BUSH-SICK LAND.

New Zealand Herald, Volume LXVIII, Issue 20767, 9 January 1931, Page 16

BUSH-SICK LAND.

PROBLEMS OF DEFICIENCY.

SOIL AND PASTURE DEFECTS. NEED OF MINERAL SUPPLEMENT. In granting a sum of money, over a term of years, for investigational work on the mineral content, of New Zealand pastures, tho Empire Marketing Board made a valuable contribution toward tho solution of somo of the moro serious stock-raising troubles, and principally those known as deficiency diseases, in the Dominion. Initial instructions to the director of tho grants, Mr. B. C. Aston, chief chemist to the Department of Agriculture, indicated that tho money was given for tho express purpose of testing tho application of tho work at tho Rowett Research Station, Aberdeen, to New Zealand pastures. Yet tho Imperial authorities were aware that various areas in the Dominion exhibited evidence of mineral deficiency, and decided, as a consequence, that experiments would do much to demonstrate tho valuo of mineral supplements.

Two kinds of evidence were mentioned as necessary in determining the occurrence of deficiency, viz., that derived from feeding experiments, and that derived from grass analysis. Recognising, however, that without experiments on animals in the field tho results of mero analyses would be more or less unconvincing, Mr. Aston decided to concentrate on tho animal experimental aspect of tho investigation. Experiments with various licks, pellets and other substances were instituted with both sheep and cattle, and the success which has already attended the use of citrate of iron and ammonium suggests that tho complete control of bush sickness in cattle may bo achieved at an early date. '■ "Treatment of Sheep. A development of importance is the endeavour to use tho remedy found so successful with cattle, to accomplish tho continuous grazing and development of sheep on bush-sick lands. An experiment, begun in July, 1928, at Mamaku Demonstration Farm with a gmall flock of wethers was entirely successful in bringing the sheep back to health when they had started (in January, 1929) to become bush sick on unimproved paddocks heavily top-dressed with phosphates, and they were kept in good health for a year subsequently by tho use of iron pellets. Finally the wethers wero sold as fats, a result which Mr. Aston, writing in the current issue of the Journal of Agriculture, attributes to the iron treatment.

In the same issue Mr.- Aston writes: "It is a well-known fact that in some areas bush sickness does not affect cattle, but that sheep suffer badly, which may bo interpreted as a sign that such land is less bush-sick than that on which cattlo cannot bo continuously pastured. There are very largo areas which arc what naturally would be considered suitable sheep country—tussock land, danthonia, and scrub country—but on which, nevertheless, sheep cannot bo raised. Successful Lamb-raising.

"It is satisfactory to state that experiments, which have been under way over six months on a block of this type of country near Rotorua, where the runholder has been unable to raise his lambs hitherto, aro now indicating that it will bo economically possible to treat all the sheep (some 1800 in this case) with a lick composed of salt and native iron carbonate, and that as a result the sheep can bo kept healthy and the lambs raised successfully. "In thi3 experiment the treatment has been with a large mob of sheep and has been carried out on the farm of a practical runholder with an iron remedy obtained locally. Tho control animals are becoming completely bush-sick, while tho mob of lick-treated sheep and tho smaller lot of pellet-treated sheep are doing well." In a previous issue of the Journal of Agriculture Mr. Aston stated that bush sickness occurring on coarso volcanic soils is completely cured by iron treatment of tho animal. Citrate, which used to be imported by tho hundredweight, has now to be brought in by the ton to combat bush sickness, and is sold at cost price (2s 6d per pound) to tho farmers. It may bo roughly stated, ho said, that lib. will keep one cattle beast healthy for one year. Effect of Green Manuring.

A series of soil experiments has been in operation for two years with a view to test the effect of green manuring always held to be a method of soil improvement which would convert bush-sick into healthy country. This is fundamental work on soil improvement and is being undertaken without any reference to economic possibilities. Successful crops of blue lupin have been turned under on the very worst and red clover on the best of bush-sick soils. Tho results, however, will not bo available for some lime, since it takes normally six to nine months for a cattle beast to show signs of the bush sickness. Tho difficulties in connection with the automatic administration of the extra food iron to sheep are, Mr. Aston is convinced, not insuperable, although difficulties have been encountered and losses sustained. Such losses, howevor, are considered nnavoidablo in any original work where it is sought to imposo an entirely new treatment of stock on the farmers. Another method ' of automatically administering the iron remedies to stock is by incorporating them with hay or ensilage when either of these is being made, and a number of experiments arc being undertaken.