NITROGEN FERTILIZERS 311 



Manure alone does not supply the full needs of sands. Phos- 

 phate and often potash fertilizers are necessary to develop properly 

 balanced soils. 



FIG. 206. Sand without the wherewithal to produce. (See Fig. 207.) 



FIG. 207. From poor to productive sand in three years. Lime and proper fertilizers. 

 Same soil as shown in Figure 206. 



Nitrogen Fertilizers. (See index.) The low supply of organic 

 matter in these soils necessarily means a low nitrogen supply, hence 

 the urgent need of nitrogen. However, the use of commercial 

 nitrogen fertilizers, such as nitrate of soda and ammonium sulfate, 

 as the main sources of nitrogen in general farming on sands is 

 not recommended, since these fertilizers cannot take the place of 



