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Show I AGRONOMY Edited by Prof. J. S. Hogcnson, A. C. U. SOIL BACTERIA AND THE FARMER. Very few persons realize as they go about their daily tasks, as they plow, harrow, sow their crops and fill their storehouses with the gathered gather-ed crops; that the soil is really alive and that every ounce contains millions mil-lions of living organisms infinitely small, yet capable of doing great and important work. Few farmers realize rea-lize that much of the work done on the farm is done to get the soil into suitable condition for a congenial dwelling place for these living organisms or-ganisms or bacteria, so that they will live and multiply there. Few farmers farm-ers realize also that the returns they get from the soil depend largely up- Ion these micro-organisms and that without their presence in the soil it would be practically inactive and in- t tertilc to a large extent. t Bacteria arc very minute organisms that belong near the border-line between be-tween plants and' animals. Their cx-istance cx-istance was not known until quite recently. Now, however, wc know that the rivers, the sea, the earth, the air, decaying and living plants, as well as dend tissues each have their special bacterial life. Thesc- arc in-' in-' ilumcrablc and vary in size, shape, and in the chemical changes which they produce. Bacteria are, the cause of the decay of dead plant and animal tissue. They arc the great scavengers which restore again to circulation the various vari-ous elements such as carbon, nitrogen, nitro-gen, hydrogen, sulpher, etc., that are locked up in dead plants and animals. Without them the dead' bodies would accumulate and not decay until all the elements necessary for life would be locked up and the deal life would cease to Hc. Their work,, however, cause the stubble and roots of cultivated culti-vated plants, the leaves and twigs of forest trees, the vast amount of refuse re-fuse and barnyard and green manure and the dead bodies of animals to be changed1 slowly into dark humus ana finally into soil, rich in plant foods that were formerly locked up. Nitrogen is one of the essential plant foods and although the air is composed of some seventy per cent of nitrogen, plants (with the except ion of one family) do not have the power of using it. Nitrogen is takcu by the roots of plants from the soil and then only when it is combined i with oxygen in the form of nitrates which arc simple substances when compared with the complex composition composi-tion of the manures and other organic or-ganic matter from which they arc taken by bacteria. All plant ana animal tissue contain certain compounds, com-pounds, rich in nitrogen, called pro-tcids. pro-tcids. In dead tissue these compounds com-pounds are acted upon by bacteria and so decay begins. The nitrogen which the decaying organic matter contains can not be made into plant food by a simple kind of bacteria. There arc at least three steps each preformed by a definite kind of 'bac- tcria. The first step is the formation of ammonia, the second is the formation forma-tion of nitrite from the ammonia, and the third is the formation of nitrite or plant food from the nitrite. (A nitrite, No. 33, contains one more atom of oxygen than does a nitrite 1 No. 22). Without the air of these 3 bacteria, then, the nitrogen com-pounds com-pounds which manure and dead plants and animals contain would not seem j available to living plants, hence these ' would cease to be after all the nitrites ni-trites in the soil were once used up. This brings up the point of the necessity of properly caring for the s manure made on our farms so that these nitrogen compounds when they arc formed will not be lost, because they arc all soluble in water and most of them arc volatile or will escape into the air as gasscs if not restrained. Manure then should be hauled onto the land as soon after it is made as possible and should be plowed under as soon as practicable, to prevent as much loss as possible. Manure piles that arc allowed- to heat, scorched by the sun and drenched drench-ed by rains will have lost practically all of their nitrogen.. If mnaute musi be piled, it should be done under a shed and on a concave cement floor which drains toward the -center. The bacteria that do the work wc ' have thus far spoken of are air loving lov-ing bacteria. They must have a large amount of oxygen to perform their work. We see the necessity then of keeping our soil pcrrcctly cultlvatca and in good tilth so that air can enter it readily that the bacteria, our little helpers, may be able to work properly. proper-ly. If we allow our soil to become hard and baked by crushing over the surface, we hinder the work of the bacteria very materially. As soon as the oxygen in the soil air is exhausted our friends stop working and their benefits arc lost to us. Immediately after the oxygen is exhausted, another class of bacteria which is harmful to the interest of the farmer 'begins to work, (these can work in the absence of air and oxy gen) These arc -called he denitrifying denitrify-ing bacteria and will undo in a very short time all of the good work performed per-formed by the beneficial bacteria. They break down the nitrates that have been made by our friends' and which plants can use as food. The denitrifying, bacteria do this by causing caus-ing the nitrate to part with its oxygen thus leaving instead of nitrate only nitrogen gas which then escapes into the air and is lost to the soil and plants. By neglecting our soil and allowing it to bake and become compact, com-pact, this process of breaking down the nitrates is greatly encouraged. Jcthro Tull who lived during the first half of the eighteenth century said that "Tillage is manure." This is true in that tillage loosens up the soil and thus allows air to enter moro freely so that the nitrifying and no-1 no-1 dulc-forming bacteria can better per il u.- frm tncr work of making available y-W1 plant food. It was early learned that leguminous plants (pod bearers) such as luccrn, clover, peas, 'beans, vetch, etc., ap-j ap-j parcntly made the soil upon which they had grown more fertile. Why this was so was not understood until 1886 when it was discovered that these plants invariably have small knots or nodules upon their roots, j and that these knots or nodules arc the homes of a certain class of bacteria, bac-teria, called "nitfrogen-gathering or nodule-forming" bacteria. These bacteria have the power of taking the free nitrogen from the air combining combin-ing it with oxygen so that plants, upon up-on which they develop -can use it The bacteria gather more nitrogen than the plants can use and hqnee store up considerable quantity of nitrates ni-trates in the plant itself as well as in sun ounding soil. When a leguminous crop is plowed under and decays the 1 i ua soil becomes richer in nitrogen than before the crop was grown, because the crop has drawn nitrogen from the almost incxhaustablc supply of the air and has stored it in the soil so that succeeding plants can make use of it. To increase the nitrogen supply in a soil, a rotation of -crop should be practiced. This rotation should include a leguminous crop. These arc only a few of the benefits which the farmer receives from the little silent workers in the soil. By proper guidance they work greatly to his gain, but by neglect, like the energies of a neglected child, they may work to his detriment and undoing. un-doing. The farmer should understand under-stand the environment and conditions condi-tions under which the various kinds of bacteria work and develop and always al-ways have those conditions in his soil which will encourage the development devel-opment of that class of bacteria which aid and bencfiit him to the exclusion of those that work against his interest. |