PRINCIPLES OF MANURING 115 



The cause of the superior action of the 

 nitrate of soda may also depend in part on 

 the fact that, by encouraging deeper ex- 

 tension of the roots, the crop is placed in a 

 better position to withstand the effects of 

 drought. This cause, however, would operate 

 in the case of all crops, although it may be 

 more emphasized with the mangold crop. 



It may also be mentioned that when 

 nitrate of soda is applied to land, the soda 

 may displace a certain amount of potash 

 from natural combinations in the soil, and 

 the potash so liberated will become avail- 

 able for the use of plants. 



The action of these two manures depends 

 also to some extent upon the character of the 

 soil to which they are applied. There is 

 much greater danger of nitrate of soda being 

 washed out of the land than is the case with 

 sulphate of ammonia, and therefore, other 

 things being equal, one would be disposed 

 to favour the use of sulphate of ammonia on 

 light, porous sands and gravels, and especially 

 if lime is known to be abundant. Moreover, 

 such soils, being well aerated, offer conditions 

 favourable to the nitrification of the ammonia, 

 and thus encourage its early use by plants. 

 On the other hand, nitrate of soda is better 

 adapted for strong land, where the dangers 



