82 BOTANICAL GAZETTE [februaky 



potassium or both. This view is presented by Griffiths (25), 

 VooRHEES (72), and Hopkins (32). Browne (13) and Bruckner 

 (14) consider the beneficial effect of gypsum due, in part at least, 

 to the nutrient effect of the sulphur; while Vendelmans (70) and 

 HiLGARD (31) mention its beneficial effects, particularly on the 

 legumes, without giving any explanation. 



In most fertilizer experiments sulphur has been added, together 

 with phosphorus, in acid phosphate or basic slag, or with the 

 potassium in potassium sulphate or kainit. When beneficial results 

 have been obtained, the investigators have invariably ignored the 

 possible effects of the sulphur. This may lead to erroneous con- 

 clusions, as was pointed out by Liebig (37) in 1855. He said 

 that the sulphur or the calcium in the acid phosphate, or both, 

 might have had a beneficial effect on the turnips in the Rothamsted 

 experiments, as well as the phosphorus. 



Hopkins, Hosier, Pettit, and Readhimer (33) found that 

 kainit increased the yields of corn, wheat, and oats on the waste 

 hill land of Johnson County, Illinois, when used with bonemeal, 

 ground Hmestone, and crop residues^ over similarly treated plots 

 without kainit. On the plots receiving no kainit, as well as on 

 those receiving the kainit, cowpeas were grown once every three 

 years and turned under as part of the crop residues. Stewart 

 (66) compared potassium chloride and potassium sulphate as 

 fertilizers for apple orchards in Pennsylvania. He found no 

 appreciable difference in the effect of these salts. Smith (65) 

 found a greater yield of oat straw for potassium sulphate than 

 potassium chloride in pots containing Hagerstown silt loam. 



Brooks (8) compared the effects of potassium sulphate and 

 potassium chloride on alfalfa in field experiments at the Massachu- 

 setts Agricultural Experiment Station. Both plots received 600 

 pounds of bonemeal per annum, and both received 2 tons per 

 acre of hydrated hme before planting the alfalfa. Both Grimm 

 alfalfa and common alfalfa were used. Potassium sulphate gave 

 increased yields of 0.50 tons of Grimm alfalfa and 0.75 tons of com- 

 mon alfalfa over potassium chloride. In every case the alfalfa on the 

 plots receiving potassium sulphate was a darker green than on the 

 plots receiving potassium chloride. The same diflference in color 



