FARM AND FIELD.

Alexandra Herald and Central Otago Gazette, Issue 964, 3 February 1915, Page 7

FARM AND FIELD.

ORIGINAL ARTIOS.Se. (By F.0.i.) PRINCIPLES OF MANURINC. A manure is a substance which increases the fertility of the soil and causes it to grow larger crops. It is only since the beginning of the 19th century that any accurate knowledge has been obtained of the functions of manures and the principles of manuring. In its origin to manure meant to work the soil by hand, and hence to till. An early belief was that manures helped to pulverise and till the soil, and that their use to the farmer was an instrument of tillage. Our modern knowledge teaches us that while manures havo much wider uses, there is a certain germ of truth in this idea. During the 19th century various theories as to the action of manures were put forward from time to time, and gradually by continuous experiment our knowledge of the action of manures and of the means by which they increase the fertility of the soil was built up. Manures improve the soil in two main directions:—(l) By adding to it by their roots; and (2) by improving its mechanical condition so as to make it a more kindly and .suitable medium for the growth of crops.

Plants require from the soil a variety of different substances, which are sometimes spoken of as "plant foods." These really form the crude constituents from which the plant elaborates its true food. The plant is built up mainly of compounds of carbon, hydrogen, oxygen, and nitrogen, and contains in addition smaller proportions of compounds of phosphorus, sulphur chlorine, potassium, calcium, magnesium, and iron. Compounds of certain other elements are generally present also, but all those mentioned above are not only always present in plants, but are all essential in plant life. Of these elements the carbon is obtained from the atmosphere through the leaf, all the others are obtained from the soil through the root. If a soil is uniblo to supply any one of these elements of crude plant food in a state fit for assimilation by the root that soil will be infertile. It is not sufficient that the soil should contain these different elements; in order that it may !>" fertile it must contain them in a state available to the crops or grass.

POTASH AND POTATOES. It is well known that nitrogen is most essential for cereals, phosphate for turnips, and similarly that potash is the great requisite for potatoes. This does not mean that the other constituents are not also necessary—they are necessary, because without their cooperation the plant could not thrive; their presence enables the plant to make the best use of the potash. Analysis or" the tuber shows tho relative proportion of its plant food requirements. A crop of ten tons of potatoes extracts from the soil 1281b of potash, 781b of nitrogen, and 721b of phosphate per acre. As Mr. Hall, of the experiment farm, says: "Potash is essential, as the potato is a starchmaling plant." Another point to be noticed is that the potash' to be properly utilised by the plant during its growth must bo in a form readily soluble, hence the potash in commercial fertilisers yields better results than the [>otasb in farmyard manure. These are facts which have been established by numerous experiments at agricultural stations, and have been proved by field practice on a large scale. Not only is potash necessary to enable the plant to produce a largo crop, it has also the very valuable propertv of helping the plant to resist disease, a pioporty which is particularly valuable with the crop in question. * So Professor Desprez, well known as a practical agricultural scientist in France, found after a careful investigation of potato disease in the important potato growing districts in tho north of France, that one of the. causes contributing to the development of the malady was the lack of available potash in tho soil. "••-4fc»-

LIME WATER FOR CALVES. Lime water is so easily mado and is so useful on the farm that it is a wonder that a supply of it is not kept for some purposes, such as treatment for troubles like diarrhoea and indigestion. Calves which are being fed from the bucket often . benefit considerably by being given some lime water. The proportions may bo of some such ratio as a quarter or one-third of lime water to the ration of milk. This prevents acidity and also the formation of tho milk into unduly largo and indigestible curds. Lime water is made by adding two ounces of slaked lime to, say, half a dozen pints of water. The mixture should bo stirred briskly and then allowed to settle. The undissolved matter will go to the bottom of the vessel and the lime water can then be poured off. 'Jlio solution is then readv for use. FERTILISING MICROBES. Professor Bottomley delivered a lecture on "Bacteria of the Soil" recently. In tho soil, he said, microbes were comparatively few near the surface, where they were under the influence of sunlight. They mostly congregated at a depth of three to six inches, and had an average theoretical power of multiplication from one to 10,000.000 in twenty-four hours, but this rato was not actually maintained, for their own products checked their increase. Their function was to break up organic matter into food and refuse. Tho fertility of soil depended on the number of bacteria it contained. An organism named Azotobacter, and discovered about ten years ago, would, in the lecturer's opinion, revolutionise agriculture. Its uower of absorbing enormous quantities of nitrogen from the atmosphere and converting it into nitrogenous manure was estimated as equivalent to 28 c.rt. of nitrate of soda to the acre in one month. Knowing the money value of each cows milk for the month, and the cost of her feed, one can find the net value of each cow in the herd each month sho is giving milk. This can be ascertained only by regular and systematic weighing and testing. - The nitrogen in humus -must he changed into ammonia and nitrates before it becomes available to crops. Fresh vegetable residues have been found to undergo this change more

readily than old huiniis substance. Lime •assists ; n hastening the change.

Warm milk roffers a great [attraction to various species of Bacteria, which are always present in great numbers in the air of the cowshed. In order to keep the milk, as free as possible from bacteria, the first step is to milk in a cleanly manner, and to remove the freshly-drawn milk from the milk-ing-shed. The milk should then be well cooled, unless it is to be separated at once, or made into cheese.