Talks on Manures Part 3

CHAPTER III.

SOMETHING ABOUT PLANT-FOOD.

"The Doctor is in the main correct," said I; "but he does not fully answer the question, 'What is manure?' To say that manure is plant-food, does not cover the whole ground. All soils on which plants grow, contain more or less plant-food. A plant can not create an atom of potash. It can not get it from the atmosphere. We find potash in the plant, and we know that it got it from the soil and we are certain, therefore, that the soil contains potash. And so of all the other mineral elements of plants. A soil that will produce a thistle, or a pig-weed, contains plant-food. And so the definition of the Doctor is defective, inasmuch as it makes no distinction between soil and manure. Both contain plant-food."

"What is your definition of manure?" asked Charley; "it would seem as though we all knew what manure was. We have got a great heap of it in the yard, and it is fermenting nicely."

"Yes," I replied, "we are making more manure on the farm this winter than ever before. Two hundred pigs, 120 large sheep, 8 horses, 11 cows, and a hundred head of poultry make considerable manure; and it is a good deal of work to clean out the pens, pile the manure, draw it to the field, and apply it to the crops. We ought to know something about it; but we might work among manure all our lives, and not know what manure is. At any rate, we might not be able to define it accurately. I will, however, try my hand at a definition.

"Let us a.s.sume that we have a field that is free from stagnant water at all seasons of the year; that the soil is clean, mellow, and well worked seven inches deep, and in good order for putting in a crop. What the coming '_season_' will be we know not. It may be what we call a hot, dry summer, or it may be cool and moist, or it may be partly one and partly the other. The 'season' is a great element of uncertainty in all our farming calculations; but we know that we shall have a season of some kind. We have the promise of seed-time and harvest, and we have never known the promise to fail us. Crops, however, vary very much, according to the season; and it is necessary to bear this fact in mind. Let us say that the sun and heat, and rain and dews, or what we call 'the season,'

is capable of producing 50 bushels of wheat per acre, but that the soil I have described above, does not produce over 20 bushels per acre. There is no mechanical defect in the soil. The seed is good, it is put in properly, and at the right time, and in the best manner. No weeds choke the wheat plants or rob them of their food; but that field does not produce as much wheat by 30 bushels per acre as the _season_ is capable of producing. Why? The answer is evident. _Because the wheat plants do not find food enough in the soil._ Now, anything that will furnish this food, anything that will cause that field to produce what the climate or season is capable of producing, is manure. A gardener may increase his crops by artificial heat, or by an increased supply of water, but this is not manure. The effect is due to improved climatic conditions. It has nothing to do with the question of manure. We often read in the agricultural papers about '_shade_ as manure.' We might just as well talk about _sunlight_ as 'manure.' The effects observed should be referred to modifications of the climate or season; and so in regard to mulching. A good mulch may often produce a larger increase of growth than an application of manure. But mulch, proper, is not manure. It is climate. It checks evaporation of moisture from the soil. We might as well speak of rain as manure as to call a mulch manure. In fact, an ordinary shower in summer is little more than a mulch. It does not reach the roots of plants; and yet we see the effect of the shower immediately in the increased vigor of the plants. They are full of sap, and the drooping leaves look refreshed. We say the rain has revived them, and so it has; but probably not a particle of the rain has entered into the circulation of the plant. The rain checked evaporation from the soil and from the leaves. A cool night refreshes the plants, and fills the leaves with sap, precisely in the same way. All these fertilizing effects, however, belong to climate. It is inaccurate to a.s.sociate either mulching, suns.h.i.+ne, shade, heat, dews, or rain, with the question of manure, though the effect may in certain circ.u.mstances be precisely the same."

Charley evidently thought I was wandering from the point. "You think, then," said he, "manure is _plant-food that the soil needs?_"

"Yes," said I, "that is a very good definition--very good, indeed, though not absolutely accurate, because manure is manure, whether a particular soil needs it or not." Un.o.bserved by us, the Deacon and the Doctor had been listening to our talk. --"I would like," said the Deacon, "to hear you give a better definition than Charley has given."

--"Manure," said I, "is anything containing an element or elements of plant-food, which, if the soil needed it, would, if supplied in sufficient quant.i.ty, and in an available condition, produce, according to soil, season, climate, and variety, a maximum crop."

CHAPTER IV.

NATURAL MANURE.

We often hear about "natural" manure. I do not like the term, though I believe it originated with me. It is not accurate; not definite enough.

"I do not know what you mean by natural manure," said the Deacon, "unless it is the droppings of animals." --"To distinguish them, I suppose," said the Doctor, "from artificial manures, such as superphosphate, sulphate of ammonia, and nitrate of soda." --"No; that is not how I used the term. A few years ago, we used to hear much in regard to the 'exhaustion of soils.' I thought this phrase conveyed a wrong idea. When new land produces large crops, and when, after a few years, the crops get less and less, we were told that the farmers were exhausting their land. I said, no; the farmers are not exhausting the _soil_; they are merely exhausting the acc.u.mulated plant-food in the soil. In other words, they are using up the _natural manure_.

"Take my own farm. Fifty years ago, it was covered with a heavy growth of maple, beech, black walnut, oak, and other trees. These trees had shed annual crops of leaves for centuries. The leaves rot on the ground; the trees also, age after age. These leaves and other organic matter form what I have called natural manure. When the land is cleared up and plowed, this natural manure decays more rapidly than when the land lies undisturbed; precisely as a manure-pile will ferment and decay more rapidly if turned occasionally, and exposed to the air. The plowing and cultivating renders this natural manure more readily available. The leaves decompose, and furnish food for the growing crop."

EXHAUSTION OF THE SOIL.

"You think, then," said the Doctor, "that when a piece of land is cleared of the forest, harrowed, and sown to wheat; plowed and planted to corn, and the process repeated again and again, until the land no longer yields profitable crops, that it is the 'natural manure,' and not the soil, that is exhausted?"

"I think the _soil_, at any rate, is not exhausted, and I can easily conceive of a case where even the natural manure is very far from being all used up."

"Why, then," asked the Deacon, "is the land so poor that it will scarcely support a sheep to the acre?"

"Simply because the natural manure and other plant-food which the soil contains is not in an available condition. It lies dead and inert. It is not soluble, and the roots of the plants cannot get enough of it to enable them to thrive; and in addition to this, you will find as a matter of fact that these poor 'exhausted' farms are infested with weeds, which rob the growing crops of a large part of the scanty supply of available plant-food."

"But these weeds," said the Deacon, "are not removed from the farm. They rot on the land; nothing is lost."

"True," said I, "but they, nevertheless, rob the growing crops of available plant-food. The annual supply of plant-food, instead of being used to grow useful plants, is used to grow weeds."

"I understand that," said the Deacon, "but if the weeds are left on the land, and the useful plants are sold, the farmer who keeps his land clean would exhaust his land faster than the careless farmer who lets his land lie until it is overrun with thistles, briars, and pig-weed.

You agricultural writers, who are constantly urging us to farm better and grow larger crops, seem to overlook this point. As you know, I do not take much stock in chemical theories as applied to agriculture, but as you do, here is a little extract I cut from an agricultural paper, that seems to prove that the better you work your land, and the larger crops you raise, the sooner you exhaust your land."

The Deacon put on his spectacles, drew his chair nearer the lamp on the table, and read the following:

"There is, on an average, about one-fourth of a pound of potash to every one hundred pounds of soil, and about one-eighth of a pound of phosphoric acid, and one-sixteenth of a pound of sulphuric acid. If the potatoes and the tops are continually removed from the soil, it will soon exhaust the potash. If the wheat and straw are removed, it will soon exhaust the phosphate of lime; if corn and the stalks, it will soon exhaust the sulphuric acid. Unless there is a rotation, or the material the plant requires is supplied from abroad, your crops will soon run out, though the soil will continue rich for other plants."

"That extract," said I, "carries one back twenty-five years. We used to have article after article in this strain. We were told that 'always taking meal out of the tub soon comes to the bottom,' and always taking potash and phosphoric acid from the soil will soon exhaust the supply.

But, _practically_, there is really little danger of our exhausting the land. It does not pay. The farmer's resources will be exhausted long before he can exhaust his farm."

"a.s.suming," said the Doctor, who is fond of an argument, "that the above statement is true, let us look at the facts. An acre of soil, 12 inches deep, would weigh about 1,600 tons; and if, as the writer quoted by the Deacon states, the soil contains 4 ozs. of potash in every 100 lbs. of soil, it follows that an acre of soil, 12 inches deep, contains 8,000 lbs. of potash. Now, potatoes contain about 20 per cent of dry matter, and this dry matter contains say, 4 per cent of ash, half of which is potash. It follows, therefore, that 250 bushels of potatoes contain about 60 lbs. of potash. If we reckon that the tops contain 20 lbs.

more, or 80 lbs. in all, it follows that the acre of soil contains potash enough to grow an _annual_ crop of 250 bushels of potatoes per acre for one hundred years."

"I know farmers," said Charley, "who do not get over 50 bushels of potatoes per acre, and in that case the potash would last five hundred years, as the weeds grown with the crop are left on the land, and do not, according to the Deacon, exhaust the soil."

"Good for you, Charley," said the Doctor. "Now let us see about the phosphoric acid, of which the soil, according to the above statement, contains only half as much as it contains of potash, or 4,000 lbs. per acre.

"A crop of wheat of 30 bushels per acre," continued the Doctor, "contains in the grain about 26 lbs. of ash, and we will say that half of this ash is phosphoric acid, or 13 lbs. Allowing that the straw, chaff, etc., contain 7 lbs. more, we remove from the soil in a crop of wheat of 30 bushels per acre, 20 lbs. of phosphoric acid, and so, according to the above estimate, an acre of soil contains phosphoric acid to produce annually a crop of wheat and straw of 30 bushels per acre for _two hundred years_.

"The writer of the paragraph quoted by the Deacon," continued the Doctor, "selected the crops and elements best suited to his purpose, and yet, according to his own estimate, there is sufficient potash and phosphoric acid in the first 12 inches of the soil to enable us to raise unusually large crops until the next Centennial in 1976.

"But let us take another view of the subject," continued the Doctor. "No intelligent farmer removes all the potatoes _and tops_, all the wheat, straw, and chaff, or all the corn and stalks from his farm. According to Dr. Salisbury, a crop of corn of 75 bushels per acre removes from the soil 600 lbs. of ash, but the _grain_ contains only 46 lbs. The other 554 lbs. is contained in the stalks, etc., all of which are usually retained on the farm. It follows from this, that when only the grain is sold off the farm, it takes more than thirteen crops to remove as much mineral matter from the soil as is contained in the whole of one crop.

Again, the ash of the grain contains less than 3 per cent of sulphuric acid, so that the 46 lbs. of ash, in 75 bushels of corn, contains less than 1 lbs. of sulphuric acid, and thus, if an acre of soil contains 2,000 lbs. of sulphuric acid, we have sufficient for an annual crop of 75 bushels per acre for fifteen hundred years!

"As I said before," continued the Doctor, "intelligent farmers seldom sell their straw, and they frequently purchase and consume on the farm nearly as much bran, shorts, etc., as is sent to market with the grain they sell. In the 'Natural History of New York,' it is stated that an acre of wheat in Western New York, of 30 bushels per acre, including straw, chaff, etc., removes from the soil 144 lbs. of mineral matter.

Genesee wheat usually yields about 80 per cent. of flour. This flour contains only 0.7 per cent of mineral matter, while fine middlings contain 4 per cent; coa.r.s.e middlings, 5 per cent; shorts, 8 per cent, and bran 8 per cent of mineral matter or ash. It follows from this, that out of the 144 lbs. of mineral matter in the crop of wheat, less than 10 lbs. is contained in the flour. The remaining 134 lbs. is found in the straw, chaff, bran, shorts, etc., which a good farmer is almost sure to feed out on his farm. But even if the farmer feeds out none of his wheat-bran, but sells it all with his wheat, the 30 bushels of wheat remove from the soil only 26 lbs. of mineral matter; and it would take more than five crops to remove as much mineral matter as one crop of wheat and straw contains. Allowing that half the ash of wheat is phosphoric acid, 30 bushels remove only 13 lbs. from the soil, and if the soil contains 4,000 lbs., it will take three hundred and seven crops, of 30 bushels each, to exhaust it."

"That is to say," said Charley, "if all the straw and chaff is retained on the farm, and is returned to the land without loss of phosphoric acid."

"Yes," said the Doctor, "and if all the bran and shorts, etc., were retained on the farm, it would take eight hundred crops to exhaust the soil of phosphoric acid; and it is admitted that of all the elements of plant-food, phosphoric acid is the one first to be exhausted from the soil."

I have sold some timothy hay this winter, and propose to do so whenever the price suits. But some of my neighbors, who do not hesitate to sell their own hay, think I ought not to do so, because I "write for the papers"! It ought to satisfy them to know that I bring back 30 cwt. of bran for every ton of hay I sell. My rule is to sell nothing but wheat, barley, beans, potatoes, clover-seed, apples, wool, mutton, beef, pork, and b.u.t.ter. Everything else is consumed on the farm--corn, peas, oats, mustard, rape, mangels, clover, straw, stalks, etc. Let us make a rough estimate of how much is sold and how much retained on a hundred-acre farm, leaving out the potatoes, beans, and live-stock. We have say:

Sold.

15 acres wheat, @ 40 bushels per acre 18 tons 5 " barley, @ 50 " " 6 "

15 " clover seed, 4 " " 1 ton.

------ Total sold 25 tons.

Retained on the farm.

15 acres corn, @ 80 bushels per acre 33 tons.

Corn stalks from do. 40 "

5 acres barley straw 8 "

10 " oats and peas, equal 80 bushels of oats 12 "

Straw from do. 20 "

15 acres wheat-straw 25 "

15 " clover-hay 25 "

Clover-seed straw 10 "

15 acres pasture and meadow, equal 40 tons hay 40 "