February, 1912.] 



115 



Edible Products. 



in both the plants and fruit as shown by 

 these figures. Considering the fruit 

 alone, which is, after all, the only part 

 of the plant really lost to the soil, it is 

 seen to contain more than twice as much 

 pure potash as all the other manurial 

 ingredients put together. 



Surely it is then small matter for 

 wonder, when this relatively enormous 

 quantity of potash must be absorbed by 

 the plant in a iew months, that banana 

 cultivation must be abandoned as soon 

 as the soil has been depleted of its read- 

 ily available plant food, because not 

 only must the plant absorb all the 

 manurial constituents contained in the 

 fruit, but also the large quantities of 

 these substances required to build up 

 the plant body itself. Taken together, 

 the quantities ot manurial ingredients 

 in plant and fruit are enormous, and 

 they must be present in the soil in 

 readily available form it the quickly 

 growing plant is to produce truit at all, 

 and here in a nutshell we have the 

 secr9t of the rapid exhaustion and conse- 

 quent abandonment of even the richest 

 and most fertile banana lands. 



But need these lands be abandoned ? 

 Is it not possible in the case of bananas, 

 just as with all other crops, to return to 

 the soil the plant food constituents 

 removed and to maintain indefinitely 

 the productiveness of the plantation? 



These questions have been most 

 emphatically answered in the affirm- 

 ative, wherever exact scientific experi- 

 ments on manuring of bananas have 

 been carried out. 



In Queensland the experiments carried 

 out under the direction of Mr. J. C. 

 Bruennich, Chief Agricultural Chemist, 

 have all been planned with the object of 

 finding out the most suitable combina- 

 tion of artificial fertilisers. Mr. Bruen- 

 nich had evidently been so firmly con- 

 vinced from his preliminary investiga- 

 tions, that only a complete manure 

 would meet the case, that he has not 

 thought it worth while including incom- 

 pletely manured plots in any of his 

 experiments. 



The trials arranged by the writer in 

 Queensland were, however, simpler and 

 designed in the first place merely to 

 demonstrate to the planters the need 

 for a complete manure, and more than 

 anything else, the necessity of including 

 Potash in their mixtures. 



For this reason, the essential feature 

 of the plan of each experiment was that 

 one plot received a certain mixture of 

 artificials furnishing phosphoric acid 

 and nitrogen only, while another plot 

 received in addition to the same quan- 



tities of phosphoric acid and nitrogen fl 

 a certain quantity of potash. 



Other things being equal; the difference 

 in yield between two such plots, gives 

 the increase due to the potash. 



As the local conditions under which the 

 Queensland experiments were carried 

 out, varied very much, it was thought 

 advisable to modify the dressings accord- 

 ingly, and for this reason, it seems 

 better to state the results of each indivi- 

 dual experiment separately, in the first 

 place, before grouping all experiments 

 together with a view to arriving at an 

 average result. 



The following table gives a summary 

 of the results, not only of the Queens- 

 land experiments, but also of two ex- 

 periments carried out in Fiji, one of 

 which was an official experiment of the 

 Department of Agriculture. 

 . A study of this table will show that 

 in every case the planters have received 

 very handsome returns for the money 

 spent on potash. The net profits are in 

 each case calculated from the value of 

 the crop as stated by the experimenter 

 from the ruling market price on his 

 plantation in the year in which the ex- 

 periment was carried out. The figures 

 therefore, afford a very fair criterion 

 of the returns to be expected from the 

 judicious use of potash manures. Aver- 

 aging all the figures, one arrives at the 

 very interesting result that for every 1/ 

 spent on potash, the planter received 6/ 

 in return. 



The results of the official experiments 

 of the Queensland Department of Agri- 

 culture, have not yet been published. 

 The basis of the complete manure used 

 in these experiments, is, however, equi- 

 valent to the following dressing : — 

 per acre. 

 1^ cwts. Sulphate of Potash 

 4 ,, Superphosphate 

 2 ,, Sulphate of Ammonia 



Mr. J. C, Bruennich in his Annual 

 Report for 1910, says :— " We find that 

 Cavendish bananas, which are the best 

 croppers, remove yearly, 123 lbs. potash 

 in the fruit alone. Our figures agree 

 very closely with some given by Pro- 

 fessor Hilgard, who found 63"! % of 

 potash iu the ash of the fruit, and 27 - 6 % 

 in the ash of the leaves, The amount 

 of potash we supplied in our manuring 

 experiments, is, therefore, not sufficient, 

 and should be nearly doubled." 



Many of the Queensland experimenters 

 also reported that they considered the 

 dressings given in the writer's experi- 

 ments were insufficient and from the re- 

 sults of all the experiments, as well as 

 from Mr. Bruennich's data, everything 

 points to the following as a very suitable, 



{Continued on page U7,) 



