Bulletin 174. November, 1899.
Cornell University Agricultural Experiment Station.
ITHACA, N. Y.
THE PROBLEM OF
Being Suggestions for Investigation
L. H. BAILEY.
PUBLISHED BY THE UNIVERSITY,
ITHACA, N. Y.
BOARD OF CONTROL:
THE TRUSTEES OF THE UNIVERSITY.
THE AGRICULTURAL COLLEGE AND STATION COUNCIL.
JACOB GOULD SCHURMAN, President of the University. FRANKLIN C. CORNELL, Trustee of the University. ISAAC. P. ROBERTS, Director of the College and Experiment Station. E]MMONS L. WILLIAMS, Treasurer of the University. LIBERTY H. BAILEY, Professor of Horticulture. JOHN H. COMSTOCK, Professor of Entomology.
STATION AND UNIVERSITY EXTENSION STAFF.
I. P. ROBERTS, Agriculture.
G. C. CALDWELL, Chemistry.
JAMES LAW, Veterinary Science.
J. H. COMSTOCK, Entomology.
L. H. BAILEY, Horticulture.
H. H. WING, Dairy Husbandry.
G. F. ATKINSON, Botany.
M. V. SLINGERLAND, Entomology.
G. W. CAVANAUGH, Chemistry.
L. A. CLINTON, Agriculture.
B. M. DUGGAR, Botany.
J. W. SPENCER, Extension Work.
J. L. STONE, Sugar Beet Investigation.
MRS. MARY ROGERS MILLER, Nature-Study.
A. L. KNISELY, Chemistry.
C. E. HUNN, Gardening.
W. W. HALL, Dairy Husbandry.
A. R. WARD, Dairy Bacteriology.
L. ANDERSON, Dairy Husbandry.
W. E. GRIFFITH, Dairy Husbandry.
MRS. A. B. COMSTOCK, Nature-Study.
ALICE G. McCLOSKEY, Nature-Study.
OFFICERS OF THE STATION.
I. P. ROBERTS, Director. E. L. WILLIAMS, Treasurer. EDWARD A. BUTLER, Clerk. Office of the Director, 20 Morrill Hall.
CORNELL UNIVERSITY, ITHACA, N. Y., Nov. 1, 1899. HONORABLE COMMInSSIONER OF AGRICULTURE, ALBANY.
Sir:~ The one perennial inquiry at an Experiment Station is how to restore land to its original producing power. We have made many experiments and investigations to determine the problems at issue. A popular summary of these studies is given herewith. The chemical part of the subject has been prepared by G W Cavanaugh, under the supervision of Professor Caldwell. Full reports of three years' experimenting with fertilizers are now being compiled for publication in bulletin form.
This bulletin comprises the following subjects: Part I. How to Understand the Problem.
A. Some reasons why lands become impoverished.
B. How to reclaim depleted lands. Part II. A Crusade with (the Farmers.
A. Reading-Lessons Nos. I and 2.
No. I. The Soil: What it is.
No. 2. Tillage and under-drainage: Reasons why.
B. Answers to the Questions on Five Reading-Lessons.
No. I. The Soil: What it is.
No. 2. Tillage and under-drainage: Reasons why.
No. 3. Fertility of the land: What it is.
No. 4. How the plant gets its food from the Soil.
NO. 5. How the plant gets its food from the Air.
I. P. ROBERTS, Director.
Plan of a set of plats upon which the farmer may ask the soil and the plant what fertilizers are needed (See p. 95)
I S plat.
2 K plat. 20 lbs. muriate of potash.
3 N plat. 20 lbs. nitrate of soda, or 4o lbs. tankage or dried blood.
K N plat. 20 lbs muriate of potash. or 20 lbs. muriate of potash.
K4 N ~ 20 lbs. nitrate of soda. 40 lbs. tankage, etc.
5 0 plat. No fertilizer.
6 P plat. J 40 lbs. plain superphosphate with 15% phosphoric acid.
7 K P plat. 20 lbs. muriate of potash.
7 40 lbs. superphosphate.
20 lbs. nitrate of soda, (40 lbs. tankage, etc.
8 N K Pplat. 20 lbs. muriate of potash, or 20 lbs. muriate of potash.
140 lbs. superphosphate. 1 40 lbs. superphosphate.
9 N P plat. 20 lbs. nitrate of soda, f 40 lbs. tankage, etc.
40 lbs. superphosphate. or140 lbs. superphosphate.
Size of plats i-IO acre. Upon each plat the same crop is to be grown, care being taken that the seed is pure and that each plat receives exactly the same amount of seed.
S, means stable manure; K, potash; N, nitrogen; P, phosphoric acid
0. no fertilizer.
The best arrangement is to have plats as narrow as they can be and still carry a reasonable number of rows of the crop, and, unless the field is too large, extending from one side to the other, and across all unlike strips. Such an arrangement would reduce the labor of planting and tillage to a minimum, besides securing the probable advantage of greater evenness in results.
A set of plats seventeen and one-half feet wide would carry five rows of corn or potatoes, with three and one-half feet between the rows; there would then be three rows to harvest for the measurement of the crop, the two outside rows being rejected. For cereals, as wheat, rye, barley and oats, plats as wide as could be sown with the drill, with two or three feet vacant spaces between the plats, would answer. For small fruits, plats carrying three rows should be taken, the fruit of the inner row only being harvested for the measurement of the crop.
THE PROBLEM OF IMPOVERISHED LANDS.
Part I. HOW TO UNDERSTAND THE PROBLEM.
" Some of my land will not produce a crop, although my father raised good crops on it. What shall I do to make it productive ?"
This is a common type of question. It is easily asked, but very difficult to answer. The first thing to do is to find out why the land is unproductive. The remedy then follows as a natural consequence. The disease must be diagnosed, as the physicians say, before it can be cured.
If the cause of the unproductiveness is to be discovered, the land itself must be studied carefully, and the history of the field should be known. The man who is on the spot-the farmer himself-has the best opportunity to determine the cause of the trouble. One value of an education and of experiment station teachings is to help the farmer to work out his problems for himself. He can not only solve many of his problems better than the experimenters can, but he derives pleasure from the quest, and great comfort in being able to master his difficulties.
The farmer who hasworn-out land must study and experiment for himself. It is the object of this bulletin to suggest how this may be done. We will specify some of the leading causes of unproductiveness, and then suggest inquiries
A. Some Reasons Why Lands Become Impoverished.
i. They may lack tillage and good care. It is significant that impoverised lands are usually those which have been neglected. From insufficient or improper tillage, lands become cloddy, hard, unresponsive and foul. In such cases, it may be necessary to resort to summer fallow to correct the errors,-to bring the land
92 BULLETIN 174.
back into prime condition ;but it is rare that well farmed fields need fallowing. See part II, paragraphs 7, 8, 9, 14, 16, 25.
2. They may lack humus or vegetable mold-When in native conditions, in regions of sufficient rainfall, lands are covered with vegetation. As this vegetation dies it becomes incorporated with the soil as humus, making the soil mellow, dark-colored and rich. It enables the soil to hold moisture, lessens extremes of temperature, hastens chemical activities, and itself supplies plant-food. When vegetable matter is withheld from the soil, the humus is not replenished, and it is gradually used up. The soil then becomes hard, "dead," very dry in dry weather and very muddy in wet weather, and is subject to great extremes of temperature. If the original basis of the soil is clay, the land bakes and becomes lumpy when plowed; if sand, it becomes loose and leachy. See Part II,, paragraphs 5, 6.
One great value of stable manure is to supply humus. Green cropping is also exceedingly useful. A rotation of crops in which sod is one factor tends to maintain the supply of humus. Catch-crops (sown between other crops) may be nsed to replenish the humus ; also cover-crops (those sown in fall for a winter cover). Long continued cropping with one or with similar crops tends to deprive the soil of humus. When the farmer does not properly care for the land, nature tries to force him into another rotation. This is well illustrated in pastures and meadows, in which daisies and wild carrot force out the poor st and of grass. Most of the depleted lands in New York are suffering more for humus than for plant-food.
To determine by experiment whether a soil has sufficient humus is difficult because the forms of available humuts-producing materials also contain plant-food. Humus may be supplied by muck, stable manure, leaves or green-crops. All these contain the different plant-food, and also a large amount of vegetable matter. To test whether a soil needs humus, apply these materials to several plats of ground, leaving one or more without them for checks. Stable-manure might be applied to one plat, muck to another, a green-crop of clover, barley, buckwheat, etc., turned under on another. Nature uses leaves for making humus in the woods.
THE PROBLEM OF IMPOVERISHED LANDS. 93
3. They may need draining.-Under-draining lowers the watertable (or the zone of standing water), causing the soil to become deeper and mellower. Well-drained soil is drier in wet weather and moister in dry weather than soil which is underlaid with a high and hard subsoil. Most of the cold, wet and so-called sour" lands need draining to make them productive. Even though they are not too wet for tillage, they may need the drainage for the purpose of deepening the soil and causing it to hold more air and moisture. Deep-rooting plants, as clover, tend to make soils deeper. Subsoiling has a similar tendency, but its effect usually is not permanent. Consult Part II., paragraphs 9, page 99.
4. The soil ma' become acid.-There are some cases in which the soil becomes sour to a degree that is injurious to many plants. This is true of some sandy uplands and sometimes is indicated by growths of sorrel, daisies and golden rod. The acid in soil can be detected by its reddening blue litmus paper (to be had at drug stores or at this Station). This over-acid condition often acccompanies a lack of humus, and sometimes may be corrected by adding humus. It is also relieved by the use of ashes or lime, which have the power of neutralizing or sweetening acids. The ashes or lime should not be plowed in, but harrowed in after plowing, as lime tends to work downward. When experimenting with humus (see next page,) an application of ashes on an adjoining plat may help solve the problem.
5. The soil may lack in useful plant-food.-Sonie of the leading plant-food elements may be nearly or quite exhausted ; or, as is more usually the case, they may be in an unavailable condition or locked up. The chemist can tell if the soil which he analyzes lacks plant-food ; but another sample of soil from the same field may be very different in composition. There is very little uniform soil in New York, for nearly all of it is mixed glacial soil. But the chemist cannot tell how much of the plant-food is available to plants. Food which is nearly unavailable when he analyzes it, may be made available by a change in conditions or by better tillage; and that which is clearly available may become unavailable the same season. In certain very pronounced cases of depleted lands, the chemist may render much direct aid ; but in
94 BULLETIN 174.
general he can only suggest and advise, not prescribe. The only sure way to find out whether more plant-food is needed is to experiment on the land in question.
B. How to Reclaim Depleted Iands.
i. f you think that they lack humus, apply stable manure or turn underagreen-crop. The best general green-crop isred clover, but it does not catch well on very sandy, and very hard soils. Then begin with any crop which will grow-rye, buckwheat, corn, beans, anything to get a start. If the land produces weeds when left to itself, it is good enough to produce something else. Turn the weeds under, sow something, turn it under, sow again; in two or three years the results will be seen.
2. Till frequently and wisely.-Many depleted .lands need tillage more than humus or plant-food. Usually, they need both. Prepare the land thoroughly for the green-crop. Plow when the land is most fit. In very hard clays, try fall-plowing.
3. If the land is so poor that it is wholly bare, determine whether it is very acid. fIit is, apply lime or ashes.--Apply some fertilizer to enable you to get a start of plants. The start once made, the future is yours. Plow under herbage; add plant-food as your experiments suggest.
We have lands which are now so completely run out that the sand drifts and no plants can obtain a foothold. It is probable that they can be reclaimed, although it is a question if the reclamation will always pay. Analyses have been made of samples of some of these lands, and it is found that they contain liberal supplies of potash and phosphoric acid, but almost no nitrogen. They are also almost wholly lacking in humus. The soils are so leachy that an application of nitrate of soda or other very soluble materials would probably be of little avail. Probably the best means of recuperating these lands is to make applications of stable manure and then to sow rye or some other cover-crop for the purpose of making a body of humus in the soil. If stable manure cannot be had, tankage will be found to be a good substitute since it contains nitrogen in a more or less insoluble form. We advise persons who have such lands to experiment with a small piece and when the experiments
THE PROBLEM OF IMPOVERISHED LANDS. 95
prove successful to extend them to a larger area. In the Old World, spurry is used to begin the reclamation of such lands. Seed can be had of the leading seedsmen.
4. Experiment with the land to determine what ilanlfood it needs.-To test the need of fertilizers, a trial of five plats may be helpful :
On the first, apply nitrate of soda at the rate of 200 lbs. per acre.
On the second, 200 lbs. superphosphate.
On the third, apply nothing.
On the fourth, 200 lbs. muriate of potash.
On the fifth, iooo lbs. lime.
The results will in so ne measure indicate which of the elements of plant-food is needed.
For a more complete and conclusive method of testing fertilizers, the reader is referred to Bulletin 129. The plan of experiment, as outlined by that publication, is reprinted at the beginning of this bulletin.
Part II. A CRUSADE WITH THE FARMERS.
In the winter of 1898-9 this Station discussed a seriesof soil and fertility questions with the members of the ReadingCourse (8605 persons). Five Reading-Lessons were issued, two of which pertained directly to soil problems; and these two Lessons are reprinted here. With each Lesson there was issued a series of questions designed to bring out the points in the Lesson. The replies which were received to these questions afford an excellent index to the state of the popular mind on subjects connected with the fertility of the land. The questions were designed to elucidate underlying truths or principles, and correct answers to them will do much towards spreading sound ideas of maintaining and increasing the productive power of the land. We therefore reprint the questions and give answers to them. These questions and answers cover all the five Lessons: The Soil: What it is ;" "Tillage and Under-Drainage: Reasons Why;' Fertility of the Soil : What it Is ; ".. How the Plant Gets its Food from the Soil; "How the Plant Gets its Food from the Air." These answers are written by H. P. Gould, but have been approved by specialists in the various subjects.
96 BULLETIN 174.
A. Reading-1,e sson s Nos. i and 2.
LESSON NO. i. THE SOIL.: WHAT IT IS.
I. The basis of soil is-iragments of rock.-As the earth cooled, the surface solidified into rock. The processes of nature have been constantly at work breaking up this rock and making it into soil.
2. Weathering is the great agency in making rocks into soil.Rain, snow, ice, frost have worn away the mountains and deposited the fragments as soil. Probably as much material has been worn away from the Alps as still remains and this material now forms much of the soil of Italy, Germany, France, Holland. Our own mountains and hills have worn away in like manner.
3. Weathering is still active.-All exposed rocks are wearing away. Stones are growing smaller. The soil is pulverized by fall plowing.
4. Thiefparticles of soil are worn and transported by water.Every stream carries away great quantities of soil and deposits it in the shallows and the bays. After every rain, the streams and ponds are muddy and roily. Observe the sediment or fine mud which remains when a "mud puddle" dries up. The rivulet may carry away tons of earth every year ; and this earth is deposited somewhere, and sometimes it may perhaps, come into use again for the growing of plants. Many of our best and richest farm lands are the deposits of former streams and lakes. Such lands are fine and silk-like. Most lowlands belong to this category ; and even some of our higher lands are formed f rom deposits from water. The mixed and varied character of soils is largely due to the fact that they are the results of transportation from different places.
Observe the flat lands about lakes. These flats are formed by the deposition of material from the surrounding highlands ; but they are often exposed before their natural time by the lowering of the water level in the lakes. All lakes and ponds are filling up. Nearly every stream makes a delta at its mouth ; but if the stream into which it empties is swift, the delta may be carried away.
THE PROBLEM OF IMPOVERISHED LANDS. 97
Observe, also, the broad rounded hillocks and knolls in valleys and ravines. Many of them have attained their present form from the action of moving water.
Every farmer knows that overflowed lands are rich. He has heard of the wonderful fertility of the Nile. He should explain these facts.
5. All productive soils also contain organic matter.-Most
organic matter is the remains of plants and animals. As found in soils in a decaying condition, it is called humus. It is the humus which gives the soil its dark or rich look. It also tends to make soils loose warm and mellow. It holds moisture. The addition of humus makes soils loamy. A sandy loam may be defined as a soil of which the original mineral matter is sand, and a clayey loam is one of which the basis is clay. Soils which have no humus are hard, dead and unproductive.
6. Humus is supplied by means of roots and stubble, green-crops and barn manures.-[f the farmer practices a rotation of which meadow and pasture are a part, the supply of humus will be maintained. In such cases, green-manuring is unnecessary except now and then upon lands which are very hard or poor. The roots and stubble, with the droppings of the animals on the pasture, and manure applied with one of the crops in the rotation, keep the land well supplied with vegetable matter. Whenever possible, it is better to feed the crop to stock and return the manure to the land, than to plow the crop under ; for one will get back the greater part of the fertilizing value of the crops and maintain the animal at the same time. In western New York, there are hundreds of acres of refuse cabbage lands, and at this day there are thousands of tons of herbage on the ground, and no stock to eat it. It is wasteful.
Many soils which are said to be worn out are robbed of their humus rather than of their plant-food ; others have been injured in their texture by careless or faulty management. In supplying humus, it is better to add small quantities often. Lands which are under constant tillage, in corn, wheat, oats, potatoes, may be supplied with humus if catch-crops are sown with the crop, now and then, late in the season. Rye, Canada peas, crimson clover, and the like may be used for this purpose. Plow them under as
98 BULLETIN 174.
soon as the land is ready in the spring, even if the plants are not large.
Observe how the forest supplies its humus. Year by year the leaves add to the soil cover, which slowly passes into vegetable mold or humus. The trunks finally decay and pass into the soil. The work is effectively done, but it consumes time ; and man is in a hurry. When the forest is removed, the land is usually productive. It is called ''virgin soil,'' notwithstanding the fact that an enormous crop of trees has just been taken from it, and that it may have grown hundreds of suc 'h crops. The real virgin soil is the barren soil. But however rich this forest soil may be when the timber is first removed, it generally soon loses its exuberant fertility. The pigmy crops of the farmer seem to be harder on the soil than the gigantic crops of Nature. Some of this loss of productivity is due to the loss of humus.
A rotation diminishes the exhaustion of plant-food, supplies nitrogen in leguminous crops, one crop leaves the land in better condition for another, the roots and stubble improve the texture of the soil, it keeps weeds in check, provides for continuous labor because stock is kept.
The rotation should differ with the kind of soil and general style of farming. The Cornell rotation is:
Clover and timothy, i year,
A good rotation for weed-infested land is
Sod, i year,
Potatoes, or some other tilled crop,
Oats or barley.
On fruit farms, rotations are not so practicable as on grain farms; but the fields which are not in fruit can often be worked in rotation to great advantage. The general tendency of fruitfarmers is to keep too little stock. If stock cannot be kept, the humus can be maintained by catch-crops and cover crops.
7. The fertility of the land is its power to produce crops. It is
THE PROBLEM OF IMPOVERISHED LANDS. 99
determinedby three things the texture of/he soil, its richness in planfood, and its available moisture.-The texture of the soil is its physical condition,-as to whether it is mellow, loose, leachy, cloddy, hard, and the like. A rock or a board will not raise corn,and yet it may contain an abundance of plant-food. The plant cannot get a foothold: and it would do no good to apply fertilizers. Spreading potash on a lump of clay is not farming: it is the wasting of potash. A cow will not appreciate the fanciest ration if she is uncomfortable ; neither will a plant. It is only on land which is in good tilth that fertilizers pay. The better the farming, the more it will pay, as a rule, to buy plant-food : but poor farming cannot make it pay.
8. Nature secures good texture in soil by growingfplants in it.Roots make the soil finer, and plants supply it with humus. Plants break down the soil by sending their roots into the crevices of the particles, and the root acids dissolve some of it. Observe Nature working at this problem. First the moss" or lichen attacks the rock ; the weather cracks it and wears it away ; a little soil is gathered here and there in the hollows ; a fern or some other lowly plant gains a foothold ; year by year, and century by century, the pocket of soil grows deeper and larger ; and finally, the rock is worn away and crumbled, and is ready to support potatoes and smart-weed. Or, the rock may be hard and bare, and you cannot see any such process going on. Yet, even then, every rain washes something away from it, and the soil beneath it is constantly receiving additions. Some soils may be said to be completed: the rock is all broken down and fined. Other soils are still in process of manufacture : they are full of stones and pebbles which are slowly disintegrating and adding their substance to the soil. Did you ever see a rotten stone"?
The longer plants are grown on any soil, and returned to it, the richer the soil becomes. But Nature has centuries at her disposal; man has but a few short years and must work rapidly, and he cannot afford to make mistakes.
9. The texture of the soil may be improved (I) by underdraining, (2) by tilling, (3) by adding vegetable matter, (4) by adding certain materials, as lime, which tend to change the size of the soil particles.-The reader will say that Nature does not practice tile-drain-
100 BULLETIN 174.
ing. Perhaps not ; but then, she has more kinds of crops to grow than the farmer has, and if she cannot raise oaks on a certain piece of land she can put in water-lilies. We have an entire lesson devoted to drainage and tillage, and also one to manures and fertilizers. It is enough for the present to say that the roots which are left in the ground after the crop is harvested are very valuable in improving the soil. This is particularly true if they are tap-roots,-if they run deep into the soil. Clover bores holes into the soil, letting in air, draining it, warming it and bringing up itsplant-food. Roberts reports (" Fertility of the Land," p. 345) that a second growth of clover, two years from seeding, gave a yield of air-dried tops of 5,417 lbs. per acre, and of air-dried roots 2,368 lbs. in the first eight inches of soil. Add to this latter figure the weight of roots below eight inches and the stubble and waste, and it is seen that the amount of herbage left on the clover field is not greatly less than that taken off. In this instance, the roots contained a greater percentage of nitrogen and phosphoric acid than the tops, and about the same percentage of potash.
Make an estimateof what proportion of the plant growth you raise is actually taken off the field. Figure up, as accurately as you can, the part left in roots, stubble, leaves and refuse. Even of maize, you do not remove all from the field. This calculation will bring up the whole question of the kind of rootsystem which each sort of plant has. Have you ever made a close examination of the roots of potatoes, maize, wheat, clover, cabbages, buckwheat, strawberries, Canada thistles, or other crops ? From what part of the soil do these plants secure their nourishment? What power have they of going deep for water? What proportion of them is root ? Because the roots are hidden, we have neglected to examine them.
Io. The soil is plant-food,, but this food becomes usable or available slowy.-Roberts has compiled the analyses of 49 representative soils, made by American chemists, and the following is the result: "The tables reveal the fact that even the poorer soils have an abundance of plant-food for several crops ; while the richer soils in some cases have sufficient for two hundred to three hundred crops of wheat or maize. The average of 34 analyses
THE PROBLEM OF IMPOVERISHED LANDS. 101
gives to each acre of land, eight inches deep, 3,217 pounds of nitrogen, 3,936 pounds of phosphoric acid, and 17,597 pounds of potash, and this does not include that which is contained in the stones, gravel and sand of the soil which will not pass through meshes of one-fiftieth of an inch, which, by weathering and tillage, slowly give up their valuable constituents. "-Roberts, "Fertility of/the Land," p. 16.
Fortunately, this great store of plant-food is largely locked up, else it would have leached from the soil or have been used up long ago. By careful husbandry, a little of it is made usable year by y-ear ; and the better the management of the land the more of this food is available to the plant. When the farmer has done his best to get out of the land all that it will give him, then he may add fertilizers for bigger results.
Plant-food is available when it is in such condition that the plant can use it. It must be both soluble and in such chemical form that the plant likes it. Plant-food which is not soluble in rain water, may still be soluble in soil water (which contains acids derived from the humus) ; and the acid excretions from the roots may render it soluble. But solubility is not necessarily availability, for, as we have said, the materials must be in such combination that the plant will take them. Thus, nitrate of soda (Na N 03) is available because it is both soluble and in the form in which the plant wants it. But nitrite of soda (Na NO.) is not available although it is soluble,-the plant does not like nitrites.
ii. Nitrogen must probably be in the forin of nitrates before it/can be used by most plants.-Nitrogen is abundant. It is approximately four-fifths of the atmosphere, and it is an important content 'of every plant and animal. Yet, it is the element which is most difficult to secure and to keep, and the most expensive to buy. This is because the greater part of it is not in a form to be available, and because, when it is available, it tends to leach from the soil. It is available when it is in the form of a nitrate-one part of nitrogen, three parts of oxygen, united with one part of some other element (Na NO,, nitrate of soda; K NO,, nitrate of potash or saltpetre; H NO,, nitric acid, etc). The process of changing nitrogen into nitrates is called nitrification. This pro-
102 BULLETIN 174cess is the work of germs or microbes in the soil : and these germs work most efficiently when the soil is not water-logged, and when it is well tilled. The farmer should make his available nitrogen supply as he goes along ; and he makes it with tile drains, plows, harrows and cultivators.
But there are some plants which have the power of using the nitrogen which is in the air in the soil. These are leguminous plants, -clovers, peas, beans, vetch, alfalfa. If, therefore, the farmer cannot secure sufficient nitrogen by other means, he may use these plants as green-manures. If his system of farming will not allow him to use these plants, or if he does not secure sufficient nitrogen when he does use them, then he can go to the warehouse and buy nitrogen.
12. The soil is not a mere inert mass : it is a scene of life and activity.-This is the new and the true teaching. Soil which is wholly inactive is unproductive. Movements of air and water, actions of heat and evaporation, life-rounds of countless microscopic organisms, decay and disintegration of plants and soil particles, -these are some of the activities of the fertile soil. If our ears were delicate enough, we could hear the shuffle of the workers, the beating of the hammers, and the roll of the tiny machinery. All things begin with the soil and at last all things come back to it. The soil is the cemetery of all the ages, and the resurrection of all life. If the soil is not idle, neither should the farmer be.
LESSON NO. 2. TILLAGE AND UNDER-DRAINAGE: REASONS WHY.
13y John 11. S5pencer.
13. The difference between black and while.-Two farmers are neighbors. Mr. White has made a study of potato culture for a number of years, and, as a result, now has an average yield, one year with another, of about 2oo bushels per acre from a field of three to five acres. Mr. Black is considered a fairly good farmer. as farmers go, but has given potato culture no special study. He manages his crop as his neighbors do. His methods are those which have been a tradition for several generations, and they had their origin when the country was new and high cultivation was impossible on account of the stumps and lack of tools, and also because the virgin soil made it unnecessary. His annual yield is not far from 6o bushels per acre. In other words, Mr. Black has to plow, harrow, furnish seed, plant and cultivate about ten acres to secure as many potatoes as Mr. White does from three acres. Both men sell their product to the same dealer, and we will assume that they receive the same price per bushel. The cost of producing a bushel of potatoes must be very much more with Mr. Black than it is with Mr. White. No manufacturer or merchant could withstand the keen competition in trade if handicapped as Mr. Black is. When the respective farms were reclaimed from the forest, they were considered to be alike in character of soil, and the rain falls impartially on each.
Why the difference in cost of production between Black and White? There are many points of difference in their methods, but we are free to say that one of the essential differences is in tillage.
14. The plant needs water.-When Mr. White contemplates a crop of potatoes, he proceeds to make an estimate of what the crop will require and how he can provide for that demand. Perhaps the greatest of all needs is water. By turning to Cor-
104 BULLETIN 174.
nell Experiment Station Bulletin 120, page 419, it will be seen that in a dry season a bushel of potatoes requires about three tons of water for its production. If Mr. White expects 200 bushels of potatoes per acre, he must somehow manage to provide 6oo tons of water for each acre. He has no facilities for irrigation, and his only resource is to make the soil a reservoir. He must store the supply left by winter snows and spring rains, and also the irregular rainfall that cones during the season's growth. Speaking in broad averages, in soils most commonly met with, this storage possibility amounts to about 300 tons of water per acre in the first eight inches of the soil. It must be understood that this amount is not in the form of standing water, for water standing in the soil for any length of time injures both soil and plant.
15. The most useful form oJ waterfor plants is film moisture.Water is capable of assuming many forms,such as steam, vapor, ice, or free-moving liquid. The condition most valuable in the soil is none of these, but is in the form of film moisture. This film moisture can be shown by dipping a marble into water and observing the film of water surrounding it on all sides. When each soil-grtin is covered with film moisture, as the marble is, the ideal conditions of soil moisture exist. This form of water is largely imi(e, nldent of gravitation and travels readily in all directions, at ,. be seen by dipping a cube of sugar into a spoonful of coffee. ItL is capable of transporting plant-food to the roots of plants from remote corners, where the roots do not reach.
It will be observed that film moisture is held only on the surface of soil-grains. The more the soil is pulverized, the more soil-grains there will be, and therefore the greater amount of surface to hold film moisture.
The difference in the capacity of lumpy and fine soils to hold film moisture is surprising to one who has not given the question study. George W. Cavanaugh, assistant chemist at the Cornell Experiment Station, has very graphically shown this by the following experiment: He put small marbles in a tumbler, as shown by Fig. 22, and the total amount of film moisture that the marbles would carry is represented in the tube placed beside the
THE PROBLEM OF IMPOVERISHED LANDS. IO5
tumbler. The soil in the other tumbler (Fig. 23) is of the same
weight as the marbles in Fig. 22, and it represents the marbles reduced to the fineness of common sand. Its capacity for holding film moisture is represented by the water in the standing tube (Fig. 23). The weight of material is the same in each tumbler, and thereason why one holds three times more film moisture than the other is due to the increase of surface that comes by dividing
a coarse lump into fine particles.
The marbles represent the careless tillage o f Mr.
Black, and the finer particles the thorough l ge of
han Mr. Black, a White plows about one-third deeper than Mr. Black, and thereby makes another addition to
the capacity of his reservoir.
The coarse cil, as represented by the marbles, willlose
its film moisture by evapora Lion much more readily than the soil represented by Fig. 23, particularly if the surface of 'he latter is covered by fine particles representing
16. Tillage makes plant-food available. -Another difference in the culture given by 1 L ck and White is that the better tillage enables the plant to realize more food than all fertilizers which may be "d. There is also a benefitinmak -. Lvailfood that nature has put
I in the soil. Broadly
stated, the native plantfood amounts toas
much as can be bought
in $2,000 worth of comniercial fertilizers.
FIG. 2 2- 1 ate held by The finer soil has anoth- FIG. 23- Water held by
a coarse soil. er advantage in afford- a fine soil.
ing a greater area for root
pasturage. It is not uncommon for farmers to think of plant-food in the soil as in the condition of salt or sugar which is capable of being immediately dissolved by water and at once appropriated by
io6 BULLETIN 174.
the plant, or like potash in ashes that can be soaked ont. Plantfood exists in this form only to a limited extent. A man might famish if locked in a granary filled with wheat; yet a chemist would say that there was enough food near him to feed a hundred men. This illustrates how nature has stored much of the plant-food in the soil. It has to go through many changes before it can be appropriated by the plant. The soil is a factory in which the work of preparation is carried on.
17. The soil is a laboratory.-Sotne of the agents employed in this factory are film moisture, air and heat ; and if these are not furnished in the proper extent and condition, the factory runs in a sluggish way, if it does not stop altogether. Good tillage does much to hasten the activities of this factory by allowing free ingress to the soil of film moisture, air and heat. Air is necessary for a supply of oxygen, and heat to facilitate fermentation and other vital processes.
The importance of air and heat in the soil brings us to the question of drainage. Air cannot enter a soil freely which is filled with standing water, and growth of micro-organisms is hindered.
18. Wet soils are cold.-Standing water is a great absorbent of heat. If no provision is made to drain it away, it must be evaporated away. Thereby heat is lost. The soil is cold. A great many barrels of water can be standing on an acre of ground and not attract much attention.
To appreciate the amount of heat necessary to evaporate water, one has only to chop, split and burn beneath a caldron kettle enough wood to evaporate a barrel of water. Every barrel that is evaporated from the soil by the sun absorbs as much heat as is expended by the, wood used under the kettle. The soil and plants are perhaps chilled for want of that heat. This is the reason that a wet soil is said to be cold.
19. Drained soils resist drought. -Some farmers have the notion that well drained soil will not withstand a drought as well as an undrained soil. The contrary is true. Everyone who has tilled the soil is familiar with places that are wettest in a wet time and driest in a dry time. When these places dry at all, they dry like a brick. A wet soil can never be tilled so as to present
THE PROBLEM OF IMPOVERISHED LANDS. 107
the greatest amount of surface for film moisture and give it a mellow texture to receive a gentle saturation of air ; and standing water robs it of much heat required by the soil and plants.
20. Drainage makes a soil reservoir. -T here is a place in every soil at which the free water stands. This place is called the water-table. It may be three inches down, or a hundred feet. It is the bottom of the soil reservoir, the bottom of our dish-pan. This dish -pan, or the upper and tillable soil, is the reservoir. Itis the part in which the water is held as films on the soil particles. These films travel from particle to particle, the general tendency being upward because the moisture is passing off near the top of the soil by means of evaporation and appropriation by plants. Moisture is constantly supplied from the water-table below. We speak of this movement as capillary attraction.
Under-drainage lowers the wvatei -table. It lowers the bottom of the dish-pan ;and thereby there is a deeper reservoir above it for the holding of film moisture and the distribution of roots.
But, the reader says, if the water-table supplies moisture to the upper soil, then it must be useful and necessary. Certainly; but it must not be too high, for roots of farm plants do not thrive in standing water. If the upper soil is well tilled, capillary attraction will bring the moisture up.
21. Do not let the moisture getaway. -We want this film moisture in the upper soil in order that roots may use it. The plants do not use it, to any extent, after it has passed off into the atmosphere. Therefore, stop this water before it reaches the atmosphere.
How ? Put a layer of loose dry earth between the moist soil and the atmosphere. This layer will stop the upward capillary flow. This layer is the earth-mulch. It conserves, or saves, moisture.
2 2. Dry and hard soils way be benefitted by under-drainage. The water-table is lowered. Air is admitted. The soil does not puddle. It becomes fine. Under-drainage makes wet soils dry by removing the free water ; it tends to make dry soils moist by deepening the reservoir and fining the particles of soil.
23. What tillage tools are for.-Some tools, as plows, are to mellow up the soil and to deepen the moisture reservoir.
io8 BULLETIN 174.
Others, as cultivators, are to tear up and to pulverize the soil to greater or less depths. Cultivators lift and turn the soil. The spring-tooth harrow is really a cultivator. Other tools, as harrows, prepare the surface of the soil. They make the seed-bed and put on the earth-mulch. The true harrows stir the soil, but do not lift or invert it.
24. Weeds do not firesist in well-ti/led lands.-The first and greatest value of tillage is to put the soil in such condition that plants can grow, and then to keep it so. Incidentally, it prevents those plants from growing which we do not want,-the weeds. Usually, the process is reversed: weeds make us till, and we get the other benefits without knowing it. The best tillage prevents weeds rather than kills them.
25. Summer-/allowing is a means of cleaning land and of correcting mistakes.-It may be necessary to fallow the land in order to clear it of stones, stumps and brush. But after the laud is once thoroughly subdued, sunmmer- fallowing is very rarely necessary if the land hAs been well handled. If the land has been plowed when too wet and thereby has become lumpy, if it has been allowed to become foul with weeds, or if it has lost heart by too continuous cropping with one kind of -crop, summer-fallowing is a good means of bringing it back into condition. The better the farming, the less the necessity of summer-fallowing. In the old days, the poor tillage tools rendered fallowing more necessary than it is to-day.
.Fallowing is tillage; and tillage liberates plant-food. Some of this plant-food may leach away and be lost, although the small rainfall of the summer months,-during which time fallowing is practiced, -makes this loss slight.
26, The kind of tillage should vary wi/k the soil, the time oy ,year, the kind o crofi;-Too many farmers seem to think that tillage is tillage, no matter how it is performed. The same tool is used for clay or sand or muck, and for fitting the land for wheat or corn or apple trees. A harrow that is best for one field may be worst for the adjoining field. A man would not think of using a buggy for carrying grain to market, but he will use one tool for many kinds of work. The work is not only poorly done, but it is not economical. It costs too much. Persons who will
THE PROBLEM OF IMPOVERISHED LANDS. lo9
economize to the smallest degree in expenditures of money may be very wasteful in expenditures of labor and muscle.
Persons are always asking if deep plowing is best. The question cannot be answered on general principles. Deep plowing may be best for one field and one crop, and shallow plowing best for another field and another crop. The same remarks will apply to fall-plowing and spring plowing. One must first learn principles, or the why; then the practice, or the how, will come easy.
NOTE. The reader should have other sources of information than this Lesson. He may read our Bulletins i 19, Texture of the Soil ;" 120, "The Moisture in the Soil ;" 72, The Cultivation of Orchards ;" and the three bulletins on potato culture (Nos. 130, 140, 156). His library should also have King'p Soil and Robert's "Fertility of the Land."
B. Answers to the Questions on the Five Lessons.
NO. z. THE SOIL: WHA T IT IS.
Many of the questions in this lesson are intended merely to call attention to certain fundamental facts and to promote thought and discussion.
I. Have you ever observed the influence of weather ufion soft slaty rock jutting out on embankments and in railroad cuts.?
2. Have you ever taken a glass of muddy water from a flowing stream and allowed it to stand until the sediment had settled? What is this sediment?
These questions are intended merely to call attention to this process of soil formation and transformation.
3. Imagine a branch of this stream bringing rotted slate rock and another bringingfine sand. When mixed in the main stream and deposited on some bar or overflowed field, what kind of soil would the mixture make?
A sandy or clayey soil, the exact nature of which would be governed by the relative proportion of the different ingredients. Such a mixture might also contain much decaying vegetable or organic matter, and this would make the physical condition of the soil such that it would be very fertile.
110 BULLETIN 174.
4. What is inorganic matter ?
All matter which is not a part or product of a living organism is inorganic or mineral matter, as a stone or a piece of iron. The bulk of the soil is made up of finely pulverized stone and is therefore inorganic matter.
5. What is organic. mailer?
Matter which has life or has been produced by living organisms. An animal or a tree, either living or dead, is organic matter. The humus of the soil is decaying organic matter.
6. Why are soils from which a thrifty forest growth has been removed capable at once of producing good farm crops ?
Largely because of their good physical condition, due chiefly to the presence of large quantities of humus.
7. Have you ever observed lichen (sometimes called. moss") growing on bare rock or on a tombstone ?
This question is intended to call attention to the fact that low forms of plant life are important in the early stages of soil formation.
8. If any great amount of lichen should become mixed with the disintegrated rock, would it be humus and form a weak soil that )night produce an order of plants a little larger and stronger than lichen ?
This mixing of the moss with the pulverized rock would be the first step toward making a soil of good physical qualities.
9. As the higher orders of plants come in and die down and mix with the soil, would the process increase the productive power of the soil ?
Yes, within certain limits. The more decaying vegetable matter the soil contains, generally the more productive it is.
io. In instances in which soil has been removed by grading, could a new soil be well made by adding commercial fertilizer alone? W What would you apply first to such land?
The addition of humus would be of first importance. Commercial fertilizers would do little good applied to a soil in which there is no decaying vegetable matter. This would
propably be the condition in the case assumed in the question.
I I. If humus in soil under cultivation is perishable, ought it not to be the farmer's first care to keep good the quantity firstt found in the virg in soil?
THE PROBLEM OF IMPOVERISHED LANDS. I II
Yes; and this can be done only by adding humus from time to time in the shape of barn-yard manure and other forms of organic matter.
12. In addition to the humus returned to the soil in manure, from forage fed to stock, and by plowing under stubble and roots, do you think it a good plan to so7v some cover-crop in corn rows at last cultivation, and on oat and wheat stubble as soon as the crop is off, for plowing under the following spring?
Usually a cover-crop is desirable, and especially so if the soil is lacking in humus.
13. What are good crops for this purpose ?
Crimson clover, vetch, peas, rye, rape, barley, oats.
14. Which of these are leguminous plants? Name all the kinds of leguminous plants you know ?
The first three named. All the clovers, alfalfa, vetch, peas, beans, lupines.
15. Why is it advised to plow under the green-crops as soon as the land can be worked in the spring ?
These crops, if allowed to grow, would give off into the air much moisture needed by the permanent crop; and besides this, if left until they had made a large growth, there might not be enough moisture in the soil to cause them to decay.
16. Do you think a rotation of crops helps the soil to bear the strain of successive cropping ? If so, why ?
Yes: this practice admits of supplying humus by means of cover-crops'; it admits of tillage which sets free plant-food ; and as different kinds of plants require different proportions of the various plant-foods a rotation prevents an unequal depletion of plant-food, as might be the case if one kind of crop was grown continuously for a long time.
17. Are you aware that plan-food exists in the soil in both available and unavailable forms, and that when plants have used up most of the available portion we call the soil worn out.?
Most soils, even though unproductive, contain plant-food in large quantities, but it is in such condition or chemical form that plants cannot get it.
I8. Is it true that your soil is capable of being made an active laboratory in which changes will take place and some of this unavailable plant food be made usable?
112 BULLETIN 174.
It is only when the soil is in such condition that certain changes can take place, that the unavailable plant-food becomes available to the plant.
19. Are you aware that when the texture of your soil is poor, or in other words, your laboratory is out of order, the best commercial fertilizers or stable manures will not give the best results ?
The texture or physical condition of the soil is of first importance. A stone contains plant-food, but it will not grow crops because of its physical and chemical condition.
2o. Do you know that heat and air are important agencies in the changes going on in the soil, as they also are in the changes in a barrel of cider or in yeast in a pan of dough ?
Chemical changes in'the soil cannot take place to the best advantage when the air is excluded, or when certain definite temperature cannot be maintained.
2 1. Does standing water on soil have a detrimental or beneficial effect on the heat and air ? Why ?
Detrimental, because it keeps the temperature too low and excludes the air; and soil texture is impaired.
22. How can you make the soil laboratory do the best work?
By making and preserving the best physical condition possible.
NO. 2. TILLAGE AND UNDER-DRAINAGE: *REASONS WHY.
I. What proportion of farmers in your neighborhood farm it like Mr. Black ?
Apply the test to yourself, and see if you are using good, economical business methods in carrying on your farm.
2. How is farming to be made to pay,-by gelling higher prices or by cheapening cost of production ?
Prices are largely beyond our control ; the cost of production very largely rests with us. At least, this is true within certain limits.
3. Do you expect permanently. higher prices for farm produce?
The past may be taken as a reasonably fair indication of the future.
4. Do you set a certain yield before your mind when yov are preparing for a crop? Or do you expect to be content with what comes f
THE PROBLEM OF IMPOVERISHED LANDS. 113
In the first case, you are farming with your head as well as with your hands, and the aim is to control circumstances as much as possible: the work is done on a good business basis. In the latter case, you are allowing yourself to be ruled entirely by circumstances and your work is not conducted in a good businesslike manner. The same careful, judicious business management is necessary in farming that is needful in a successful commercial enterprise.
5. An inch of rainfull weighs about 113 tons to the acre. About 3oo tons of water is required to produce one ton of dry mailer. Do you have rainfall enough in June, July and August to maintain a heavy crop of Indian corn or cabbage ?
In considering this question one lnust'keepin mind the factthat much of the rain-fall drains off into streams, especially on hilly land ; also that large quantities are evaporated before the plants can take it up. On account of these losses only a part of the rain is availablefor the plants. Usually therainfall in midsummer is not sufficient to maintain a heavy crop, and so we must try to save, by thorough cultivation, what fell earlier in the season.
6. Does surface tillage make soil moist, or keep it moist?
It keeps it moist by preventing the soil from drying out. When soil is left undisturbed for a long time, and it becomes packed down, the moisture in the soil works toward the surface and is evaporated, passing off into the air. Tillage makes a surface mulch which the soil moisture cannot readily pass through. It is equivalent to covering the soil with a layer of straw or a board. Every farmer knows how moist it is under a pile of straw which has remained in the same place for some time, or under a board. This straw or board does not make the soil moist but prevents it from becoming dry. This is what tillage does.
7. Why does deeplallfplowing make soils" warm" or "early" in spring ?
Land so treated tends to dry out earlier in the spring than unplowed soils; and soils which dry out early in the spring are "warm and consequently early."
8. Whzal prop6orlion of farmers in your vicinitfi practice underdrainage ?
The important point to be considered is, Does your farm need under-draining?
114 BULLETIN 174.
9. How many of the farms need under-drainage?
There is comparatively little land which will not be improved by under-draining.
IO. How deep and how jar apart would you lay under-drains?
The distance apart should be governed in a measure by the depth: the deeper the drains, the farther apart they may be placed. The contour of the land and the nature of the soil will also influence very materially in the matter. In a general way we may say that in moderately porous soils drains three feet deep should be from 30 to 40 feet apart.
i i. Do the farmers of your neighborhood have enough diferent kinds of tools to enable them to till their land cheaply and efficiently ?
This will depend upon the nature of the soil and the kind of crops grown. It is a good question to think about.
12. How many different kinds of tillage tools should a man have to.farm it properly if he has Ioo acres devoted to general farming, of which half is clay' and half sandy soil?
This question is too general to admit of any one fixed answer. Each farm differs in some respects from every other, and the tools used on the one farm probably would not be exactly suitable in all details for another farm. Let each man answer.
13. How often would you till afieldof corn orpotatoes?
Often enough to keep the soil-mulch in good condition,-that is, light and loose. Study this question.
14. Why do i'ou till your corn or potatoes? Are weeds the leading problem in your mind "
The keeping of the soil-mulch light and loose should be the leading idea. When this is done, few if any weeds can grow.
NO. 3. FERTILITY OF THE SOIL: WHAT IT IS.
i. Do plants obtain all their foodfrom the soil?
A part comes from the soil and a part from the air.
2. Wtat do you mean when you say that soil is exhausted,-that it has no more plant-food in it, or merely that it fails to produce crops ?
When a soil merely fails to produce a crop, it is usually said to be
THE PROBLEM OF IMPOVERISHED LANDS. 115
exhausted, regardless of the amount of plant-food which it may contain.
3. May a soil fail to produce crops and yet not be exhausted of plant-food?
Yes; the plant-food must not only be present but it must be in such a form that the plantscan use it. The physical condition of the soil also has much to do with the size of the crop. A soil which is hard and lumpy, containing an insufficient amount of humus, will not produce a good crop, even though it contains an abundance of plant-food.
4. If there are 13 plant-foods which are positively essential, why do we commonly speak of only 3 of them as plant-foods-of nitrogen, potash, phosphoric acid ?
All the other plant-foods are sufficiently abundant in an available form in most soils, so that they do not have to be considered in maintaining the fertility of the land.
5. Do you know if there is any difference between phosphorus and phosphoric acid? Write the chemical symbolfor each.
Phosphoric acid is a certain amount of phosphorus plus a certain quantity of oxygen. The symbol for phosphorus is P; for phosphoric acid, P,O,.
6. Is there any difference between potassium and potash? Write chemical symbols for each.
Potash is potassium plus oxygen, combined in a certain definite proportion. K stands for potassium; K-O for potash.
7. Write the chemical symbols for calcium and lime.
Ca is the symbol for calcium; CaO stands for lime.
8. Where do phosphorus, potassium and calcium come from,fromnt the ground or from the air? Are they gases or solids?
They come from the ground. They are solids.
9. Where does oxygen come from ?
It comes from the air; about onV-fifth of the air is oxygen and four-fifths nitrogen.
Io. Do you know if phosphorus, potassium and calcium exist in nature in their fure state?
In nature they exist only as compounds with other substances.
i i. Does oxygen exist anywhere in a pure or uncombined state?
Ix16 BULLETIN 174.
Yes; oxygen exists in the free or uncombined state in the atmosphere. About one-fifth of the atmosphere is oxygen.
12. Of what is water composed ? Write its chemical formula.
Of hydrogen and oxygen; the symbol or formula is HO.
13. Of what is ammonia composed? Is it a gas or liquid ? Can you buy pure ammonia at the drug store ?
It is composed of nitrogen and hydrogen (N H,). It is a gas. Ammonia of the drug stores is water which has absorbed some of the ammonia gas.
14. Does the plant feed on ammonia directly?
Very little if at all. It must first be changed to a nitrate.
15. What is the composition of a nitrate? Write the formula for nitrate of potash and nitrate of lime.
Nitrates are the result of treating substances with nitric acid. F6r nitrate of potash it is K NO3,; for nitrate of lime, Ca (NO,),.
16. In what kind of materials does nitrogen otcur? Name some common things which you think contain nitrogen.
Nitrogen occurs in organic materials, as in plants and animals. In meat, leather, hair, milk,humus of the soil, cotton-seed meal, etc.
17 Is nitrogen a solidor agas?
It is a gas.
18. Are nitrates of polash and soda solids, liquids or gases?
They are solids.
19. Are nitrates soluble? Is there danger of their being lost from the soil ?
Yes. Loss is likely to occur, especially on land which remains for a long time with no crop on it.
20. What is an amendment ?
A substance which, while it has little or no value as a plantfood itself, acts in such a manner as to make plant-food already in the soil more available, or which improves its texture.
21. Is the soilin your garden sour? Try it.
See Reading-Lesson No. 3, page 7.
22. In what materials can you buy phosphoric acid for fertilizer purposes?
The most common materials are forms of bone. South Carolina rock and Florida rock are ancient deposits of fossilized
THE PROBLEM OF IMPOVERISHED LANDS. 117
bone. Ground fresh bones are sometimes used as a source of phosphoric acid.
23. in what can you buy potash.
The common commercial forms of potash are sulfate of potash and muriate of potash. Wood ashes is also a source of this plant-food.
24. In what can you buy nitrogen ?
Sulfate of ammonia and nitrate of soda are common forms. Cotton-seed meal, dried blood and tankage are some of the organic sources.
25. Are there any home fertilizers, o? common farm materials (aside from barn manure), in which you can g-et these elements ?
The plowing under of green-crops, like clover, peas, vetch and the like will furnish nitrogen ; wood ashes furnish the only home supply" of potash ; phosphoric acid must usually be purchased from the dealers.
NO. 4. HOW THE PLANT GETS ITS FOOD FROM THE SOIL.
i. Do the root-hairs finally, become roots, or do 1heV stay on as the main root grows ?
The root-hairs never become roots. As the young rootlets which bear the root-hairs enlarge and their tissues become hard, the root-hairs perish.
2. Are there root-hairs on old roots.
3. On what part of the roots are the root-hairs ?
On the young, tender rootlets.
4. Where does the radish plant, which you grew in moss or cloth, get nourishment for making the first root-hairs ?
This nourishment probably comes from the food-material stored up in the seed.
5. Why doparticles of soil adhere to a youngplant of wheat or cabbage when it is pulled up ?
Because the root hairs and rootlets are so numerous and in such close contact with the soil. The finer the soil, the closer and more extensive this contact is.
6. What do you understand by a solution ?
A substance dissolved in a liquid.
iI8 BULLETIN 174.
7. Giv2 an example of a substance which will dissolve in water, and one which will not.
Sugar will dissolve; sand will not.
8. May materials which are insoluble in rain water be soluble in soil water? Why? (Consult Less. 3.)
Yes. Because the soil water contains carbonic acid gas in solution and this increases the dissolving power of water.
9. Does warming the water increase its power to make substances soluble ?
1o. Write a definition of osmosis. (Consult dictionary or some school book on physics or natural philosophy.)
It is the tendency of two liquids of different density to pass through a membrane or porous wall which separates them.
ii. Why does the soil water go into the root-hair ?
It is largely on account of this osmotic tendency or action. The outer walls of the little root-hairs constitute the membrane ; the sap or moisture in the cells of the root-hairs and the soilmoisture represent the two liquids separated by the membrane. (See Reading-Lesson 4, fig. 3.)
12 Why does not the liquid in the root hair flow out into the soil?
Because the sap in the hairs is denser than the water or moisture in the soil; that is, it contains a larger percentage of solid matter in solution. When two liquids of different density are separated by a membrane, the passage of the liquid through the membrane is in the direction from the less dense to the more dense.
13 What would happen il the liquid in the root-hair and that in the surrounding soil were of equal density ?
There would be little or no movement of the water from the soil into the root-hairs and the plants would die.
14. Must all food materials in the soil be in solution before the plant can use them ?
15. Does the plant ever utilize materials which are insoluble in the soil water ? How ?
Yes; the roots of plants are slightly acid and this increases the dissolving power of the moisture in contact with the roots.
THn PROBLEM OF IMPOVERISHED LANDS. 119
16. How is it that plants can live and grow in a soil which is dust dry ?
Even the soil which seems to us dust dry really contains very minute amounts of water; and so long as this is the case osmotic action goes on though, of course, very slowly when the soil is "dust dry."
17. Can your soil be so loose as to have too much air for the good of the plants ?
Yes. This is sometimes the case in very light sandy or gravelly soils.
18. Do you understand that you can smother the root as well as the top of the plant ? How ?
Yes. The roots need air as well as the top. Soil which is constantly soaked with water prevents the air from coming in contact with the roots; smothering results as one of the effects of too wet land.
19. At what season do you suppose that corn roots absorb the most moisture ?
When the corn is making its most rapid growth.
20. At what season do you have the least rainfall ?
During -the summer season when plants are growing most rapidly.
21. If you knew that you would not have sufficient rainfall in August to maintain your potato crop, how would you plan to secure the moisture ?
Prevent evaporation so far as possible by means of a surface mulch. This means thorough tillage.
22. Name one way in which plants are injured by too strong dressings of potash or nitrogen.
If applied in such large quantities that the soil moisture dissolved larger proportions than were contained in the sap-that is, if the density of the soil moisture became greater than of the saposmotic action would be from the plants to the soil and the plants thus giving up their moisture to the soil, would wilt.
23. Ifall the potash in your cornfield were to become suddenly available, what would happen ?
The corn would be killed and heavy rains might leach much of the potash from the soil.
120 BULLTIN 174.
24. How might you apply muriate of potash so that strawberry plants would be injured ?
By applying in large quantities too close to the plants.
25. Would it be an easy matter to injure old apple trees by muriate of potash ? Why ?
If applied in very large amountsdirectly overtheroots, injury might follow ; but such injury is rare.
26. If you put the fertilizer in the hill, will not the roots grow beyond and away from it, as the plant grows ?
Yes, to a large degree.
NO. S. HOW THE PLANT GETS ITS FOOD FROM THE AIR.
i. What portion of its dry substance does the plant secure from the soil ?
The amount is variable, but on an average about 3 per cent. Some varieties of plants take up much more and others less than 3 per cent.
2. What one substance or compound is taken in most profusely by the plant ?
3. How does the plant get its water,-through roots or leaves?
Through the roots.
4. In what part of the plant does the water ascend-through the young wood, or between the bark and wood?
It ascends through the young wood.
5. Where does the plant get its carbon ?
From the air.
6. How does it take in its nitrogen,-by roots or leaves ?
By the roots.
7. Where is the starch manufactured ?
In the leaves and other green parts.
8. From what substances is the starch made ?
From carbon dioxide and water.
9. Of what elements is starch composed ?
Of carbon, hydrogen and oxygen.
io. Into what is the starch changed before it is transported?
It is changed into sugar.
i i. What use is made of the material after it is transported ?
THU PROBLEM OF IMPOVRRISHRD LANDS. 121
It is used in the growth of the plant.
1 2. Through what part of the plant does the s/arch-like material (or elaborated sap")pass ?
It diffuses through the layers of the inner bark.
13. The root takes in water containing food: Can it use this food material directly in making root-growth ? Why?
No. This food material is taken into the plant in a crude condition, and it must be transported to the leaves where it unites with other materials before it can be used in the growth of the plant.
14. Why is starch stored in seeds and tubers ?
To be used by the seedlings or new plants when growth first begins, and before the plants are sufficiently developed to take their food from the soil and air.
15. Is starch stored in twigs in the fall?
I6. Are the flowers of peaches, and other early bloomingplantsi fedfrom food taken in at the root at the time, or from materials stored in the twig ? (Think how the potatoes sprout in the bin.)
From materials stored in the twig the year before. It is for this reason that the condition and health of the trees this year influence so largely the crop of next year.
.17. /Uill mulching the roots qf a peach tree with straw when the ground is frozen delay the blooming in the spring ?
No ; because there is food enough in the twigs to feed the blossoms, and as soon as the weather is warm enough this food is available.
18. Soil water holds very little food for plants ; the roots must take in enormous quantities of water; what becomes of some of this water?
It passes off through the leaves.
19. Is the waterwhich evaporates from the soil of any direct use to the plant ?
No, not of itself.
2o. The plant needs water,-it sweats it out; how shall wa manage so that thefplant can have all the water it needs?
An abundance of water goes into the soil (in New York) every year, but it is not equally distributed. When the plants need it most is the time when there is usually the least rain. The only
122 BULLETIN 174.
way we can help the plants (unless we irrigate) is to preserve the moisture so that it becomes available when it is most needed. This may be done by draining the land, and in this way increase the storage capacity of the soil (See Lesson No 2) ; and by keeping a good earth-mulch on the surface so as to prevent, as much as possible, the evaporation of the water from the soil.
21. Write down all the substances (or materials) you know which the plant must have in order to live and grow.
Nitrogen, phosphorus, potash, lime, iron and sulfur were given in Lesson No. 3 as some of the necessary plant-foods. Carbon, hydrogen and oxygen are also necessary.
22. Which one of these does nature supply in sufficient abundance, without any thought on your part ?
23. What ones can you help nature to supply .
Nitrogen, potash, phosphoric acid, lime and water.
24. Name all the congenial conditions (or agencies) which the plant must have in order to be comfortable and to grow.
A certain temperature ; a certain water supply ; a certain amount of humus; good texture; and a sufficient supply of plantfood.
25. What ones of these canyou help nature to supply or maintain.
We can influence the water supply, add plant-food and humus, and maintain good texture.