II.] NITRATE OF SODA USED ALONE 57 



soil by between 200 and 300 lb. per acre per annum, 

 this quantity representing the base it has itself sup- 

 plied. The bad texture of the land induced by the 

 use of nitrate of soda is not easily removed ; lime is 

 of no service in this case, because it only adds another 

 alkali ; a better remedy is to be found in the simultaneous 

 application of an acid manure like superphosphate. 

 Better still, when an active nitrogenous manure is 

 needed, instead of nitrate of soda alone a mixture of 

 sulphate of ammonia with nitrate of soda might be 

 employed ; for, as will be seen later, sulphate of 

 ammonia acts on soil like an acid, hence a mixture 

 of the two manures ought to make a better source of 

 nitrogen than either alone. 



Amongst farmers a certain amount of prejudice 

 against nitrate of soda still lingers ; it is described as 

 a " stimulant," even as a " scourge," and is regarded as 

 producing a crop to the detriment of the fertility of the 

 land. To a certain extent it is true of nitrate of soda, 

 as of an}' other fertiliser containing only a single con- 

 stituent of a plant food, that its continued use alone 

 must increase the draft upon the other nutritive elements 

 in the soil, in this case phosphoric acid and potash. 

 Nitrate of soda, also, is such an active source of nitrogen 

 and nitrogen is so dominant a factor in producing growth 

 that large crops can often be grown for a time by the 

 help of nitrate of soda alone. But so far from nitrate 

 of soda being specially harmful in this way, the Rotham- 

 sted experiments show that the yield of any crop is 

 maintained with nitrate of soda alone better than with 

 any other single manure. For example, the produce of 

 mangolds with nitrate of soda alone averages 10^ tons 

 for twenty-seven years, as against 10 tons with rape 

 cake alone, and under 6 tons with ammonium salts 

 alone. But, of course, the true answer to such criticism 



