62 



HORTICULTURE 



LECT. IV 



addition of these last three elements to the soil, 

 showed the presence of lime and magnesia in the roots, 

 proving that the land naturally contained them. 



It may be stated as a rule that the most economical 

 form of nitrogen for use as a manure is nitrate of 

 soda, though sulphate of ammonia runs it closely, 

 and the popular belief that these splendid fertilizers 

 tend to impoverish the soil is now pretty well ex- 

 ploded. With a combined application of nitrogen, 



3 



FIG. 13. THE GOOD EFFECT OF NITROGEN. 



1. Grown with phosphoric acid and potash, as in bone-meal and kainit. 

 'J. With nitrogen in addition, as in a small dressing of nitrate of soda. 

 3. The result of a full dressing of this fertiliser in combination with the 

 others. (Wagner.) 



potash and phosphates, in adequate proportions, the 

 soil is well stored with food for crops and plants, 

 or, in other words, rightly manured. 



It is inattention to the addition of mineral manures 

 that has given rise to the idea that nitrogen, 

 either conveyed as nitrate of soda or sulphate of 

 ammonia, exhausts or scourges the land. That 



