The liii.i.KTTX 11 



Station, ill an address before the Pennsylvania State Boaivl of Agricul- 

 ture at llarrisburg, was asked l>y a farmer wlietlicr there would Ui any 

 injurious effect from mixing acid phosjihate with limestone and wood 

 ashes. Dr. Tliorne replied: "Xo. no injurious effect to the acid phos- 

 phate. You should nol mix nitrate of soda witii it, but the phosphoric 

 acid will not suffer any harm.*' 



On February 2!)th of this year we asked I)r. Lining L. \'an Slyke, of 

 the Geneva E.\])eriment Station, Xew York, whether, in his opinion, 

 detrimental results would foHow mixing f!00 j)()unds of ground limestone, 

 400 i)Ounds of acid pliosphate, and 200 pounds of cotton-seed meal, thus 

 making a fertilizer mixture with ground limestone substituted for pot- 

 ash. To our iiKjuiry, Dr. \'an Slyke repdied : "The mixture of 600 

 pounds of ground limestone. 400 pounds of acid phosphate, and 200 

 pounds of cotton-seed meal can be made without objection if the mix- 

 ture is made within a few days previous to application to the soil." 

 There is no higher authority on soil chemistry in the United States than 

 Dr. Van Slyke. 



In his discussion of the effects of carbonates of lime on the soil, 

 Prof. J. S. Brogdon. of Atlanta, Ga., Secretary Chemical Industries, 

 Georgia Chamber of Commerce, and of the Georgia Section of the 

 A. C. S., agrees with Dr. Van Slyke in saying "when acid jihosphate is 

 api)lied to the soil, if there is a deficiency of carbonate of lime in the 

 soil, the phosphoric acid will combine with the iron and aluminum of 

 the soil to form the phosphates of iron and alnmiiiuni ; but in soils con- 

 taining any reasonable amount of lime, dicalcium* i)hosphate will be 

 formed. The former are of much lower solubility than the latter, con- 

 sequently their phosjihoric acid is much slower in reaching the plant. 

 Applications of carbonate of lime are of great value on soils because 

 they form DICALCIUM PHOSPHATES, and so increase the amount 

 of phosphoric acid soluble in water. 



"As has been previously mentioned, ground limestone has no tendency 

 to absorb moisture from the atmosphere, while acid jihosphate has a de- 

 cided tendency in that direction, due to the fact that free phosphoric 

 acid easily ab.sorbs moisture from the atmosphere. Acid phosi)hate 

 which analyzed 18 per cent in the i>ile, in one instance, proved to be 

 strongly acid, and when reduced to 16 jx'r cent by the use of ground 

 limestone the most delicate chemical test failed to find the slightest 

 trace of free acid, and on account of this there was a decided t(Midency 

 for the acid ])hosphat<' to remain dry, even tlniugli it was exposed to 

 damp atmosj)here. 



"A mixture of 80 per cent pliosphate, 20 per cent ground limestone, 

 covering some fifty analyses, may be summarized in saying that the 

 amount of moisture remainded unchanged, that the total phosj)horic 

 acid was not affected, whereas the water soluble was found to decrease 

 and the citrate solubles found to increase the same amount, that biung 

 approximately 6 per cent, this change being due to the formation of 



