Vol. XVI No. 405. 



THE AGRICULTUKAL NEWS. 



339 



ratio of transpiration, would be likely to produce more 

 harmful results than those having thick leaves with 

 a lower ratio of transpiration. 



It is also evident that the effect on the soil des- 

 cribed will be more noticeable in dry districts, than in 

 those where heavy periodic rainfall can wash down the 

 concentrated salts from the higher levels, to which the 

 upward flow of moisture has raised them, back to lower 

 levels by natural irrigation. Thus the action of 

 a tamarind tree or a clump of bamboo on the surround- 

 ing soil in a dry island like Antigua, would probably 

 be more persistently harmful than in the wet island of 

 Dominica. 



In fact there is a tendenc}' in all soils for the 

 upper layers to become over saturated with alkali salts 

 because of the moisture How, which tendency, in 

 practically rainless regions, gives rise to desert areas of 

 more or less extent. By irrigation, combined with good 

 rainage, these areas have been converted in many 

 instances into fertile farms, because the undesirable 

 excess of salts has been washed out of the soil. 



The practical remedies for infertile patches caused 

 by the influence of soil-toxic trees may be put into 

 a small compass. The first step is to remove the tree; 

 then the soil must be improved by deep cultivation 

 and the addition of organic manures; and lastly, the 

 drainage must be efficient, so that the deleterious 

 excess of salts may readily pass out of the soil. To 

 this end it is hardly necessary to add that, irrigation 

 where possible, is a most valuable ai9. ' 



A MODERN CUBAN SUGAR FACTORY. 



Cuba is now exporting millions of tons of sugar, and it 

 seems likely that the export will continue to increase, if 

 sufficiency of labour is obtainable. An article in the Louis- 

 iana rianter, September 22, 1917. gives a short interesting 

 account of the wonderful efficiency of a large moflern Cuban 

 ceniral factory. It is true that the natural advantages of 

 Cuba for the cultivation of sugar-cane are great It possesses 

 fertile soil, tropical climate, and adequate rainfall. 

 Still the position of Cuba in the sugar world is probably 

 chiefly due to practical scientifie work of sugar engineers, 

 chemists, and machinery manufacturers. 



The chief factor of increased output of sugar has been 

 the use of larger and stronger mills, exerting pressure many 

 times over on the canes. Some of the leading f-ictories i>l 

 the present day employ a series of four or more three-roller 

 mills together with one or two cane crushers. 



It has also been found that a certain amount of macera- 

 tion in the piocess of crushing contributes to success in extract- 

 ing the maximum of the sugar content of the canes. In view 

 however of tlie fuel value of the megass, maceration is 

 nut carried out to such a thorough extent as would destroy 

 its vahie completely in this direction. 



The article referred to above gives an account of 

 the work for the last crop season of the Delicias central 

 factory in Cuba, which shows that 743,762 tons of cane 

 were ground and .544,924 bags of sugar made, equiva- 

 lent to some 90,000 short tons of sugar. The calculated 

 normal extraction of juice was 8265 per cent, of the weight 

 of the cane, and the sucrose extraction 95 18 per cent, 

 of sucrose in cane. Maceration, as referred to above, was 

 done to the extent of 2919 per cent., presumably in propor- 

 tion to the whole weight of the diluted juice. The average 

 rate of gtindinsj for the crop was 8622 tons of cane per hour. 

 The final result of the whole crop was 11 98 per cent, of 

 sugar to the weight of cane. 



This array of figures demonstrates the success of scientific- 

 control in every direction in the modern manufacture of sugar 

 on a large scale. That the scale is very large will be recog- 

 nized by readers in the small sugar-growing islands of the 

 West Indies, when it is realized that the output of sujar of 

 this one Cuban factory is just about equal to the uiiitod. 

 output of Barbados, Antigua, atd St. Kitts. 



MOTOR TRACTORS FOR SUGAR-CANE 

 CULTIVATION. 



On another page of this issue will be found the- 

 opinion of the Consulting Engineer of the Royal Agricultural 

 Society of England on the probable future of motor tractors 

 in agriculture. In the Louisiana Planter, September 29, 

 1917, appears a letter to the editor from a correspondent in 

 British Guiana, pointing out the difficulties of using motor 

 tractors in cultivation of cane fielfis in that colony, and. 

 suggesting possible modifications in structure of the machines, 

 which would render them suitable for employment under the 

 local conditions. 



In commenting on this letter, the editor points out 

 the immense expense which would be incurred by any tractor 

 engine manufacturer in making any serious modification of 

 the machine. An enormous market would have to be open 

 to such a modified machine, before a manufacturer wi)uld_ 

 enttrtain any such idea. He still believes that the motor 

 tractor is bound to play an important part in the cane 

 cultivation of the future. He suggests that some of the 

 difficulties pointed out by his British Guiana correspondent 

 may be overcome by a change in the plan of laying out 

 fields. 



The problem of the use of motor tractors for cultivatioa 

 of small fields, especially on those of irregular surface, such 

 as is the case on probably most estates of the smaller islands, 

 seems not to have been faced as yet in these islands. Motor 

 tractors up to the present are being used for other purposes, 

 such as haulage of cine, and this with good results. But 

 probably some sugar planter will have to take the bull by 

 the horns, or rather the motor by the wheel, and experiment 

 at his own risk of losing money for the benefit of himself 

 and other planters. 



From the Blue Book Report of the Turks and CaicoB 

 Islands for the year 1915, it would appear that the salt 

 industry of these islands is in a fai-ly flourishing condition, 

 whereas the export of sponges in consequence of the war 

 is much diminished. An interesting item of export is conchs 

 which are exported for food to the neighbouring republic of 

 Haiti. Upward of 1,750,000 conchs were exported during 

 the year, the value of which was £1,715. 



