No. 4.] HOW TO BUY FERTILIZERS. 221 



taiiier. The only figures that need be printed to comply with 

 this law in some States are the percentage of total nitrogen, 

 available phosphoric acid, insoluble phosphoric acid, and of 

 total potash, but Rhode Island requires soluble phosphoric 

 acid. The fertilizer bag sometimes has printed on it, or on 

 the tags attached, a number of figures which might at first 

 seem to be unnecessary, such as the equivalent of nitrogen 

 in ammonia; but in some States this is required by law, 

 so in order to meet all State requirements both are often 

 given. The equivalent of potash in sulphate of potash is 

 necessary to show the fact, in case it is not all from muriate. 

 These figures may be misleading to some persons not thor- 

 oughly acquainted with fertilizer lore, and it would be a step 

 in the direction of intelligent understanding of these matters 

 if the fertilizer laws could all be tnade uniform as concerns 

 these requirements. 



The figures on the bag are on a percentage basis. For ex- 

 ample, a fertilizer w'ith 2 per cent nitrogen, 5 per cent phos- 

 phoric acid and 6 per cent potash, would contain in 1 ton, 

 40 pounds of nitrogen, 100 pounds of phosphoric acid and 

 120 pounds of potash. 



While it is unnecessary for a farmer to carry in his head 

 the exact analyses of the fertilizing materials, as these are 

 published annually in the fertilizer bulletin of the Massa- 

 chusetts Agricultural Experiment Station, it is desirable 

 that he should have a working knowledge of the make-up 

 of the principal raw materials, which are as follows : — 



Xitrate of soda contains about 15.5 per cent nitrogen. 

 Sulphate of ammonia contains about 20.5 per cent nitrogen. 

 Acid phosphate contains about 12-16 per cent available phosphonc 

 acid. 



Basic slag contains about 12-18 per cent total phosphoric acid. 

 Muriate of potash contains about 50 per cent potash. 

 High-grade suli^hate of potash contains 48-49 per cent jiotash. 



In order to find the money value of fertilizers another 

 essential factor must be brought into use, namely, the value 

 per pound of the several fertilizing ingredients. 



This information is published annually by the directors 



