October i, 1882,] 



THE TROPICAL AGRICULTURIST. 



291 



render the remainder more fine; and as soon as this begins 

 ^ to coiom" or to approach a ripening condition, the trusses 

 should he raised on twigs or small branches of any kind, 

 or even neatly staked and tied up, so as to keep the 

 fruit clean, by removing it from the surface of the soil, 

 and to allow the air to circulate freely among the ripening 

 berries. This gives also au attractive appearance to the 

 plants, ana is better than allowing the fruit to hang round 

 the sides of the pots and in contact with them. Some 

 have objected to this practice, contending that the natural 

 position of the fruit of the Strawberry plant is upon the 

 surface of the soil. There can, however, be little \vroug 

 in assisting or even improving upon Nature in this respect, 

 and a Strawberry plant growing in a pot is, of course, 

 in an artifical condition. It is also equally necessary to 

 prevent the fruit of plants growing in the open air from 

 resting upon the surface of the soil, which, if allowed to 

 do so, however fine it may be, it is nevertheless almost 

 sure to be rendered useless by having the grit from the 

 soil washed upon it by hea\'y falls of rain. Various 

 means have been resorted to as a remedy for this evil. 

 What are known as Strawberry tiles have been invented 

 and highly recommended, but from some cause (possibly 

 their expense) they do not appear to have ever come 

 into general use. The raising of the tarsses of fruit from 

 the surface of the soil upon twigs or small branches has 

 also been suggested, and to some extent practised. But 

 it increases the temptation which ripe fruit presents to 

 the blackbird, &c., it also involves considerable trouble, 

 and can hardly be recommended. Tanner's bark in the 

 neiglibourhood of towns or where this material can be 

 readily obtained is very frequently used, with the desired 

 effect for the purpose of mulching the surface of the 

 soil and preventing the same being washed upon the fruit. 

 It has also the very desirable property of driving away 

 slugs, snails, woodlice, and other troublesome pests, which 

 are always sure to attack ripe fruit, clean straw of any 

 kind may also be effectually used for the purpose; indeed 

 it is quite possible that from the use of this material in 

 early times, that this dehcious fruit may have derived its 

 designation of the straw berry. Another material, which 

 is perhaps more extensively used for the purpose than 

 any other, although by no means free from objections, 

 but in most garden establishments it comes to hand readily, 

 and is certainly not unsuited to the purpose in view — 

 this is the short grass, or the mowings of the lawns, &c. 

 But weather tiles, straw, or grass be used for the purpose, 

 the soil between the lines of plants should previously 

 have a good dressing of soot, gas lime, or even a slight 

 sprinkling of salt, as any of these will have the effect of 

 keeping away most of the insect pests which have been 

 alluded to until such time, at least, as the fruit has been 

 secured. But in addition to all that has been recom- 

 mended, it will be necessary in country places, or wherever 

 birds are prevalent, to protect the Strawberry plantations 

 with nets, or wirework, as soon as the fruit approaches 

 to a ripe condition. — P. GKiEVi", Bury St. Edmunds. — 

 Gardeners' Chronicle. 



MANURES AS ABSORBENTS OF WATER. 



BY A. STEPHEN' WILSON. 



{Continued from page 268.) 

 Fourth Series. 



The fourth series of comparisons consist-ed of some of 

 the same manures as were used in the third series. They 

 were taken from the same dried heaps, but put into cups 

 of a different form, the intention being to have confirmation 

 of results under various circumstances. The cups were 

 placed in the same floor upon a board, so as to avoid 

 adhesive moisture. 



In this experiment the cups were deeper and had less 

 surface than in the previous case, but the order of absorptive 

 power is nearly the same as before. The period of exposure 

 was the same as in the third series, but the Potato' 

 manure — the most powerfully absoi'ptive of the set — has 

 hero only taken up 59 per cent, while in the previous 

 casf it took up 92 per cent. Probably the difference is to- 

 be "'xplained partly by the difference in area of surface 

 expos ftd ; but there are evidently other consideration in- 

 volved, because in this case the deepef cup of cow-dung 

 with less surface has the higher weight of absorbed moisture. 



namely, 19 as against 16. I shall not at present attempt 

 to explain this difficulty, as it in no way affects the main 

 contention. 



Fifth Sekies. 



The fifth series of comparisons was also with some of 

 the same manures as above, dried in the same way, but 

 tested in another form of cups, and in the same' place 

 as the others. 



Here the coproHte dissolved with sulphuric aci<i absorbs 

 four times as much water as the same coprolite merely 

 grouud to a fine flour. In the third series the dissolved 

 phosphate took up five times as much as the ground 

 phosphate. The difference no doubt arises from causes 

 acting in relation to difference of surface exposed ; but 

 that the superplmsphate absorbs a large amount of moisture 

 more than the ground phosphate is clear. It is clear also 

 that the guano, as compared with the soil and the ground 

 phosphate, has a high hygrosorptive power. 

 Deductions. 



No new property in any of the substances here experi- 

 mented with is assumed to be discovered; but only some 

 of the well known properties assumed to be set perhaps 

 in a new light. Into the composition of guano, super- 

 phosphate, and the various Turnip and Potato maniu-cs, 

 entt'r large quantities of various salt of a highly deliquescent 

 character — that is, salts which are highly hygrosorptive. 

 The large percentages of sulphate of potash and ammonia 

 in Potato and Turnip manures, explain why,4n the above 

 experiments, these manures absorb such large quantities 

 of moisture, A comparison of the composition of the 

 superphosphates with the undissolved materials of which 

 they are formed, also explains why these materials, after 

 being treated with sulphimc acid, became more absorptive 

 of moisture. 



Now if in a dry season part of a Turnip crop, for 

 example, is laid down with a hygrosorptive manure and 

 part with a non-hygrosorptive, the plants in the first 

 case will be better supplied with water than in the 

 second case. 



How Roots Get "Water. 



But how do the roots of plants get water? In plants 

 which grow in water in its liquid from, the roots iire 

 directly in contact with water, and the naatter seems plain. 

 But with plants which grow in drained land, where there 

 is no water in a liquid from, the aspect of thmgs is 

 different. 



I filled pots of clear glass with small stones and loose 

 open soil up to near the brim and finished with a thin 

 layer of good soil. Seeds of Oats, Wheat, and Barley 

 were then planted close round the edge, so that their 

 roots would come down near the clear glass though and 

 amongst the openings made by the small stones and lumpy 

 soil. Whenever a fresh growing root appeared in an 

 available position, a low power objective was directed upon 

 it, and it was found that the root-hairs were covered with 

 innumerable vesicles of moisture. I therefore concluded 

 that in dry soils the roots of plants do not go in search 

 of water — the water comes in search of them. The water 

 which they need is condensed upon their root-hairs, and 

 thence absorbed into the tissue. 



Now a manure which has a highly hygrosorptive capacity 

 will keep the soil around the roots of plants better charged 

 with moisture than a manure of the opposite character ; 

 evaporation will fill the interspaces of the soil with vapour, 

 and will thus enable the moisture withdra^vn from the 

 air to be condensed on the roots. Whether any part of 

 the food of a plant may be condensed in soultion upon 

 the root-hairs in addition to mere water may be a question. 

 "Liebig has suggested," say Johnston and Cameron, "that 

 plants do not take up their food in solution, seeing that 

 it is so sparingly soluble in the liquid present in the soil. 

 It seems, however, improbable," they add, "that solid 

 matters could pass into the organisms of plants, and we 

 can hardly accept Liebig's theory, at least in its entirety, 

 until our knowledge of the physical condition in which 

 the fool of plants exists in the soil is considerably en- 

 larged" (pp.229, 230, nth ed.). The ''solution" implied by 

 Liebig was solution in liquid water. But if any part of 

 plant food — ammonia, for example — may be vaporised and 

 condensed within the vesicles on the roots, a different 

 view is opened up. 



