Filter-press Refuse.
In the defecation of cane juice, certain chemicals are often used to precipitate the impurities, which are removed from the subsiders after the clear juice has been drawn off, and sent to the filter presses, where it is filtered through heavy cloths. This material contains coarse particles of bagasse together with other impurities including the lime and phosphoric acid which were used in this work. The composition of the material depends upon the original composition of the juice and the amount of the different chemicals that has been used in the clarification. In any event, it makes a most valuable fertilizer because of the organic matter, nitrogenous bodies, phosphoric acid, and lime that it contains. This organic material is an ideal substance to be applied to the worn-out cane lands (which consist almost entirely of mineral substances) since it induces bacterial action, and during its decomposition certain acids are freed, such as carbonic, nitric, and organic acids. These have the power to act upon the mineral constituents and thus liberate other plant-food elements. The filter-press mud can very well be mixed with the bagasse ashes, and scattered about the cane rows as an almost complete fertilizer for sugar cane, the only element lacking being nitrogen, which was lost in the burning of the bagasse.
It will be remembered that in the synthesis of sucrose, which consists of carbon, hydrogen, and oxygen, there are none of the plant-food elements used which are sought for in commercial fertilizers. These are used only in building the fibrous stalk of the cane and they may all be recovered in the bagasse and cane-juice impurities. The carbon, hydrogen, and oxygen which are used practically all come from the air and water.
It is a custom to-day to cart this ash to piles or depressions some distance from the factory. In some places it is thrown into the river, or cast into the sea—an absolute loss.
Planters must not depend upon commercial fertilizers for their supply of plant-food material, when there is such an abundance of natural fertilizer being wasted. The cost of the artificial fertilizers in many cases is considered prohibitive and often unnecessary. In order to build up a great sugar industry here, the material at hand must be used, while money should be spent for modern apparatus and equipment.