and nitrifying agents. Sandy land is improved also by having the 

 interspaces filled with vegetable matter, which greatly increases its 

 absorptive capacity. A leading difference between the commercial 

 fertilizer and the barnyard manure lies in this secondary function 

 possessed by the latter, viz.: that of improving the physical character 

 of the soil. (See Voorhees on Fertilizers.) The commercial fer- 

 tilizer cannot be counted on to improve greatly the physical character 





10. — Place the manure where the feeding roots can iise 

 it, not in a pile at the hase of the tree only. 



of the soil ; its chief function is to furnish plant-food. The indirect 

 or secondary effects of commercial fertilizers are slight. The com- 

 mercial fertilizer adds to the soil the essential food constituents, 

 while the barnyard manure does this and in addition helps to make 

 the constituents, already in the soil, serve as food to the plant. 

 These considerations sliow at once the value of barnyard manure 



395 



