SOILS FERTILIZERS. 127 



On the availability of the potash in " rapakivi " and pegmatite granites, 

 O. AsciiAN (Ztschr. Anorgan. Chem^, 7^ (1012), No. 1, pp. 55-73; ahs. in Jour. 

 8oc. Chcm. Indus., 31 (1912), No. //, p. 195). — These granites were subjected to 

 various treatments, including the action of lime water, sulphuric acid, hydro- 

 chloric acid, calcium chlorid, lime and salt mixture, and peat, in order to find a 

 practical means of rendering the potash which they contain in the form of 

 feldsjiar available for fertilizing purposes. 



The results indicate that treatment with acids is not a practical method. 

 Practically conii)]ete solution of the potash was obtained by fusion with 

 calcium chlorid or with lime-salt mixture, the former being considered perhaps 

 the better method if the calcium chlorid can be obtained cheaply. The greater 

 part of the potash was made soluble as hydroxid by heating under pressure 

 with lime water. The solubility of the potash and phosphoric acid in the fine 

 ground feldspar was increased to a marked extent in the course of 6^ months 

 when mixed with moor soil at the rate of 1 part of feldspar to 9 of soil. The 

 solubility was still further increased when ammonium sulphate was added to 

 the mixture. 



Factors influencing the availability of rock phosphate, E. Truog {Wiscon- 

 sin Sta. Research Bui. 20, pp. 11-51, figs. .'/). — Previous investigations on this 

 subject are reviewed, and studies of the effect of fermenting manure and grass, 

 and of thoroughness of mixing with the soil, on the availability of floats are 

 reported. 



In laboratory experiments in which organic matter was compostetl with raw 

 phosphates there was little or no solvent action of the fermenting material. 

 The solvent action was apparently measured by the amount of phosphate 

 which the water containing carbon dioxid could hold in solution, and in the 

 laboratory experiments a state of equilibrium in this respect was quickly 

 reached and there was no further solvent action. Under field conditions, how- 

 ever, there was a continual removal of the dissolved substances, resulting in 

 conditions which greatly increased the solvent action of the carbon dioxid. 



The mixing of floats with manure caused an immediate decrease in the solu- 

 bility of the phosphoric acid in 0.2 per cent citric-acid solution, indicating 

 " that the availabilitj' of phosphates as measured by a solvent like 0.2 per cent 

 citric acid may be entirely different from availability as measured by grow- 

 ing crop." 



When floats was thoroughly mixed with the feeding area of the soil its avail- 

 ability was increased to such an extent that some species of plants were 

 apparently able to secure almost an adequate supply of phosphoric acid from 

 this material. Apparently the carbon dioxid given off by the plant roots was 

 instrumental in increasing the availability of the phosphoric acid of the floats. 

 The addition of manure to the soil greatly increased the carbon dioxid in-oduc- 

 tion and for a short time measurably increased the solvent action on floats. 



The general conclusion, therefore, is that the use of organic matter in con- 

 nection with floats increases its availability to plants. "The organic matter 

 brings about this increased availability by favoring a more efficient initial 

 mechanical distribution of the floats with the soil and by favoring the chemi(ial 

 and biological processes that give rise to carbon dioxid and other agencies 

 which attack floats and ultimately give the material a finer and more uniform 

 distribution through the soil." 



Report of a reconnoissance of the Lyon nitrate prospect near Queen, 

 W. Mex., E. E. Fkee {JJ. 8. Dept. Agr., Bur. Soils Circ. 62, pp. 6, figs. 5). — 

 The examinations reported show the occurrence of small amounts of potassium 

 nitrate, but not enough " to have any important commercial value." 



