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CHEMISTRY SECTION. REPORT OF B. C. ASTON, F.1.C., F.N.Z.INST., CHIEF CHEMIST. Mineral Content of Pastures Investigation. This work occupied chief place, and has made considerable advances during the year. Inquiries have been received regarding the composition of licks for supplementing the natural pasture as a ration for stock or to correct various disorders. Probably this method of supplying deficient mineral food constituents will have a greatly extended use in the near future. Rotorua Pumice or Nearby Volcanic Lands.—Attention ha.s been devoted largely (1) to the carrying-out of large-scale lick and pellet-feeding experiments, with the object of discovering the most economic method of supplying assimilable iron to ruminants, especially sheep ; and (2) to the growth and collection of representative samples of pasture plants and mixed pasture free from contamination, for analysis. Both the feeding of pellets containing meals and citrate of iron and ammonium, and of a lick composed of common salt and finely ground native carbonate of iron (a local product), have succeeded in the case of sheep, which previously it was impossible to keep for any length of time, or rear, on bush-sick land. Proba.bly some of the good effect of the pellets is due to the concentrated food in the form of meals which they contain. As this is an expensive and unessential ingredient it is hoped that suitable licks may be found sufficiently palatable to enable pellets to be dispensed with. Carbonate of iron added to ensilage during the building of the stack was found to be an effective and economical method of administering iron to cows and calves, widely applicable in the bush-sick areas; analysis shows that the iron is thus rendered more soluble. A prominent settler on bad bush-sick country (Mamaku) has introduced sheep, and intends breeding them on this type of country. He is confident of keeping all stock healthy with the aid of iron-carbonate treatment, which he has succeeded in giving automatically to the whole flock. He carries 1,000 sheep, and has 350 ewes now in lamb at Mamaku. Doubtless, therefore, with little additional expense or trouble, the whole of the lands affected with bush sickness in any degree can be farmed without fear. This opinion, arrived at before with regard to cattle-farming, can now be asserted with regard to sheep-farming, and this certainty of being able to keep both kinds of stock on the same country will make it much easier to farm than if the worst country had to be restricted to cattle. To name only two reasons : a better utilization of pasture is effected in the mixed grazing of sheep and cattle, and the diverse quality of the products gives a better chance of making bush-sick country pay, than if only one class of stock were carried. In making ensilage it is recommended to dissolve 1 lb. of the iron ammonium citrate in water, mix with molasses, and spray on to the layers of ensilage from time to time as the stack is building, .1 lb. of the citrate to ] ton of ensilage. The option secured over a deposit of spathic ore at Huntly has been kept alive, and the ground material distributed free or at cost price to farmers in bush-sick areas in small quantities for experimental purposes. Results have been very encouraging, and many requests for a supply of the material have been received. The fine grinding of this hard iron ore has been generously undertaken, practically free of charge, by the Challenge Phosphate Co., at Otahuhu, a service much appreciated. Analysis of the herbage produced by pot experiments with limonite from Whangarei showed that its incorporation with pumice soil did not increase the amount of iron taken up by the plant. Possibly, however, a use will be found for the limonite as an ingredient in stock-licks for providing iron directly to the animals. Stock-feeding experiments with limonite from Whangarei and from Onekaka, Nelson, are now in progress in the Rotorua district. Green-manuring experiments for the improvement of the pumice soil have been proceeded with in two localities. Good crops of (a) red clover and (b) lupins have been ploughed in and the areas resown in pasture. The drainage water from the lysimeter has been regularly collected and analysed. Applications of superphosphate made to the surface soil have not led to loss of phosphate in the drainage water. Ngaroma.—During May, 1930, an inspection was made of experiments which have been in progress for several years at Ngaroma, an isolated block of country where there appears to be more than one deficiency disease. On the whole, the results were distinctly encouraging. In one case a farmer's milk-yield had shown a substantial increase on manuring with superphosphate, while a further increase had followed the addition of sulphate of iron to the superphosphate. Carbonate of iron as a lick was also reported on favourably. Poverty Bay Back Country.—Experiments have now given indications of the nature of the deficiency effects experienced in sheep in parts of this area. Animals depastured on affected paddocks well top-dressed with superphosphate and basic slag became sick equally with those on untreated areas, thus indicating that deficiency of phosphate could not be responsible, and adding proof that lack of iron is the principal factor. The pastures have an abnormally low iron content. Two other instances of iron deficiency trouble in sheep on stations between Napier and Gisborne have been investigated. In both cases the trouble has occurred on easy country with a surfacecovering of pumice, and soil and pasture analyses and the symptoms point to it being due to iron deficiency. The soils are " sandy silts " similar to those near Rotorua. Steep country, from which the surface-covering of pumice had been denuded, was not affected. Waitomo County.—Some reorganization of the work in the Mairoa and Kopaki areas has been made as a result of the experience already gained. Carefully controlled experiments have been initiated at Mairoa to compare the effect of various top-dressings on the health of sheep. A large series of replicated enclosed plots with different top-dressings have been established at Kopaki and Mairoa.

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