SOILS FERTILIZERS. 821 



nitrate in sandstones and other rocks and of small amounts of nitrates derived 

 from bat guano in caves. 



The conclusion is that the only hopeful outlook for the existence of workable 

 beds of potash salts in Texas is in the brines as found at Spur and in the 

 almost wholly unknown region southeast of and bordering New Mexico. 



Potash from kelp, F. K. (^amkkon iJL .S'. Dept. Agr. Rpt. 100 (1915), pp. 

 122, plff. 40, figs. 2, maps 3.'f). — This consists of a series of reports, accompanied 

 by detailed maps of the kelp groves of the Pacific coast and islands of the 

 United States and Lower California, on the following subjects: Pacific Kelp 

 Beds as a Source of Potassium Salts, by F. K. Cameron ; The Kelp Beds from 

 Lower California to Puget Sound, by W. C. Crandall; The Kelp Beds of Puget 

 Sound, by G. B. Ripg; Tlie Kelp Beds of Southeast Alaska, by T. C. Frye; and 

 The Kelp Beds of Western Alaska, by G. B, Rigg. These reports and maps are 

 the result of careful surveys of all of the commercially available kelp beds 

 from Cedros Lsland to Cape Flattery, about half the beds available in south- 

 east Alaska, and the major i)art of the beds on the southern slopes of the 

 Alaska Peninsula. 



On the basis of a large number of analyses which show that the Pacific coast 

 kelps, in a dry state, contain about 16 per cent of potash, corresponding to 

 about 25 percent of potassium chlorid, it is estimated that the 390 square miles 

 of kelp beds already mapped on the Pacific coast are capable of producing 

 annually 59,300,000 tons of fresh kelp, equivalent to 2,266,000 tons of potassium 

 chlorid. 



" What it would cost to obtain the pure potassium chlorid from kelj) can not 

 be stated, as sufficient experience is not yet accumulated to justify exact esti- 

 mates. It should be easier to extract the iwtassium chlorid from kelp than 

 from the Stassfurt salts. But the cost of harvesting the kelp as well as the 

 subsequent manipulation is, at the present time, s-peculative. It is easy to show 

 by 'paper calculations' enormous profits in obtaining pure potassium chlorid, 

 iodin, and possibly other products from the kelp. Since, however, the dried 

 kelp will average more than 25 per cent potassium chlorid, since the organic 

 matter decomposes very readily, and there is present nitrogenous matter equiva- 

 lent to about 2 per cent nitrogen and some phosphate, it seems i)robable that 

 kelp in the dried state, either alone or in mixture with other materials, such 

 as fish scrap and standard phosphate carriers, is the form in which it is most 

 likely to find at first a market as a fertilizer. 



" It is also impracticable to give any close estimate of the value of the 

 possible kelp harvest. Assuming that all the potassium chlorid were extractetl 

 and marketed as such, the value at present prices would be approximately 

 $90,000,000. whereas if the crop were all re^luced to driod kelp and sold at 

 current figures for both potash and nitrogen content, the value would be in 

 excess of $150,000,000." 



The general conclusion from the investigations already made is "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." 



Radium as a fertilizer, C. G. Hopkins and W. H. Sachs (Illinois 8ta. Bui. 

 177 (1915). pp. SS9-'i01). — Experiments by others on this subject are reviewed, 

 and field experiments with corn and soy beans in which tlie radium fertilizer 

 was used at rates furnishing 0.01, 0.1, and 1 mg. per acre are reported. 



The soy beans followed the corn on the same land without additional appli- 

 cation of the radium fertilizer. Of six trustworthy average results with corn, 

 three were for and three against radium. Of eighteen averages with soy beans, 

 nine were for and nine against radium. In all cases the average variation 

 94863°— No. 9—15 3 



