14 The Bulletin 



MIX GROUND LIMESTONE WITH ACID PHOSPHATE IM- 

 MEDIATELY BEFORE APPLYING IT TO THE SOIL FOR 

 THE DOUBLE PURPOSE OF SUBSTUrUTlNG THE GROUND 

 LIMESTONE FOR POTASH IN THE FERTILIZER MIXTURE, 

 AND FOR PREVENTING THE IMMEDIATE FORMATION OF 

 THE INSOLUBLE PHOSPHATES OF IRON AND ALUMINUM. 



No doubt other experiments could be cited that would seem to prove 

 the opposite of the conclusions justified from the above data, but the 

 facts ^nd conclusions incorporated in the foregoing discussion are 

 vouched for by the most eminent authorities in the entire field of agri- 

 cultural research and are in complete harmony with careful observation, 

 practical farm exj>erience, and carefully planned and wisely interpreted 

 field experiments, as well as in accord with ordinarv common sense and 

 reason. THEY ARE, MOREOVER, IN ACCORD WITH THE 

 FARMER'S BEST INTERESTS AT THIS TIME, AS A MEANS 

 BY WHICH HE MAY REDUCE THE EXORBITANTLY HIGH 

 PRICE OF HIS FERTILIZERS. 



No attempt has been made to leave the impression that acid phos- 

 phate mixed with ground limestone will not revert to what is called di- 

 calcium and, to some extent, to triealcium forms. But these forms of 

 phosphorus are STILL AVAILABLE TO THE CROPS, WHILE 

 THE IRON AND ALUMINUM PHOSPHATES ARE ENTIRELY 

 OUT OF REACH OF THE PLANTS. 



All agree that ordinary acid phosphate will slowly revert to the rela- 

 tively insoluble forms even while stored in bags and unmixed with any- 

 thing, but on being applied to and mixed with the soil will revert to the 

 entirely insoluble forms of iron and aluminum i)hosphates with great 

 rapidity. The farmer thus loses much of his phosphatic numures which, 

 IF THEY HAD BEEN MIXED WITH (^VLCIUM CARBONATE 

 AT FIRST AND APPLIED TO THE SOIL IN THIS MIXED 

 CONDITION, would have remained in a condition available to the 

 crop through the gradual solution of tlie di- and tri-calcium phosphates 

 by the various acids found in the ordinary soil solutions. THERE- 

 FORE, SINCE ACID PHOSPHATE, WHEN APPLIED TO ORDI- 

 NARY NORTH CAROLINA SOILS, IF NOT IMMEDI.VTELY 

 TAKEX l^P P,Y THE PLANTS, ALWAYS REVERTS, WirillX 

 A VERY SHORT TIME, TO THE MORK OR LESS INSOLLBLE 

 FORMS, IT IS OF THE FIRST IMPORTANCE TO THE 

 FARMER THAT IT I5F PERMITTED TO ClIAXGE IXTO 

 FORMS FROM WHICH SUCCEEDING- CROPS CAN SECURE 

 IT WITH RELATIVE EASE. 



From tlu! evidence at hand, we feel justiticil in olTi'iiiig the farmers 

 of North Caroliiui the following t'ertilizcr fonmilas conlaiiiing calcium 

 carbonate a.s a substitute for jjotasli. The practice of using limestone 

 to lilM'rate inert soil jjotash is too well (>stiil)lislied for serious discussion 

 at this time. These and similar fnniiulas are not entirely new, but have 

 Ik'cii used f(tr some time with tlie liest of results; ;in(l \ho fanner's own 



