ALUNITE AND KELP AS .POTASH FERTILIZERS . 



The soil used in the first experiment was the Carrington loam a 

 soil which is known to respond well to potash fertilizers in field prac- 

 tice. The soil was treated with the various fertilizers in pans on 

 October 22, was well mixed by sifting, and was potted October 28. 

 Three pots, each holding about a pound of soil, were used for each 

 treatment. Six wheat plants were planted in each pot. The plants 

 grew until November 29. At the end of the experiment the plants- 

 were cut and the green weights recorded. The results of the test are 

 given in Table I. The last column gives the relative growth of the 

 different treatments. The growth of the check or control is taken as 

 100. The third column gives the green weights of the three cultures 

 in each treatment. 



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



and potassium chloride. 



By examination of the table it is seen that each of the potash fer- 

 tilizers produced an increased growth over the untreated so'l. The 

 raw alunite used in amounts of 25 to 500 pounds of K 2 O per acre 

 increased growth from 10 to 20 per cent. The best results were 

 secured with 50 to 100 pounds of potash (K 2 O) per acre. The aver- 

 age increase over the untreated soil of the five amounts was 14 per 

 cent. When the growth is compared with that produced by the 

 ignited alunite it is seen, that this caused larger growth with each 

 amount used than did the raw alunite. The increase in growth with 



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