January i, 1884.] 



THE TROPICAL AGRICULTURIST, 



459 



COMPENSATION FOK UNEXHAUSTED MANURES. 



About two years ago a series of papers issued from the 

 peu of Sir J. B. Lawes, ou the " Fertility of Soils," which 

 appeared fii'st in the JyricHHural Gazette, and were after- 

 wards revised aud published iu the form of a pamphlet. 

 Now we have before us a similar publication, from the 

 same emineut authority, on the " Compensation for Un- 

 exhausted Manures," iu which the author maintains that 

 the objection of the landowners to legislation upon ten- 

 ants' claims would be considerably lesseued if the value 

 of the claim could be more correctly ascertained. 



Dividing the coustitueuts which exist iu oiu* crops into 

 two portions, we learn that carbon and water are obtained 

 from the atmosphere, while the nitrogen aud mineral sub- 

 stances are derived from the soil. The atmosphere fur- 

 nishes from 90 to 95 per cent, aud the soil from 5 to 10 

 per cent of the dry suljstance of crops. The stock of fert- 

 ility which exists iu soils, though generally large, is for 

 the most part in a latent form. , 



The nitrogen, for instance, which is in combination with 

 carbon, dous not appear to be available to auy extent for 

 the food of ijlauts until it has been separated from the 

 carbon, aud by combmation with oxygen has assumed the 

 form of nitric acid. Its manuring properties we know are 

 then very great. 



The various mechanical operations which take place ou 

 the farm or iu the garden — ploughing, digging, trenching, 

 harrowing, rolling, hoeing — have for their one object the 

 formation of mtric acid. A fertile soil is one competent 

 to hberate and reiider available for the use of plants a 

 considerable amount of active nitrogen from its store of 

 organic nitrogen, while au abundant season is one in which 

 the crops are enabled to taki.^ up an unusual amount of 

 tliis active plant-food by means of their roots. 



In an ordinary agreement Sir John supposes the laud- 

 lord to say to the tenant: — "You may have uulimited 

 powers to extract what you cau from the atmosphere, as 

 it is the commou property of us all ; but of the ingredi- 

 ents of the soil — which are my property — you must only 

 sell such amount as is contained in animal products or 

 gi'ain. You must not sell hay, straw, or roots." 



The reason of this restriction is obvious enough wheu 

 we consider that in relation to the money value, grain, 

 meat and milk remove the minimum of fertility, that is 

 of nitrogen, from the soil; this is plainly shown in the 

 following table: — 



Number of Pound 6 of A'ltrof/en contaiacd in ^it'oduce that 

 would si'n for £10. 



2501b. 



4281b. 



5101b. 



Hence the soil constituents removed iu £100 value of 

 animals sold off the farm could be replaced by an expend- 

 iture of about £5 ; wliile the same money value sold off 

 in Swedes could not be replaced for less than £-10. 



In the pamphlet before us Sir John brings forward many 

 illustrations from his experiments at Kothamsted to show 

 that unexbaustod fertility is to be found quite as much in 

 the crops growu as in any substance still iu the soil which 

 has yet to be taken up by a crop. In a well-fed pasture 

 it is quite probable that from CO to 70 per cent of the 

 uitrogeu of the grass would be returned to the soil in the 

 urine from the animals, and if the summer were not too 

 dry, a considerable amount of this nitrogen would be avail- 

 able for the production of active growth in the same year. 

 ■\Vhile a pasture may not produce more dry substauce 

 when fed than wheu made into hay, an equal ilry weight 

 of the fed gi-ass would be much richer than hay in nitro- 

 gen, ash, and digestible food. 



If, therefore, the stock of organic nitrogen in the soil 

 is reduced by arable farming, with its coustaut tillage oper- 

 ations aud absence of active vegetation during a consider- 

 able part of the year, we might naturally expect that the 

 organic nitrogen would again accumulate during the form- 

 ation of a permanent pasture ; aud we are told that it is 

 quite possible for a tenant to divert the fertility from the 

 arable part of his farm, and thus form a pasture by means 

 of the inherent fertility which is the property of the land- 

 lord, and not from fertility which he has himself imported. 



The following results give us some valuable evidence 

 beai'ing upon this point : — 



Table siioiriny the Amount of ]Viti'0(;eji pet' cent iti the first 

 9 inches ofthy soil in several fields at Rothantsted. 



Nitrogen per cent. 



1. Boot crops grovm continuously by mineral man- 



ures ... ... ... ... 0-0:)3i 



2. 'U'heat crops grown continuously by mineral 



maniu-es ... ... ... ... 0*1000 



3. Ordinary arable land j'lst laid down to pasture... 01235 



4. Pasture laid down in 1872 ... ... 0-1.509 



5. Pasture laid down in 1863 ... ... 0-1740 



6. Pasture laid down in 1858 ... ... 0-2048 



7. Pasture laid down in 1838 ... ... 0-1949 



8. Very old pasture, age unknown ... ... 0-2486 



Multiplying these figures by 2^, the product will repre- 

 sent the number of pounds per acre of nitrogen in the 

 first 9 inches of soil. Thus No. 1 field will contain 2,335 

 lb. of nitrogen, and No. 2 field 2,500 lb. As No. 3 rejjre- 

 seuts the composition of ordinary arable land, we see the 

 reduction of fertility which has followed the removal of 

 crops for a number of years where im nitrogen has been 

 employed as manure. The various accumulations of nitro- 

 gen are not only interesting, but extremely instructive ; 

 more especially as they have taken place under the most 

 opposite modes of treatment. 



Field No. 6, for instance, which has received alternately 

 cither an annual application of purchased dvuig or of arti- 

 ficial manures, has been mow"n for hay every year since 

 it was first laid down in 1858. 



In field No. 5 stock has been fed with decorticated cotton 

 cake, and no hay taken for the last eighteen years. 



The analyses of No. 8 w;us made after twenty unman- 

 ured crops of hay had been removed. 



Assuming that aU these soils were originally virgin past- 

 ure, we are able to trace the reduction of their fertility 

 dining some centuries of arable cultivation by comparing 

 the nitrogen of the old pastm-e No. 8, with that of No. 

 3, the land just laid down to grass. If, again, we com- 

 pare No. 3 with the soil of the two experimental fields, 

 Nos. 1 and 2, we see the loss which h:is taken place by 

 a more exhaustive mode of cropping without the restor- 

 ation of any substance containing nitrogen for a period of 

 about thirty years. 



In the composition of the various pasture lands we maj 

 trace the accumulation of nitrogen in the soil as the pa-stun- 

 approaches matiu-ity. But in all the instances recoriled, 

 Sir John says, the pastures have been formed by lar^( 

 imports of both nitrogen aud of minerals, aud that ttir 

 amount and cost of these would certainly form an import- 

 ant item if the value of an established pasture is made 

 the subject for compensation. — Gardeners' Chronicle. 



FIBRE PLANTS OF INDIA. 



BY .1. -W. MINCHIN (of OOTAC'AjrUKD, MADBAS PBES.) 



The cultivation and treatment of fibre plants in India, 

 has occupied the attention of the Society of Arts on several 

 occasions. The great botanist, Dr. Forbes Royle, first 

 suggested the importance of the fibre-producing plants of 

 India in 1854; and Dr. Forbes Watson, in an exhaustive 

 paper before the Society, in 1860, enumerated the most 

 important varieties ; having, with the assistance of the Indiait 

 Government, collected specimens, and prepared plates 

 representing them, which were published in the Journal 

 of the Society (vol. viii. p. 448). Mr. Leonard Wray read 

 a paper on Indian fibres in 1869, and it was again the 

 subject of an article by Mr. P. L. Simmomls, in 1873. 



Notwithstanding these frequent di.scussious aud the 

 thorough knowledge that has been obtained of the value 

 of the different prmcipal Indian fibres, and of their cultiv- 

 ation and production, there has been no great commercial 

 movement in the export of these fibres, and this is due 

 to the difficulty that has been encountered iu the treat- 

 ment. The cost of preparing the fibre lor the market by 

 the native method of hand-scraping beiu^ prohibitive, and 

 no machines or process for the economic;! preparation ou 

 a large scale having, until lately, been in'roduced. 



For the valuable fibres strength aud bri,;htuess of colour 

 are es-wntial. The ordinary process of retting or ferment- 

 ation in stagnant water cannot bo followed. 



