BUSH SICKNESS.

New Zealand Journal of Agriculture, Volume XIII, Issue 4, 20 October 1916, Page 274

BUSH SICKNESS.

PROGRESS OF THE INVESTIGATION.

A visit was made last month by the Hon. W. D. S. MacDonald, Minister of Agriculture, to the Department’s bush-sickness experimental farm at Mam'aku, in order to look into recent operations carried out there. Mr. MacDonald, who for some time represented the district, has taken a keen practical interest in the bush-sickness investigation for a number of years. In the course of an address given by him. at Rotorua during his visit to the district Mr. MacDonald, after paying a tribute to the work of the departmental officers concerned, made the following statement on the subject under notice :

The progress of the investigation into the cause of bush sickness and the measures necessary for combating it has been necessarily slow, seeing that each of the various experiments which have had to be undertaken with cattle and sheep have occupied any time from six months to two years. But, though slow, steady and definite progress has been made, and the position to-day may be summarized as follows :

i. The cause of the trouble lies in the fact that the soil is deficient in certain chemical constituents which should be available to be taken up by the herbage if animals feeding upon it are to maintain sound health and condition.

2. Analyses of soil, grasses, and parts of the bodies of animals living in the affected country all show a deficiency of iron as compared with what is found in outside “ healthy ” country.

3. . Treatment of affected animals with syrup of phosphate of iron, if continued steadily over a sufficiently long period (from eight to twelve weeks), will effect a cure even in animals in the advanced stage of the trouble and kept entirely on bush-sick land during treatment. This has been proved over and over again. Licks containing iron have also proved useful, although not so certain in their effects as the administration of the syrup of . phosphate of iron. Experiments in the direction of applying medicinal treatment in a simple way by treating the drinking-water are also in operation.

4. It is recognized that treatment such as this, while of the utmost value as proving the correctness of the opinions arrived at as to the cause of the trouble, is not to be looked upon as a final solution of the matter, seeing that, it involves time, trouble, and expense.

5. What is really required, and what the Department is aiming at, is to find a means of prevention; in other words, to endeavour to do away with the cause of the trouble. With this in view experiments in treating the soil have been carried out, and up to a certain point these have been very successful.

6. It has been proved that the application of phosphatic manures, in the form of top-dressing, so improves the soil conditions that both cattle and sheep can be carried in good health for a much longer period than they could be on non-treated land. In addition, the generally increased nutritive value of the herbage enables the animals to do better in every way. The particular value of the top-dressings lies in the fact that they stimulate root-growth and root-action in the food plants, thus enabling them to take up more iron. There is iron present in the soil, but it is almost entirely in the form of silicate of iron, which is extremely insoluble and unavailable for plants. It is probable that some chemical action takes place as a result of phosphatic manuring which renders some of this iron available.

7. Our experience at Mamaku Farm shows that the application of suitable top-dressings increases the. value of the land for grazing purposes by at least 75 per cent., and possibly 100 per cent, for the time being. When the effect of the first top-dressing has disappeared the land is still better than it was at the beginning, and though further manuring is then needed a tangible and permanent increase in the value of the land has been attained, and it only needs good farming to continue this.-. As the soil becomes more consolidated as a result of carrying an increased quantity of stock, and at the same time accumulates humus, it will become more naturally fertile, require top-dressing to a less extent, and become more healthy for stock.

8. The most suitable manures for use as top-dressings are, in order of merit, as follows: (a) Superphosphate and basic slag—equal parts mixed ; (b) superphosphate and lime ; (c) guano. Basic slag alone, though it produces an abundant growth of herbage, does not seem so suitable for combating bush sickness as do the manures above mentioned. This is probably due to the lime contained in it. Lime alone seems to do more harm than good in connection with bush sickness.

9. With our present knowledge it is clear that with good farming methods and the judicious use of top-dressings the land affected can be profitably utilized for grazing and fattening stock—both sheep and cattle. Grazing operations on these lines have paid handsomely at the Mamaku Farm. Dairying has also been carried on at the farm, and will continue to be carried on; but it is clear that we have not yet reached a stage when settlers can be confidently advised to take up this land for dairying purposes if they intend to carry their cows on the land continuously year after year. We have been able to milk some of the farm cows for two seasons successively, but no longer, and not in the case of all of them.; and it is still a most difficult matter to rear calves to maturity. No doubt if we had given the cows a change to outside country once a year they could have been carried on, but to do this would have destroyed the true value of this branch of the experimental work, since it would have been only repeating what is already being done successfully by settlers in the district.

10. The research work, will be carried on vigorously, and a new series of experiments is about to be initiated. A soil survey of all the known affected area is also to be carried out.