JaSuih* I, 1884.] 



THE TROPICAL AGRICULTURIST. 



503 



freshly bestowed on the soil, the free acids they contain 

 have attached more lime and once more become iusoluble, 

 but afterwards they are precipitated in such a finely 

 di^nded state, that the rootlets of the plant can easily 

 absorb them. Were lime not available, the accumul- 

 ation of fi'oc acids in some soils would soon come to 

 act prejudicially on the welfare of the plants which the 

 farmer thuu^'ht to encourage. "Without its presence and 

 use, the quickened decomposition of soils full of such inert 

 organic matter as peat, is almost impossible. Other bases 

 — potash, ammouia, or soda — may perhaps be available, 

 but the first two are too valuable to be allowed to serve 

 such purposes as the cUoaper and more plentiful lime can 

 even more efficiently perform. Comparing the compositiou 

 or the analyses of the ordinary crops of cultivation with 

 that of wood, we can at once see why it is that timber 

 acts decidedly in the way of increasing the fertility of the 

 soil and not towards its deterioration. 8ome tables in a 

 recent httle book on * Agricultural Chemistry,' by Mr. War- 

 ingtou, which we have by us at present will sufficiently 

 answer the purpose. From these we learn that a crop of 

 wheat yielding 30 bushels to the acre, and with its straw 

 included, requires from the soil within that area 45 lb. of 

 nitrogeu, 227 of phosphoric acid, and 279 of potash ; and 

 a 30-bushel-to-the-acre crop of beans, 99 lb. of nitrogen, 

 31-5 of phosphoric acid, and 8M of potash. A two-ton 

 crop of clover hay will take from each acre 102 lb. of 

 nitro-^en, 25'1 of phosphoric acid, and 87'4 of potash. Seven- 

 teen tons of turnips, 22 of mangels, and 6 of potatoes, 

 all with their respective leaves and stems, will absorb 120, 

 147, and 67 lb. of nitrogen, 33-1, 491, and 2CyS lb. of 

 phosphoric acid, and 143*8, 262*5, and 70-5 lb. of potash 

 from their several acres of soil. Unfortunately the amount 

 of nitrogen in a season's increase of Pine and Beach wood 

 quoted is not given, but Mr. AVarington writes that a year's 

 mcrease of Piu« timber is ' produced with a consumption 

 of only 2^ lb. of potasli and 1 of phosphoric acid per acre 

 per annum; with Beech timber the quantities required are 

 rather larger. The nitrogen contained in timber is very 

 small in amount, but the actual quantity required by a 

 forest has not been accurately ascertained.' From the fore- 

 going data, we caimot be very far wrong in saying that 

 a single moderate crop of mangels will extract from an 

 acre of soil almost as much potash as can be required by 

 the annual growths of a forest covering a like area through 

 the long space of a hundred years ; indeed, we may say for 

 the lifetime of the trees. And during the same time an 

 acre of forest trees will only require the use of twice as 

 much phosphoric acid as ^vill be needed to serve the pur- 

 poses of a single crop of the roots in question on an equal 

 plot of ground. The figures reveal also the necessity that 

 farmers are under of manuring liberally in order to insure 

 lax'ge retiu-ns, and show the advantages that result from 

 a judicious rotation of crops, and the need there is in many 

 cases to restrict the removal of certain crops to be con- 

 sumed at a distance fi'om the farm, unless some equiv- 

 alent is to be returned in their stead to the soil. The 

 nitrogen and phosphoric acid, and potash contained in 

 growing trees are concentrated mostly in the leaves and 

 twigs and tender branches — the parts tliat are seldom re- 

 moved from forest ground. The roots descend far and 

 feed on the subsoil, eating into and disintegi-ating the 

 hardest rocks themselves, and they are independent of the 

 surface soil for their nourishment. The leaves fall annu- 

 ally and decay, and thus they gradually come to enrich 

 the surface soil of plantation ground ; each year they 

 are adding to it the bulk of the valuable bodies that 

 the roots have extracted from the depths beneath. And 

 at the same time they, and the decomposing parts of 

 the trees that reach the ground, increase the soil's 

 .share of its beneficial organic or *mould,' matter — spokc-n 

 of by some as Iniiitus. The nitrates of soil occupied by 

 trees are not nearly so apt to be washed out as they 

 are from soil und<^ tillage and underdrained. What of 

 the rainfall in woods that is not carried away in the 

 surface drains is eventually taken up by the trees and 

 evaporated from their leaves. Any nitrates that niay find 

 their way to the subsoil will soon be seized on by the 

 roots of the trees, and be once more transferred to 

 the sm-face. And then again it is questionable whether 

 the process of nitrification can go on in damp and shaded 

 woods. At any rate, the more it is hindered, the less 



chance there will be of waste of the gradually accu' 

 mulating nitrogenous matter. The thinner the trees on 

 the ground, and the drier the soil, the greater likeli- 

 hood there will be of its ijroceeding. And these are the 

 places where we meet with * grass, brackens, and other 

 weeds.' Now it has been found, and wo have it on the 

 good authority of Sir J. B. Lawes, that there is far less 

 waste of nitrates from soil continually covered with 

 herbage than from bare soils or those that cairy a crop 

 during only certain seasons of the year; that, moreover, 

 there is less waste from a badly cleaned field than from 

 a well weeded one; but let that be no excuse for dirtiness. 

 The grasses, and some of the weeds, are rarely altogether 

 dead or dormant, even in the dead of winter, and their 

 roots are ever ready to avail themselves of what is going 

 in the soil. As the nitrates are formed they are made 

 use of ; and so with other plant food in the soU. The 

 growth of each season being left to ^vither, the decayed 

 matter gradually comes to be assimilated to the mould 

 that gathers in the network of rootlets beueath such herbage, 

 and which constitutes the great agricultural virtue of old 

 sward — so full of matter that insures enourmous crops of 

 corn. And thus the natural process of enriching the sur- 

 face soil at the ex])ense of the subsoil and the atmosphere 

 may go on indefinitely so long as the trees remain unfelled, 

 and the amiual growth of herbage is not removed, but 

 allowed to die and decay where it grew. — E. H. — Journal 

 of Forestry. 



Syrian Silk. — The Central Blutt fiir Text'd IndvMrie gives 

 some details as to a vegetable substance somewhat re- 

 sembling silk, to which attention has lately been drawn 

 by its having been exhibited in Greece. It is stated that 

 this substance is a silky-haired portion of a tree-like shrub 

 which comes originally from America, but is found iu Syria 

 and the South of Europe (A&depias Syrue)y of the family 

 of the Asclepiades. It is also known as the Syrian silk- 

 plant. The substance in question is used for stuffing very 

 soft cushions, when mixed with silk and wool. Tliis Syrian 

 silk is used in different tissues. The milky juice of the 

 plant is said to be poisonous, and the luu^h stalks can 

 be used in the same manner as the corresponding portions 

 of the hemp plant. — Journal of the Society of Art^. 



Bamboos. — In looking through one of the London parks 

 some short time since, we were rather struck by the 

 paucity of the efforts that had been made with the genus 

 Bamhusa in the decoration of those parts of the place 

 called the subtropical garden, for with the solitary excep- 

 tion of one large group, and one or more small sohtary 

 groups standing near the water, there was nothing more 

 to be seen. This is the rather to be wondered at. as many 

 kinds are hardy enough to .stand out with but little pro- 

 tection iu the latitude of London. The Bamboos are capital 

 centre pieces for sunny courts, formally arranged with some 

 distinct large-leaved plant, as Gimnera scabra or G. maui- 

 cata, Aralia papwifera, cut down to a low height, not loft 

 with bare crooked legs of 6 feet or more, as they are 

 sometimes seen ; Polygonum cuspidatum, Bocconia cordata, 

 or coloured -leaved Canuas, and Gladioli with bright flow- 

 ers, or dwarf Ricinus, Uke Gibsoni, Tlie above are all cap- 

 ital margin plants for a group. It need hardly be said 

 that any of the Palms, hardy enough to endure our cool 

 summers, will assort beautifully with the Bamboos — especi- 

 ally when the specimen is tall enough to show up from 

 out of a dense thicket of the other. Aletris (Drac:ena) 

 fragrans, when grown to 5 or 6 feet high, and ('ostus 

 iraperialis grow well together ^\-ith it. Panicum sulcatum 

 is an effective plant to work in ^vith Bamboos that attain 

 ft height of 7 feet or more, being capable of forming a 

 foreground undergrowth — or surrounding belt — the pendul- 

 ous foliage of the one contrasting well with the slender 

 erect growth of the other. Among the sorts wliich are 

 useful to plant in this country are B. metake, which will 

 grow, when well e.stablished m good soil, from 7 to 9 feet; 

 B. aurea striata, smaller ; B. Fortunei, quite a miniature 

 kind. — Gardenei's' Chronicle. 



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