16 The Bulletin 



which to supply the necessary nitrogen for normal crop production. Look 

 at the facts from whatever angle one may, the logic of the situation drives 

 one to this inevitable conclusion. 



RELATION OF LIME CARBONATE TO ACID PHOSPHATE. 



We will now turn to another and more important phase of this matter, 

 namely, that in which the circular contradicts the advice given in 

 Bulletin ISTo. 220, concerning the mixing of ground limestone with acid 

 phosphate and ammoniated fertilizers and as a substitute for potash in 

 the fertilizer formula, and for prolonging the availability and increas- 

 ing the efficiency of the acid phosphate in the soil. 



On page 6 we find this statement : "Generally, it will be unwise to 

 mix finely ground limestone with acid phosphate, as it is illogical 

 and unwise, for the reason that the lime is likely to have an in- 

 jurious effect upon the available phosphoric acid content in the acid 

 phosphate." While the Pennsylvania Station mixed caustic lime with 

 soluble phosphate with excellent results. Bulletin ISTo. 220 of the North 

 Carolina Department of Agriculture does not advise such practice. It 

 does advise, however, the mixing of ground limestone and marl with acid 

 phosphate for the double purpose of suhstituting lime carhonate for 

 potash in the fertilizer formula and for preventing the imm,ediate for- 

 mation of the insoluble phosphates of iron and aluminum in the soil; and 

 this advice has been taken with gratifying results by dozens of farmers 

 the past season. In support of its proposition the Extension Circular, 

 JSTo. 24, cites some work by Brackett & Freeman of the South Carolina 

 Experiment Station in which they found that acid phosphate mixed with 

 ground limestone tended to revert from the monocalcium to the trical- 

 cium form. JSTo other experiment in support of this proposition is cited. 

 But the following quotation from a letter from the J. L. Yance Fertili- 

 zer Company of Chilhowie, Va., 1914, will show the seriousness of the 

 above objection : 



"We have also made tests as to the effect of ground limestone causing 

 reversion of available phosphoric acid, and while we have found that 

 there is a slight reversion after the limestone has been alloived to set in 

 the mixture for two or three months, there is no appreciable reversion 

 where it is used within a reasonable time. Even where it is allowed to 

 set as much as three or four months, the reversion is not sufficient to be 

 an objection. 



"Our experience with ground limestone is that it puts our goods into 

 the finest possible mechanical condition, and we prefer it to anything we 

 have tried in the way of a filler." 



On the same page of the circnlnr avp find a plon for the manufncturors 

 of acid phosphate, as follows: "The manufacturer of acid phosphate 

 has gone to considerable expense and trouble to put upon the 

 market a material which will contain a higher per cent of available 



