The Bulletin 



Volume 28. North Carolina State Board of Agriculture! Number 7. 



Entered at the Raleigh Post-office as second-class mail matter. 



The Bulletin is published monthly by the State Board of Agriculture. 



RALEIGH, JULY, 1907. 



I.— FEETILIZER ANALYSES. 



Fall Season, 1906 — Spring Season, 1907. 



BY B. W. KILGORE, STATE CHEMIST. 



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 fall months of 1906 

 and the spring months of 1907, and therefore represent the charac- 

 ter of fertilizers the farmers have used on the crops of the past year. 

 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 whether or not they contained the fertilizing constituents 

 in the amounts they were claimed to be present. 



terms used in analyses. 



Water-soluhle 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 a 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 sul- 

 phuric 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 phos- 

 phate is what is kno^vn as water-soluble phosphoric acid. 



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

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



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