20 The Bulletin 



fix 60 to 70 per cent of tlie water-soluble phosphates into insoluble, or, 

 as measured by these solvents, into unavailable form. Where lime was 

 mixed with equal quantities of iron and aluminum hydroxides the 

 fixation of phosphoric acid was not so great, as 57 per cent was 

 available, showing that a part combined with the lime. Where calcium 

 and magnesium carbonates were used as a fixing agent the resulting 

 compounds tvere completely dissolved and would have to be classed as 

 available." The entire contents of the May Bulletin, ISTo. 220, of the 

 North Carolina Department of Agriculture should noAV be read carefully 

 for further information on this subject. This bulletin contains fertilizer 

 formulas in which limestone is substituted for potash and mixed with 

 acid phosphate and cotton-seed meal. 



The farmers were urged to use these formulas the past season in which 

 lime carbonate is substituted for potash and mixed with acid phosphate 

 and cotton-seed meal to make a complete mixture for our general farm 

 crops, including tobacco. Some forty or more took the advice of Bulle- 

 tin No. 220 and used the formulas. 



Thirty-one of these farmers have reported results by letter which we 

 have on file for public inspection, while ten or twelve reported verbally. 

 Out of the forty or more who actually tested the advice given in 

 Bulletin JSTo. 220, thirty-nine were highly pleased with the results, while 

 the other three could not make a definite statement on account of the wet 

 weather. A number of them said they got as good results by using these 

 formulas, that cost them, perhaps, not over $15 a ton, as from the 

 regular 8-2-2 that cost, last season, over $30 a ton. It will be seen, there- 

 fore, that in addition to the unimpeachable evidence already given, we 

 have here thirty-nine witnesses for Bulletin ISTo. 220, and against Exten- 

 sion Circular, No. 24, which opposes such action on the part of the 

 farmers. 



The following letter from the N. P. Pratt Commercial Fertilizer 

 Laboratones in Atlanta, Ga., will show what the leading commercial 

 fertilizer experts of the South think of the contents of Bulletin No. 220, 

 concerning the mixing of ground limestone with acid phosphate.. The 

 letter follows ; copy of the analysis referred to follows this letter : 



Atlanta, Ga., July 21, 1916. 

 Hon. W. a. Graham, 



Commissioner of Agriculture, 

 Raleigh, N. C. 

 Dear Sir: — My attention has just been called to the Bulletin of the North 

 Carolina Department of Agriculture, Whole No. 220, which has been issued 

 to the people of the Slate by your direction. Please permit me to congratu- 

 late you on the publication of this bulletin in the interest of agriculture in 

 North Carolina. Your recommendations constitute a forward movement in 

 the interest both of the farmers and of the manufacturers and mixers of 

 commercial fertilizers, and its good effects are going to be heard from. 



There is one point in connection with the use of natural lime carbonate 

 as a part of the commercial fertilizer mixtures wliich appears not to have 



