REPORT OP THE DIRECTOR AND STATE GEOLOGIST 1903 



121 



use; and the material so acted on is usually clay, which is essen- 

 tially a hydra ted silicate of aluminum with certain percentages 

 of potash and soda, and is derived from the decomposition of 

 the feldspar of granite rocks. Shale and slate are modified forms 

 of this material and are acted on in the same way as the clay in 

 its plastic form. 



In the greensand region of New Jersey I talked with a farmer, 

 who said that he had for many years used greensand, but that, 

 as time went on, he failed to get a proportionate increase in the 

 crops from the application of this material. He gave a light 

 coating of lime to a meadow, and on that portion where the 

 lime was applied, the crop was nearly twice as heavy as on the 

 portion not so treated. Inasmuch as greensand marl contains 

 about 3^ of potash, the explanation seems to be that the lime 

 set the potash free, with a marked increase in the crop. 



Boussingault discovered that an increased percentage of 

 potash in the ashes of clover was apparently the result of the 

 application of gypsum to the soil. His experiments carried on 

 for two years on the same land gave the following results.^ 



Ashes free from CO^ 



1841 



Silica 



Oxids (iron manganese and 



alumina) 



Lime 



Magnesia 



Potash 



Soda 



Sulfuric acid 



Phosphoric acid 



Chlorin 



1842 



Land with 





Land with 





gypsum 



No gypsum 



gj'-psum 



No gypsum 



270 



113 



280 



97 



28.1 



22 7 



10.4 



12.7 



2.7 



1.4 



(?) 



.6 



79.4 



32.2 



102.8 



32.2 



18.1 



8.6 



28.5 



7.1 



95.6 



26.7 



97.2 



28.6 



2.4 



1.4 



.8 



2.8 



9.2 



4.4 



9 



3 



24.2 



11 



22.9 



7 



10.3 



4.6 



8.4 



3 



From the foregoing it will be seen that the best results from 

 the application of gypsum will be obtained from the application 

 to soils containing potash in an insoluble form. 



^Storer. Agricultural Chemistry. 1887. 1:206, 216, 

 ley, Gypsum Deposits of Kansas, p. 127. 



Quoted by Grims- 



