224 



JOURNAL OP HORTICULTURE AND COTTAGE GARDENER. 



[ March 13, 1873. 



fronds, belouging to a well-known exhibitor, brought £10; and 

 the splendid Oncidium macranthum, £9. 



A cATALo-iTE is printed b}' M. Kodembourg, head-gar- 

 dener, and M. K. Morren, Director of the Botanic Garden 

 belonging to the University of Lit'ge, of upwards two hundred 

 species of the interesting order Buomkliace.'E cultivated in it— 

 an evideuco of the /.eal with which scientific botany is pursued 

 in Home quarters on the Continent. — {Nature.) 



ON THE RELATIVE VALUE OF CLARIFIED 

 AND UNCLARIFIED SEWAGE. 



The following j^apor by Mr. William Paul, F.K.H.S., Wal- 

 tham Cross, was road before the Biitish Association for the 

 Advancement of i^oience attheiiieetiug at Brighton last year; — 



I TAKE it as a good sign of the times that the sewage question 

 is engaging the attention of some of the first and most earnest, 

 minds in the country. Every individual in England is interested 

 in iL fromasanitary 2"oiut of view, and to householders of limited 

 means it is a question of vita] imporLance from a monetary point 

 of view. Our sewage mutit be effectually got rid of at whatever 

 cost. "We live by breathing as well as by eating and drinking, 

 and our sewage cannot any longer be allowed to pollute the air 

 we breathe and the water we drink, thereby increasing the 

 death-rate among the weakly and enervating tlie strong. If wc 

 can dispose of it at small cost, ratepayers will be charged low 

 rates ; if only at great cost, high rates ; and the difference be- 

 tween high rates and low rates is equivalent to the difference 

 between ease and anxiety, comfort and hardships, in thousands 

 of English homes. 



Bui I am not here to-day to enter into all the bearings of this 

 wide aud diflicuH question, but merely to state my views of the 

 value of " claritied " and '* unclaritied" sewage as manures, 

 and I contend that tlie vegetable physiologist and practical hor- 

 ticulturist should be able t*) throw some light on this branch of 

 the subject. I may. perliai>s, be permitted to state that I have 

 looked long and earnestly at this (piestion, both from the theo- 

 retical and practical point of view, and from numerous experi- 

 ments have arrived at the conclusion that sewage, when " clari- 

 fied," is a most valuable manure for porous or well-drained 

 soils, even when cultivated according to the recognised systems. 

 On the other hand I have no faith in the value of sewage of any 

 kind, or for any land, if used in an "unclarified" or sludgy 

 state, unless accompanied with a laborious and costly system of 

 cultivation. 



In order to show clearly the grounds of my preference for 

 ( larified over unclarified sewage, it would seem necessary to 

 advert briefly to the sources whence plants derive their food, 

 aud to the conditions favourable to the free use of this food. 

 Plants feed on the air through their leaves, aud on water 

 through their roots. Aud here it is important to bear in mind 

 that the roots of plants can no more absorb solids from the soil 

 than the leaves can absorb solids from the air; water and ^ases 

 are their food, thej^ cannot eat like animals, they live by breath- 

 ing and drinking. Whatever earthy or metallic compnunds 

 may be found in the ashe.sof plants after ineiueration must have 

 been introduced there in a state of solution, or have been manu- 

 factured within the plants tliemselves. " The water absorbed 

 by the roots contains matters held in solution ; thcbe are de- 

 posited in the plant, and remain there with about a third part 

 of the water, the rest escaping almost as pure as distilled water.'' 

 ~(De Candolle " Physiologio Veg^tale," tome I. p. 11 •.) Now our 

 best vegetable physiulogists are of opinion that carbuuie acid 

 enters tlie plant both in the water and the air ; the oxygen is 

 afterwards set free by the agency of solar light, the carbon re- 

 maining behind in a solid state. I need not enlarge on the 

 manner in which plants feed tiirough their leaves because, 

 practically speaking', wo cannot influence them through this 

 channel; in out-of-door culture at least we can only iufiueneo 

 them through their roots. To this end — 1st, we pub on or into 

 the soil such manures as wo judge likely, or have found liy ex- 

 }>erience, to promote the development of certain parts of plants ; 

 and '2nd, we keep the soil loose or open by ploughing, harrow- 

 ing, hoeing, digging, and the like, that the air and sun heat may 

 freely enter the soil and render these manures readily available. 

 This embraces the theory and practice of cultivatiou. 



Now, highly important as is> the use of appropriate, manures 

 to aid in the development of our growing crops, as a cultivator 

 I attach more importance than is commonly attached to the 

 physical conditions of the soil, especially to keeping the surface 

 loose aud the soil porous that the water may get away, and that 

 the air and s\ni heat may follow wherever L!ie water or clarified 

 sewage goes. The clarified sewage is food placed within reach 

 of the roots ; the presence of air renders this food more plentiful, 

 and tlie sun heat stimulates the roots to feed. The fertility of 

 the soil is, therefore, largely influenced by the amount of air aud 

 heat which it contains. This brings me to the principal oh- 

 jection which I liavo to urge against putting sewage on the land 



in an unclarified or sludgy state. I am free to admit that the 

 sewage clarifies in its passage downwards, presenting to the 

 roots the same food as if the sewage had been previously clari- 

 fied ; but the surface of the earth is thereby made to act as a filter, 

 and the physical conditions of the soil are altered. The un- 

 clarified sewage in jiassing through the soil has become clarified' 

 but the pores of the soil are more or less closed against the 

 passage of air, and a solid or half-liquid glutinous mass rests on 

 the surface of the earth, thi'owing back the sun heat. The food 

 is there, but the stimulants of air and sun heat are shut out or 

 greatly diminished, and the fertility of the soil is impaired in a 

 corresponding degree. Horticulturists know well the import- 

 ance of earth-heat, as many of their highest efforts depend on it. 

 The greatest authority on this subject (Lindley in the " Theory 

 of Horticulture," p. l-JOl, thus alludes to it: — 



"Itmayhenco be cou-^iderccl an axiom in horticulture that all plants re* 

 quire the tioil as well as the iitmoapheio iu which they grow to corre.spoiiil in 

 temperature with that of the countries in which thoy ai-e imtives. It has also 

 been already shown that the mean temperatuio of the soil should be above 

 that of the atraoyphore."' 

 Again (page loH) — 



" As scarcely any of our cultivated crops are natives of countries so cold a'i 

 our own, it is manifest that they all require to have the earth wormed for them, 

 or are much the better for it.'' 



The free access of air to the soil in which plants grow ia not less 

 important than that of heat. 



" The x-oots of plants. nntwith>stauding their underground position, are suh- 

 ject to the action of the iiii' which permeates the eai'th. We ha\ e lonr: known 

 tliat trees suffer if we inter the base of the stem in such manner as to ex- 

 clude the ail- from theh roots. The roots suffer more from contact with 

 stagnant water, even when rich in nutritive matters, than when in contact with 

 runnin;;; water, because the latter brink's them a constant supply of o\yj;en. 

 M. Th. de Saussure found that plants whose roots were placed in j,'as deprived 

 of free oxygen died at the end of a few days, whilst those placed in contact 

 with the atmosphere lived and prospered." — ('' Physiologic V( j^.tale,'' tome 1., 

 pages l;J6-7.) 



Many years ago I used unchu*ificd sewage extensively, aud 

 for a lengthened period. The lesults were not satisfactory until 

 I adopted the ^jractice of stirring the surface of the soil after 

 every application of the sewage. The results then exceeded my 

 expectations, but when estimated were not foimd equivalent to 

 the largely increased cost of labour. Afterwards the sewage was 

 clarified by the use of quicklime and used for a lengthened 

 period in this state ; this was jtidged better than the use of tin- 

 clarified sewage without labour, but not equal to its use witli 

 frequent hoeings. At present I have two large cesspools into 

 which the sewage is diverted aud allowed to settle, becomiu" 

 almost clear by subsidence, in which state it is freely used aud 

 found most valuable.* In conclusion, I would say that I am of 

 opiuion that the sludge iu sewage is valuable as a maiuire. Bnl 

 I object to its application to the surface of the soil in a semi-liquid 

 state. If so ai^plied the surface of the soil should be constantly 

 stirred and broken, which, of course, involves considerable ex- 

 pense. It then becomes a question whether it is not more 

 economical in separate the sludge, employing it as a solid ma- 

 nure or for other purposes, leaving a clarified liquid behind for 

 irrigation. 



VEGETATION AND GARDENING IN EGYPT. 



Ei.vn has no woods or thickets. It would hardly possess a 

 single tree without the care of man. From this dearth of wood 

 follow several obvious consequences, which may he worth noting. 

 First, all the houses of the lower class — that is, of the great 

 mass of the people of l-jgypt, must be built of crude, or sun- 

 dried luick. There is no wood for jiosts and planks, or to burn 

 brick for such folk as they. This obliges them to live iu houses 

 that are singularlj' mean; and, accordiug to our ideas, in- 

 sulficient for their p\u*pose. They can only have a ground-floor, 

 for no ceilings can be made without wood. Nor, for the same 

 reason, can they have any roofs, there is no wood for rafters. 

 Nor, if they could manage to get the rafters, would they be able 

 to get the fuel for burning the tiles. It follows tliat only a part 

 of what ought to be the roof can be covered-in, and that in the 

 rudest way, for protection against what Heaven may send in the 

 way of heat, or cold, or wet. This partial covering is very in- 

 effectual. It consists of a few Palm leaves, or of the stalks of 

 the Millet and Maize, laid horizontally from wall to wall ; upon 

 this Wheat and Barley straw is generally piled till it has been 

 consumed by the donkeys, and goats, and camels, and buffaloes. 

 Such is the rule ; a real serviceable roof being the exception. 

 These roofless ground-floors, which arc the house, must also be 

 flooiieas, for there is no wood either for flooring or for burning 

 floor-In-icks. Then the floor must be dust. This makes every 

 houbc a flea-preserve. 



A further consequence is, that within these floorless, roofless, 

 windowless, doorless mud enclosures there can be no such thing 

 as furniture— nothing to sit upon, nothing to stow imything 



■^ From esporimonta not completed when this paper was read, I found a 

 marked differeuce in GeraniumB watered with sewage claritied by simple sub- 

 sidence, and with eewage clarified by lime, iu every case iu favour of the 

 f jrmtr.— W. P. 



