ALUNITE AND KELP AS POTASH FERTILIZERS. 



ignited alunite over the untreated soil varied from 35 to 43 per cent, 

 the average increase being 40 per cent. The growth with the raw 

 alunite was not as good as with similar amounts of potash as potas- 

 sium sulphate and potassium chloride. The average increase with 

 potassium sulphate was 38 per cent and with potassium chloride was 

 31 per cent. The effect of ingited alunite was about the same as that 

 of potassium sulphate, and greater than that of the potassium 

 chloride. 



Kelp produced a considerable increase in growth over the untreated 

 ^oil. The increase varied with the different amounts, from 17 to 43 

 per cent. The average increase over the untreated soil was 31 per 

 cent. The increased growth was about the same as that produced 

 by potassium chloride, and was slightly less than that resulting from 

 the use of potassium sulphate. It should be here noted that the 

 potash in the kelp is in the form of the chloride. 



Another experiment was made to test the effect of these potash 

 compounds, using this time a different soil. Otherwise the details of 

 the experiment were the same as in the first test. The soil used in 

 this test was the Volusia silt loam. The plants grew from Novem- 

 ber 19 to December 21. Three pots were used for each treatment. 

 The results are given in Table II. 



TABLE II. Effect of alunite and kelp on growth, as compared with potassium sulphate 



and potassium chloride. 



[Cir. 76| 



