THECUBAREVIEW 31 



CANE SUGAR SOIL AND FERTILIZATION 

 IN CUBA 



By Ahin Fox, Agric. B.S. 



Cane sugar "Saccharum officinarum" belongs to a large family of grasses. Its soil in 

 Cuba varies in chemical composition and physical properties, but, as a rule, that rich in plant 

 food, with a large water holding capacity is the best. 



Where irrigation is not practised clay or heavy- loam callable of carrying a large amount 

 of moisture is to be selected and even with irrigations the soil must be sufficiently retentive to 

 prevent rai)id percolation and consequent financial loss, because of many cxi)ensive irrigations 

 and washing away of soluble plant food. 



Fertile soils always have an abundance of humus or vegetables matter. Cuban soils, 

 subject to heavy rainfalls which stimulate luxuriant vegetation, are almost universally adapted 

 to the growth of cane sugar. The vegetation in its transformation into humus furnishes 

 organic acids which decompose the soil particles into very fine earth. Such soils in course of 

 time become rich in organic matter, which supplies nitrogenous food, as well as in very finely 

 divided earth, with its mineral supply. Both retain the excessive moisture essential to the 

 health}', profitable cane growing, but especially the humus retains this moisture. 



Cane, like every other plant, needs for its growth a nimiber of chemical substances, but as 

 most natural soils supply a large part of these ingredients in abundance, it is necessary here 

 to consider only those which in cultivated soils are frequently more or less lacking. 



These are potash, phosphoric acid, and nitrogen and their relative relation to the cane crop 

 has been the subject of important investigation and study. It was found that the absence of 

 either of them was fatal to the life of the cane sugar plant and that, with an insufficient supply 

 of any one of them, the plant grew "slowly," but when all were present in ample quantities 

 it grew rapidly. 



By chemical analysis of a crop we can learn the quantities of potash, phosphoric acid and 

 nitrogen required to produce good results of sugar. 



If the cane-growing soil were without plant food, all of which had to be artificially applied, 

 the question of manuring would be one of simple calculation of the amount of fertilizer in- 

 gredients contained in the crop, but there is already present in the soil a certain amount of 

 such food available to the plant with no need of supplying it artificially. 



Chemical analysis of a soil discloses the quantities of each plant food-ingredient present 

 in it, but as the larger part of its potash, phosphoric acid and nitrogen exists in an insoluble, 

 unavailable form, it is far more important to learn what and how much is availably present. 



Unfortunately chemical science has not yet succeeded in finding a method wherebj' the 

 available can be distinguished from the nonavailable plant food contained in a soil. Some 

 such methods were designed and are now used by some chemists, but it is the prevailing 

 opinion of scientists that accurate and reliable information is not conveyed thereb}', and that 

 its nearest approach is reached through the indirect way of so-called field or fertilizer experi- 

 ments. Such judiciously planned and carefully conducted experiments have been made in 

 many cane-growing districts in Cuba and valuable information has been obtained and con- 

 clusions have been drawn from them. 



For cane where fertilizer requirements have not been ascertained by practical experiments, 

 the safest and best plan is to use that which contains a liberal amount of potash, a moderate 

 amount of phosphoric acid and an excess of nitrogen. 



The best forms of plant food, for the average conditions are for potash, high grade sul- 

 phate of potash, for nitrogen, nitrate of soda and sulphate of ammonia, and for phosphoric 

 acid, acid phosphate. 



My experiments on two mixtures of fertilizers are showTi below : 



