Vol. XIV. No 



TI1H AGRICULTUKAL XKWS 



37.") 



by actual experiment in the field, and so far no ready method 

 has been discovered by which tin- availability oi the niti 

 in the soil can be estimated, i - regards the small 



amount present in the form oi nitrati 01 ol ammonium salts. 

 It will be seen, therefore, that chemical analysis ol an 

 I sample of soil can b irdlj « expected to supplj 

 a v< ry accurate ana reliable means of determining its manurial 

 requirements, and it is probable thai a simple field experiment 

 would yield better r< suits. 



Itisnotonly a question of what the soil contains l>ut 

 i what the plant needs. A plant is a living thing, and 

 its i i ds are not const ml but vary with the conditions under 

 which it is grown. Thus a plant n more phosphates on 

 a clay soil than it would on a sandy soil, and it needs more 

 potash on a sandj or peat soil than "ii a Loam. Again a plant 

 growing in a district receiving 32 or more inches of rain is in 

 greater need of phosphates than in districts with less than 

 2 1 inches of rain. 



Further, under present conditions, an isolated mechanical 

 analysis cannot be considered of much value to the farmer 

 By means of a mechanical analysis i is possible to measure 

 the proportions of particles of diffi rent degrees of coarseness 

 in the soil, ami so determine 1 extent the ability of 



the soil to meet the plant- requirements as regards the 

 supply of water ami the proper aeration of the soil. At 

 present, b iwever, it is probable that an experienced farmer 

 would be able to gain more useful and accurate information 

 by examining the land carefully at different times of the 

 year. 



DIREI I [OSS IN w III' II \ 



OIL \ s u.t -is mai i;i: i -nil.. 



While isolated soil analyses are of little practical value 



at present, there ar i ' two directions in which an 



analysis can afford useful assistance. 



1. A tanner may wish to know whether he has any 



able chance of obtaining results similar to those 



-irited by field experiments on another farm in the 



Ideality. Wheresuch experiments have shown the advantage 



pplying lime, phosphates or potash, the analyst can 



determine whether similar results are likely to be obtained 



mi the soil which he analyses. The element ol uncertainty 



will always be present, but there is ■ ry prospect that the 



will prove to be correct, fn this waj the farmer 



saved much time md expense in carrying out the 



experiment for himself. 



2. A soil analysis may also prove of assistance where 

 a tanner proposes to introduce a system ol cropping or 



known to give g 1 results elsewhere in the locality, 



but before doing so wishes to compare his soil with thai on 

 which the system is successful. Analysis may reveal differ- 

 which although nol ofr iou o c isual inspection are of 

 importance to the su :cess o) the enterprise. Two 

 heavy soils, for instance, maj look very similar, but one may 

 owe its heaviness to wry fine particli -. and the other to silt 



particles, and methods successful in one ca-e mi\ prove 

 failures in the other. 



3. A farmer entering anew farm may wish to obtain 

 complete information as to the possibilities of tin- soil, with 

 a view to taking up some special branch of production, or 

 ascertaining for what special crops the soil is suited. A soil 

 analysis will -how whether the soil and general conditions 

 resemble those obtaining where the proposed system of 

 farming is known to be a success. Where important 

 differences are revealed the tanner may be able, with the 

 a-sistance ..)' the agricultural expert, to modify the scheme 



, to tdapt it to the possibilities of hi- soil. 



It will be gathered h im the above n tha the 



maximum assistance can only be obtaim I fi inalysia 



when data are available foi comparison with soils of the 

 same type. Fortunately ile iJSuntrj is no« provided with 

 .i _- : aized schemes un.lei which 



in.iv be made and the results recorded. Soil surveys sup- 

 plying fairly full information with regard to special classes 

 ol soil in a limited arei, and carefully conducted field 

 experiments, are being carried out in man} pari of the 

 country. As time goes on, therefore, the possibility "I 

 setting up comparisons will steadily increase and analyses 

 will be of correspondingly greater value. 



Before deciding to have a soil analysis carried out, the 

 farmer should apply to the Country Agricultural Organiser, 

 who will advise him whether material for a comparison is 

 available, and whether the analysis would be likely to give 

 useful results. 



RUBBER MACHINERY. By Henry C. Pearson 



\e» \ork. The India 'Rubber World, 1915. Pp. 113, 

 figs. 428. Price sr.. 



Mr. Henry C. Pearson, editor of the India Rubber World, 

 may be congratulated on the successful completion ol si 

 ardu "is a task as that represented by the present volume, 

 which amounts to nothing less than a standard encyclopedia 

 of machines used in rubber manufacture. Every phase of 

 the industry would appear to have received attention — crude 

 rubber washing,. drying, preparing of ingredients, mixing, 

 preparing of fabrics, calendering, vulcanizing; calei 

 drives and safety stops: presses and moulds; spreaders and tub- 

 ing machines; machines used in the manufacture of reclaimed 

 rubber and cements; temperature regulating device-: extracting 

 machines for wild rubber, for deresination; laboratory equip- 

 n.. i i, testing machines ami devices; these are the principal 

 matters dealt with. 



While the body of the book lies outside the range of 

 tropical agriculture, we may infer its general excellence from 



the last mentioned -eel ion devoted to rulilui laboratory 

 equipment, much of which we are in a position to appreciate. 



\i u\ ol the device- -hown contain features of special interest 

 and ingenuity, and might be usefully imitated in other 

 bi.mehcs of agricull ural and industrial chemistry. 



Chapter II on crude rubber drying, and Chapter XIX 

 temperature recording and controlling devices are interesting 

 to US from the circumstance that these matt, rs, and i 

 quently the machinery pretaining to them, are important in 

 many different branch.- of tropical agriculture. 



■ book will no doubt be found an important addition 

 to the library of all those involved in the production or 

 manufacture of rubber, especially for purposes of reference. 



There is a' good index, and the chapters are subdivided into 

 -. The printing is excellent, and the illustration- are 

 abundant and remarkably clear in every detail. 



