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Canberra Times, Friday 19 April 1929, page 2

Menace of Pasture Deterioration

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Preservation of health rather than prevention of disease should be the aim of those concerned with stock, pointed out the Chief Veterinary Surgeon of the Department of Agriculture in a lecture delivered before the Institute of Stock inspectors. It might seem a fine distinction in terms, but health preservation took the matter of disease prevention further back. Disease prevention was too often not attempted until disease had appeared, whereas health preservation stressed the idea of preventing disease appearing at all. Especially was such action possible in connection with conditions due to food deficiency and malnutrition.

The speaker referred to the wide need for greater attention to question of feeding, and the serious effect of insufficient or unsatisfactory feed or the health and productivity of stock. The veterinary officers and inspectors of the Department had been asked to consider existing conditions in this respect very seriously, and their comments had been invited. Some of these were very illuminating. On the subject of mineral deficiency, as a result of continuous grazing without any attempt to replace what was taken out of the land, the report of the Stock Inspector in the Armidale district was quoted.

THE PENALTY OF CLEARING

The writer referred to the decreased sheep-carrying capacity of pastures within that district as compared with thirty years ago, and deprecated strongly what was called "highly improving" grazing land by the general denudation of green timber. This, in his opinion, constituted the main cause of a decreased carrying capacity of land, and in the next twenty years, he considered the fact would be generally realised, and sylviculture would be adopted. The result of "ringing out" heavily timbered good sheep counutry was that, provided normal seasons prevailed, and area was not overstocked, the feed increased to abundance. After ten years the timber was stacked, burnt off, and the area cleared. Between fifteen and twenty years after being ringbarked, during which period the area hadd been continually grazed, indications of a falling-off in the body of feed became evident, and the grazing capacity during normal years now commenced gradually to diminish. Only be giving the area a good spell to allow for seeding, a practice by no means general amongst graziers, could the pastures recover temporarily.

At first the country was rich in natural manurial elements acquired from decaying vegetable matter in the leaves, bark, and wood. As the area was opened up and grazed over, these elements gradually (after a period of fifteen to twenty years, perhaps longer), became consumed or removed by grasses, winds and rains. Only in gullies where the humus had accumulated for centuries, was their presence evident in a luxuriant growth of feed. The hills in summer produced a short shoot, which, unable to survive the heat and winds, burnt off, leaving bare slopes, because these "highly improved" ridges had lost the natural fertilising agents provided by decaying vegetable matter from the timber. His observations had proved to him that the grasses were much superior on country on which the dead timber was left to rot, and thus provide a manurial substance, than on country where the limber had been burnt off.

GREATER DEMAND ON PASTURES

One aspect of the reduced sheep-carrying capacity of pastures during the last thirty of forty years had perhaps been overlooked—he referred to the greatly improved wool-yielding capacity of the sheep, which had been advanced from about 5 lb to perhaps double that quantity. From their knowledge of sheep and wool it was recognised that the sheep producing the modern fleece required more or an improved feed to the old type producing a 5 lb fleece. Consequently country which carried 1,000 sheep of the old type thirty years ago, was now capable of grazing only perhaps 750 of modern type. The result of the increased wool produce must be an increased demand from the soil. The manural elements passed from the animal were incapable of compensating the soil for the mineral food extracted through grazing, and as a consequence the soil, gradually denuded of its natural fertilizer, and after years of grazing, produced feed which was deficient in the more essential mineral elements necessary to produce or sustain healthy animal life.

To combat disease by the preservation of health or to win back a general healthy condition of our flocks was undoubtedly only to be obtained by returning to the soil that which we had for years been extracting in producing wool and carcase. The era was not far distant when pastoralists in general would recognise the necessity of cultivation as the direct means of preserving the health of the stock. Messrs Gattenby and Horsefall, of the Forbes district, had proved this during the 1902 drought by obtaining remarkably favourable results, with sheep on cultivated areas, assisted by irrigation. Messrs. H. White, of Bald Blair and L. Dutton of Urandangie, Guyra, had for years adopted the scheme of cultivating grazing areas. The condition of their stock and holdings should convert the most prejudiced person.

A WIDELY NOTICEABLE CONDITION

In some districts which had been more recently developed, the truth of the foregoing observations might not be recognised, commented the lecturer. Those districts were approaching or were at the peak, they were still living on the reserves of food material stored up in the soil through unknown periods of time during which the demand on the soil was practically nil. when that reserve became exhausted, they would begin to go downhill, and the result would be malnutrition and ill health in the stock. The thing was a mathematical certainty. The length of time before such a tendency was exhibited would depend on the richness of the soil.

Now was the time to take action in districts which were not yet suffering.

By doing so, a vast amount of future disease would be prevented. As regards those districts which were already on the down grade, steady and constant work would be necessary to bring them back to such a level that they would satisfactorily maintain healthy stock.

Cases constantly come under notice where even alluvial soils, ordinarily rich in all plant foods and minerals, had owing to long periods of cultivation and grazing, without any attempt to carry out manuring, become poor in certain plant foods, and definitely deficient in minerals. This mineral deficiency was widely noticeable, and was by no means less apparent in many of the wheat districts than elsewhere because the manuring of the crops was not without some residual value.

 


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