32 EXPERIMENT STATION RECORD. 



Investigations on the fertilizing - value of dried superphosphates, A. Gre- 

 ooiREand J. Hendrick (Bui. Agr. [Brussels], JO (1904), No. 2, pp. 185-201, fig. 1).— 

 Chemical studies and pot experiments with barley to determine the effect of drying 

 superphosphates on their fertilizing value are reported in detail. 



The conclusions reached were that the physical changes brought about by the 

 heating were without effect on the fertilizing value of the product; partial dehydra- 

 tion brought about by heating to 165° C. increased the activity of the phosphoric 

 acid to a notable degree; the mixture of soluble calcium salts resulting from heating 

 monocalcium phosphate to 165° C. until it lost 2 molecules of water was as a rule 

 more effective than crystallized monocalcium phosphates; the calcium metaphos- 

 phate produced by dehydration of monocalcium phosphate was of no value as a fer- 

 tilizer; calcium pyrophosphate produced by complete dehydration of bicalcium 

 phosphate is also of no fertilizing value. 



A contribution to the study of phosphatic slag, A. Gregoire and J. Hendrick 

 (Bui. Agr. [Brussels], SO (1904), No. 2, pp. 202-209). — Ammonium citrate containing 

 per liter 210 gm. citric acid, 43 gm. ammoniacal nitrogen, and 30 gm. of ammonium 

 fluoric! dissolved about half as much of the phosphoric acid of Thomas slag as 2 per 

 cent citric acid. Pot experiments with barley indicated that a large part of the 

 phosphoric acid insoluble in the ammonium citrate containing fiuorid was readily 

 assimilable by plants. 



On the influence of liming on the availability of phosphoric acid in com- 

 mercial fertilizers, B. Sciiclze (Fuhling's Landw. Zlg., 53 (1904), Nos. 5, pp. 186- 

 188; 6, }>p. 216-222; 7, pp. 201-265). — A series of pot experiments is reported, from 

 which the conclusions are drawn that the phosphoric acid of bone meal produces an 

 effect in soil poor in lime which very closely agrees with that indicated by the solu- 

 bility in citric acid; liming reduces the effect of water-soluble phosphoric acid least, 

 of citric-acid soluble phosphoric acid more, and of bone phosphoric acid most; the 

 most injurious effect was produced by liming with burnt lime in the spring, the least 

 by applications of calcium carbonate in the fall; the action of the phosphoric acid of 

 bone depends not only upon the form and time of application but also upon the 

 kind of plant, mustard, for example, utilizing it more completely than oats; liming 

 injuriously affects the phosphoric acid of the soil, rendering it less soluble; the acid 

 compounds of the soil are apparently of considerable value in rendering difficultly 

 soluble phosphates available. 



On the influence of liming and marling on the yield of vetches, R. Ulbricht 

 (Landw. Vers. Stat., 00 (1904), No. 1-2, pp. 135-140, pi. 1). — Pot experiments during 

 1897, 1899, and 1903 are reported. The results show that vetches, like serradella 

 and lupines tested in previous experiments, are injuriously affected by large applica- 

 tions of lime or marl, although not as sensitive as the latter and in some cases actually 

 benefited by small applications of lime or marl. 



Concerning the function of sodium when used in nitrate of soda, H. J. 

 Wheeler et al. (Rhode Island Sta. Rpt. 1903, pp. ..'37-207, pi. 1 ).— This article reviews 

 the work of other investigators on the function of sodium as a plant nutrient, and 

 summarizes the work of the authors which has been carried on at the Rhode Island 

 Station for a number of years. The objects and results of this work are briefly 

 summarized as follows: 



"The experiments were designed to throw light upon the question whether the 

 frequent greater effectiveness of nitrate of soda as compared with sulphate of ammonia, 

 when employed at such rates that each furnishes like amounts of nitrogen, is due to 

 a direct manurial action of the sodium, as claimed by Wagner and Dorsch, or in part 

 to other causes. 



"Other experiments at this station with about 200 varieties of plants have shown 

 conclusively that plant growth is very greatly influenced by the chemical reaction of 

 the soil, or by compounds formed as a result of the reaction, a fact which seems 



