920 EXPERIMENT STATION RECORD. 



(E. S. II.. V2. 1). DoO). They cousisted of ii coinparisoii, on moderately stiff 

 clay soil uaturally quite well drained, of double superphosphates (both soluble 

 and reverted), dissolved boneblack. dissolved South Carolina rock, iron and 

 aluminum phosphate, boneblack, raw bone meal, phosphatie slag, ground South 

 Carolina rock, and groimd Florida soft phosphate, these materials furnishing 

 all forms of phosphoric acid found in fertilizers and including all of the 

 phosphates genei-ally found in the market at the time the experiment was 

 begun. 



The average result^■. on ('> crops of corn, 2 of wheat, and ."> of hay show that 

 "(1) the highest total average yield was obtained with reverted phosphates; 

 (2) reverted phosphate or iron and alumina [phosphate] produced a higher 

 yield than reverted phosphate of lime; (3) insoluble phosphates produced a 

 slightly higher total ilverage yield than soluble phosphates and at about one- 

 half the cost; (4) slag phosphate produced better results than bone meal and 

 at less cost; (5) soluble phosphates produced the best yields of wheat; (6) 

 Florida soft phosphate produced the best yield of corn; (7) reverted phos- 

 phates produced the best yield of hay; (8) insoluble South Carolina phosphate 

 rock produced a higher total average yield than dissolved South Carolina rock ; 

 (9) insoluble South Carolina phosphate rock produced a little higher yield than 

 boneblack; (10) bone meal produced a better yield of wheat than any other 

 source of insoluble phosphate, but all other sources produced better grass." 



General information on phosphates is given in an appendix to the bulletin. 



The decomposition of dicalcium phosphate by water, K. Buch (Zt-schr. 

 Anorrjan. Clicin., 52 (1907), No. 3, pp. o2o-3'il. fig. 1). — This is substantially a 

 continuation of Rindell's work on the same subject first published in 1899. 



A series of experiments is reported which show that under the action of 

 water dicalcium phosphate is transformed iijto tricalcium phosphate. Whether 

 this is the limit of the transformation or the latter continues until a basic 

 compound is formed, the tricalcium phosphate being merely a comparatively 

 stable intermediate product, was not determined, although there is evidence 

 to indicate that this is the case. 



On the intervention of micro-organisms in the utilization of insoluble 

 phosphates of the soil by plants, S. de (^kazia and U. Ckrza (Arch. Funnacol. 

 8pei\ e Hci. Aff., 6 (1907), Ao. 1, pp. 6-17; abs. in Chent. Ccntbl., 1907, I, No. 

 16, p. 1214). — Culture experiments with Aspergillus niger, Penicillium glaucum, 

 and P. hrevicaule in media to which insoluble tricalcium phosphate was added 

 are reported, showing that these organisms were quite active in rendering the 

 phosphate soluble. Tlie general conclusion drawn is that under ordinary field 

 conditions a certain amount of insoluble phosphate is dissolved by the water 

 which circulates in the soil and another consideral)le portion is dissolved by the 

 action of micro-organisms, a part of the latter being used by the organisms in 

 their growth and the remainder being immediately available for the use of the 

 higher plants. 



The action of the phosphoric acid of high and low percentage Thomas slag, 

 W. ScHNEiDEWiND, D. Meyer, aiid H. Frese (Latulw. Jahrh., S-i (1906), No. 6, 

 pp. 937-9^0, pi. 1). — The results here reported of pot experiments with oats and 

 rye on artificial soil (75 per cent sand and 25 per cent of humus loam) indicate 

 that the phosphoric acid of high percentage and low percentage Thomas slag 

 are about equally effective pound for pound. The experiments further show 

 that the phosphoric acid of slags insoluble in citric acid is practically without 

 effect in increasing the yield of crops. With oats superphosphate, precipitated 

 phosphate, and Welter's phosphate (prejiared by fusing raw phosphate with 

 lime and silicates) were about equally effective and much more effective than 



