COMMERCIAL FERTILIZERS AND THEIR USE 



247 



young plants, after that stored up in the seed has been 

 exhausted, and before they are strong enough to make 

 available their own food. 



FIG. 45. Wheat Plots fertilized in Different Ways. 

 (From left to right.) 



Complete Fertilizer (Com.). Phosphate Fertilizer, P. 



Potash Fertilizer, K. Nitrogen Fertilizer, N. 



No Fertilizer, Check. 



Commercial fertilizers may assist in promoting desir- 

 able bacterial changes in soils resulting in the elabo- 

 ration of plant food. Before they are used, however, 

 careful field trials should be made. 



295. Experimental Plots. A piece of land well tilled 

 and of uniform texture should be used for field trials 



