lev, J, me.] THE TROPICAL AGMCUtTURTSt, 



53 i 



vibo threaten to build either bazaar huts or wash- 

 iug tanks for dhobies on the site. The interposition 

 between the grounds of the Eileu Sanitarium and 

 liotanir Garden of buildings of this sort would be 

 a great blot on the amenity of the neighbourhood ; 

 and I trust the Commissioners may reconsider their 

 decision juid see their way towards restoring the 

 ground to horticultural purposes, Sales of plants to 

 the extent of 'i\&25 (against an estimated revenue 

 of RHI«') were ma<-le at the garden during the 

 year. Mr. Jaffrey has worked with much enthusiasm 

 and energy under rather depressing circumstances.* 



The thanks of the Lieut. Governor are again due to 

 Dr. King and his subordinates for the escoUent work 

 done during the year. 



♦ 



EAETHING-UP. 



The ridge, consisting of earth heaped round the 

 base of the plant, exercises very diverse actions ; 

 often useful, it is sometimes without sensible action 

 — occasionally the effect is even hurtful. The practice 

 considerably modifies the physical constitution of the 

 soil ; it. moreover, exercises a very important inrtuence 

 on the manner of growth of plants. The temper- 

 Rtiu:e in the raised mound, as compared to the 

 temperatUBS of the level ground, has been found 

 greater by V to 2 .5 C. at mid-day at a depth of 

 III centimetres during the day from .June to August; 

 this fact has been proved in various soils. At night, 

 on the contrary, the temperature has been found to 

 be 1° lower in the ritlges. During winter it is 

 generally the raised soil which is coldest. Generally 

 when the sun is shining, the ridge aids the heating 

 of the soil ; when the sun has set, the ridge pro- 

 duces a coaling effect. These results are easy to 

 explain ; the ridged soil offers a greater surface to 

 the sun, it receives the rays less oblitiuely, the soil 

 there is very dry, and it takes a less quantity of 

 heat to warm it; thus it is natur.il that it should 

 be warmer during the ilay ; during the night, on 

 the contrary, the radiating surface is greater on the 

 ridge, it is more mellow, more easilj' penetrated by 

 the cold air ; if there has been rain, the surface of 

 evaporation is more extended, the temperature 

 necessarily falls lower there than in the level soil. 

 This increa.sc in the toniper-iture of the soil re-acts 

 on the plants by aiding the development of root.s, 

 by favouring the absorption of water, and generally 

 by hastening their development. Experiments have 

 shown that the more carbonic acid there is in the 

 soil the colder it is; now the presence of carbonic 

 aeiil proves the existence of inferior org niisnis whose 

 work it is to elaborate the organic matter which 

 forms the nourishment of plants: it is thus in the 

 ridges that the phints find most food. But, it must 

 not be forgotten that these inferior organisms only 

 work when the soil contains exactly the proper 

 amount of water which is indispensible to them ; if 

 the soil is too dry their work stops. If by earth- 

 ing up wo dry the soil Loo much we lessen or even 

 destr.ty its fertility, and this explains to us why 

 this practice may even become injurious. During 

 one >eason the quantity of water existing in different 

 sorts of soil, both in ridges and on the flat, was determ- 

 ined. One hundred parts of soil contained of water — 

 Sand : Sand : 

 Olay, limestone, flint Peat. 

 On ridges ... 16-35 10-3.3 1-22 43-99 17-74 

 On the flat ... 17-48 1-2-23 2-52 51-64 20-01 

 This table clearly shows that the soil of the ridge 

 is always the drier ; but it is in the siliceous sand 

 that it loses the greatest proportion of water, so 

 that it is in this kind of soil that the disadvant- 

 ageous results are chii fly manifested. To sum up, 

 the ridge will be useful on compact soils, rich in 

 humus, holding water, and situate in moist climates; 

 wlnle in dry regions cultivation should be carried ou 

 on the tl-it. 



We have said that the ridge e.xercises a very 

 important action on the manner of development of 



* Uis death bae since b«eu reported,— Kd. 



plants. On many species of plants, in addition to 

 favouring the development of true roots, it promotes 

 the development of adventitious or secondary roots; 

 this m.ay be seen in kidney lieans, broad Beans aud 

 m Turnip.!. Some species have not the power of 

 making a 'ventitious roots. Grasses, for example, as 

 ■Wheat, Kye, Bariey, Oats, Millet, Buckwheat, da 

 not form new roots. | ?] Such plants do not rcpiiro 

 the earth to be heaped up rounil their stem. There 

 are even plants which are enfeebled by *his tci-.>(- 

 ment, because it causes an unueces.sary lengthening 

 of their stem, as in th.ise plants in which the stem 

 tei. i:iates at the surface of the soil in a rosette of 

 1 -aves. If you put earth ou such a stem you 

 induce it to elongate so as to produce its leaves on 

 the surface to a length equal to the depth of Iho 

 soil over it, and this lengthening is etfected at the 

 expense of the materials which were destined to 

 develop the other organs of the plant. Some very 

 interesting eomijarisons have been made betneeii 

 Beetroots grown undur identical conditions, with the 

 exception that one lot was grown on ridges aud the 

 other was not. The average for one Beetroot is 

 found to be : — 

 ^'eight of the leaves ... 



,. ,, J, radicles ... 



1, I. •, root 



„ ,, „ whole plant 



The ridge produces a diminution in the numbers 

 of the leaves and in the development of r.adicles;it 

 promotes lengthening above the ground, aud with 

 the lengthening of the stem there is a corre.spoml- 

 ing diminution of the imdergrouml and useful part 

 of the plant. Evidently the ridge had lessened the 

 total weight of the plant .and the weight of the 

 underground and utilisable parts. 



In the case of Turniiis, it may be noticed that 

 the riilge prevents the crown from becoming green 

 so that it remains tender and preserves the texture 

 of the root ; this latter is a great advantage in a 

 plant used for food for cattle. 



The ridge is greatly used in the culture of 

 Potatos; it produces such marked results that the 

 tuber is planted almost on the surface; but if the 

 Potatos are plante.l deep the ridge is of no use, 

 and is even often hurtful to the plant. In those 

 kinds of soil where ridges produce bad results 

 becau.'se they draw from the soil the humiilitv which 

 is indispcu.sible, the tubers must be planted "deiply, 

 and allowed to develop in level ground. Let us 

 remark here that the culture on the flat will slightly 

 favour the growth of weeds, on account of the main- 

 tenance of too great an amount of moisture in the 

 soil; but these can ea-ily be got rid of with tlxr 

 hoe. Wth the gre.-iter luiinber of plants for «-liich 

 the ridge is useful, it is important to hoe the weeds 

 as soon as possible; if we wait too long we risk 

 touching and injuring the plants. In growing old 

 they have partly lost their faculty of f.rrning ad- 

 ventitious roots, and they profit much more from 

 the work of new roots than from those which were 

 formed earlier. 'With Potatos the tubers which ;ire 

 devi-loped on the new stolons have more time to ripen. 



We have seen th.it the soil is drier in ridged 

 land than in the plain ground, it would thereforo 

 be useful to sow, in certain lands, plants on the 

 ridges, although these plants do not derive any direct 

 advantage from it, for example. Beetroots. The 

 ridges running north and south have a much mere 

 uniform temperature than those going from east to 

 west; the south side is always drier than the north 

 side. The ridges directed from north to south 

 exhibit great uniformity in the evaporation of water 

 from both their surfaces; it is evident that the.se 

 arc conditions favourable for the development of 

 plant.s. Some Beetroots from ridges running north 

 and south were ripe in September, tho.se from ridges 

 running cast aud west were only ready in Octolu-r, 

 the former contained 1225 per cent of sugar, the 

 latter 10-62 per cent.— Dii. WotiNV iu Annaici 

 Agronomiqaci.—Gardentii' Chronicle, 



