because the 'specials' are not properly compounded, and sec- Food for 

 ond, because the needed plant food can be thus procured at P1>nts 

 lower cost."* l8 9 



The continuous use of muriate of potash may so far de- 

 plete the soil of lime that an occasional application of this 

 material may be required in case of such use. The sulphate of 

 potash may be a safer material to use where a growth of 

 clover is desired than the muriate, and therefore it may often 

 be wise to use the sulphate. The high-grade sulphate should 

 be selected. 



These materials should as a rule be mixed just before 

 use, and applied broadcast (after plowing) and harrowed in 

 just before planting the seed. Where Nitrate of Soda is to 

 be used in quantities in excess of 150 pounds per acre, one-half 

 the amount of this salt may be withheld until the crop is j or 

 4 inches high, when it may be evenly scattered near the plants. 

 It is unnecessary to cover this, though it may prove more 

 promptly effective in absence of rain if cultivated in. 



The quantities recommended are in most cases moderate. 

 On soils of good physical character it will often prove profit- 

 able to use about one and one-half times the amounts given. 



Terms Used in Discussing Fertilizers. 



NITROGEN may exist in three distinct forms, viz., as 

 Nitrates, as Nitrogenous organic matter, as ammonia salts. 



NITRATES furnish the most readily available forms of 

 Nitrogen. The most common is Nitrate of Soda. 



NITRATION, or Nitrification, is the process by which 

 soluble Nitrate is formed from the less available and less 

 soluble Nitrogen of sulphate of ammonia, dried blood, cotton- 

 seed meal, tankage, etc. It is due to the action of microscopic 

 organisms, and all nitrogenous fertilizers must undergo this 

 process of Nitration before plants can use them. 



PHOSPHORIC ACID, one of the essential fertilizing ingre- 

 dients, is derived from materials called phosphates. It does 

 not exist alone, but in combination, most commonly as phos- 

 phate of lime in the form of bones and Rock phosphate. 

 Phosphoric acid occurs in fertilizers in two forms available 

 and insoluble phosphoric acid. 



*U. S. Department Agricultural, Farmers' Bulletin, 65 and 84 (Experiment 

 Station Work, II, page 27; VII, page 5). 



