ALUNITE AND KELP AS POTASH FEETILIZERS. 5 



Each of these potash fertilizers had a beneficial effect on Volusia 

 silt loam. The raw alunite again produced less increased growth than 

 the ignited alunite. This was true with each amount of the substances 

 used. The raw alunite was not as effective as potassium sulphate 

 and potassium chloride. However, the ignited alunite was more 

 effective. The average increase for the raw alunite was 16 percent, 

 for the ignited alunite 31 per cent, for potassium sulphate 25 per 

 cent, and for potassium chloride 22 per cent. 



As in the first experiment kelp again produced considerable 

 increase in growth. The effectiveness in producing plant growth 

 was practically the same as that of potassium sulphate and potassium 

 chloride. Kelp gave as an average 23 per cent increase in growth, 

 potassium sulphate 25 per cent, and potassium chloride 22 per cent 

 increase. In addition to the amount of potash added to the soil by 

 the kelp, it contains a small amount of nitrogen and phosphorus, 

 which should be effective in the soil. From these two experiments 

 it seems that the dried kelp and ignited alunite are about as effective 

 potash fertilizers as the salts, potassium sulphate and potassium 

 chloride. 



Approved: 



JAMES WILSON, 



Secretary of Agriculture. 



WASHINGTON, D. C., January 30, 1918. 



ICIr. 70J 



ADDITIONAL COPIES of this publication 

 -tX may be procured from the SUPEEINTEND- 

 ENT OF DOCUMENTS, Government Printing 

 Office, Washington, D. C., at 5 cents per copy 



' OOVCHW*MT PRIM UNO Of PlOfl I 



