Crops and Methods for Soil Improvement Part 2

The Right Bacteria.--The word "bacteria" has had a grudging admission to the vocabulary of practical farmers, and the reason is easily stated. The knowledge of bacteria and their work is recent and limited.

They are many in kind, and scientists are only in the midst of their discoveries. The practical farmer does well to let bacteriologists monopolize interest in the whole subject except in so far as he can provide some conditions that have been demonstrated to be profitable.

The work of bacteria must come more and more into consideration by the farmer because nature uses them to produce a vast amount of the change that is going on around us.

In consideration of the value of legumes we must take into account the bacteria which they have a.s.sociated with them, and through which they obtain the atmospheric nitrogen. This would be a negligible matter, it may be, if all legumes made use of the same kind of bacteria. It is true that the bacteria must have favorable soil conditions, but they are the same favorable conditions that our plants require. A fact of importance to the farmer is that the bacteria which thrive on the roots of some legumes will not serve other legumes. This is a reason for many failures of alfalfa, crimson clover, the soybean, the cowpea, hairy vetch, and other legumes new to the region.

Soil Inoculation.--The belief that the right kind of bacteria may be absent from the soil when a new legume is seeded, and that they should be supplied directly to the soil, has failed in ready acceptance because examples of success without such inoculation are not uncommon.

Even if the explanation of such success is not easy, the fact remains that legumes new to a region usually fail to find and develop a supply of bacteria adequate for a full yield, and some of these legumes, of which alfalfa is an example, make a nearly total failure when seeded for the first time without soil inoculation. Experiment stations and thousands of practical farmers have learned by field tests that the difference between success and failure under otherwise similar conditions often has been due to the introduction of the right bacteria into the soil before the seeding was made.

Explanations offered for any phenomenon may later become embarra.s.sing in the light of new knowledge. We do not really need to know why an occasional soil is supplied with the bacteria of a legume new to it. We have learned that the bacteria of sweet clover serve alfalfa, and this accounts for the inoculation of some regions in the east. We believe that some bacteria are carried in the dust on the seed, and produce partial inoculation. Other causes are more obscure. The cowpea trails on the ground, and carries its bacteria more successfully than the soybean. Most legumes require a soil artificially inoculated when brought into a new region, failing otherwise in some degree to make full growth.

Method of Inoculation.--The bacteria can be transferred to a new field by spreading soil taken from a field that has been growing the legume successfully. The surface soil is removed to a depth of three inches, and the next layer of soil is taken, as it contains the highest percentage of bacteria. They develop in the nodules found on the feeding roots of the plants. The soil is pulverized and applied at the rate of 200 pounds per acre broadcast. If the inoculated soil is near at hand and inexpensive, 500 pounds should be used in order that the chance of quick inoculation may be increased. The soil should be spread when the sun's rays are not hot, and covered at once with a harrow, as drying injures vitality. The soil may be broadcasted by hand or applied with a fertilizer distributer. The work may be done at any time while preparing the seed-bed. The bacteria will quickly begin to develop on the roots of the young plants, and nodules may be seen in some instances before the plants are four weeks old.

Pure cultures may be used for inoculation. Some commercial concerns made failures and brought the use of pure cultures into disrepute a few years ago, but methods now are more nearly perfect, and it is possible to buy the cultures of all the legumes and to use them with success.

Prices continue too high to make the pure cultures attractive to those who can obtain inoculated soil with ease. If land has been producing vigorous plants, and if it contains no weeds or disease new to the land to be seeded, its soil offers the most desirable means of transferring the bacteria.

The claim is made by some producers of pure cultures that their bacteria are selected for virility, and should be used to displace those found in the farmer's fields. The chances are that, if soil conditions are good, the bacteria present in the soil are virile, and if the conditions are bad, the pure cultures will not thrive. All eastern land is supplied with red clover bacteria, just as some western land possesses alfalfa bacteria, and partial clover failure has causes wholly apart from the character of its bacteria.

We do not have definite knowledge concerning duration of inoculation nor the manner in which it is maintained when legumes are not growing, but we do know that when a legume has once made vigorous growth in a field, the soil will remain inoculated for a long term of years.

CHAPTER V

THE CLOVERS

Red Clover.--Wherever red clover thrives there is no more valuable plant than this legume for making and keeping soils productive under ordinary crop-rotations. The tyro in farming finds his neighbors conservative in thought and method, and may rightly see room for improvement. He naturally turns to new crops that are receiving much exploitation, but should bear in mind that the world nowhere has found a superior to red clover as a combined fertilizing and forage crop for use in short rotations. Farmers turn aside from it because it turns aside from them. There has been increasing clover failure in our older states for a long term of years. It has become the rule to seed to timothy with the clover in the short crop-rotations as well as in the longer ones, and chiefly for the reason that clover seeding has become no longer dependable. In many regions the proportion of timothy seed used per acre has been made large because the clover would not surely grow. In the winter-wheat belt, where the custom has been to make such seedings with wheat, timothy being sown in the fall and clover the next spring, this increase in the timothy has made matters worse for the clover, but it has helped to insure a sod and a hay crop. "Clover sickness," supposedly resulting from close clover rotations, and the prevalence of plantain and other weeds, have been a.s.signed as a partial cause of clover failure. It is only within recent years that the true cause of much failure has been recognized.

Clover and Acid Soils.--There are limited areas in which some clover disease has flourished, and in some years insect attacks are serious.

Barring these factors which have relatively small importance when the entire clover area is taken into account, the causes of clover failure are under the farmer's control. The need of drainage increases, and the deficiency in organic matter becomes more marked. The sale of hay and straw, and especially the loss of liquid manures in stables, have robbed many farms. These are adverse influences upon clover seedings, but the most important handicap to clover is soil acidity. There is sad waste when high-priced clover seed is put into land so sour that clover bacteria cannot thrive, and there is ten-fold more waste in letting land fail to obtain the organic matter and nitrogen clover should supply. When land-owners refuse to let their soils remain deficient in lime, clover will come into a prominence in our agriculture that it never previously has known.

Methods of Seeding.--It is a common practice to sow clover in the spring, either with spring grain or with wheat or rye previously seeded in the fall. This method has much to commend it. The cost of making the seed-bed is transferred to the grain crop, and there is little outlay other than the cost of seed. Wheat and rye offer better chances to the young clover plants than do the oat crop which shades the soil densely and ripens later in the summer. The amount of seed that should be used depends upon the soil, the length of time the sod will stand, and the purpose in growing the clover. When soil fertility is the one consideration, 12 to 15 pounds of bright, plump medium red clover seed per acre should be sown. A fuller discussion of the principles involved in making a sod and of seed mixtures is given in Chapters VII and VIII.

Fertility Value.--Attempts have been made to express the actual value of a good clover crop to the soil in terms of money. The number of pounds of matter in the roots and stubble has been determined, and a.n.a.lyses show the percentage of nitrogen, phosphoric acid, and potash contained. The two crops harvested in the second year of its growth likewise have their content of plant-food determined. If the total amounts of nitrogen, phosphoric acid, and potash have their values fixed by multiplying the number of pounds of each ingredient of plant-food by their respective market values, as is the practice in the case of commercial fertilizers, a total valuation may be placed upon the clover, roots and top, as a fertilizer. Such valuation is so misleading that it affords no true guidance to the farmer. In the first place, the phosphoric acid and potash were taken out of the soil, and while some part of these materials may have been without immediate value to another crop until used by the clover, no one knows how much value was given to them by the action of the clover. Again, no one knows what percentage of the nitrogen in the clover came from the air, and how much was drawn from the soil's stores. The proportion varies with the fertility of the land, the percentage of nitrogen taken from the air being greater in the case of badly depleted soils.

A big factor of error is found in the valuations of the ingredients found in the crop. All plant-food is worth to the farmer only what he can get out of it. He may be able to use 50 pounds of nitrogen per acre in the form of nitrate of soda, at 18 cents a pound, when growing a certain crop, but could not afford to buy, at market price of organic nitrogen, all the nitrogen found in the clover crop, and therefore it does not have that value to him.

On the other hand, these estimates do not embrace the great benefit to the physical condition of the soil that results from the incorporation of a large amount of vegetable matter.

Discussion has been given to this phase of the question in the interest of accuracy. Values are only relative. The practical farmer can determine the estimate he should put upon clover only by noting its effect upon yields in the crop-rotation upon his own farm. It is our best means of getting nitrogen from the air, it provides a large amount of organic matter, it feeds in subsoil as well as in top soil, bringing up fertility and filling all the soil with roots that affect physical condition favorably, and it provides a feed for livestock that gives a rich manure.

[Ill.u.s.tration: Red clover on the farm of P. S. Lewis and Sons, Point Pleasant, W. Va.]

Taking the Crops off the Land.--The feeding value of clover hay is so great that the livestock farmer cannot afford to leave a crop of clover on the ground as a fertilizer. The second crop of red clover produces the seed, and, if the yield is good, is very profitable at the prices for seed prevailing within recent years. The amount of plant-food taken off in the hay and seed crops would have relatively small importance if manure and haulm were returned without unnecessary waste. Van Slyke states that about one third of the entire plant-food value is contained in the roots, while 35 to 40 per cent of the nitrogen is found in the roots and stubble. Hall instances one experiment at Rothamstead in which the removal of 151 pounds of nitrogen in the clover hay in one year left the soil enough richer than land by its side to produce 50 per cent more grain the next year. He cites another experiment in which the removal of three tons of clover hay left the soil so well supplied with nitrogen that its crop of Swede turnips two years later was over one third better than that of land which had not grown clover, the application of phosphoric acid and potash being the same. When two tons of well-cured clover hay are harvested in June, removing about 80 pounds of nitrogen, 45 to 50 pounds are left for the soil. The amounts of potash are about the same, while phosphoric acid is much less in amount.

Physical Benefit of the Roots.--While the roots and stubble contain less than two fifths of the total plant-food in a clover crop, one may not safely infer that the removal of the crop for hay reduces the beneficial effect of the clover to the soil fully 60 per cent, or more.

The roots break up the soil in a way not possible to a ma.s.s of tops plowed down. They improve the physical condition of the subsoil as well as the top soil. The amount of the benefit depends in part upon the nature of the land. Its value cannot be surely determined, but the facts are called to mind as an aid to judgment in deciding upon the method of handling the clover crop.

Used as a Green Manure.--Where dependence must be placed upon clover as a fertilizer, little or no manure being returned to the land, at least one of the two clover crops within the year should be left on the land.

The maximum benefit from clover, when left on the land, can be obtained by clipping it before it is sufficiently heavy to smother the plants, leaving it as a mulch. When the cutter-bar of the mower is tilted upward, the danger of smothering is reduced. Truckers, remote from supplies of manure, have found it profitable to make two such clippings just prior to blossoming stage, securing a third heavy growth. The amount of humus thus obtained is large, and the benefit of the mulch is an important item.

Some growers clip the first crop for a mulch, and later secure a seed crop. The early clipping and the mulch cause increase in yield of seed.

A common practice is to take one crop off for hay, and to leave the second for plowing down the following spring. Early harvesting of the clover for hay favors the second crop.

When to turn Down.--When the maximum benefit is desired for the soil from a crop of clover, the first growth should not be plowed down. Its office should be that of a mulch. In its decay all the mineral plant-food and most of the nitrogen go into the soil. The second crop should come to maturity, or near it. As a rule, there is gain, and not loss, by letting the second crop lie on the ground until spring if a spring-planted crop is to follow. Some fall growth, and the protection from leaching, should equal any advantage arising from rotting the bulky growth in the soil. In some regions it is not good practice to plow down a heavy green crop on account of the excessive amount of acid produced. When this has been done, the only corrective is a liberal application of lime.

Mammoth Clover.--When clover is grown with timothy for hay, some farmers prefer to use mammoth clover in place of the medium red. It may be known as sapling clover, and is accounted a perennial, though it is little more so than the red. It is a strong grower and makes a coa.r.s.e stalk but, when grown with timothy, it has the advantage over the red in that the period of ripening is more nearly that of the timothy. It inclines to lodge badly, and should be seeded thinly with timothy when wanted for hay. The roots run deep into the soil, and this variety of clover compares favorably with the medium red in point of fertilizing power, the total root-growth being heavier. While its yield of hay, when seeded alone, is greater than the first crop of the red, its inclination to lodge and its coa.r.s.eness are offsets. It produces its seed in the first crop, and the after-growth is small, while red clover may make a heavy second crop. Its use should become more general on thin soils, its strong root-growth enabling it to thrive better than the red, and the lack of fertility preventing the stalks from becoming unduly coa.r.s.e for hay. The amount of seed used per acre, when grown by itself, should be the same as that of red clover.

Alsike Clover.--A variety of clover that may have gained more popularity than its merit warrants is alsike clover. It is more nearly perennial than the mammoth. The roots do not go deep into the subsoil like those of the red or the mammoth, and therefore it is better adapted to wet land. It remains several years in the ground when grazed, and is usually found in seed mixtures for pastures. It is dec.u.mbent, and difficult to harvest for hay when seeded alone. It is credited with higher yields than the red by most authorities, but this is not in accord with observation in some regions, and it is markedly inferior to the red in the organic matter and the nitrogen supplied the soil in the roots.

The popularity of this clover is due to its ability to withstand some soil acidity and bad physical conditions. In regions where red clover is declining on account of lack of lime, one may see some alsike. The rule is to mix alsike with the red at the rate of one or two bushels of the former to six bushels of the latter. As the seed of the alsike is hardly half as large as that of the red, the proportion in the mixture is greater than some farmers realize. The practice is an excellent one where the red will not grow, and the alsike adds fertility, but when the soil has been made alkaline, the red clover should have nearly all the room. Alsike is a heavy producer of seed.

Crimson Clover.--Wherever crimson clover is sufficiently hardy to withstand the winter, as in Delaware and New Jersey, it is a valuable aid in maintaining and increasing soil fertility. It is a winter annual, like winter wheat, and should be seeded in the latter half of summer, according to lat.i.tude. It comes into bloom in late spring. The plant has a tap-root of good length, but in total weight of roots is much inferior to the red. This clover, however, compares favorably with red clover in the total amount of nitrogen added to the soil by the entire plant when grown under favorable conditions. It is peculiarly fitted for a cover crop in orchards and wherever spring crops are removed as early as August, or a seeding can be made in them, as is the case with corn. Even when winter kills the plants, a successful fall growth is highly profitable, adding more nitrogen before winter than red clover seeded at the same time. Where the plants do not winter-kill, they are plowed down for green manure when in bloom in May, or earlier in the spring to save soil moisture and permit early planting, although a good hay for livestock can be made, and the yield is about the same as that of the first crop of red clover.

In the northern states a large amount of money has been wasted in experimental seedings with crimson clover, and it is only in exceptional cases that it continues to be grown. There is reason to believe that many of these failures were due to lack of soil inoculation. The Pennsylvania experiment station is located in a mountain valley where winters are severe. Crimson clover is under test with other cover crops for an experimental orchard, and success with it has increased as the soil has become fully inoculated. This view is supported by the experience of various growers in the North, and while crimson clover can never make the success in a cold climate that it does in Delaware, there is a much wider field of usefulness for it than is now occupied. Experiments should be made with it under favorable conditions respecting moisture and soil tilth. Fifteen pounds of seed should be used, and the seed should be well covered, as is the case with all seeds sown in mid-summer.

CHAPTER VI

ALFALFA

Adaptation to Eastern Needs.--The introduction of alfalfa into the eastern half of the United States will prove a boon to its depleted soils, encouraging the feeding of livestock and adding to the value of manures. It will affect soils directly, as does red clover, when farmers appreciate the fact that its rightful place on their farms is in rotation with grain. Under western conditions, where no other crop can compete with it in value, as is the case in semi-arid belts, its ability to produce crops for a long term of years adds much to its value, but in eastern agriculture this characteristic is not needed. On most soils of the east it will not remain productive for more than four to six years, and that fact detracts little from its value. It should fit into crop-rotations, adding fertility for grain crops. When grown in a six-years rotation with corn and oats or other small grain, it furnishes a rich sod for the corn, and the manure made from the hay helps to solve the farmer's fertility problem.

Fertility and Feeding Value.--Vivian says that "the problem of the profitable maintenance of fertility is largely a question of an economic method of supplying plants with nitrogen." The greatest value of alfalfa to eastern farming lies in its ability to convert atmospheric nitrogen into organic nitrogen. It has no equal in this respect for relatively long crop-rotations, storing in its roots and successive growths of top far more nitrogen within three or four years than is possible to any other of our legumes. A good stand of alfalfa, producing nine crops of hay in the three years following the season of seeding, will produce from nine to twelve tons of hay. Good fields, under the best conditions, have produced far more, but the amounts named are within reach of most growers on land adapted to the plant. A ton of hay, on the average, contains as much nitrogen as five or six tons of fresh stable manure. Thus there comes to the farm a great amount of plant-food, to be given the land in the manure, and in addition the roots and stubble have stored in the ground enough nitrogen to feed a successive corn crop, and a small grain crop which may follow the corn. Moreover, the roots have filled the soil with organic matter, improving the physical condition of the soil and subsoil.

[Ill.u.s.tration: Alfalfa on the Ohio State University Farm.]

Another gain is found in the content of phosphoric acid and potash in the manure, much of which was drawn from soil supplies out of reach of the other farm crops. The profit from introduction of alfalfa into a region's agriculture is very great.

Alfalfa makes a nutritious and palatable feed for livestock. A ton contains as much digestible protein as 1600 pounds of wheat bran.

Climate and Soil.--The experimentation with alfalfa by farmers has been wide-spread, and the percentage of failure has been so large that many have believed this legume was unfitted to the climate and soil of the country east of the Missouri River. Successful experience has shown that it can be made to take a considerable place in eastern crop-schemes. The climate is not unfavorable, as is evidenced by large areas of good alfalfa sods on thousands of farms. The abundant rainfall brings various weeds and gra.s.ses into compet.i.tion with it, and that will remain a serious drawback until growers learn to clean their surface soils by good tillage before seeding.

Any land that is sufficiently well drained to produce a good corn crop in a wet summer can grow alfalfa if the seed-bed is rightly made. The loose soils are more difficult to seed successfully than is the land having enough clay to give itself body, although most experimenters select their most porous soils. All farms having good tilth can bring alfalfa into their crop-rotations.

Free Use of Lime.--The conditions requisite to success in alfalfa-growing are not numerous, but none can be neglected. Alfalfa should be given a calcareous soil when possible, but an acid soil can be made favorable to alfalfa by the free use of lime. There must remain a liberal amount after the soil deficiency has been met, and when the use of lime is on a liberal scale, the pulverized limestone makes the safest carrier. However, 50 bushels of stone-lime per acre can be used safely on any land that is not distinctly sandy, and that amount is adequate in most instances.

Inoculation.--The necessity of inoculation has been discussed in Chapter IV. Eastern land would become inoculated for alfalfa if farmers would adopt the practice of mixing a little alfalfa with red clover whenever making seedings. Some alfalfa plants usually make growth, securing the bacteria in the dust of the seed, presumably. The addition of one pound of alfalfa seed per acre would a.s.sist materially in securing a good stand when the day came that an alfalfa seeding was desired.

Fertilization.--The ability of alfalfa to add fertility to the farm, and directly to the field producing it when all the crops are removed as hay, does not preclude the necessity of having the soil fertile when the seeding is made. The plants find compet.i.tion with gra.s.s and other weeds keen under eastern skies where moisture favors plant-life. In their first season this is markedly true. There should be plenty of available plant-food for the young plants. Stable manure that is free from the seeds of pernicious weeds makes an excellent dressing. It is good practice to plow down a heavy coat of manure for corn and then to replow the land for alfalfa the next season. A top-dressing of manure is good, affording excellent physical condition of the surface for starting the plants. Eight tons per acre make a good dressing.

If land is not naturally fertile, mineral fertilizers should be applied. A mixture of 350 pounds of 14 per cent acid phosphate and 50 pounds of muriate of potash is excellent for an acre of manured land.

In the absence of manure, 100 pounds of nitrate of soda and 50 pounds of muriate of potash should be added to the mixture. If the materials are wet, a drier must be used. The fertilizer should be drilled into the ground prior to the seeding.