SPECIAL CIRCULAR January, 1919 



MASSACHUSETTS AGRICULTURAL EXPERIMENT STATION 



Department of Plant and Animal Chemistry. 



THE VALUE OF APATITE AND BARIUM SULFIDE 

 (Barium-Phosphate) 



By H. D. Raskins 



This material is not a chemical combination of barium and phosphorus 

 as perhaps the name would indicate, but is a mechanical mixture of an in- 

 soluble or three lime phosphate, similar to Canadian apatite, with about 7 

 per cent of barium sulfide. Apatite in its natural state is recognized as the 

 most insoluble of the natural phosphates. 



Among the claims of the manufacturers of the so-called Barium-Phos- 

 phate are the following: 



1. That its phosphoric acid is available as a source of plant food. 



2. That it will favor early maturity of crop. 



3. That it furnishes sulfur in a form readily accessible to the growing 



plant. 



4. That it sweetens the soil by the alkaline salt barium sulfide. 



With reference to these claims, the present state of our knowledge leads 

 us to say : 



1. Our experiments indicate that an insoluble phosphate similar to 

 apatite, mixed with about 7 per cent of barium sulfide (Barium-Phosphate) 

 when used in pots without manure, but in one instance with a green cover 

 crop, gave up little if any phosphoric acid to the crop grown.* 



2. Barium-Phosphate used with and without manure in a field experi- 

 ment conducted in 19 18, did not favor the early maturing of the corn crop 

 over that grown on adjoining plots without the use of the Barium-Phosphate. 



3. It is conceivable that the barium sulfide which is mixed with the 

 apatite may eventually furnish some soluble sulfur compounds. It is hardly 

 conceivable that the average soil which received annual manure and fertili- 

 zer applications would be found deficient in available sulfur compounds, as 

 manure contains much soluble sulfates, and most mixed fertilizers contain 

 an abundance of sulfur in the form of calcium sulfate, or gypsum, resulting 

 from a union of the calcium oxide with sulfuric acid, with which the raw 

 phosphate is treated in making the acid phosphate. 



4. Provided the Barium-Phosphate does have a sweetening effect on 

 the soil, it must be relatively small as only about 7 per cent of the product 

 is claimed to be barium sulfide. This would mean that in a 1,000 pound 

 application, which is the average amount recommended by the company, 



