WoL. VIII. No. 177. 



THE AGRICULTURAL NEWS. 



4r 



FERMENTATION OF PEN MANURE. 

 An article already referred to in the Aijri- 

 cidtaral News (see Vol. VII, p. 169) lately appear- 

 ed in the Journal of the British, Board of Agri- 

 culture and Fisheries (Vol. XV, N.j. 1), which dealt in 

 an exhaustive way with the composition and storage of 

 farmyard manure, the fermentation and aecomp.inying 

 changes in composition undergon© by the manure 

 during storage and after application to the land, the 

 loss of nitrogen (in the form of ammonia gas) from the 

 manure, that readily takes place if the greatest care is 

 hot e-xercised to prevent it, and also the chief methods 

 of preventing this escape of ammonia. 



The proportion of nitrogen that i.s lost under average 

 conditions of storage would by most persons be regarded as 

 Kurprisiiigly large. From e.xperiments referred to, which 

 were carried out in Germany about ten years ago, it is seen 

 that even with the most careful management, 13 per cent, 

 of the nitrogen was lost from the dung. , This loss increases 

 very rapidly if conditions be less favourable, and if the 

 manure is merely allowed to accunudate in a loose heap, as 

 much as 30 or 40 per cent, of the nitrogen may escape. The 

 uiininmm loss takes place if the manure is trampled under 

 tlie animals in a deep bed or pit. 



The account that is given of the bacterial and 

 other changes occurring in farmyard manure should be 

 of interest to planters, since, in the main, they apply 

 also to the pen manure of the West Indies. Some of 

 the facts conveyed should also be of value, as they may 

 indicate points in which the preparation and methods 

 of application of pen manure on estates may be niodi- 

 iied with a resulting .saving in nitrogen. The following 

 notes form a summary of portions of the article 

 mentioned : — 



Pen manure, which is originally a mixture of solid 

 e.xcremeut, urine, and litter, soon undergoes changes in com- 

 position that in the main are brought about by bacteria. 

 One of the most important of these chiinges is the conver- 

 sion of the urea of the urine into carbonate of ammonia. 

 This conversion into ammonium carljonate is exceedingly 

 rapid; in the liquid draining from a \;ud or a manure heap, 

 little or no urea can be detected, so complete has been the 

 change to ammonia. If loss of nitrogen is to be prevented, 

 ~the liquid containing the carbonate of ammonia must be 

 protected from evaporation. Otherwise, the higher the 

 temperature, and the more extensive the surface exposed to 

 the air, the greater will be the loss of ammonia passing off 

 in a gaseous condition. This volatilization of ammonia causes 

 most of the loss of nitrogen that takes place in making 

 pen manure. In addition, however, there are always present 

 various bacteria which oxidize the ammonia of annnonium 

 <;arbonate to free nitrogen gas and water. Loss of nitrogen 

 in this way is always increased when the manure heap is in 

 a loose condition. 



The so-called ' putrefactive ' bacteria are also abundant 

 in fresh manure, and their function is to convert the in.solu- 

 ble nitrogenous bodies (proteids) of the straw into soluble 

 bodies, ammonia being the final substance formed. It may 

 be mentioned, too, that the reverse action to this is also in 

 progress at the .same time ; the multiplying bacteria seize 

 upon the soluble forms of nitrogen, and convert them into 

 insoluble proteins in their body tissue. Owing to this fact, 

 -in long-stored manure, most of the annnonia lias returned to 

 a proteid form. 



The most characteiistic change that takes place in pen 



inanure is the destruction of the trash, and its conversion 

 into ' humus. ' Trash and other carbonaceous matter, when 

 spread out thin and ex[iosed to the air, are subject to attack 

 from a number of organisms, Avhich completely convert the 

 material into carbon dioxide, water, and inorganic ash. The 

 importance of keeping tlie manure heap compact and protec- 

 ted is therefore apparent from this fact alone. Anaerobic 

 bacteria, i.e., those capable of acting in the absence of oxygen, 

 and whose activities therefVire are not acconqianied by' 

 oxidation processes, are chiefly responsible for the conversion 

 of trash and other similar material into the indefinite brown, 

 acid substance known as ' humus. ' 



It will be seen that the changes occurring in the making 

 and storage of pen manure are very coraiJlex. In the early 

 stages bacterial action is most rapid, and it is concerned 

 chiefly with the soluble nitrogenous compounda like urea. As 

 soon as the first violent reactions are over, the rate of cliange 

 slows down considerably ; and it now consists mainly in the 

 attack of the anaerobic bacteria upon the carbohydrate 

 material of the trash. During this second change but little 

 loss is exi)erienced by the nitrogenous compounds if the 

 mass be kept tiglirtly pressed and moist, so as to exclude air ; 

 there will be no loss of fertilizing constituents, only a gradual 

 decline in weight as some ot the carbon compounds are 

 converted into gases. 



One other change S(5iiiethnes takes place when the 

 manure is allowed to get loose and dry ; instead of bacteria, 

 fungi begin to develop \ eiy rapidly, and the whole mass 

 becomes permeated with the mycelium. It is generally 

 agreed that manure in this state is seriously deteriorated, 

 but no analyses of such material are available. 



At the close of the article, the best methods of prevent- 

 ing the lo.ssof nitrogen are discussed. A well-known German 

 investigator found that the only practical means of reducing 

 the loss of ammonia was to place a layer of old well-rotted 

 manure as a basis for the new heap This had a distinctly 

 beneficial eft'ect, which was possibly owing lo the fact that 

 the carbonic acid, of whicli there is a constant evolution, 

 combined with the free ammonia, fixing it as carbonate of 

 ammonia, and so preventing its escape in the gaseous form. 



PARA RUBBER SEEDS. 



It shoidd be a matter of interest to those who 

 have planted, or contemplate planting. Para rubber 

 trees (Hevea hrasiliensis) to know that the seeds of 

 these trees, which are usually produced in abundance, 

 are liliely in the future, when available in sufficient 

 ipiantity, to prove of sorne value as a commercial 

 product. In reference to the extending rubber 

 industry of the British colonies, the latest report 

 of the Imperial Institute contains the following 

 note • — ■ 



In connexion with the present extensive planting of 

 Para rubber trees, the fact that the abundant seeds of thi.s 

 tree can be utilized as the source of a valuable oil may 

 become a matter of commercial importance in the near future, 

 when the seeds will be available in quantities far in excess 

 of those required for planting. The investigations conducted 

 at the Imperial Institute have proved that this oil, which 

 resembles linseed oil, will probably command about the .same 

 {jrice as the latter commodity, whilst the residue of the 

 seeds from which the oil has been expressed may prove to be 

 serviceable locally as a feeding stutt' for cattle. It is there- 

 fore possible that a valuable .subsidiary industry may arise iii 

 connexion with rubber planting. 



