Vol. XVII. No. 422. 



THE AGRICULTURAL XEWS. 



197 



EXPERIMENTS IN YAM AND CASSAVA 

 CULTIVATION IN TRINIDAD. 



At a meeting of the Board of Agriculture, Trinidad, 

 a full report of which appeared in the Fort-of- Spain Gazette, 

 May 17, 1918, Mr. W. G. Freeman, Acting Director of 

 Agriculture, submitted some interesting facts with respect 

 to experiments in the cultivation of yams and cassava which 

 had been carried out at the St. Augustine Experiment Station 

 by the Agrienltural Officers in charge. The results of these 

 experiments will be useful to those interested in the culti- 

 vation of these crops. 



The yam plants were put into the ground at the end 

 of May and the beginning of June 1917, and were reaped 

 in the last two weeks of February 1918. 



In the first experiment on the yield of three different 

 varieties-- Barbados Lisbon. Horn, and Red yams — these 

 were planted in trenches 3 feet apart, the plants being 2 feet 

 apart. The Lisbon proved a most prolific yielder, giving an 

 estimated yield of 18'47 tons per acre, which at 3c. per B). 

 •would be a crop of the value of •'S!1,24L18 per acre. 



A second experiment was mide with the object of 

 ascertaining whether it was preferable to use the top, 

 centre, or bottom portions of the tubers for planting purposes. 

 The results showed that the difference is very small, and 

 within the limits of experimental error. There is appar- 

 ently therefore no advantage in selecting any special part of 

 the tubers for planting purposes- A third experiment with 

 regard to the method of planting had for its object the 

 determination of two points: (1) whether it is more profit- 

 able to plant in holes or in trenches, and (2) what is the 

 best planting distance. 



In this experiment trenches were dug 2 feet wide by 

 18 inches deep, 4 feet apart, and planted at distances of 

 18 inches, 2 feet and 4 feet apart, respectively. One set of 

 loles was dug 2 feet wide by 18 inches deep, at distances of 

 4 feet by 4 feet, and 4 feet by 3 feet, respectively. 

 Another set of holes was dug 2 feet wide but only 

 8 inches deep; trash and manure were applied to one-half 

 of these holes as is usually done, whereas no trash nor manure 

 was put in the others, which were simply refilled with loose 

 earth from around, and the soil diawn up in a hill over the 

 holes 



Barbados Lisbon yams were planted throughout these 

 plots. 



The results obtained showed that, notwithstanding the 

 higher cost of preparation, it is more advantageous to have 

 deep holes, i.e , 18 inches deep. It also was shown that 

 a larger profit is obtained per acre from close than from 

 distant planting; 3 feet by 2 feet or 4 feet by 18 inches has 

 given the best results. It should be mentioned, however, 

 that the further distances give a larger return per hole, and 

 the largest yams. But this is not an advantage, as very large 

 tubers do not sell as readily as smaller ones. Trenching is 

 more expensive than holeing, but as it permits of closer 

 planting it is likely to be more profitable. 



Moreover, the land is better prepared for subsequent 

 crops, especially if the untrenched portion of the first year 

 is worked up for the second year. Holes 4 feet by 3 

 feet gave 1,460 tons and ^782-49 net profit per acre. 

 Trenches 4 feet apart, planted at distances of 18 inches 

 and 2 feet, gave 1,506 and 1,422 tons, with a profit of 

 $745-90 and .$70306 per acre, respectively. With trenches 

 3 feet apart and planted at a distance of 2 feet, a yield of 

 1,847 tons was obtained giving a profit of ■*975 06 per acre. 



To ascertain what w^mld be the loss on yams if stored 

 for a long time, 100 ft), of freshly dug yams were weighed 



on February 13, and reweighed at intervals of three or four 

 days. On April 26, about ten weeks later, they had lost 10 

 per cent, in weight. During the last two weeks, however, the 

 loss in weight wa.$ very slight. 



The total area under yam cultivation at St. Augustine 

 Experiment Station during 1917 was 14,462 square feet, or 

 practically V-acre, from which 10,090 ft». of yam were 

 reaped, i.e. 13i tons per acre. The value of the crop at 

 3c. per ft>. works out at -1911 73, and the total cost of 

 cultivation, including the purchase of plants, was -f 197 '85 

 per acre, leaving a profit of ■'5713-88 per acre. 



Experiments in the cultivation of cassava on the yield 

 of fifteen varieties showed between 5 31 and 7 41 tons of 

 roots per acre. 



With regard to the best planting distance for cassava, it 

 is found that 3 feet by 3 feet has generally given the highest 

 yield per acre. It also appears that the centre portion of 

 the stems is more suitable for cuttings than either the less 

 mature or the very old portion.?. 



An experiment for testing the relative merits of plant- 

 ing on the flat, on banks, or in forked holes showed that 

 though a slight increase may be obtained trom the two latter 

 methods, the increase in crop scarcely justifies the extra cost 

 of banking or holeing. 



A new experiment was started with the object of 

 ascertaining which was the best month or time for planting 

 and reaping cassava. Accordingly, from May 23, 1916, and 

 thence monthly, duplicate plots were planted of the some 

 variety. All of these plots were reaped between October 

 and November 1917, so that the cassava was from six to 

 seventeen months old when reaped. 



In another set of experiments, twelve duplicate plots 

 were planted between April 29 and May 4, 1916. Two plots 

 were reaped on November 2, 1916, and thence monthly, so 

 that the cassava was also from six to seventeen months old 

 when reaped. The percentage of starch was estimated in 

 samples from all of these plots. 



The results obtained from these experiments show that: 



1 . The yield of roots has increased generally from 

 month to month with the age of the plants, and it is probable 

 that a still larger yield would have been obtained if the 

 plants had been allowed to remain more than seventeen 

 months. It was 129 tons at six, and 5-80 tens at seventeea 

 months. 



2. The percentage of starch does not necessarily increase 

 with the age of the plants, but depends chiefly on the 

 weather prevailing at the time of reaping. For example, the 

 highest percentage of starch (28 9 per cent.) was obtained in 

 March from cassava ten months old, whereas the same variety 

 sixteen months old, reaped in September, only contained 

 19'47 per cent, of starch. This is entirely due to weather 

 conditions, i.e. the ten-months-old cassava was reaped dur- 

 ing the dry season, whereas the sixteen- months-old cassava 

 was reaped in rainy weather. Although the yield of roots 

 in September was nearly 30 per cent, more than that reaped 

 in March, still a larger amount of starch was obtained in 

 March than in September, viz. 1,534 ft>. as against 1,348 B>. 

 per acre. 



It is evident, therefore, that the best time for reaping 

 cassava is in the dry season, about February- March, and the 

 cassava should then be not less than fifteen to seventeen 

 months old, so as to obtain a good yield of roots. These 

 experiments, however, do not show conclusively which is the 

 best time for planting. 



Incidentally these experiments show that a yield of noi 

 less thin H tons of starch per acre maybe obtained froofc 

 cass.iva seventeen months old, reaped in March. 



