VOLCANIC ASH

Evening Post, Volume CIX, Issue 101, 1 May 1930, Page 11

VOLCANIC ASH

EFFECT ON SOILS

FAR-REACHING RESEARCH

NORTH ISLAND PEOBLEM

, It is well known that agriculturists are faced with special difficulties in the farming of the large areas of volcanic soils which are to be found in the North Island. "Bush-sickness," typically seen years ago at Mamaku, has long been recognised as being a special bane of the stock industry in different parts of the territory covered by volcanic deposits. The difficulty which has been encountered in finding an economic and practical remedy for "bush-sickness" has~resulted in great loss to farmers and has delayed the settlement of large areas of the territory because of the difficulty in recognising land which un- . der farm niaangeinent is likely to become unhealthy for stock. Sickness of > stock similar to the "bush-sickness" associated with the Mamaku sector occurs at Kopaki, 'Cc Puke, and other places which are widely separated. More recently an examination of stock conditions in the Te Euiti district has shown that volcanic deposits in this locality are associated with indifferent '■ or poor results from stock. At the request of the Minister in Charge of the Department of Scientific and Industrial Eeseareh (the Hon. H. Atmore), Mr. T. Bigg, of the Cawthron Institute, Nelson, recently examined the - different types of volcanic deposit and their relation to stock ailment. It was found that volcanic deposits covered a very large part of the whole country between Kawhia Harbour and Napier. The deposits apparently came from twomain centres, one in the vicinity of Eotorua and the other near Lake Taupo. The material from the Botorua' centre could easily be distinguished from that haying its origin in th& Taupo locality. It was found that the Mairoa locality, in wiheh dopiness of sheep occurs, is located on the finer material coming from the Eotorua centre. Taupo deposits were identified at Kopaki, Putaruru, and Mamaku, where "bush-sick-ness" or stock ailment similar to "bush-sickness" are known to occur. It would appear that "bush-sickness" • is associated with the Taupo deposit "- and not the Eotorua deposit. A careful examination of the chemical character- , isties of the Taupo deposits is exceed* z ingly desirable in order'that the, reasons for "bush-sickness" may be elucidated, suggests Mr. Eigg, who added that there can be no doubt that a soil survey of the whole area covered by volcanic ash is exceedingly desirable both from the .'■,. point of view of elucidating the problems affecting the stock industry on volcanic soils, and also from the point of view of the rapid development of the country for agricultural purposes. In view of the occurrence of stock ailments on soils included within the volcanic belt, it has become increasingly difficult to make any very specific recommendations concerning the development of large areas of unoccupied ' country in the central portion of the North Island. Obviously a classification of all soils in the' whole territory— not confined solely to the Botorua district—is highly cfesirabte before land settlement can proceed with any rapidity. In view of the different nature of stock ailments as exemplified at Mairoa and Mamaku, it is clear, that the. : chemical characteristics of this volcanic • deposits in different parts of the territory vary widely. A careful study of the nature of the soils associated with the different types of stock ailment , phonld .provide, fresh .clues foir -the economic treatment of the soils, and should enable such soils to be recognised in other parts of the country. MANY VOLCANIC SHOWERS. A study of the volcanic deposits in different parts of the country suggests to Mr. Eigg that much of the 1 •volcanic ejeetainenta came from only -two centres, one in the vicinity of Eotorua'-and the other near to Taupo. Material from these two .sources can easily be recognised as essentially different iin characteristic properties. Little difficulty was experienced in recognising at once the two types of volcanic ash wherever they occurred. '. In each case, eruption of ash and ejeetamenta nuist have, taken place over very long periods for several distinct showers possessing different colours, and properties can be seen -in road cuttings. At Mairoa, : five distinct showers of Eotorua ejeetamenta frequently 10 to 15 .. feet in total thickness can be seen. At Napier, in a brick quarry no less than nine showers of Eotoxua ash can be traced, of a total thickness of some 25 feet. .The Taupo deposits are of more recent origin. They cover large areas of the original Eotorua showers, and are not ■so extensive'in character.as the Bptorua deposits. At least four- distinct showers can, however, Teadily be detected in road cuttings between Taupo " and Tarawera on the road to Napier. .On the, outskirts of the zone covered ; by Taupo deposit it is frequently difficult to recognise more than one shower • of Taupo material. ' This consists of 'very fine particles remarkably uniform . in size. ,'v. In many parts of the country, ash de- > posits have been removed by slumping, j ; by wind action, or by river erosion. 'Where the original land surface was steea only a small depth of ash cover- § remains, and inplaces it has been cely removed. The Waikato river idenuded the ash covering from jj areas in the vicinity of Hamilton Cambridge. In places the ' later V; showers have been removed, but vestiges of early showers of Botorua de» v.posits can be seen. Wind'has porbably removed much volcanic deposit on - the hill land between Eskdale and Lake Te Pohue (Napier sector), for little can now bo seen.' • . : t It is evident, concludes Mr. Bigg in "his report, that much work will be i& ■■ quired before the identification of i all soils in the territory can be completed. This is particularly true of the dis- ;-' tricts in the vicinity of Botorua, where several distinct showers of volcanic • ash of very recent origin covering much older depostis have been identi- ■•; fled. It, however, does seem probable that in regard to the older de- ' posits which are of a very widespread character, lines of demarcation between "deposits of different origin will be easy 'to recognise. Further, it may safely be predicted that travelling away from the centre of origin of any one of these deposits a gradation in size of particles will be found enabling a rough soil classification of large, areas of country to be made on a bask of textural changes. ■ . Although further work is required to establish completely the hypothesis advanced in explanation of soil differences which occur in the central Ncrth Island territory, there can be no doubt that a soil survey based on the dsmarca- . tion of (1) deposits of different origin, (2) changes in texture, will be of immense value in the development of the country. Not only will new clues be provided for the successful prosecution of the investigations on stock ailment now proceeding in the territory, .'..but it will also enable a very wide application of the results to be made.

Drugs to the value of over £218 have been supplied in four and three-quarter years to one panel patient in Britain who lias been treated for diabetes for Bin*; years, '