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CHEMISTRY SECTION. REPORT OF B. C. ASTON, F.1.C., F.C.S., CHIEF CHEMIST. Mineral Content of Pastures. Deficiency disease in stock, attributable to mineral deficiency in the pasture, has received a large share of attention during the past year. The work in New Zealand on iron-starvation already published was mainly instrumental in obtaining for New Zealand a grant from the Empire Marketing Board for the further investigation of the mineral content of pasture. One of the conditions of the grant was that certain types of officers should visit the Rowett Institute and spend some time in investigating the methods used at that institution. Mr. R. E. R. Grimmett, of this Department's chemical staff, left New Zealand at the end of April, 1927, and returned to New Zealand in March, 1928. Mr. T. Rigg, previously an officer of this Department's Chemical Laboratory, but now of the Cawthron Institute, Nelson, also visited the Rowett Institute for some weeks in 1927. While at the Rowett Institute Mr. Grimmett investigated the " pining " disease in sheep which occurs in the Cheviot Hills and other localities in Scotland, a disease which the writer of this report predicted in 1924 would be found to be the same as " bush-sickness "in New Zealand. Mr. Grimmett found that there was a low iron-content of the pasture in " pining " districts as compared with districts in which there was no " pining " ; that " pining " was curable by the same methods as adopted in New Zealand for the cure of bush-sickness—-the administration of iron remedies—and that .there were certain physiographical features of the " pining " areas which were distinct from the " non-pining " areas, features which were paralleled in the bush-sick districts in New Zealand. He also carried out pot experiments with " pining " and " non-pining " soils, and analysed the herbage grown on them, eliciting the fact that when the pots were placed under stagnant conditions requiring drainage there was an unusual absorption of manganese by the plants compared with pots in which free drainage conditions prevailed, while indications pointed to iron-absorption being similarly affected, though more slowly than manganese. This fact is again, substantiated by the analysis of plants growing under stagnant conditions in the Rotorua district, where the same iron and manganese content was found, and where bush-sickness does not occur, but where sick animals make a speedy recovery. The influence of excessive manganese in the natural form will be tested in the field. The results of this work go to show the importance of increasing the water-holding capacity of pumice soils. The most obvious method would seem to be by increasing the organic matter or " humus " content by greenmanuring, so frequently urged in past Journal articles. The scheme of work to be undertaken under the Empire Marketing Board's grant for research on the mineral content of pastures will for the first two years be restricted to those areas where there is a definite and chronic malnutrition in domestic stock which cannot be referred to any other cause than the food-supply, which is apparently present in suitable amount for the normal maintenance and development of stock. The general lines upon which the work is being carried out were laid down by Dr. Orr, of the Rowett Research Institute, as follows (a) The analysis of samples of pastures, and, where considered desirable, of soils, to determine the mineral content of pastures in different areas and in different seasons. The analysis of soil and pasture samples is being actively carried on in connection with the two distinct deficiency diseases (iron and calcium deficiency), and it is hoped to add a typical phosphate deficiency area at a later date. (b) The correlation of minerals with other constituents and with the nutritive value of the pasture as determined by its carrying-capacity, and the health, rate of growth, and production of animals grazing on it. Field experiments are being carried out in the direction desired. (c) Feeding tests to determine the effect of feeding to grazing-animals mixtures of mineral salts or foodstuffs rich in minerals found to be deficient in the pastures. (d) Experiments to determine where and to what extent information obtained under (a), (b), and (c) cf>n be used for the improvement of pastures. Further demonstration experiments are being initiated in both cases with a view to modifying the existing farming practice with regard to animal and soil treatment, so as to accord with the experimental work and the theories which have been deduced from it. Temporary expert officers have been appointed, and it is hoped to appoint others to help in this work for a term of years. Iron-starvation in New Zealand. (Bush-sickness.) The use of iron-ammonium citrate as a medium for the prevention and cure of this deficiency disease in ruminant stock has increased greatly, about 4 cwt. having been sold by the Stock Inspectors at Rotorua and Tauranga during the past year, an amount which represents some 58,000 doses. The users of this remedy have been circularized, and their experiences published for the benefit of all in the affected districts. It is intended to try forms of iron other than this and the sulphate, both for stock-lick and for pasture top-dressings. Huntly iron carbonate (spathic iron-ore) is being thoroughly tried out, both as a top-dressing and as a lick. An interesting fact was discovered on the writer's visit to the Atiamiuri Road Settlement on a silt type of soil quite different from the ordinary pumice types. Here there is no bush-sickness, and dairy herds give good returns. In addition to the fact of a large area of the land being of a

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