POSSIBLE SOURCES OF POTASH IN THE UNITED

STATES.

By FRANK K. CAMERON,

Bureau of Soils.

INTRODUCTION.

It is traditional in European countries for the several Governments to maintain a peculiarly active interest in the salt supplies, this state of affairs being especially well exemplified in the historical "salt monopolies " by which the Governments were assured of a certain revenue from a necessity for every citizen. About 1845 the German Government authorities, in an effort to increase the output of salt from the Magdeburg-Halberstadt region (better known as the Stassfurt region), drilled into the salt-bearing strata. Ultimately the main body of rock salt was penetrated, but in the upper layers or overburden there were found to be large quantities of "bitter" salts or a mixture of potash and magnesium salts which, designated as "abraunsalz," were regarded as worthless impedimenta. About 1870, mainly under the influence of the distinguished savant Liebig, the value of the bitter salts as a soil amendment or “fertilizer" was established, and from that time hence the potash salts have been the most valuable output of the mines. The use of potash salts became widespread throughout the world, wherever intensive agricultural methods and fertilizers were employed.

Practically, and with a few comparatively unimportant exceptions, the world's supply has always come from the German mines, and the Government, as a practical conservation measure, regulates and controls the mining and sale of the product. The material is marketed through a "Kali Syndikat" made up from all the mine ownerships and under the supervision of governmental officials, the quantity which may be produced and marketed being allotted amongst the mines, and prices fixed by the Syndikat, with the general restriction that no greater amount shall be exported than is sold in the German Empire.

It is obviously desirable that the United States should be independent of any other nation for its supply of a necessary product. Quite aside from the political arguments usually advanced in this connection, the Stassfurt deposits are not inexhaustible and are, moreover,

subject to various vicissitudes which might at any time spell disaster for this nation, which is so largely dependent upon agriculture for its welfare and stability. From time to time, and in spite of every care and precaution, a boring has become flooded, with the inevitable abandoning of the mine and permanent loss of the potash contents at least. In the past this has attracted considerably less general attention than its importance deserved, because the general market was not affected greatly and because often the particular management affected has sunk new shafts in the neighborhood and resumed operations. Recently one of the mines has been flooded, with the result that overnight, as it were, 1 per cent or more of the world's visible supply of potash disappeared.

Within the past few years certain American importers of potash salts, endeavoring to develop trade arrangements of greater advantage to themselves than had hitherto prevailed, brought on a controversy with the Kali Syndikat, which in turn led to diplomatic exchanges between the Governments of the United States and Germany and attracted considerable attention in the public prints. In consequence of the attention and interest thus aroused, Congress directed that special investigations be promptly instituted by the Bureau of Soils and by the United States Geological Survey to determine the possibility of obtaining, on a commercial scale, potash salts of American origin.

These investigations have been in progress at the present writing for about 18 months. They have stimulated private enterprises to a considerable extent, and the result of these several activities appears to be sufficient to show that the commercial production of potash salts from American sources and in quantities sufficient to meet the growing needs of the Nation is quite practicable. The investigations in this direction are by no means completed, are, in fact, yet in their infancy, and what the ultimate possibilities of American potash may be can not be predicted as yet. Before describing the more important American sources of potash, a brief résumé will be given of some possible minor sources.

MINOR SOURCES.

WOOD ASHES.

Of the minor possible sources of potash, the one which has attracted most attention is wood ashes. The quantity of sawdust produced in this country amounts to nearly 6,000,000 tons annually, which, if burned properly, might yield approximately 6,000 tons of potassium carbonate. But the sawdust is accumulated at so many widely distributed points, many of which are so poorly situated as regards transportation and other economic facilities that there seems

but small possibility of sawdust ever having any importance as a source of potash, except, possibly, in a very local way under exceptionally favorable conditions.

A relatively unimportant quantity of wood ashes is produced in this country. Some is imported from Canada. For the fiscal year ending June 30, 1910, there was imported a little more than 5,000 tons, valued at about $66,000. Figures for the tonnage of the succeeding years are not available, but as the valuation of the imports of ashes, beech wood, and lye were $50,973 (1911), and $40,212 (1912), it is evident that wood ashes as a source of potash is not only comparatively unimportant in the United States, but such as it is, it is rapidly falling off. Wood ashes command, however, a comparatively high price. Thirteen brands on the Massachusetts market, averaging 3.77 per cent potash (KO), sold for an average price of $12.60 per ton.

WOOL WASHINGS.

Next to wood ashes may be considered wool washings, or "suint,” which in some parts of Europe have been utilized as a source of potash. The foreign matter removed from wool by scouring varies widely, from 15 to 70 per cent, and is known commercially as "wool yolk." This material contains: (1) Sand, earth, etc; (2) wool grease, which is insoluble in water but which forms emulsions with soaps and alkaline solutions; and (3) "suint," or dried sweat, soluble in water and containing the potash salts. By treating the raw wool with warm water previous to scouring, the suint is dissolved, and in this way the potash salts of wool yolk may be recovered. Generally, however, all three classes of constituents are removed together in the scouring process and allowed to go to waste, since the recovery of potash and fatty acids can not be accomplished economically, except on a large scale.

Suint consists chiefly of the potassium salts of fatty acids which, when calcined, yield an ash having a composition approximately as follows:

The quantity of potash which might be recovered from suint can not be accurately estimated. Wool in the grease, or raw wool, contains potassium which, expressed as potassium carbonate, approximates 5 per cent. The wool cut in the United States may be taken, in round numbers, as 160,000 tons, so that the maximum possible yield of potassium carbonate would be something less than 8,000 tons,

worth possibly $500,000. Considering the wide distribution of the wool cut in America and the slight probability that the individual scourers could be induced to recover potash, or even suint, wool does not promise much as a possible source of potash. It is reported that some of the larger slaughterhouses and packing establishments are running washings from their sheep through peat, thus absorbing quite completely the potash and enriching the peat for subsequent use as a filler in mixed fertilizers.

POMACE AND VINASSE.

The pomace from wine presses, vinasses from sugar mills, and other wastes are possible, but not probable, sources of potash. Generally these wastes, if usable at all, could be more advantageously employed in some other manner, possibly for direct application to the soil. On the other hand, no very definite statements in this connection are justified, for these substances have not been thoroughly investigated.

ARTIFICIAL NITER.

The artificial production of niter or potassium nitrate is still practiced largely in various parts of the world, notably in India, where recent governmental investigation seems likely to bring about some technical improvements in the time-honored practices. The United States imports annually about 3,000 tons of potassium nitrate, worth approximately $200,000, a very small percentage of which goes into fertilizers, it being utilized mainly in the manufacture of certain types of explosives and fireworks. The United States could, of course, if necessity arises, produce enormous quantities of potassium nitrate. But the economic and social conditions in this country are such that it is extremely improbable that any commercial production will ever be attempted.

SUNFLOWERS AND DESERT PLANTS.

In Russia sunflowers grown on waste lands are gathered and potash obtained by incinerating the stalks. It has been proposed to follow this idea by growing sunflowers on some of the desert areas of the United States, and several propositions have been advanced to gather indigenous plant growths on desert and waste lands and produce potash by burning them. None of these proposals have yet assumed sufficiently definite shape to warrant consideration as a commercial proposition. While some attention has been given the matter by the Bureau of Soils, the data have not justified any serious expectations of commercial possibilities in this direction.

CARBONATE PONDS OF NEBRASKA AND VICINITY.

In certain of the Western States, notably in western Nebraska, are a number of small lakes or ponds whose waters are quite saline, and contain noticeable proportions of potassium carbonate. The explanation of the origin of the potassium carbonate which has received most credence is that the vegetation of the surrounding country has been repeatedly burned over and that the potassium carbonate from the resulting "wood ashes" has been leached out by rain and carried into the lakes, which have no outlet or relatively inefficient outlets. The climate being semiarid, the evaporation is high, and consequently a considerable segregation and concentration of potassium carbonate has occurred in some of the lakes. None of these lakes, nor all of them in the aggregate, probably contain enough potash to give them any great general economic importance, though some of the individual localities might justify working. Indeed, preparations have been made to work one or more of them. There is no present expectation, however, that the potassium carbonate to be recovered is to go into the fertilizer market.

ROCK SALT AND BRINES.

The United States contains a number of rock-salt deposits and many salt wells. An examination of a large number of the brines, salt, and bittern from these wells and deposits has been made, as well as a study of the theoretical and practical principles involved in the separation of potash salts from the other products yielded. Potash is invariably a constituent, but never in quantities that would justify any attempt to obtain it thus commercially, excepting possibly in the case of the potassium carbonate lakes of Nebraska already discussed, and at Searles Lake, in California, which will be discussed presently in connection with the desert basins. Certain of the American salt deposits, notably those in New York, Michigan, Ohio, Kansas, and possibly in Louisiana, are enough like the deposit at Stassfurt in origin and general geologic features to suggest the probability of segregated deposits of potash. From theoretical considerations as well as practical experience at Stassfurt, it would be expected that potash layers, if existing at all, would be found above. the main salt bed. No such layers have been observed in the case of any American deposit, and they have been sufficiently explored now to make quite remote the probability of American sources of potash from such deposits.