one-half of all known matter. Silicon is next in abundance, amounting to more than one-fourth of the solid crust of the earth. Aluminum is third in abundance (about seven per cent), aluminum silicate being common clay. Iron, calcium, pota.s.sium, sodium, and magnesium, in this order, complete the eight abundant elements, which aggregate about ninety-eight per cent. of the solid crust of the earth.

"It is worth while to know that about two and one-half per cent. of the earth's crust is pota.s.sium, while about one-tenth of one per cent. is phosphorus; also that when a hundred bushels of corn are sold from the farm, seventeen pounds of phosphorus, nineteen of pota.s.sium, and seven of magnesium are carried away.

"The acids formed from the decaying organic matter not only liberate for the use of crops the mineral elements contained in the soil in abundance, but they also help to make available the phosphorus of raw phosphate, when naturally contained in the soil, as it is to some extent in all soils, or when applied to the soil in the fine-ground natural phosphate from the mines.

"Now the increase or decrease of organic matter in the soil is measured with a very good degree of satisfaction by the element nitrogen, which is a regular const.i.tuent of the organic matter of the soil; and you are already familiar, Mr. Thornton, with the amounts of nitrogen contained in average farm manure and in some of our most common crops."

"Yes, Sir, I have some of the figures in my note book and I mean to have them in my head very soon. But, say, that organic matter seems to be a thing of tremendous importance, and I'm sure we've got mighty little of it. I think about the only thing we'll need to do to make this old farm productive again is to grow the vegetation and plow it under. As it decays, it will furnish the nitrogen, and liberate the phosphorus, pota.s.sium, calcium, and magnesium; and we may have plenty of all of them just waiting to be liberated."

"That is altogether possible," said Percy; "but it must be remembered that your soil is acid and consequently will not grow clover or alfalfa successfully, or even cowpeas very satisfactorily.

A liberal use of ground limestone and large use of clover may be sufficient to greatly improve your soil; but if I am permitted to separate Miss Russell and the Thorntons "--Mr. Thornton's hilarious "Ha, ha" cut Percy short. He crimsoned and the ladies smiled at each other with expressions that revealed nothing whatever.

"Now let me finish," Percy continued, when Mr. Thornton had somewhat subsided. "I say, if I am permitted to separate Miss Russell and the Thorntons from about three hundred acres of their land, I shall certainly wish to know its total content of phosphorus, pota.s.sium, magnesium, and calcium, before I make any purchase; and, if you will remember the pot cultures and the peaty swamp land, I think you'd agree with me.

"Well, I shall be mighty glad to know that myself," said Mr.

Thornton, "and we shall much appreciate it if you can tell us how to secure that information."

"We can collect some soil to-morrow," Percy replied, "and send it to a chemist for a.n.a.lysis."

"Good," said Mr. Thornton; "now just one more question, and I think I shall sleep better if I have it answered to-night. Just what is meant by potash and phosphoric acid?"

"Potash," said Percy, "is a compound of pota.s.sium and oxygen. The proportions are one atom of oxygen and two atoms of pota.s.sium, which you may remember are single-handed and weigh thirty-nine, so that seventy-eight of pota.s.sium unite with sixteen of oxygen. A better name for the compound is pota.s.sium oxid: K20. The Latin name for pota.s.sium is kalium, and K is the symbol used for an atom of that element. If you were to purchase pota.s.sium in the form of pota.s.sium chlorid, which in the East is often called by the old incorrect name 'muriate of potash,' the salt might be guaranteed to contain a certain percentage of potash, which, however, consists of eighty-three per cent. of pota.s.sium and seventeen of oxygen."

"Just what is this pota.s.sium chlorid, or 'muriate of potash'?"

"Pure pota.s.sium chlorid contains only the two elements, pota.s.sium and chlorin."

"But didn't you say that it was guaranteed to contain potash and that potash is part oxygen? Now you say it contains only pota.s.sium and chlorin."