I. ANALYSES OF FERTILIZERS— SPRING SEASON, 1913. 



By B. W. KILGORE, 

 W. G. HAYWOOD, J. M. PICKEL, J. Q. JACKSON, and E. S. DEWAR. 



The analyses presented in this Bulletin are of samples collected by 

 the fertilizer inspectors of the Department, under the direction of the 

 Commissioner of Agriculture, during the spring months of 1913. They 

 should receive the careful study of every farmer in the State who uses 

 fertilizers, as by comparing the analyses in the Bulletin with the 

 claims made for the fertilizers actually used, the farmer can know by 

 or before the time fertilizers are put in the ground whether or not they 

 contain the fertilizing constituents in the amounts they were claimed to 

 be present. 



TERMS USED IN ANALYSES. 



Water-soluble Phosphoric Acid. — Phosphate rock, as dug from the 

 mines, mainly in South Carolina, Florida, and Tennessee, is the chief 

 source of phosphoric acid in fertilizers. 



In its raw, or natural state, the phosphate has three parts of lime 

 united to the phosphoric acid (called by chemists tri-calcium phos- 

 phate). This is very insoluble in water and is not in condition to be 

 taken up readily by plants. In order to render it soluble in water and 

 fit for plant food, the rock is finely ground and treated with sulphuric 

 acid, which acts upon it in such a way as to take from the three-lime 

 phosphate two parts of its lime, thus leaving only one part of lime 

 united to the phosphoric acid. This one-lime phosphate is what is 

 known as water-soluble phosphoric acid. 



Reverted Phosphoric Add. — On long standing some of this water- 

 soluble phosphoric acid has a tendency to take lime from other sub- 

 stances in contact with it, and to become somewhat less soluble. This 

 latter is known as reverted or gone-back phosphoric acid. This is 

 thought to contain two parts of lime in combination with the phos- 

 phoric acid, and is thus an intermediate product between water-soluble 

 and the original rock. 



Water-soluble phosphoric acid is considered somewhat more valuable 

 than reverted, because it becomes better distributed in the soil as a con- 

 sequence of its solubility in water. 



Available Phosphoric Acid is made up of the water-soluble and re- 

 verted ; it is the sum of these two. 



Water-soluble Ammonia. — The main materials furnishing ammonia 

 in fertilizers are nitrate of soda, sulphate of ammonia, cotton-seed meal, 

 dried blood, tankage, and fish scrap. The first two of these (nitrate 

 of soda and sulphate of ammonia) are easily soluble in water and be- 



