Vol. IV. No. 86. 



THE AGKICULTURAL NEWS. 



235 



GREEN MANURES IN CEYLON. 



Since the establishment of the E.xperiment Station 

 at Peradeniya, Ceylon, in 1902, a considerable 

 amount of work has been done in connexion with green 

 manuring, a detailed account of which is presented in 

 the report for 1904. Tiie following is a brief summary 

 of the more important results : — 



Definite results were obtained cku'iiig the year with tea, 

 cacao, rubber, cocoa-nuts, and paddy, and it is exjiected that 

 the cultivation of green manures will play an important part 

 in the near future. 



Among the advantages of green manuring may be 

 mentioned : the prevention of loss of soluble plant food which 

 takes place when tropical soils are left exposed, particularly 

 in newly opened clearings ; the provision of a large quantity 

 of organic matter which is markedly deficient in most Ceylon 

 soils ; the reduction of the amount of wash ; the protection 

 of the soil from the sun, regulating the moisture 

 conditions of the soil, so that bacterial activity, which is 

 responsible for the liberation of much plant food, is more 

 uniform throughout the year. If leguminous plants are 

 used, there is the additional advantage that large (piantities 

 of atmospheric nitrogen are fixed V>y the plant and 

 ultimately added to the .soil. It must be remembered that 

 nitrogen is one of the most important, and at the same time 

 the most costly, of the essential ingredients of plant food. 



A wide variety of plants has been under experiment ; 

 among them species of the following genera : Crotalaria, 

 Alhizzta, Phaseolus, Vigna, together with the pigeon pea 

 and the ground nut. 



Preference for arborescent forms, such as species of 

 Erythrina and Albi:r.ia is shown in some cases on account of 

 the more permanent nature of the shade and the greater 

 mechanical effect of the tree roots. But this .system has its 

 disadvantages : in any case if trees are used for shade, as in 

 the case of cacao, they should be kept under control by 

 frequent lopping. 



An important advantage accruing from green manuring 

 is that, if the green manure is sown in proper quantities on 

 clean land at the right season, weeding becomes almost 

 negligible within two or three months from sowing. In some 

 instances in these experiments the saving in weeding, apart 

 from other questions, more than paid for the cost of the 

 original seed, and uprooting and burying the green manure. 

 In the case of new clearing.s, the best cover within the 

 shortest time was obtained by cultivating herbaceous forms 

 such as those mentioned. Considering the heavy cost 

 incurred by weeding new clearings, it is impossible to 

 exaggerate the necessity of seriously considering this question. 

 Species should lie selected that do not flower frequently and, 

 if possible, thost' which have the power of absorbing nitrogen 

 from the air. 



The success of green manures, especially the herbaceous 

 forms, depends, to a large extent, on the weather following 

 the sowing of the seeds. The seeds should be sown when 

 rain may be expected. 



Brief reference was made in a former issue of the 

 Agricidtaral Neivs (Vol. Ill, p. 424) to the use of 

 ground nuts in Ceylon for green manuring. The 

 experiments therein referred to have been continued 

 and are thus reported on : — 



This plant grows rapidly, has a short life-history, and is 

 one of those which has the power of absorbing atmospheric 

 nitrogen. It is therefore suitable as a green manure, and 

 the best variety for this purpose is found in the Poadicherry. 



For purposes of green manure this product can be grown 

 under most cultivations up to. 2,-500 feet, but least of all in 

 old tea. I mention the question of the ground nut for green 

 manure to draw attention to the fact that it absorbs atmos- 

 pheric nitrogen which compensates to some degree for that 

 removed by the crop, and to suggest that any exhaustion 

 following repeated crops of this product can be partially 

 counterbalanced by its cultivation in this form. The 

 Pondicherry variety grown in a young clearing will produce 

 about 4 tons of fresh, green material jier acre per year. This 

 material — roots, leaves, and stems — contains 0-914 per cent, 

 of nitrogen. 



In our experiments the Pondicherry \ariety was selected 

 because it produces only a small crop of nuts and a large 

 amount of leaf and thin stems. It has a trailing habit, and 

 usually dies down every four tii six months, and if planted 

 between every alternate line of tea may yield about 4,000 lb., 

 or more, of green material per acre per year. In a young 

 clearing as much as 9,000 ft. of material fit to be buried was 

 obtained within a year. The fre.sh material contains 0'914 

 per cent, of nitrogen. 



GRENADA BOTANIC STATION. 



Mr. R. D. Anstead, B.A., Agricultural Super- 

 intendent at Grenada, has forwarded the following 

 notes on the progress made by plants and seeds sent 

 from time to time by the Imperial Commissioner of 

 Agriculture : — 



The improved Guinea corn did not germinate at all, but 

 the ear of improved Indian corn germinated well, and the 

 plants are very large, clean, and fresh looking. A plot has 

 been formed of them which is now blossoming freely and 

 gives every promise of a good yield. 



The Tortola pigeon peas are also doing very well, and 

 have made a plot of large, bushy, compact shrubs, which will 

 soon be in flower. 



Telfairia pedata, and Min-a Uviiifjstoneana both germin- 

 ated well; the former has been planted out in the gardens, 

 and I am trying to find a suitable situation for the latter to 

 be tried, as elevations in the gardens are all too low for it. 



Almost every seed of I'ardllnia harbadensis germinated, 

 and seedlings have this week been planted out in the 

 gardens against trellis work. 



The Canavalia ensiformis has been sown as a green 

 dressing, and all the seeds have germinated ; while seedlings 

 of Ipomoea Bona-Nox and /. veiitricosa have been planted 

 out in the gardens. The former is a common wild plant 

 here. 



CASTILLOA AS SHADE FOR CACAO. 



In continuation of the article on p. 219 of the 

 Agricultural Ah'ws on the use of Castilloa as shade 

 for cacao, the following extract from a letter from 

 Captain j\[. Short, of Richmond, Tobago, to the 

 Imperial Commissioner of Agriculture, dated June 

 11, 190.5, is published for general information: — 



I am glad that you consider the rubber trees here very 

 healthy and that so far they do not appear to have any 

 injurious effect where shading cacao trees. As I keep 

 accurate returns of the yield of each cacao piece throughout 

 the year, and also check yearly the number of bearing trees 

 in each piece, I can tell to within a few pounds the annual 

 yield of each piece per acre, so that I shall be able to tell if 

 the yield of cacao under rubber falls off as both grow older. 



