Vol. X. No. 247. 



THE AGRICULTURAL NEWS, 



335 



PINE-APPLE 



EXPORTATION 

 NATAL. 



FROM 



Experiments have been made recently in connexion with 

 the exportation of pineapples from Xatal to England, and 

 they are given attention in the Agricultural Journal of the 

 Union of South Africa, Vol. II, p. 83. The account shows 

 that the purposes of the experiments were to ascertain the 

 best means of packing and forvt-arding the fruit and to gain 

 some knowledge of its market value. It is pointed out that 

 the time which elapses between the picking of the fruit and 

 its arrival in the London sale rooms is at least twenty-three 

 days, and if the exportation of pines from all districts suitable 

 for growing them is considered, the time extends to thirty 

 days. 



It is stated that the trial shipments have been promising 

 in some respects, and disappointing in others. Their 

 spasmodic nature fits them merely to indicate the lines upon 

 which further extensive trials should be made. The experi- 

 ments were conducted with the small 'Natal' pineapple and 

 the larger 'Cayenne' variety, usually known as the 'Small' 

 and the 'Queen'. The former has been recognized recently 

 by Mr. Fawcett, the late Director of Agriculture in .Jamaica, 

 as the 'Ripley'. 



In regard to the practical work entailed in harvesting 

 and exportation, it was found, first of all, best to cut the 

 bottom bracts from the fruits instead of tearing them away 

 in the usual manner. Another matter of importance is that 

 the pines were never placed in heaps or allowed to come into 

 contact with one another in any way. The fruits were cut 

 at a place 1 \ to '2 inches along the stalk, the cut being 

 made straight acro.ss. There was no advantage in 

 sealing or singeing the cut ends. The pine-apples were 

 sized and graded when being packed: it is advised that 

 at least two grades should be made, and defective pines 

 should never be shipped. For ventilated hold shipment it 

 was necessary to employ single-layer boxes; these are 

 equally suitable for use in cool chambers, but in this case 

 double-layer boxe.s, provided that they hold not more than 

 one dozen fruits weighing If to 2 A lb., may be employed. 

 The fruits are always packed in alternate positions, whether 

 the package has one or two layers. 



For shipments in ventilated holds, closed boxes should 

 be used, as it has been found that the free access of air 

 causes the fruit to acquire an unsightly, leaden-grey colour. 

 The material best recommended for packing is well shredded, 

 thoroughly dry and white maize husk.s. < )f the readily avail- 

 aVjle material, wood wool of the quality usually employed in 

 packing crockery was found tn be best, while the fine grade 

 wool proved to 1)6 disadvantageous. When wood wool is used 

 it should be placed above and below the fruits, and in such 

 a way as to protect them from contact with the sides of the 

 boxes ; the packing should be tight in order to prevent bruising. 

 A matter which is not essential, but which is useful, is the 

 wrapping of each pine in a couple of layers of soft paper, 

 and it is suggested that the crowns should also be wrapped 

 when the fruits are being shipped in a ventilated hold. The 

 fruits, before wrapping, should be carefully brushed in order 

 to remove any grit and sand that may be adhering to them. 

 A final matter of more general interest is that the treatment 

 of pine-apples with preservatives containing formalin proved 

 to be most disastrous. 



PROTOZOA AND SOIL SICKNESS. 



The Annual Etporl of the Porto Rico Agricultural 

 Experiment Station for 1910 (issued on July 17, 1911) 

 contains an article by Oscar Loew, Physiologist at the 

 Station, in which the question is considered as to the suggested 

 connexion between the smallest forms of animal life found 

 in the soil (Protozoa) and the inability of the soil to produce 

 crops (soil sickness). It is pointed out that it is difficult to 

 discover these protozoa under the microscope, but that they 

 can be easily seen after a nutrient solution has been added 

 to the soil, and a short time has been allowed to elapse. 

 The suggestion is made that some of the protozoa may be 

 encysted in the soil, particularly in dry seasons, and that 

 they develop afresh in the food supplied by the nutrient 

 medium employed. One of the best ways of demonstrating 

 their presence is to make cultures of the soil in the usual way 

 for the nitrogen-fixing organisms (Azotobacter). A method 

 of determining the presence of protozoa and Azotobacter is 

 reproduced in the report as follows: — 



'For sake of convenience the test for both Azotobacter 

 and protozoa may be mentioned here. A conical fiask of 

 about 100 c.c. capacity, provided with a cotton plug and 

 containing 1-5 to 20 c.c. of glucose nutrient solution, free 

 from nitrogen compounds, and -5 grams calcium carbonate, is 

 sterilized and then about 10 grams of the carefully collected 

 soil is added After shaking well the mixture is left at IG" 

 to 25°C., protected against the direct rays of the sun, for 

 one to three weeks. The glucose nutrient solution men- 

 tioned contains 1 per cent, glucose, 02 per cent, mono- 

 potassium piio.sphate, and 0'02 per cent, magnesium sulphate. 

 A film of Azotobacter cells, gradually turning brownish, will 

 appear, accompanied by various other microbes and by 

 protozoa ' 



Attention is drawn to the theory of A. D. Hall, based 

 upon the work of Russell and Hutchinson (see Agricultural 

 Neivs, Vol. IX, p. 33), that the protozoa in the soil are injur- 

 ious because they prey upon the bacteria that change organic 

 nitrogen compounds into compounds of ammonia, and thus 

 make them available. The criticism is made that it was not 

 stated in the paper by the authorities mentioned above, in 

 which their work was described, whether the increase of 

 ammonia after disinfecting the soil was oljserved immediately 

 after treatment or after several days, when the number of 

 microbes began again to increase. Doubt is also thrown on 

 the circumstance as to whether all the protozoa were killed by 

 disinfecting. The obtaining of an increase of ammonia imme- 

 diately after disinfection would make possible another explan- 

 ation than that of Hall, for some experimenters have observed 

 an increase of soluble organic matter in the soil after treat- 

 ment with antiseptics. The suggestion is made, further, that 

 the influence of protozoa in relation to soil sickness can only 

 lie properly estimated when their relative numbers atdifl'erent 

 levels have been ascertained, and when more is known of the 

 extent to which they are capable of affecting the multiplica- 

 tion of the bacteria. 



To summarize, it is indicated that, while Loew agrees 

 that Hall's theory may be correct in special cases, it does not 

 serve as a general statement, and other possible causes of soil 

 sickness than the action of protozoa are brought forward, such 

 as: (1) the reduction in number of the beneficent organisms 

 through large increases in the total number; (2) an unhealthy 

 increase in the number of certain injurious microbes of fer- 

 mentation and denitrification; (3) the presence of injurious 

 parasitic organisms, which eat away the fine roots and root 

 hairs of the plants, thus inhibiting their power of absorption 

 from the soil; and (4) the existence of various harmful kind.s 

 of soil bacteria, both noi' -parasitic and parasitic. 



