394 



The Supplement to the Tropical Agriculturist 



keeping it constantly moist, and the large 

 amount of organic matter resulting from the fall 

 and decay of the leaves, &c, the beneficial effect 

 is very marked. This is especially so on soils 

 poor in organic matter as are many of our Ceylon 

 soils, and for products, such as Para Rubber, 

 which require a humid atmosphere and an 

 ample supply of moisture in the soil. 



The composition of the plant is shown by the 

 following analysis of the various parts made by 

 the Acting Chemist, the whole plant when sun- 

 dried losing on an averago 70 per cent, of mois- 

 ture : — 



Mechanical Analysis. 



PerCent. Per Cent 



42-0 



Composition of Air-Dried Plants. 



Chemical Analysis. 



! >' 



12-00 

 84-36 



and Fruit. ; 

 42 



per cent 

 80 

 £0-14 

 10-16 

 3-81 



30-80 



Green- ™ 



, stems - air^ried. 



42 



per cent per cent 



12-00 11-07 



81-20 82-71 



3-80 6-31) 



1-04 'i-16 



-0 -60 

 14-46 



20-B4 



31-13 

 12-91 

 17-00 



4'oa 



Moisture at 100" C 

 Organic matter 

 Ash 



Nitrogen 



The ash contains— 

 Lime 

 Magnesia 

 Potash 



Phosphoric acid 

 Sulphuric acid 3'06 8*02 6-46 6*67 



Chlorine 2-80 6-03 3-21 4'32 



Soluble silicates 8-50 5-00 1-30 4-03 



Sand 0-45 6-48 0"21 2-89 



The proportion of nitrogen is very similar to 

 that in some of the leguminous plants, but in 

 this case it has been entirely derived from the 

 soil. The chief ash constituents absorbed are 

 lime potash, and magnesia, with a small amount 

 of phosphoric and sulphuric acids. 



The plant appears to have the power of readily 

 decomposing silicates. All the nitrogen and 

 mineral matter is, of course, returned to the soil 

 on the decay of the plant, and left in a readily 

 available condition for the other product. 



An average growth of the plant 10 in. deep 

 yields about 26,100 1b. of fresh green material 

 per acre, or, allowing 70 per cent of moisture 

 lost on air drying, equals 7,830 lb. of air dried 

 material. This amount of matter would contain 

 the following quantities of the chief consti- 

 tuents per acre : — 



169 lb. nitrogen . . 500 lb. ash 



the latter containing— 



155-6 lb. lime 32 8 lb. sulphuric acid 



64 5 lb. magnesia 21'6 lb. chlorine 



85-0 lb. potash 21 - 5 lb. soluble silicates 



2r3 lb. phosphoric acid 



Another plant of somewhat similar growth, 

 which during the last few years has spread 

 enormously in Ceylon, is the Mikania scandens, 

 belongling to the natural order Compositce. 

 It can be seen covering the scrub jungle and 

 trees along the Colombo line from Peradeniya, 

 and has spread down the Mahaweli-ganga to 

 Trincomalee. Under suitable conditions of soil 

 and climate, it should be as useful as Passlflora 

 fcetida in smothering other more harmful 

 weeds, especially coarse grasses. The following 

 analysis shows its chemical composition : — 

 Per cent. 



Moisture lost on air drying . . 85 56 



Organic matter, ash, &c. ... 14'44 



Moisture 

 Organic matter * 

 Ash 



Per Cent. 

 11-00 

 81-J4 



100-00 



* Containing nitrogen 2'35 percent. 

 The ash contains of the more important con- 

 stituents : — 



Por Cent. Per Cent. 



Lime .. 820 Soda .. 5-03 



Magnesia . . 7 - 04 Phosphoric acid . . 4 - 60 



Potash .. 42-77 



Mikania scandens thus differs considerably 

 from the Passiflora fcetida in containing only 

 about one-fourth of the lime, and two and a 

 half times as much potash. It would, therefore, 

 while growing tend to compete more with the 

 rubber, which also requires much potash, but 

 this would be returned to the soil as the plant 

 decayed. In rubber it should not be planted 

 within 4 feet of the stems, and care should be 

 taken that it spreads over the intervening space, 

 and not be allowed to climb the trees themselves. 



The weight of green material per acre is vari- 

 able, but is very similar to that of Passlflora 

 fostida, and would represent the following 

 amounts of plant food removed from the soil per 

 acre, but returned again on the decay of the 

 plants : — 



containing — 



23-46 lb. line 



20-14 lb. magnesia 



132-36 lb. potash 



14-32 lb. soda 



13"10 lb. phosphorieacid 

 But, besides the actual weight of material that 

 can be obtained for weighing at any one time, 

 there is continuous fall of leaf from the trailing 

 stems, as the lower ones are smothered by the 

 new growth. This increases steadily with the 

 age of plant, so that after a year's growth the 

 above figures could be at least doubled, and the 

 humus gained would amount to 8,000 to 10,0001b. 

 per acre. 



The plant dies down after flowering and seed- 

 ing, when the land should be cleaned and another 

 crop grown if desirable. Although it is sug- 

 gested to grow these crops to increase the humus 

 and water-holding capacity of the soil, and at 

 the same time to smother other weeds, and pro- 

 tect the soil from sun and rain, they are not in- 

 variably applicable, since, unless they are knoivn 

 to grow faster than otfier weeds in the district, 

 they will be useless for the prevention of the 

 growth of stronger grasses, and may themselves 

 be smothered out. 



February, 190y. 



M. KELWAY BAMBER. 



Rubber in the Congo. Collection in Two 

 Districts Suspended by Belgium. — Brussels, 

 Feb. 5.— The Minister of the Colonies has 

 telegraphed to the Governor of the Congo, 

 informing him that the collection of rubber in 

 the districts of Abirand Mongalla is suspended, 

 and requesting him co take measures to modify 

 the r6gime in these territories in regard to the 

 collection of revenue.— London Times. 



