524 AGRICULTURAL ANALYSIS 



likely that all the potash added, even in the form of soluble 

 potash salts, is actually used, and the amount that can be sup- 

 plied by ground rock is still an unknown quantity." 



The quantity of feldspar ground in short tons and the cost 

 of production is given in the following table for the years 1901- 

 5 inclusive: 



PRODUCTION AND VALUE OF FELDSPAR, 1901-1905. 



[Short Tons] . 



Crude. Ground. Total. 



Year Quantity. Value. Quantity. Value. Quantity. Value. 



I9CI 9,960 $21,669 24,781 $198,753 34.741 $220,422 



1902 21,870 55,501 23,417 194,923 45,287 250,424 



I93 13,432 51,036 28,459 205,697 41,891 256,733. 



1904 19,413 66,714 25,775 199,612 45,188 266,326 



1905 14,517 57,976 20,902 I68,l8l 35,419 226,157 



443. Possible Harmful Effects of Ground Feldspar. "The ques- 

 tion is frequently asked whether there is possible danger to the 

 land in experimenting with the use of ground feldspathic rock. 

 It is well known that in some cases, notably with tobacco, in- 

 jurious effects are produced by the continued use of the soluble 

 potash salts, particularly the sulphate and muriate. Feldspar 

 grains of various sizes are normally present in many soils; it 

 does not, therefore, seem possible that any harmful effect could 

 follow the application of ground rock. As has been pointed out 

 in an earlier portion of this paper, feldspar consists of the al- 

 kaline elements, soda, potash, and lime, combined with alumina 

 and silica. After decomposition, hydrated aluminum silicate, the 

 essential base of all clays, is left behind, the alkalies and the 

 silica being set free in a condition in which they can be ab- 

 sorbed by the root action of plants. It would seem, therefore, 

 that whatever the value of the results obtained no possible harm 

 can follow the experimental use of ground felspar in reasonable 

 quantities." 



444. Extract of Potash from Ground Rock. "The discussion of 

 the use of ground rock as a source of potash is not complete 

 unless it includes the extraction of potash by chemical and elec- 

 trical processes. If future experiments should demonstrate that 

 fast-growing crops are dependent on very soluble forms of 



