The Beneficial Bacteria

The Beneficial Bacteria The Farmers' Invisible Friends By Dr. J. E. Greaves, Bacteriologist, Utah Agricultural College The terms "bacteria," "microbe" and "micro-organism" suggest to the minds of many some minute body, usually animal, which inhabits everything in the world, and the function of which is to make man miserable — a something which is injuri- ous and the sooner the world is freed of them the better it will be for the human race. This, however, is a wrong attitude, for, in the first place, they are minute plants and not animals, and, in the second place, there are many more beneficial bacteria than there are injurious ones. It is very conservative to state that there are at least ninety-nine beneficial bacteria upon this universe to every one that is injurious, and it can be further stated, without fear of contradiction, that without them life upon this planet would be impossible! When we come to real- ize these facts the study of bacteria takes on a new and more interesting aspect. But, we may ask, if this be true, why do we hear so much concerning the injurious microbe and so little concerning the beneficial one. There are two main reasons for the existence of this condition: namely, when an outlaw com- mits some crime against human society it is heralded far and near and all hear of it. The machinery of the law is set m operation to apprehend the culprit and bring him to justice. So it is with these outlaws in bacterial society. ihe typhoid, or perchance some other disease-producing organism, attacks £ome individual or it may be an entire community. We hear ot the horrors of the disease. If it be typhoid we hear of the long-drawn-out fight between the human individuals on the one hand and the invisible enemy on the other If it be not checked we find it spreading to other places, and, during the Dark Ages sweeping like a prairie fire over a whole continent. So this

882 IMPROVEMENT ERA him and given him a place in the Rogue's Gallery. All have heard and are on the lookout for him. On the other hand, while we see and admire the magnifi- cent structures and complex institutions which have been reared by the mind and hand of man, we see and pass on. In many cases we do not stop to contemplate the countless millions living and dead who have contributed their mite that things might be as they are. Man does not have to protect himself against these honest toilers; hence, they go by unnoticed. They do not have the sensationalism to their work that there is to the work of the other class. So it is with the countless billions of beneficial bacteria; they toil on day and night, generation after generation, accomplishing good for the human race. We do not miss them for they have always helped us. They never become discouraged, but toil on for good until conditions be- come intolerable when they die and in many cases are re- placed by the bacterial outlaw. In a study of the beneficial bacteria we turn first to the soil, for from this — either directly or indirectly — man draws heavily for his food, clothing, and necessities of life. The soil is not as man may think — a dead, inert mass, but it is teeming with life! Both invisible plants and animals inhabit it by the millions. These have been at work within it long before man began to till the soil. In the formation of soil from the primitive rock, bacteria played no small part. The changes wrought by the elements first giving them a foothold. The changes of temperature which occur tear huge rocks from their mooring and break them into fragments. It is a well- known fact that most substances, when heated, often expand and contract in varying degrees so that parts are put under a strain, and the strain at times is sufficient to cause cracks of varying sizes to occur in the rock, a result which may be illustrated by the sudden cooling of hot glass or the sudden heating of cool glass. Throughout the long, hot days of summer, the rocks are heated to a comparatively high temperature, as the boy realizes who has chased barefooted over their surface in quest of grasshoppers or butterflies. At night they cool. This is repeated day after day. This continued heating and cooling grad- ually causes small crevices to appear in even the most resistant. These become filled with water and dust; when the cold nights of autumn come this water is frozen. In freezing, the water ex- pands and the rocks are broken into pieces; so it continues day after day and year after year, until the rock becomes a fine powder, but even then the plant food is insoluble and cannot be taken up by the plant. Long before it has reached the form of powder, bacteria start to grow upon the surface of the rock and in the crevices, and in their growth they form acids which

THE BENEFICIAL BACTERIA 883 act upon the insoluble plant foods bringing them into solution. Bacteria continue their work long after the rocks have been changed to soil, each day liberating a little more plant food for the growth of plants during that day. During the year the bacteria are able in a fertile soil to liberate enough plant food for the production of a good crop. When manure is applied it not only supplies food for the growing crop, but it also supplies food for the micro-organiems and they in turn liberate more of the insoluble constituents of the fine rocks within the soil. So we find millions of them in every ounce of soil struggling, to be sure, for their very existence, but always rendering a little more inorganic plant food available for the farmer's crop. One of the essential elements for crop production, and the one which is usually in the soil in the smallest quantities, is nitrogen. This, unless it be applied to the soil in the form of the costly fertilizer, sodium nitrate, must be prepared for the plant by bacteria. The farmer finds his crop is limited directly by the speed with which these classes of organisms prepare the food for his growing crop. If they are active, other things being favorable, he will get a good crop, but if they do not play their part — everything else may be ideal — and yet there is no crop. Bacteriological examination of cultivated soils has shown that usually those which are richest contain the greatest num- ber of bacteria. The number in the soil is dependent upon the quantity and character of food the bacteria find in the soil. If the soil is rich in plant residue, barnyard manure, and the like, many bacteria will be found there pulling these substances to pieces, liberating gases and acids which act upon insoluble particles of the soil and render them soluble. One class of or- ganisms changes the protein constituents of the soil into am- monia. This type we speak of as the ammonifiers. One can often detect their activity from the odor of ammonia coming from manure heaps. Most plants cannot, however, use nitrogen in the form of ammonia; it must be in the form of nitrates. This transforma- tion is brought about by two distinct types of organisms. One of them feeds upon the ammonia produced and manufactures nitrous acid. Should the change cease at this point and nitrous acid accumulate in the soil in large quantities, plants would rot grow upon it for this is a poison to plants. But in soils properly cared for only minute quantities of nitrous acid are found. As soon as it is formed another type of organism feeds upon it and manufactures for the growing plant nitric acid. This, when formed, reacts with other constituents of the soil, such as limestone, and it is ready to be taken up by the plant to manufacture nourishing food, beautiful flowers, or fragrant perfumes for the human family.

884 IMPROVEMENT ERA Were it not for bacteria the world in time would be filled with neverchanging organic matter. The plant residues, trees, and animal bodies, would remain stored up in the soil, and with it that element, carbon, which in the form of carbon dioxide, is required by all green growing plants. Bacteria in getting the energy which they require in their life activity are continually liberating carbon so that it may start again on its wonderful journey of construction. And if the carbon and nitrogen could but speak to us what tales of wonderment they would tell, and the chemist, bacteriologist, and farmer would each be much wiser, for many of the changes through which carbon and nitro- gen pass, due either to the action of the lower plants, bacteria, or the higher plants with which the farmer deals, are so com- plex that even the scientist with his apparently magical meth- ods cannot follow them. We have considered so far only the plant food found in the soil and the changes through which it passes, but the farmer is usually more concerned with that substance which is lacking from his soil, and which must be placed within the soil; other- wise his yields are low. In many cases the lacking element is nitrogen and he notes from the fertilizer quotations that the elements will cost him fifteen cents a pound if he purchase it in the form of sodium nitrate, ammonia sulfate, or dried blood. If he stops to make a simple calculation he finds that it would cost him fifteen dollars for enough to produce one hundred bushels of wheat, and seven dollars and fifty cents for enough to produce one ton of alfalfa hay. And in these calculations it has been assumed that he could get back in the form of corn, wheat or alfalfa every pound of commercial nitrogen which he applied to his soil, which, on the face of it, is an utter im- possibility. So he has to look to other means of getting nitro- gen for his growing crop, and here again bacteria come to his rescue. There are seventy-five million pounds of atmospheric nitro- gen resting upon every acre of land. But none of the higher plants have the power of taking this directly out of the air. One family of plants, the Leguminosae, in which are included peas, beans, alfalfa, clover and many others, if properly infected by bacteria, have the power of using this atmospheric nitrogen and, under this condition and with these plants, nitrogen no longer remains the limiting element of crop production. For these microscopic organisms which live within small nodules upon the alfalfa are master chemists, and within their small laboratory they can bring about changes which man can only imperfectly imitate with costly machinery and under the action of powerful electric currents. In some of the experiments car- ried on at the Illinois Experiment Station these minute org-m-

THE BENEFICIAL BACTERIA 885 isms were found to be able to increase the first cutting of alfalfa hay $37.80 per acre, and this counting it only at the same price as we would have to pay on the market for an equivalent quan- tity of nitrogen in the form of a commercial fertilizer! If these crops be plowed under, the fertility of the soil would be in- creased to just that extent. One writer has said of them, "They not only work for nothing and board themselves, but they pay for the privilege." This is strictly true, for all they require is a plant on which to grow and a well aerated soil containing lime- stone. They cannot work in an acid soil. We have another set of nitrogen-gathering organisms within the soil which differs from the above in that they can live free in the soil and gather nitrogen, and they may, under ideal conditions, gather appreciable quantities of nitrogen. It is quite possible that much of the benefit derived from the summer fallowing of land is due to the growth of this class of organisms within the soil, storing up nitrogen for future gen- erations of plants. For it has been found that they are more active and found in greater numbers in such a soil. All the work which the farmer puts upon the soil to render it more porous reacts beneficially upon this class of organisms, for they not only love atmospheric nitrogen and oxygen, but they are absolutely essential to their life activities and they must be gotten from within the soil, for the minute organisms cannot live upon the upper surface of the soil, for to them the direct rays of the sun means death. But these are only a few of the many who help the farmer. They are at work in his silo rendering the food more palatable and nutritious for his cattle. They are working in his milk and cream, and if they be the right kind they give to the butter and cheese its desirable flavor. They take part in the tanning of leather, the retting of flax, the curing of tobacco, and, in short, they help us in a hundred and one ways in which we lit- tle suspect. And one of the most fascinating and instructive tasks set for man is to learn how to increase the work of the beneficial bacteria and to suppress or entirely weed out the in- jurious bacteria. Logan, Utah. Hark! the trumpet. Heroes, rally! Freedom's land shall still be free. Lo! they swarm from hill and valley, Loyal sons of Liberty. — Orson F. Whitney, L. D. S. Hymns.