Edible Products. 



118 



[August, 1910. 



nourishment is actually there, but with 

 the cultivated tree it is different. If the 

 nourishment is not available when 

 needed, the growth becomes stunted and 

 it succumbs to any one of the enemies to 

 which the tree is subject. Furthermore, 

 cultivation increases the availability of 

 the plant foods, £>ut usually not in equal 

 degrees, for each one of , them, and the 

 consequence is that the tree feeds on an 

 unbalanced ration. This is actually 

 what takes place in most soils. The 

 humus originally in the soil together 

 with that from grass ploughed under 

 year after year, supplies nitrogen faster 

 than the inorganic soil furnishes potash 

 and phosphoric acid. The nitrogen is 

 further increased by growing leguminous 

 plants which, when ploughed under, 

 supply too large an amount of nitrogen 

 in proportion to the potash and phos- 

 phoric acid to make a healthy growth of 

 a citrus tree or a good quality of fruit. 

 This is probably the chief reason for the 

 large number of trees suffering from 

 gum disease in Cuba, and it is unques- 

 tionably one of the reasons why lemon 

 stock suffers more than orange, because 

 the lemon being a faster grower and a 

 more voracious feeder it overfeeds to a 

 greater extent. In the light sandy soils 

 like some of those in the extreme west 

 end of the Island and in the Isle of Pines, 

 gum disease is seldom prevalent, but in 

 those places there is no question about 

 fertilizers being necessary as trees will 

 simply not grow without them. It is in 

 the heavier soils that the question arises 

 how to fertilize and what to use. 



For several years after planting it is 

 not so much the question of a deficiency 

 in plant food, it is more a balancing of 

 the plant food elements present in the 

 soil- As meutioned above, an overabund- 

 ance of nitrogen causes a growth of 

 soft tissue, and. the sap, from some cause 

 not fully explained, leaves a deposit of 

 a thick viscous gum under the bark 

 Avhich breaks out in spots and causes the 

 bark to die. While gum disease may 

 also be caused by other means such as 

 mechanical injury to roots or top or 

 injury to roots by drought or too much 

 water, malnutrition is probably more 

 frequently the cause than any of those. 



The trouble does not readily disappear 

 by applying potash, phosphoric acid , lime, 



etc., but these ingredients if used in time 

 are good preventatives. An application 

 of about half a ton of air-slaked lime 

 per acre is very beneficial to most of the 

 Cuban soils, and three pounds of acid 

 phosphate together with one pound 

 sulphate of potash applied around each 

 tree once a year, the first two years, 

 will be found beneficial also. The third 

 year the amount should be doubled, and 

 with a good crop of legumes the trees 

 will be, not alone healthier and larger, 

 but will be in condition to bear a small 

 crop of marketable fruit the fourth 

 year. How much to apply after that 

 and whether nitrogen should be 

 added or not will depend upon the 

 couditions of the trees^ If the growth 

 is vigorous and the colour dark green, 

 which will undoubtedly be the case 

 where a heavy crop of legumes is grown, 

 nitrogen will not be necessary. The 

 amount of fruit and the quality of it 

 will determine the amount of potash 

 and phosphoric acid necessary. 



The role of potash is especially in 

 giving the fruit flavour and shipping 

 quality, and it always pays to apply as 

 much of it as experience shows to give 

 the best results. For fruit production, 

 phosphoric acid should be applied in the 

 proportion of about one part to two 

 parts of potash, or in other words, 1*5 

 pounds 16 % acid phosphate or l - 25 pounds 

 20 % Basic slag to 1 pound sulphate of 

 potash. 



On the lighter soils the fertilizers now 

 in use are more or less uniform in com: 

 position, being about 3 % nitrogen, 5 % 

 phosphoric acid and 5 % potash for young 

 trees and 3 % nitrogen, 6 % phosphoric 

 acid and 12 % potash f or bearing trees. 

 Such fertilizers are being applied accord- 

 ing to the character of the soils and 

 quite frequently according to the size of 

 the owner's pocket book. The paying 

 quantity in a medium light soil will be 

 about 2 pounds the first year, 4 pounds 

 the second year, 6 pounds the third 

 year, 9 pounds the f ourth year, and about 

 15 pounds the fifth year. What will be 

 needed after that we do not know much 

 about in Cuba yet, but it is probable 

 that the Florida standard of 30 to 50 

 pounds per year per full bearing tree 

 will be found to pay here. 



