4 BULLETIX 3 3, PORTO EICO EXPERIMENT STATION 



Table 1. — Annual shipments of citrus fruit from Porto Rico for the fiscal 



period 1910-1928 1 



Year 



1910 

 1911. 

 1912. 

 1913. 

 1914. 

 1915. 

 1916. 

 1917. 

 1918. 

 1919. 



1 According to United States customs figures. 



A grove-to-grove census, taken shortly after the hurricane of Sep- 

 tember, 1928, showed that there were then on the island approxi- 

 mately 6,000 acres planted with 430,000 grapefruit trees of all ages. 

 Table 1 shows that 891,940 boxes of grapefruit in the fresh state 

 were exported in 1928 and that 334,207 boxes of the canned fruit 

 were shipped. If 3,793 boxes of fruit are allowed for local consump- 

 tion, the island will be found to have produced a total of 1,230,000 

 boxes of grapefruit that year. This production from 300,000 full- 

 bearing trees would give an average yield of slightly more than 4 

 boxes per tree. The table also shows that while production has in- 

 creased steadily fluctuation has been considerable from year to year. 



NATURAL REQUIREMENTS 



SOILS 



That the citrus tree is not very exacting as to its soil requirements 

 is well illustrated by the fact that the groves are found on soils 

 covering a wide range from beach sand to heavy clay. A systematic 

 study of existing groves reveals differences in growth of tree due to 

 soils which were not readily discernible at the time of planting. This 

 is true especially of the region between Bayamon and Arecibo, which 

 is bordered by the ocean on one side and by the railroad and in 

 places by the public highway on the other. The soils of this region 

 vary from sand that is almost devoid of colloidal matter to clay 

 containing less than 25 per cent sand. The growth of the trees fur- 

 nishes information regarding the chief limitation of each soil type. 

 The white sand is poor because it does not retain enough moisture 

 and plant nutrients to supply the needs of the trees under existing 

 conditions. The darker sand, containing 2 to 3 per cent colloidal 

 matter, of which about 1 per cent is organic, is excellent, provided 

 the subsoil is pervious and the water level is not too variable. The 

 red sandy soils containing upwards of 10 per cent colloidal matter 

 are suitable for tree growth, provided they do not cement. Cementa- 

 tion is caused by the high amount of iron and the colloidal state in 

 which it is present in these soils, and it prevents the trees from devel- 

 oping properly. The clay soils in this region vary from 20 to 60 per 

 cent clay and are similar to those found in other regions. 



Oranges 



Boxes 

 296, 058 

 349, 442 

 277, 422 

 353, 690 

 348, 927 

 200, 311 

 404, 451 

 503, 318 

 603, 226 

 373, 679 



Grape- 

 fruit 



Boxes 

 48, 441 

 96, 189 

 118, 937 

 216, 247 

 206, 200 

 276, 583 

 296, 645 

 435, 890 

 549, 125 

 417, 369 



Canned 

 grape- 

 fruit 



Boxes 



Year 



1920 

 1921 

 1922 

 1923 

 1924 

 1925 

 1926 

 1927 

 1928 



Oranges 



Boxes 

 336, 625 

 162, 395 

 388, 882 

 732, 973 

 192, 363 

 336, 761 

 463, 709 

 311, 294 

 546, 463 



Grape- 

 fruit 



Boxes 

 419, 629 

 667, 637 

 360, 530 

 460, 951 

 666, 657 

 579, 736 

 809, 038 

 692, 052 

 891, 940 



Canned 

 grape- 

 fruit 



Boxes 



102, 143 

 123, 461 

 201, 888 

 344, 660 

 334. 207 



