Vol. VIII. Xo. 193. 



THE AGRICULTURAL NEWS. 



297 



The Preservation of Copra. . 



Experiments have been conducted at the Paris 

 Colonial Gardens for the purpose of investisfatintj the 

 value of sulphur dioxide lor the preservation of copra. 

 Samples treated with the gas in 1905 still show no 

 signs of detei-ioration. Another trial has recently been 

 made on a large scale with a consignment of 3,000 

 cocoa-nuts received from the Jlalay Archipelago. In 

 the process, the nuts are cut in two and then exposed 

 to the action of the sulphur dioxide, and it has been 

 found that its intiuence is to preserve the copra in its 

 original condition. Other methods for the attainment 

 of the same end have been found successful at the 

 Chemical and Physical Laboratories, Little II ford, 

 Essex. The former of these consists in impregnating 

 the copra and the packages containing it with oil of 

 thyme, which is applied in a fine spray, about half 

 a Huid ounce of the oil being vised for each hundred- 

 weight of copra. The second consists in washing, 

 soaking or spraying the copra well with a warm, 

 saturated solution of boric acid, sun-drying the product 

 before it is packed and then du.sting the top layers 

 with a little of the finely-powdered acid. This applica- 

 tion has the merit of being odourless.' 



Bacteria and Soil Nitrification. 



Recent experiments conducted in Germany have 

 shown that the nitrifying bacteria are most abundant 

 in the top soil to a depth of 4 inches,, but the absence 

 of humus and oxygen causes them to be rare at a depth 

 of 20 inches. The addition of atmospheric nitrogen to 

 soils through the agency of bacteria (nitrification) takes 

 place best at temperatures about 2.5 to 27 C. (77 to 

 8rF.). Nitrification is not delayed by the presence of 

 small amounts of soluble organic substances ; it is 

 probably accelerated by this, as it has been found that 

 the addition of 1 per cent, of certain sugars increases 

 the activity of the bacteria. If, however, they are 

 present in greater-^iiantity, the rate of nitrification 

 decreases greatly. 



The upper layers of the soil also contain denitrify- 

 ing bacteria in large numbers. These occur irregularly 

 in the lower layers but are often found abundantly 

 at a depth of 3 feefc. The temperatures at which 

 these bacteria grow best are almost the same as those 

 for the nitrifying bacteria. 



Iron Content and Colour of Soils. 



A paper read at the fortieth general meeting of 

 the American Chemical Societj' states that a chemical 

 examination of twenty typical red and yellow soils 

 showed that their inorganic colouring matter consisted 

 chiefly of iron oxide : manganese compounds were 

 present in amounts too small to hai'e an effect on the 

 colour. It is argued that the comparatively small 

 difference in soil temperature in any two localities 

 where the tints are different is insufiicient to uphold 

 the explanation that variations in colouration are due 

 to the presence of iron oxide in various states of hy- 

 dration. The different shades are, on the contrar}', 



held to be due to the extent to which the film of oxide 

 has been deposited on the soil particles ; thin films give 

 yellow, and thicker ones red, soils. Experiments in 

 which films of iron oxide were precipitated on Sfinds 

 and grains of quartz flour of different sizes, the per- 

 centage of iron being kept constant, po that deposits 

 of different thicknesses were obtained, afforded con- 

 firmation of this view. 



How ' Marasmius ' is Spread. 



The v/ays in which the root disease of sugar-cane 

 (Marasmius ■saccl/ari) may be disseminated are con- 

 sidered in Bulletin No. (i of the Experiment Station of 

 the Hawaiian Sugar Planters' Association, entitled 

 Fiiivjus Maladies of the Sugar-cane. It is stated 

 that it appears to spread largely through the agenc}' of 

 the mycelium. Its spores do not appear to be long 

 lived, nor to have any special means for their distribu- 

 tion. They are not taken up by insects and at one stroke, 

 as it were, spread f;ir and wide over the plantation. It 

 is doubtful whether air currents play any very impor- 

 tant part in the distribution of the spores o? Marasmius, 

 Irrigation and rain-water undoubted!}' are njost effi- 

 cient means for their distribution. So are the various 

 agencies used in the culture and harvesting of cane. 

 Machineiy, men and animals at work in the cane fields 

 are no doubt often agencies in the spread of both the 

 spores and the mycelium. 



In the case of Ithi/pliallus. Clathras, and Dicty- 

 opliora, which are found in Hawaiian cane fields, 

 insects have been proved to be instrumental in spread- 

 ing the first two, and from the fact that the odour and 

 appearance of Dicii/opkora are similar to those of fungi 

 whose spores are carried by insects, it is concluded that 

 this is also disseminated by them. 



Brazilian Cacao in the United Kingdom. 



The Moiitldij Trade and (junsidar ReiJorts for 

 August 1908 states that the decision of the largest 

 imj^orters of cacao in the United Kingdom to employ 

 no more of the product from San Thomc^, Portuguese 

 West Africa, will extend the industry in Brazil. 



As the United States takes a large part of the 

 exports of Brazilian cacao, the matter of possibly large 

 incureases of the British imports thereof is of interest. 

 fii'*?^? and 190S the value of the exports^ of cacao' 

 from Brazil was £2,036,128 and £2,008,322 respe?Bi«ely, 

 of which £607,576 and £-1-86,265 worth went'to t^ftg 

 United States. 



In 1908 the exports of cacao from Brazil and 

 San Thome amounted to 31,068 metric tons and 28,765 

 metric tons, respectively. Although the cacao industry 

 in Brazil consists of little more than gathering 

 the beans from the wild trees, instead of being a 

 developed one, it is becoming one of the dependable 

 resources of the country in its export trade. The 

 production of cacao is increasing at the rate of 

 2,000,000 tb. per annum, and it might be added to 

 almost without limit. 



