Vol. XI. No. 2G7. 



THE AGRICULTURAL NEWS. 



231 



The actual crop for 1911 was only 23,400,000 lb., how- 

 ever, largely owing to the tremendous drought of March to 

 May 1911, but also because of the fact that the bulk of the 

 1906-7 plantations were somewhat neglected during 1908-9, 

 and only produced a small portion of the theoretical yield, 

 the total year's crop being about 6,000,000 tt). short of the 

 theoretical estimate. This was, however, anticipated largely, 

 and my estimate for the Peninsula, made in January 1911, 

 amounted to 12,000 ton.s, or 26,880.000 lb. which could have 

 reasonably been expected but for the drought, which threw 

 all calculations out. 



The theoretical estimate for the year 1912 is: — 



No. of acres Age of trees. Estimated yield 

 in tapping. years. per acre, in lb. 



1,000 

 350 

 350 

 350 

 350 

 350 

 325 

 300 

 250 

 200 

 125 

 60 



Estimated 

 total out- 

 put, in lb. 



50,000 



175,000 



350,000 



507,000 



1,400,000 



2,800,000 



3,250,000 



4,200,000 



8,750,000 



9,600,000 



11,625,000 



2,880,000 



263,000 45,587,000 



This is equal to an output for the present year of 20,350 

 tons. 



This crop is not, however, likely to be realized, as a good 

 deal of the older rubber is being rested from recent over tap- 

 ping, and the younger rubber is in many places still backward 

 Irom neglect, from which it is however rapidly recovering 

 since the properties were properly financed by the capital 

 rai.=!ed during the boom. 



A WORK DEALING WITH VEGE- 

 TABLE OILS. 



An article in La Cltronique C'oloniale et Financirre for 

 May 5, 1912, signalizes the publication of parts 27-30 of the 

 llandbui-li (hr Pharinakognosie, of Professor A. Tschirch, 

 dealing entirely with the .study of fatty matlers, among 

 which the vegetable oils naturally possess the greatest 

 importance. 



In a short review, the article states that it is not pos- 

 sible to give a full account of the way in which the material 

 of the work has been dealt with by Professor Tschirch. It 

 may be said, however, that those living in the colonies, 

 ■whether planters, business men or manufacturers, will find 

 in these well illustrated portions of the work, clear informa- 

 tion on the fatty matters, of tropical or sub-tropical origin, 

 that are derived from the following plants (to quote the chief 

 among them): cotton, the ground nut, sesame, the castor oil 

 plant, the coco-nut palm, the West African oil palm {Elmis 

 guineensis) and cacao. 



Each product receives attention in a chapter to itself, in 

 which is presented a large number of references. 



The article states, finally, that the handbook is a work 

 that ought to be possessed by all who are interested in any 

 way in commercial product.s, and particularly by those who 

 are engaged in commercial matters connected with the 

 colonies. 



THE AVAILABILITY OF ROCK 



PHOSPHATE. 



An account of work that has been conducted for the pur- 

 pose of finding the eft'ect of organic matter, in the shape of 

 composts and manures, on the availability of rock phosphate, 

 is contained in liesearch Bulletin No. 20 of the University 

 of Wisconsin Agricultural Experiment Station. The follow- 

 ing information is taken from a summary which appears at 

 the end of that publication. 



Experiments in the laboratory indicate that the organic 

 matter that was composted with raw phosphate exerted only 

 a slight solvent action; this was to be expected, as carbon 

 dioxide is the only free acid that is formed, and further the 

 amount of the solvent action is limited by the quantity of 

 phosphate which the water containing carbon dioxide can hold 

 in solution. 



In small experiments, the dissolved phosphate and car- 

 bonates are not removed from the place where they are 

 formed, so that the dissolving action reaches a stage at 

 which no more carbon dioxide goes into solution and acts as 

 a solvent. Under field conditions, however, the movements 

 of soil water and the absorption of food by crops cause 

 removal of the dissolved substances, so that the action of the 

 carbon dioxide as a solvent is greatly increased. It is thus 

 seen that the experiments in the laboratory failed to imi- 

 tate field conditions with respect to a most important circum- 

 stance. 



When rock phosphate is mixed with manure it immedi- 

 ately becomes less soluble in 2 per cent, citric acid solution, 

 so that it must be concluded that the availability of phos- 

 phates as measured by such a solvent is entirely different 

 from the availability as indicated by a growing crop. In 

 relation to the growing crop, again, the availability is not 

 only influenced by the solubility of the raw phosphate in 

 weak solvents, but also to a large extent by the thoroughness 

 with which it is distributed throughout the soil. 



It seems that, when the material is thoroughly mixed 

 with the soil, some plants can obtain a sufficient supply of 

 phosphate from the insoluble material, probably through the 

 dissolving action of the carbon dioxide given off by the roots. 



When manure is added to a soil, the amount of carbon 

 dioxide produced is greatly increased, so that there is aa 

 enhanced solvent action on the phosphate which the soil 

 may contain. This consideration leads to the suggestion of 

 the usefulness of mixing raw phosphate with manure, when 

 applying it to soil. On the other hand, the addition of this 

 material to a tight clay soil containing little organic matter 

 may cause the phosphate to become confined to areas from 

 which its subsequent distribution may be very slow. 



Consideration of the whole question leads to the con- 

 clusion that the use of organic matter in connexion with raw- 

 phosphate increases the availability. This result is brought 

 about through the facts that: (1) the phosphate is mixed 

 more thoroughly with the soil; (2) the formation of carbon 

 dioxide, which leads to greater solution, is increased 

 because of the favourable coudiiions that exist for the 

 chemical and biological processes that give rise to it; and 

 (3) the action of the carbon dioxide results ultimately in 

 a finer and more uniform distribution of the phosphate 

 through the soil. 



