FARMING NOTES.

Pukekohe & Waiuku Times, Volume 4, Issue 40, 25 May 1915, Page 1

FARMING NOTES.

Bacteria in the Dairy.

Bacteria—the mysterious, invisible forms of life which exist all around us—play a very important part in the dairy. There are germs who:e action is desirable— necessary-for the production of typical characteristics in butter and cheese. Others there are which do not appear to have either a beneficial or harmful effect, and there are"~ many which cause trouble.

There is a constant warfare between the first mentioned and the latter tarietiee, in jjst fie same way as the white corpuscles Hi the animal blood stream wage war against the germs which gain an entry into the body. And ir just the same way the weakest goes under, and "diseases" in milk and its product?, otherwise bad flavour?, tints, decomposition, follow when the harmful germs prwe tte strongest.

It is only within very reee»t years that the study of bacteno logy, has come so much to the front, and as more and mora i 3 constantly being discovered, the great importance of tha subject is becoming more widely known ard understood. It is orly by understanding all about the causes, of things that we can influence their growth and development in whatever way will be most satisfactory to ourselves. Fur instance, when cream is intended for butter-' making we krow, and have known for a long time, tfcat very much better flavoured butter is obtained when the cream is first nicely "ripened." It has been discovered within recent years that the process known as "ripening" is due to the influence of a certain kind ot bacteria. It has alu been discovered that these germs are to be found in all dairies, and places where milk is, and has been kept. They are in the air, utensils, etc., and they grow best in nice clean surroundings, where the temperature is moderate. They do not like extreme heat or cold, but when conditions are made favourable for them they will grow very rapidly, and soon bring about the desired change in the cream. Now, when it is known what suits these germs the best, it is quite easy to arrange things so that their growth can go on unchecked. If they are given a proper chance they will very soon overcome,any other undesired germs which may have got into the cream. But if the cream has been allowed to become badly contaminated with the undesired germs before the others have had their chance, then the malignant ones will prove the strongest, and oust the "ripening" ones, and some bad flavour or other fault will spoil the butter that is made from the cream. It is bacterial contamination which causes a lot of the troubles in cheesemaking, and it is therefore of the utmost importance that every effort be made to keep the milk as free as possible from all harmful germs, Bacterial taints may cause considerable loss, and not only by spuiling one or two days' make, when the milk is received into the dairy in a contaminated condition, but they get ; into the air and utensils, and are liable D get into the fresh supplies of milk at any time, ar.d so carry 1 on the taint from day to day. For all practical purposes, the milk of a healthy cow may be considered quite sterile (that is, entirely free from germs). As soon as it leaves the udder it is liable to contamination by bacteria, and it depends entirely on the conditions under which it is drawn and treated subsequently what sort and how many bacteria get into it. There are bacteria everywhere—in the air, in water, in the groundso it is impossible to prevent them getting into milk once it has left the cows' udder. But we can influence both the number and kind if we go about it in the right way, and the right way is to know the habits and conditions of growth of various kinds of germs, and then encourage the ones , required by making conditions favourable for them, and inhibiting the growth of the others by making life difficult for them. It must be remembered, in the first place, that bacteria arc so minute that it requires a powerful microscope to Bee them at all, and then they only look about the size oi a pin prick. The reason these minute forma of life can bring about such changes and do so much harm is because of their rapid reproduction. When conditions are favourabe, some kinds are able Jo reproduce at the rate of one becoming two every half hour, and as tbey feed on the cnemical constituents ot milk and other substances, it is quite easy to realise how Boon they bring about a change in the substance they are feeding upon. Warm new milk forms an excellent medium lor the growth ! and reproduction of a large number ol varieties of germs. Chemically, it is a very complex substance, and there are in its composition all the elements necessary lor the support of animal life. Bacteria are very near the border line between animal and vegetable, but they can obtain from milk all that ia necessary to support their life. They do not feed on one particular constituent, and remove that entirely from the milk, but they take out one or two elements, such as carbon and nitrogen, and therefore alter the nature of the constituent. The iactic acid germs, which bring about "ripening," take what they require from the sugar in the milk, and after tbey have taken out their food the sugar ha& been converted into lactic acid.

Most cf tbc germs which have a harmful ioilocncc on dairy produce make a sort of resting place

amongst dirt, and wherever there are any accumulations of tilth there will be hordes cf germs. Every time the accumulation is moved by animals or workers stirring about there will be numbers of bacteria thrown into the air, and then they settle elowly, following the law of gravitation, when not drifted hither and thither by draughts and currents of air. It follows as a natural sequence that when cowsheds are allowed to become dumping grounds for all soits (f fil'h and rubbish, milk which is drawn from the cows in such surroundings will become badly contaminated and give all sons of tiouble later in the dairy. Perfect cleanliness, fresh air, and light are the best means of preventing contamination, and discouraging the growth oT harmful germs. The mow. useful ones are then given a chance and will perform their duty and prevent undesirable changes taking place.

The United States Department of Agriculture, after careful experiments, states that rape is unrivalled as a pasture for sheep in autumn, where it can be successfully grown. As a fattening feed in the held it is without a rival in point of cheapness or effectiveness. The sheep that patture upon it do the harvesting in a most efficient manner, and with but little loss to the owner; and the manure from it is distributed over the field which produced the crop, and in a form which is readily available for the plants of the succeeding crops. While i ape, thus grown and fed, does not add fertility to the soil, unless in the plant food it brings up from the subsoil, it does not detract from the fertility when the sheep which eat it off are enclosed upon it.

In an expeiirrent which was conducted throughout Ontario for five years the mangel crop was increased six tons per acre by an application of 1601b of nitrate of Eode when the plants were 3in tall. The same quantity of nitrate of soda applied at the time that the seed was sown increased the yield of mangels 5.6 tons per acre. In that part of tbs second experiment which corresponds with the first experiment the results are, therefore, quite similar-viz,, that an application of 1601b of nitrate of soda psr acre is likely to increase the mangel crtp about six tons per acre. Under average conditions of soil and climate in Ontario the yield of mantels per acre has been increased or decreased according to the amcunt of nitrate of soda which has been applied. The highest average yield of roots per acre in the average of the past two years was produced from 2001b of nitrate of soda per acre applied when the plants were about 3in in height. This increase amounted to 8.65 tons at a cost of 25s for the fertiliser, which amounts to 2s 10* d per ton, or a trifle over Id per bushel. Becent investigations go to show tbat the soil of a field is not an inert mass, but an aggregation of a highly intricate and complex nature. The "Chemical Trade Journal" directs attention to report on tbi9 subject issued by the United States Bureau of toils. The organic matter of the soil derived from decaying vegetation is estimated to average about fifty tons per acre. Much recent progress towards a better understanding of its nature and properties is reported by the United States Bureau of Soils, and r instead of consisting chieflv of some such substance as humic acid, as wub long supposed, it proves to be made up of a great variety of compounds. The late additions have increased the number of those that have been isolated and identified to more than forty. Some of the compounds contain oily carbon and hydrogen; some carbon, hydrogen and oxygen; some carbon, hydrogen, oxygen and nitrogen; and otberß have phosphorus ar.d solphur. Isolation of these constituents has shed mucn light on the changes in the soil's organic matter. Trr c impounds represent decomposition products of fats, carbonydrates, proteins and so on, and give usefol indications of the 'process of humus formation and transformation.