NEW FERTILIZER MATERIALS AND BY-PRODUCTS. 175 



half to one ton per acre. The product carries but a small 

 amount of phosphoric acid; the use, therefore, of 400 pounds 

 of basic slag phosphate or acid phosphate per acre for crops 

 such as corn and seeding to grass will usually be found both 

 economical and effective. Rockweed may be used to advantage 

 on any soil deficient in organic matter and humus. It is not 

 a well-balanced fertilizer, however, and should ordinarily be 

 supplemented by an application of some source of available 

 phosphoric acid. 



Crude Unground Garhage Tankage (No. 5). — Crude gar- 

 bage tankage, undried and unground, is necessarily a coarse, 

 slow-acting material ; yet it has more than a local interest, as 

 most of our cities having a population of 30,000 to 40,000 own 

 municipal garbage-reduction plants, and a considerable tonnage 

 of tankage is therefore annually produced. A considerable 

 amount of this material is contracted for by the commercial 

 fertilizer manufacturer who uses it as a conditioner in fer- 

 tilizer mixtures after it has been dried and ground. In this 

 condition it is, of course, worth much more as a fertilizer than 

 in its crude state. Of late there has been considerable inquiry 

 regarding the value of the product, and requests for analysis 

 are not infrequent. In its natural state it may be worth cartage 

 to farmers living in the vicinity of the plant. The product 

 may be used like farm manures, — from 5 to 6 cords per acre 

 would not be an excessive application. It should be thoroughly 

 worked into the soil with a disk harrow, and ordinarily should 

 be accompanied by an application of lime. From 400 to 600 

 pounds of basic slag phosphate and 100 to 150 pounds of mu- 

 riate or high-gTade sulfate of potash per acre should be used 

 to supplement it. 



No. 6, Calcined Phosphate. 

 No. 7. Calcium Cyanamid. 

 No. 8. Sewage Tankage. 



