WATERPROOF AND WAX-BEARING SOILS.

New Zealand Journal of Agriculture, Volume XIII, Issue 4, 20 October 1916, Page 289

WATERPROOF AND WAX-BEARING SOILS.

B. C. ASTON,

F.1.C., Chemist to the Department.

From time to time instances of soils which will not wet have puzzled farmers, who have sent in samples from different localities for examination. These samples were, for the most part, small and represented areas widely separated.

A paragraph in my 1909 report (Annual Report of the Department, 1909, p. 469) mentions, under the heading Abnormal Soilconstituents,” three soils (J 194, from Mataroa; J 265, from Gisborne; and K 2161, from Pukutoatoa, near Woodville) to which the term “waterproof soils” had been applied, as it was stated that it was impossible for rain to wet them, the result being that nothing would grow.

Mr. C. P. W. Longdill, of Taihape, writing to the New Zealand, Times in April, 1907, says, “At Mataroa, a small township on the Main Trunk line, six miles north of Taihape, there is a curious natural phenomenon in the form of a patch, several square yards in extent, of soil, or rather dust—for nothing will grow upon itwhich seems perfectly impervious to moisture, so that, even though it rains in torrents and pools of water collect upon the area, a scratch on the surface causes the dust to rise and float on the top of the water as dry as a water-spider. .. Can you or any of your readers explain the reason of this ? It is quite possible that this dust,- being waterproof, might be converted into some substance of considerable commercial value.”

Inspector C. Watson reported on this in May of the same year as follows: “I went to Mataroa and examined the soil, of which lam forwarding a sample. The patch of soil, | chain long by 2or 3 yards wide, is located near Smith and Donald's sawmill, on the top of the bank of a creek several feet above the waterlevel. I did not ascertain the depth of soil. During the recent rain the surface of the patch of soil has been composed of thin mud | in. deep, and several pools of water have collected in depressions. When the surface layer of mud is removed the dry dust is found underneath. The ground adjoining is in grass ' it has been bush-clad, but the bush has been fallen years ago and the bulk of it burned off; ■ the surface soil is vegetable loam, with light clayey subsoil. Nothing is known locally of the patch of

soil in question further than that it is impervious to moisture. One and a half chains away is a salt-water spring. Shortly after, Mr. T. W. Tiffen, of Wheturau, Gisborne, writing me in July, 1907, says, “I am sending you a sample of soil from my property which is in its way an agricultural curiosity. It possesses the peculiarity that, excepting to the depth of I m from the surface, it appears never to get wet. This soil is form in patches. It is very light, and floats readily on water Outside these patches the ground is now sodden with water. It has struck me that the explanation may be either that these are patches containing a large amount of pumice, or that it may be fu er s earth or something of the sort. I have watched these patches - for six years, yet all through the winter they appear to be dry. I shall be glad to know what you make of it.

Mv report on the above stated, These small samples or tine sandy loams have been experimented with as far as their size would permit. The size of the particles, the combined water and the organic matter appear perfectly normal. The phenomenon is probably due to one of two causes: either to the way in which the air-spaces are locked in, or to the presence of some resinous or oily substances as from pines or other resinous trees. After ignition water is readily absorbed, as also after thorough kneading with water and subsequent drying, or after washing the soil with alcohol or ether. Ether extracts a small quantity of resinous substance from the soil. In order to extract enough of this resin for analysis a large amount of soil would be necessary-say, about 2 cwt.-but as the soil occurs only in patches it is hardly worth whi e.

Early in 1909 Mr. P. H. Lynch, of Pukutoatoa, near Woodville, left a sample of soil at the chemical laboratory with a statement that the soil over an area 6 yards in diameter would not wet, and that no grass or weeds would grow. An examination of the small portion showed that ether extracted from the soil 0-3 per cent, of a resinous matter, which united with alkali, forming a soap The extract melted easily, with a smell of pine, and the etherea solution was slightly acid. I reported in February, . X 909 that he resin was probably derived from resinous trees originally grow g on the site of the dry patch. ■ .

Up till this time the investigation was in an unsatisfactory state owing to the smallness of the samples submitted The discovery of fairly large areas of dry patches occurring at the Ruakura Farm of Instruction, on the portion situated on what was original y a part of the great Piako Swamp (now better known as the Hauraki Plains), has drawn fresh attention to the phenomena o waterproof soils. In this case there was no difficulty m securing

a large amount of soil for examination. Mr. Green, Manager of the farm, writing in September, 1915, states, “ This class of soil remains practically dry throughout the winter. After heavy rain the water lies on the surface and will not penetrate into the soil. It is difficult to secure a crop there, owing to insufficient moisture to germinate the seed. The soil is apparently full of rotten wood. If ploughed and left for a few months sorrel appears and spreads, making a thick mat of roots. The method I am adopting to bring this land into cultivation and to prepare it for permanent pasture is to apply lime and sow with rye-grass for the present; then stock heavily, feeding . out mangels and hay during winter. I should be pleased if you could arrange to have the soil analysed, and would be glad to receive any suggestions as to treatment.”

The soil contained the following constituents, calculated on the sample dried on the water-bath : Per Cent. Loss on ignition .. . . .. .. 34740 . Total . nitrogen .. . .. .. .. 0-726 Hydrochloric-acid, extract— Phosphoric acid (P 205 0 5 ) .. .. .. 0-132 Potash (K 2 O) .. .. .. .. 0-041 Lime (CaO) .. .. .. .. 0-189 Magnesia (MgO) .. .. .. ... 0-069 Citric- extract Phosphoric acid .. .. .. '.. 0-074 Potash .. .. .. . . .. 0-024

I reported that the sample was a humus soil rich in available mineral plant-food, and suggested as a form of treatment an attempt to consolidate, the ground by close stocking and feeding on the dry areas, thereby consolidating' the soil by tramping and manuring the organic (peaty) matter of the soil by the animals. It will be seen that if one could imitate the action of the pestle and mortar on the soil during rain the same beneficial result might ensue as when the soil is so. treated in the laboratory.

The next step was to examine the effect of exhausting a large quantity of -the soil by a solvent. Some 30 lb. of the soil dried on the water-bath was therefore extracted by alcohol in an apparatus in which a constant stream of hot strong alcohol was allowed to percolate through the soil. The alcoholic extract on cooling deposited a mass of yellowish crystals of a scented wax which was found to be present to the extent of o-8 per cent, of the dried soil. The air-dried crude wax commenced to melt at 65° C. and

was completely fluid at Bo° C„ cooling to a lustrous brown solid. The chemical and physical examination of this wax is now being carried out. That the abnormal character of this soil is probably due to the wax is indicated by the fact that a sample of the soil which had been exhausted by alcohol and subsequently thoroughly dried wetted easily on contact with water, which spread rapidly throughout the mass. Again, if an alcoho ic solution of the wax were added to the dry wax-extracted soil and the whole dried, the waterproof nature returned and . the soil could not be wetted by mere contact. If kneaded in a moi with .water the original' dry soil became thoroughly wetted; on drying it on the water-bath the difficulty in wetting it returned.

The most interesting point about this research is the origin o the wax, which may be due to one of a variety of dissimilar sources, probably of a vegetable nature, such as from algae, diatoms, or bacilli. As, however, the wax in this case occurs on the surface soil the possibility of it being derived from higher vegetation must ,not be excluded. Virgin portions of the drained swamp at Ruakura-at present grow a dense thicket of manuka (Leptospermum, family Myrtacese), as well as rushes, sedges, mosses, liverworts, and similar swamp-loving plants. Since the swamp has been drame bracken fern (Pteris esculenta) has taken possession of certain areas, while -huge logs occurring throughout the swamp indicate that such swampy forest-trees as kahikatea or white-pine (Podocarpus yeti-aides'), pukatea (Laurdia novae-zealandiae), occurred ; and the smaller growth of such plants as phormium (family Liliacese), a strong wax-bearing plant, toetoe (Arundo. conspicua), bullrush (Typhd), and cabbage-tree (Cordyline australis, family Liliacese) is also indicated. -

Since receiving this Ruakura soil a yellow humus subsoil occurring near the sea in the far south under a peaty soil has also become the subject of investigation. Upon this subsoil nothing would grow. On ignition in a closed crucible the dried sample lost 34 per cent, of matter, ■ burning off with a white flame (the “hydrocarbons” of the coal analyst). It yielded to alcohol and to ether a much greater quantity of extract than did the Ruakura soil (as much as 4 per cent.), and then still contained volati e matters which could be distilled at a gentle heat. . •

This being probably the first occasion on which these . abnormal constituents have been noticed in New Zealand soils, it is deemed advisable to publish this preliminary notice, as the result of the investigation may be found to throw some light on one theory of the origin of petroleum, while the discovery of - . the occurrence of wax in such quantity may have. a decided economic value.