THE USE OF FERTILIZERS 97 



correct the acidity of the soil. This fertilizer is 

 now becoming available in the United States at 

 fairly reasonable prices. While the phosphoric acid 

 still seems to cost slightly more a pound than it does 

 in acid phosphate, practical growers prefer to pay the 

 difference in a good many cases. Bone is a popular 

 form of phosphoric acid. In many cases its use 

 is economical and advisable. Its composition varies 

 considerably, however, according to the method by 

 which the bone is treated. Steamed bone contains 



TWO-YEAR ORCHARD INTERCROP SQUASHES 



relatively less nitrogen and lelatively more phos- 

 phoric acid than that which has been ground with- 

 out steaming. 



The form of potash used most is muriate, which in 

 the various grades contains from 45 to 62 per cent 

 of actual potash. The muriate, however, is nearl}/ 

 always mixed with other salts, so that as it is ap- 

 plied to the land there is seldom more than 50 per 

 cent of actual potash available. 



Two sulphates of potash are known commercially 



