Large and Small Dressings of Nitrate of Soda. 149 



maintained a place than under the ammonia-salts. A greater 

 variety, a better development, and consequently a wider and 

 deeper distribution of the roots of the mixed herbage grown 

 by the nitrate, gave it the command of a correspondingly 

 increased range of soil and subsoil. Further, the nitrogen 

 of nitrate of soda distributes more rapidly in the soil, both in 

 the upper and the lower layers, and so root penetration into 

 the latter is induced. 



Lastly, the results show that the smaller amounts of nitrate 

 acted more effectively than the larger dressing. Indeed, it 

 would appear that the limit of growth under the influence of 

 nitrate of soda alone that is, without the aid of any artificial 

 supply of mineral constituents was nearly reached with the 

 smaller quantity used. After eighteen years the heavier dose 

 of nitrate was discontinued, and a mixed mineral manure 

 (sulphates of potash, soda, and magnesia, and superphosphate 

 of lime) was applied, but does not seem to have been 

 instrumental in effecting the assimilation of any excess of 

 nitrogen unused by previous crops ; so that much of the 

 nitrogen of the heavier dressing was probably lost in the 

 drainage waters. But in the space of four years the herbage 

 had much changed; the grasses became lighter in colour, 

 and showed more tendency to form stem and to mature; 

 leguminous species (especially Lathyrus pratensis) were 

 gaining ground. The character of the miscellaneous herbage 

 was also changing. 



4. Mixed Mineral Manure Alone : Plot 7. The dressing 

 per acre per annum has been 3001b. sulphate of potash, lOOlb. 

 sulphate of soda (2001b. the first eight years), lOOlb. 

 sulphate of magnesia, and superphosphate of lime (2001b. 

 bone ash, 1501b, sulphuric acid, sp. gr. 1*7) ; the results are 

 shown in Table XXXIII., page 150. 



Thus, mixed mineral manure alone gives considerably more 

 produce than does nitrogen in the form of ammonia- salts, 

 and nearly as much as nitrogen applied as nitrate of soda. 

 Moreover, there is an increase in hay, in nitrogen, and in 



