Vol. XIII. No. 318. 



THE AGRICULTURAL NEWS. 



211 



SUGAR INDUSTRY. 



THE MANURING OF THE SUGAR-CANE. 



The question as to what feirilizers give the most profit- 

 aMe returns with the sugar-cane is discussed at some length 

 by Dr. F. W. Zerban in Sugar, for May 1914. In this article 

 the main point emphasized is that the most important 

 nutrient for sugarcane is potash. This fact, it is stated, ha.> 

 been brought to light l)y experimental work in Louisiana, 

 Hawaii, Java and several other sugar-producing countrie.s. 

 It would seem that Dr. Zerban ba.ses this conclusion largely 

 upon the results obtained in regard to the question as to what 

 quantities of the different food elements the cane takes up 

 from the soil. Experimental work in the countries mentioned 

 above has shown that the sugar-cane removes much more 

 potash from the soil than it does phosphoric acid: but of 

 course, the composition of the soil is not necessarily a criter- 

 ion as regards its requirements in this respect. Although the 

 soundness of Dr. Zerban's conclusions that ihesugarcane plant 

 makes large demands upon the potash in the soil will be ad- 

 mitted, it does not necessarily follow that potash manures will 

 appreciably increase the yield of sugar per acre. On the 

 contrary, in the West Indies it has been found that the 

 addition of potash produces little or no remunerative gain. 

 Professor Harrison in his account of sugar cane experiments 

 in British Guiana, which was published in the West Indian 

 Bulletin, Vol. XIII, No. 2, says: The addition of potash 

 when applied either as sulphate of potash or as nitrates has 

 exerted little if any effect. The normal weathering of the 

 constituents of the soil sets free for each crop potash in 

 excess of the quantity necessary for the requirements of 

 plants. This holds good under oidinary conditions of culti- 

 vation where the greater portion of potash taken up l)y the 

 plants is directly returned to the soil: but where the canes 

 and cane tops are removed from the land, as in nurseries for 

 the supply of cane plants, it is probable that partial potash 

 exhaustion will take place in the course of a very few crops.' 



Mr. H. A. Tempany, B.Sc, in discussing the manurial 

 experiments with sugar-cane in the Leeward Islands, 1912-13. 

 states that during the season under review the experiments 

 ccini prising certain applications with phosphoric acid and 

 potash were not laid out, repeated tests with these manures 

 having in the past shown that they are unproductive of 

 remunerative returns under the conditions governing the 

 performance of the Leeward Islands experiments. In the 

 Leeward Islands, as well as in Demerara, the most profitable 

 returns are obtained by the application of nitrate of soda or 

 sulphate of ammonia. In the Leeward Islands most profit 

 has been got when the land has received 40 B). of nitrogen 

 per acre as nitrate of soda. Under certain conditions, 

 notably in the case of heavy non- calcareous soils, there is 

 evidence to show that sulphate of ammonia is likely to give 

 better results. In Demerara, according to Professor Harrison, 

 nitrogen in the form of sulphate of ammonia, nitrate of soda, 

 nitrate of potash, nitrate of lime, nitrolim, dissolved guano, 

 raw guano and dried blood exerts a favourable influence upon 

 the yields of sugar-cane, and is without doubt the 

 manurial constituent which mainly governs the yield 



of that plant. This applies to every variety of sugar- 

 cane which has been under trial. \\Tien applied" in 

 quantities capable of supplying not more than 40 to 50 lb. 

 of nitrogen per acre, in ordinary seasons there is practically 

 no difference in the effects of sulphate of ammonia, dissolved 

 guano and nitrate of soda, but, on the whole, the first is 

 a preferable manure to apply Nitrate of lime, nitrolim, 

 dried blood and raw guano appear to be inferior to these. 

 In the earlier crops of the experiments the best results were 

 obtained by a mixture of nitrate of soda and sulphate of 

 ammonia: but during the latter years this mixture did not 

 prove more efficacious than did either sulphate of ammonia 

 or nitrate of soda alone. Where applied in quantities sup- 

 plying more than from 40 to 50 B). of nitrogen per acre, 

 dissolved guano and sulphate of ammonia are the best sources 

 of nitrogen for the sugar-cane on the alluvial soils of British 

 Guiana, but the latter is the more economical for applica- 

 tion. In British Guiana it is interesting to observe the use 

 of lime results in largely increased yields during the earlier 

 years of the trials. But whether or not its use results 

 in profitable increases depends on the price of sugar. Its 

 action is principally mechanical in improving the texture of 

 the land, and it is a question of much importance whether 

 its effect could not be obtained more profitably and at 

 a lower cost, by the use of light ploughs and cultivators. 



From the foregoing it will be seen that Dr. Zerban's 

 views are more physiological than agricultural, for although 

 it will be admitted that potash is an essential factor, 

 possibly the most important factor governing the synthesis 

 of sugar in cane plants, its supply in the soil is seldom so defi- 

 cient as to require the addition of potassic fertilizers. At least 

 this view would appear to hold good for the West Indies. At 

 variance with this are the statements made at the end of 

 Dr. Zerban's article referring to the results obtained from 

 certain experiments conducted by Mr. Gibbon in Porto Rico 

 during 1913, which appear to show that the addition of potash 

 produced a material incre4se in the yield of canes. 'More 

 experiments', it is stated, 'will be made to adduce further 

 evidence in this respect. But it is highly desirable that 

 many more such tests be carried out on the individual 

 plantations. For the guidance of those who wish to engage 

 in such work the writer desires to state that the potash 

 should preferably be applied to cane in the form of sulphate. 

 Kainit should generally not be used on cane because it 

 contains a large percentage of chlorine, an element which, 

 according to the researches of ilaxwell and of Eckart, of 

 Hawaii, is quite detrimental to the growth of sugar-cane. 

 Kainit may do all right if it is applied and well mixed with 

 the soil a long time before planting the cane, but in the- 

 general practice of fertilizing cane in late spring it should be- 

 avoided and sulfate of potash used instead.' 



According to The Board of Trade Journal for May 28, 

 1914, the Cuban sugar crop for 1913 amounted to 2,428,53T 

 tons, about 30 per cent, larger than the previous largest in 

 the history of the island, but owing to low prices throughout 

 the year its value was less than in 1912, being about 

 £23,000,000. Five new mills will be in operation in 1914, 

 The tobacco crop as well as the sugar crop was larger than 

 the one for 1912, and was again of excellent quality. The 

 tobacco industry is in a thoroughly prosperous condition 

 and in 1913 about 16-^), 000,000 cigars were exported, of 

 which -59,000,000 were sent to the United Kingdom. 



