THE MANURING OF THE CANE 101 



in the future the development of the internal combustion engine using alcohol 

 may stimulate each plantation to thus provide its own source of power 

 for ploughs and locomotives, together with the retention of the material 

 removed from the soil. 



Interest in the return of the molasses to the soil as manure was stimulated 

 by the results obtained in 1908 by Ebbels and Fauque 26 in Mauritius, and 

 since then numerous experiments have given rather discordant results. 

 Harrison, 27 for example, in Demerara found no increased yield following 

 on the application of molasses, but the results in Java, 13 quoted below, 

 indicate a real benefit, probably, as pointed to by the returns, due to the sugars 

 a ad not to the potash or nitrogen. 



ACTION OF MOLASSES ON THE YIELD OF SUGAR CANE. 



Cane. Sugar. Cane. Sugar. 



Tons Tons Tons Tons 



Application per acre. per acre, per acre, per acre, per acre. 



1. 545 IDS. ammonia sulphate .. 69 6-6 61 yo 



2. As in i, with 2350 Ibs. molasses 81 6-8 74 7-6 



3. As in i, with the nitrogen in 



the molasses as ammonia.. 71 6*7 65 7*4 



4. As in i, with the potash in 



the molasses .. .. 72 6*6 66 7-4 



5. As in i, with the sugar in the 



molasses .. .. 75 68 68 7-6 



Very similar results were obtained by Boname 28 in Mauritius with an 

 application of one litre (3 Ibs.) of molasses per hole (3,000 holes to the acre). 



The action of molasses on soils has been examined by Peck, 29 who found 

 that following its application there is first a decrease in the nitrogen in 

 the soil due to denitrification followed by an eventual increase over and 

 above the quantity originally present. He therefore recommends that when 

 molasses are returned to the soil an interval should elapse between the time 

 of application and planting. 



The bagasse ashes contain a considerable quantity of potash and phos- 

 phoric acid, and that proportion of this material which is recoverable is 

 usually taken back to the fields alone, or else mixed with press cake or other 

 material. Much of the potash, however, appears in the form of a potash 

 glass or slag, and much is also carried forward in a volatile state into the 

 flues and is lost. 



The press cake is particularly rich in nitrogen and in phosphates. 

 Analyses on record show much variation. Expressed as a percentage on 

 dry matter, Harrison 30 found in three samples 1*67, 2*44, and 1-08 per 

 cent. Geerligs 31 in Java found from 2 to 4 per cent., and expressed on actual 

 material Ledeboer 32 found from 0*66 to 1-59 per cent. The percentage of 

 phosphoric acid averages about 3 per cent, on dry weight. Press cake is 

 a material of the same nature as pen manure, and its effects are dispropor- 

 tionate to the quantity of nitrogen and phosphoric acid it contains. It is 

 usually applied at the rate of five tons per acre, and is indicated as being 

 most suitable for light, sandy soils. 



By far the greater quantity of plant food removed from the soil is con- 

 tained in the leaves and other waste matter. Estimating that 1,000 tons 

 of cane contain 2,500 Ibs. of nitrogen, and that the world's output of cane is 

 now 130,000,000 tons, the value of the nitrogen therein contained at pre-war 

 prices amounts to about $100,000,000, and a very great proportion of this 

 is annually wasted in the combustion of the trash. This custom obtains 



