520 EXPERIMENT STATION EECOBD. [Vol.35 



It was foxuid in the experiments that the ammonium phosphate gave as good 

 results, both as a nitrogenous and phosphatic fertilizer, as the ammonium- 

 superphosphate mixture. 



Availability of mineral phosphates for plant nutrition, W. L. Bublison 

 (U. S. Dept. Agr., Jour. Agr. Research, 6 {1916), No. IS, pp. 485-514, pis. 8).— 

 A review of literature bearing on the subject is given, and 3^ years' experiments 

 conducted at the Illinois Experiment Station on (1) the availability of phos- 

 phorus in Tennessee brown rock phosphate for wheat, oats, rye, barley, cow- 

 peas, timothy, red clover, and alfalfa, (2) the comparative productive powers 

 of six mineral phosphates for farm crops, (3) the influence of fermenting 

 dextrose and crop residues on the availability of phosphorus in finely ground 

 rock phosphate, and (4) the influence of the size of particles on the avail- 

 ability of phosphorus in mineral phosphates are reported. 



It was found that "phosphorus in rock phosphate can be assimilated by 

 farm crops in sand cultures under greenhouse conditions, even in the absence 

 of decaying residues. Crop residues, when employed in conjunction with 

 brown rock phosphates, were beneficial. Tennessee brown rock phosphate, 

 Florida soft rock phosphate, and Tennessee blue rock phosphate in the heavier 

 applications proved superior to South Carolina land rock phosphate, Utah 

 rock phosphate, and Canadian apatite, for oats, clover, and cowpeas when 

 grown in sand. The phosphorus in brown rock phosphate and Florida soft 

 rock phosphate was more soluble in water and in plant-food solutions than the 

 phosphorus in other mineral phosphates. The superiority of these two phos- 

 phates over the others tested is shown chiefly by the first crop. 



"Chemical analysis showed that the plant-food solutions applied did not 

 appreciably modify the results. The cereals produced as satisfactory yields 

 as the legumes. 



"The crop yields tended to increase as the application of rock phosphate 

 increased up to a point where the size of the pots seemed to be a limiting 

 factor, apatite being the only exception. The plants obtained their calcium, as 

 well as their phorphorus, from brown rock phosphates. No better results were 

 secured when calcium carbonate was applied than when rock phosphate alone 

 was used. There was no particular relation between the citric-acid-soluble phos- 

 phorus and the availability of these phosphates for plants. Dextrose, when 

 used as a fermentable substance, was harmful. 



"The degree of fineness is a factor which determines to some extent the 

 availability of rock phosphate, as indicated by the brown rock." 



A list of 32 references to literature bearing on the subject is appended. 



Raw rock phosphate v. acid phosphate, C. E. Thoene (Mo. Bui. Ohio Sta., 

 1 {1916), No. 6, pp. 188-192). — Experience at several of the state experiment 

 stations is reiriewed and 20 years' experience at the Ohio Station briefly sum- 

 marized, from which it is concluded "that raw phosphate rock is a useful 

 carrier of phosphorus and may be used with profit on soils requiring phosphorus ; 

 but . . . when raw phosphate and acid phosphate have been used side by side 

 under such conditions as to fully utilize the crop feeding power of the two 

 materials the acid phosphate has generally furnished available phosphorus at 

 a lower cost than the raw phosphate 



" In the 20-year experiments of the Ohio Station . . . the largest recovery of 

 phosphorus has been three-fourths of that applied in acid phosphate." 



The inter-relationships between the constituents of basic slag', S. H. Col- 

 lins and A. A. Hall {Jour. Soc. Chem. Indus., 34 {1915), No. 10, pp. 526-530, 

 figs. 3; abs. in Chem. Zentbl., 1915, II, No. 8, p. 4S1). — Plat experiments with 

 hay on soil varying from heavy bowlder clay t© medium loam, uniformly 



