THE MANURING OF THE CANE. 



The amount of plant food lost in the factory operations is that earned 

 away in the sugars together with the nitrogen lost in the combustion of the 

 megass ; roughly speaking the sugars carry away 10 per cent, of the ash 

 constituents contained in the canes, and 20 per cent, of the nitrogen is lost with 

 the megass.. In accordance with what has already been written, this would 

 represent a loss only half as great when referring to the whole crop cane and 

 trash. 



Although nearly the whole mineral and nitrogenous matters of the crop 

 are retained in the factory by-products, their economical return is a matter of 

 no inconsiderable difficulty. The filter press cake, rich in nitrogen and phos- 

 phates, is in a form easily handled, and its application presents no difficulty. 

 No loss of nitrogen need be feared if it be necessary to store the press cake over 

 lengthy periods, as the annexed analyses show. These analyses of press cake 

 from the same factory were made by the writer to test this point : 



Nitrogen per cent, 

 on dry matter. 



Fresh press cake 1'173 



Press cake 12 weeks old, exposed to weather T184 



Press cake, 100 weeks old, stored under cover 1'189 



Press cake, 100 weeks old, exposed to weather 1*172 



The megass ashes, rich in phosphates and potash, are also readily applied ; 

 in this material the potash is in great part soluble in water, and if exposed to 

 rain the most valuable constituent is leached out and lost. 



In the analyses given above, a material is referred to under the name 

 1 yeast deposit ' ; by this is meant the sedimentary deposit of dead yeast cells 

 occurring in the fermentation vats. For the particular distillery on which 

 this estimate is based, 2'5 gallons of a thick sludge of yeast cells were produced 

 per 100 gallons of wash; one gallon of this sludge contained l-43lb. solid 

 matter and *1961b. nitrogen, or 13'70 per cent, on the solids. There is here a 

 source of a concentrated nitrogenous manure which is often run to waste. The 

 deposit might be collected and applied in its natural condition or passed 

 through filter presses and obtained as a cake carrying 50 per cent, to 60 per 

 cent, water and 6 per cent, to 7 per cent, nitrogen. Per 1000 gallons of wash 

 about 50 Ibs. of such cakes would be obtained, and per 1000 acres about 

 20 tons would result. 



The material which offers the greatest difficulty with regard to its 

 economical return is the lees or distillery refuse; the following methods 

 suggest themselves. 



1 . Concentration to small bulk. 



2. Destructive distillation and incineration of residue, collecting the dis- 

 tillates and recovering the phosphates, and especially potash, in the residue. 



3. Irrigation of cane fields with lees. 



79 



