Makch j, 18^6.] THE TROPICAL AGRICLTLTURIST, 



C33 



RUBBER TREES IN OEAUA. 



The following inforiuation has been receiveii from Mr. 

 Oeorge Holdern, the Acting liritish Vioe-C'onsul at 

 Ce<u-:i, in reply to questions sant out by the 

 Huthority of the Britiah Goverunieut, with reference to 

 cultivation of the Indiarubber tree in that province :— 



Qiieri/. — What are the mimes and productive qual- 

 ities of the different kinds of rubber trees grown 

 within your ilistrict (• 



AtisKfi: — There are two kinds of rubber trees 

 known in this province, first the " Manicoba' plant 

 from which the Sernamby rubber is extracted, aud 

 secondly the " Mangabcira" from which, with the 

 application of alum, the " Mangabeira" rubber is pro- 

 duced. 



Q- — ^Vhat is the extent of land under cultivation 

 by said trees? 



■^- — The Manicoba trees are only cultivated to a 

 Very small extent on the mountains of the "Serra 

 Orando' and .Serra da l/ruburitaiua, the greater part 

 of the trees growing wild uru over the mountains, 

 at an estimated area of 2iJ leagues. On the Serras 

 of Maranguapo and I'acatuba ninny trees are to bo 

 found, but in this district they have not been cul- 

 tirat«d. The Mangabeira tree grows wild in nearly 

 every wooded district where there is a .sandy soil. 



V' — What is the nature of the soil most favourable 

 for the cultivation of the Indiarubbor tree? 



•^- — The soil most cuituble for the cultivation of 

 the "Manicoba" plant is the clay soil of the mountains. 

 For the '•Mangabeira" the sandy soil of the low 

 lands, especially towards the coast. The planting of 

 the " Manicoba" is very simple either from the seeds 

 or from slips of trees. The cultivation of this plant 

 has uot been much extended in this province, the 

 people limiting their elforts to substituting any tree 

 that many die by another from siods or slips. Most 

 of the planting has been done by nature, every year 

 when the Manicoba fruit or seed is ripe it drops off 

 the tree, and falling into suitable ground springs 

 up without any care whatever being given to it. — 

 Indiarvbber and Guttapercha Journal. 



THE ROTHAMSTED EXPERIMENT.S ON 

 SULPHATE OP AMMONIA AND OTHER 

 ARTIFICUL MANURES. 

 Many of our readers — especially those who are 

 familiar with the proceedings of the British Assocuatioii 

 for the Advancement of .Science, the Koyal Agriiniltural 

 Society, the Society of Arts, and some other scientific 

 associations — will be aware of the fact that, for many 

 years past, e.'cperiments on agricultural subjeets have 

 been conducted, on a working scale, by Sir John Bennett 

 Lawes, at his estate at Rothamstod, iu Hertfordshire. 

 Through the courtesy of this gentleman, we have been 

 furnished with some rather extensive printed memor- 

 anda as to the origin, plan, and results of the field 

 and other experiments, conducted on the farm and in 

 the laboratory at Rothamsted ; comprising also a 

 atatement of the present and previous cropping of the 

 arable land not under experiment. The report includes 

 »ome interesting experiments (probably the most 

 complete on record, as they extended over a period 

 of more than W years) on sulphate of ammonia, m 

 Gammon with nitrate of soda and other nitrogenous 

 as well as all the known kinds of manures. Sir .T. B. 

 Lawes states that he has found sulphate of ammonia 

 to be "an exceedingly valuable manure." For some 

 agricultural purposes, he considers that 1 lb. of nitrogen, 

 in the form of nitric acid, is more valuable than 1 lb 

 of nitrogen in the form of ammonia, and therefore 

 he would prefer to use nitrate of soda rather than 

 sulphate of ammonia -, as in the cas» of his experiments 

 (published some years ago) upon the iuflufiice of 

 Ditrate and sulphate respectively on the production 

 of sugar iu the beet, which led to the employment 

 of the former salt instead of sulphate of ammonia. 

 The price of sul;'' ' ■, he considers, will bo regulated 

 very much by tuc price of nitrate ; and, with so great 

 • fftU in the price of grain, farmer* cannot now aftotd , 

 80 



to pay so high a price for ammoiik ss they have 

 done in the past. Every page of his printed report, 

 he remarks, will be found to contain abundant evidence 

 as to the iinnieuso importance of ammonia as a 

 manure; and at Woburo, where experiments somewhat 

 similar to liis own have been carried on for several 

 years, salts of ammonia have proved quite equal, 

 and iu some cases superior to nitrate of soda. 



It seems that sulphate of ammonia has not always 

 yielded such good' results at Rothamsted, compared 

 with other manures, as have been realizeil at Woburu 

 and other experimental stations. There are two 

 reasons which may or may not account for this, and in 

 regard to which ammonia salts have been unfortunate. 

 The first is that the uniform practice at Rothamsted 

 has not been to use sulphate alone, but a mi.vtiiro of 

 equal parts of "sulphate ami muriate of ammonia of 

 commerce." At the present time, authorities .iiqiear 

 to be fairly will agreed that, of the various salts of 

 ammonia, the sulphate is the best for manurial purposes. 

 Bearing this in mind, it is scarcely just to the latter 

 to accept th<r results obtained from the mixture of 

 sulphate and muriate as affording an accurate indic- 

 ation of those which would be obtain< d by the use 

 of the sulphate alone. Wo do not find any explanition, 

 in the memoranda, of the reason why this mixture is 

 used in preference to pure sulphate. The .second 

 reason is one which especially bears upon the compari- 

 sons between sulphate of ammonia and nitrate of soda. 

 As a general rule, the practice at Rothamsted has 

 been to apply the former in the autumn and the 

 latter in the .spring. On this point, again, modern 

 practice points to the .spring time as the best season 

 for the application of the sulphate as well as the 

 nitrate; so, on this account, the sulphate is also at 

 some disadvantage. We do not pretend to assign the 

 extent of thi; effect of these two causes — the use of 

 a mixture of sulphate and chloride, and the application 

 in the autumn instead of in the spring- in reganl to 

 any calculations as to the value of sulphate, as 

 ordinarily manufactured at gas-works, in comjiarison 

 with other substances, but simply direct attention 

 to them. 



It is noticeable, although Sir .T. B. J,a\Ves considers 

 " that the price of sulphate must be regulated very 

 much by the price of nitrate," that to some extent 

 these two sources of nitrogen are distinct from eueh 

 oth(!r, as having special applications. It appears from 

 his n^marks that in some eases the nitrate is prefer- 

 able, whilst in others the sulphate is the more iijipro- 

 priate salt to use ; as for somc^ purposes the former 

 has been found to give the better rosull.s, while in 

 others the latter has proved to be more adv:inlagnoue. 

 It follows that these salts are not to be regarded as 

 competitors one with the other, except perhaps, to a 

 limited extent, for certain purposes to which it is 

 pos.sibla that they m^v bo e(|uaMy applicable; and that 

 there is (we are not attempting a poiulerous pun) 11 

 fair field for each salt. Here we Ikivc n strikirj 

 agreement with the remarks already niaili; in these 

 columns on this subject by Mr. F. .1. I.loyd, F.O.3., 

 in his article on "The Value of Sulphate of Ammonia 

 as a .Manure."* 



Apart from the value of the two salts respectively 

 as manures, wo would remind our readers that, as 

 set forth in the article just referred to, sulphate 

 posses.sen several practical advantages over nitrate. 

 The latter is so deliipiescent that, as a general rule, 

 it cannot he used for mixtures; and. as wo shall 

 presently sec, it is to the judicious use of mix(^d 

 manures that the farmer must look for the host 

 results. In aildition to this, it is evident that thoy 

 must follow the example of Sir. ,T. ]!. f.awes, and 

 learn to mix the manures for themselves, nillicr than 

 depend upon the purcha.<e of mixture Iroin denlers. 

 Sulphate of ammonia is efHoreseent — it loses moisture 

 by exposure to the air. In mentioning this jiroperty, 

 it is importtnt to notice that tlio lo.'s is not duo, 

 as some have supposed, to the volatilization of a part 

 of the ammonia. The alkali is in a fixed, nou-volutile 



» See Journal, Vol, xlv,, p. POP. 



