28 CHARACTERISTICS OF AMMONIA SALTS 



results obtained during twenty years, Dr. Voelcker, speaking 

 of the plot where ammonia salts are applied alone, says : 



"It is every year found increasingly difficult to obtain a 

 plant on some portions of the ammonia salts plot, and resowing 

 or transplanting has had to be resorted to. ... The 

 failure is confined to where ammonia salts have been used, 

 and as soon as one passes off this plot, be it to the unmanured 

 one on the one side or the nitrate of soda plot on the other, 



the distinction is clearly apparent The most 



probable explanation of the difference, in this respect, between 

 the action of ammonia salts and nitrate of soda lies in the fact, 

 known to chemists, that the application of sulphate of 

 ammonia results in a more rapid removal of lime from the 

 soil than is the case when nitrate of soda is employed ; and 

 the soil containing, as it did originally, but little lime, is now 

 in all likelihood deprived of it to such an extent that there is 

 not the requisite amount for the needs of the barley crop." 



All the plots receiving ammonia salts in the barley field at 

 Woburn show a somewhat greater falling off in produce during 

 the later years of the experiment than is shown by the cor- 

 responding plots receiving nitrate of soda ; it is probable 

 therefore that the want of carbonate of lime in the soil is being 

 generally felt on the ammonia plots. 



In full agreement with the facts observed at Rothamsted 

 and Woburn are the results of numerous experiments on the 

 use of sulphate of ammonia made by H. J. Wheeler at the 

 Agricultural Experiment Station, Rhode Island, United States. 

 (Experiment Station Record, VII, 377; VIII, 571). He points 

 out that, " a dangerous degree of acidity, or at least a fatal lack 

 of carbonate of lime, appears to exist in (some) upland and 

 naturally \vell-drained soils, and is not confined to muck and 

 peat swamps and very wet lands, as most American and many 

 other writers seem to assume." Experiments with such soils 

 carried on for several years showed that " sulphate of ammonia, 

 when applied without air-slacked lime, acted like a poison, 

 the injurious effects increasing with the amount applied. 

 The yields of the thirty-eight miscellaneous crops show, 

 without exception, where no air-slacked lime was used, that 



