SOILS FERTILIZERS. 123 



whatever the quantity of sohition with which it was in contact. This propor- 

 tion, however, was found to vary with different samples of clay used. 



When calcium carl)onate was shaken up with solution of ammonium salts the 

 reaction was of the same type as with clay. The addition of 10 gm. of calcium 

 carbonate to 50 gm. of clay increased somewhat the precipitation of ammonium, 

 but did not change the tj'pe of the reaction. "Since few soils would contain 

 as umch as 10 gm. of calcium carbonate per 50 gm. of clay, it may be concluded 

 that tiie main reaction when ammonium salts are applied to the soil takes place 

 with the clay, although the calcium carbonate will afterwards continue to de- 

 compose the zoolitic ammonium compound as ammonium carbonate is removed by 

 nitrification." 



Experiments of similar character with different kinds of peat showed that 

 there was no production of acidity when any of the samples of humus were 

 shaken up with the solutions of ammonium salts. In experiments with peat, 

 which had been extracted with hydrochloric acid and thoroughly washed with hot 

 distilled water, there was apparently a slight production of acid and withdrawal 

 of ammonium from solution. The ammonium had been i-eplaced by calcium, 

 small quantities of which had remained in the peat in spite of the treatment it 

 had received. " It seems, however, certain that free ' humic acid ' can to some 

 extent decompose ammonium salts with the formation of an insoluble ammonium 

 compound, and this is confirmed by the observation that whereas the humus, 

 after all mineral acid had been washed away, yielded a brown solution on shak- 

 ing with pure water, when shaken with the ammonium salt a colorless solution 

 resulted. As free ' humic acid ' does not appear to be a normal constituent of 

 soils, this experiment does not vitiate the general conclusion reached by the 

 authors that the constituents of the soil do not react with solutions of ammonium 

 salts to produce a free acid. For the acid observed in the field experiments 

 quoted a biological origin has now been found." 



Can calcium carbonate cause loss of ammonia by evaporation from the soil? 

 T. Takeuchi {Bui. Col. Agr., Tokyo Imp. Univ., 7 (1907), ^'o. 3, pp. 433-Ji36).— 

 From a study of the reaction between calcium sulphate and ammonium carbon- 

 ate and calcium carbonate and ammonium sulphate, the author concludes that 

 " there is no danger of losing any significant amount of ammonia by manuring 

 a soil with ammonium sulphate where calcium carbonate is present." 



The cause of the lower eflB^ciency of ammoniacal nitrogen as compared 

 with, nitric nitrogen (Abs. in Saaten, Diinger, u. F utter markt, 1907, No. 17, p. 

 .'fS3).- — The conclusion of Wagner that the lower efficiency of ammoniacal nitro- 

 gen is due to loss of ammonia in soils containing calcium carbonate is briefly 

 referred to. 



On the prospects for natural and artificial nitrogenous compounds in the 

 service of agriculture, K. Rordam (Tidsskr. Laiidbr. Planteavl, 12 {190')). pp. 

 SSl-.'jlO). — A detailed discussion of the present sources of nitrogenous fertiliz- 

 ers and the prospects for their use for agricultural purposes. — f. w. woll. 



On the exhaustion of the Chilean nitrate of soda deposits, W. Obst {Saaten, 

 Diinger. u. Futtermarkt. 1907, No. 11, pp. 313-317).— The possibility of the ex- 

 haustion of the Chilean deposits and of supplying nitrogen compounds by artifi- 

 cial means is discussed. 



Nitrate of soda propaganda {Asoc. Sal. Propaganda. Circ. Triincst. Jfl, 1907, 

 pp. LXyi-\-16-'>). — Detailed statistics of production and consumption of nitrate 

 of soda are given, with reviews of investigations relating to the production of 

 nitrogen compounds from the air and their comparison with nitrate of soda as a 

 fertilizer. 



127GG— No. 2—07 3 



