488 INVESTIGATION BY CULTURE EXPERIMENTS 



ciable benefit. Nitrogen (cotton-seed meal) alone gave good results. A mix- 

 ture of cotton-seed meal and phosphates gave good results." 



"The fertilizer test with peas was interfered with somewhat by the October 

 storm, but it was apparent that both acid phosphate and crude, finely ground 

 rock increased the growth of peas in a marked manner apparently doubling 

 the crop." 



In Iowa Bulletin 98, 1908, are reported the following yields of 

 clover hay from the Leon experiment field on the loess and till 

 soils of southern Iowa. 



TABLE 99. SOUTHERN IOWA FIELD EXPERIMENTS 



Mixed loess and till. 



The following comments are made in the summary of Iowa 

 Bulletin 98 : 



"Manure applied to the soil at the rate of eight tons per acre was decidedly 

 beneficial to the growth of clover." 



"Phosphorus applied to the soil as steamed bone meal nearly doubled the 

 yield of clover. The steamed bone meal was applied at the rate of 200 pounds 

 per acre." 



"Potassium, applied to the soil as potassium sulfate, did not increase the 

 clover crop. Neither did this element of plant food prove beneficial when used 

 in combination with phosphorus." 



