THE FARMER'S MAGAZINE. 



229 



annum. According to the amount (320 acres) now laid 

 down in Edinboro', in proportion to its population, 

 4,500 acres bears the same proportion to London, and 

 a high value doubtless would be obtained for the produce. 

 If the six thousand acres are considered at the average 

 returns over cost of production, which have been given, 

 namely £20 per acre, we have a return of £120,000 per 

 annum for an outlay of £90,000 upon the land, and it 

 would not be difficult to extend the pipes lower down to 

 take in the other G,000 acres of land to exhaust the 

 whole sewage of London. All such lands as are below 

 the end of the main sewer would discharge the liquid 

 drained from the farms into the Thames, only keeping 

 it, as before stated, in pipes. 



It will thus be evident that the greater value of 

 keeping the whole upon as small a surface as possible 

 is plain, and that, by what I have stated, an amount of 

 land which will be sufficient for the purpose will be ob- 

 tainable without difficulty. There are upon the district 

 in question two men, who alone hold — one 1,200 acres, 

 the other 800. 



To come back to the question. It has been thought 

 that a poor and sandy soil would be the best suited for 

 the purpose. I have said that, comparativelij , the value 

 of sandy land may be increased more than good land. 

 Poor sandy soil, worth before but little, may be so im- 

 proved by it as to be worth a considerable price ; but 

 the profits per acre I believe will be much greater with 

 good soils containing a sufficient amount of alluvial 

 matter to retain the ammonia and other fertilizers in the 

 liquid. It has been said that it has not been found to 

 answer to use the liquid-manure of the farm upon the 

 soil at Cirencester College, which is clay land. Now 

 that, very possibly, is explained by Dr. Voelcker, in the 

 last volume of the Royal Agricultural Society's Journal, 

 where he says, in reference to the oxide of iron in the 

 soil from Cirencester : " May not the oxide of iron, 

 dissolved in considerable quantities from some soils 

 through the agency of liquid-manure, be injurious to 

 vegetation; and partly account for the failure that is 

 experienced with liquid-manures on some soils?" 

 Whether this be the reason or not, and if there be any 

 connection between irrigation upon Italian rye-grass 

 and other grasses, the evidence of iVIr. Dickinson (who 

 used it for fourteen years upon a stiff clay soil at Willes- 

 den) is in favour of clay soils. Moreover, he received a 

 great number of reports from gentlemen who had irrigated 

 Italian rye-grass upon various soils, and, from due con- 

 sideration of their opinions, he places " clay upon clay," 

 and " clay upon gravel," at the top of his list; placing 

 loams next; and, lastly, sandy and poor lands, low down 

 in the scale of soils adapted to irrigation. But what is 

 more to the purpose is, that the oldest portion of the 

 Edinburgh meadows for sewage is " hard clay." The 

 difference is not always considered between arable 

 clay land and grass clay land in this question. There 

 is doubtless a very good objection to irrigating arable 

 clay lands that require operations to be carried on upon 

 them. From direct experiment it has been ascertained 

 ttiat clays and fertile soils take up much more ammonia, 

 phosphate, potash, &c., from the liquid-manure than 

 sandy soils do. The late experiments by Dr. Voelcker 

 (detailed in the last number of the Royal Agricultural 

 Society's Journal) are very interesting. As some other 

 points will show themselves, from these I will give a few 

 prominent facts, referring the reader, for the further de- 

 tail of the experiments, to the Journal. 



Dr. Voelcker took a sample of liquid-manure, which 

 he applied to four samples of various sorts ; he also took 

 a sample of liquid-manure sent to him by Mr. Mechi, 

 and applied it to a sample of Mr. Mechi's soil. The 

 first-mentioned liquid-manure contained, in an imperial 

 gallon, .35.58 grains, besides phosphoric acid, potash , &c., 



in certain quantities which I need not here detail. The 

 soils, in the proportion of 2,000 to 7,000 grains of 

 liquid, were mixed, left standing for periods of from 

 one to three days, separated, and the liquid again 

 analyzed, and the amount of various ingredients nitained 

 in the soil registered. The treatment of the liquid by 

 the various soils is very different, and very interesting ; 

 but with regard to ammonia, and nearly also in respect to 

 potash and phosphoric acid, those containing the most 

 clay took up the most out of the liquid. The following 

 table will show the proportion with respect to ammonia : 



Grains. Grains. 

 Ammonia in one gallon of liquid-manure, 



provided by Dr. Voelcker 35.58 



Calcareous stiff clay soil (clay 52, aaud 24 per 



100) takes up from the above 14.77 



Clay pasture-land (clay 48, sand 36 per 100) 



takes up from the above 14.75 



Fertile loam (clay 18, saud 76 per 100) takes 



up from the above -- ... 9.74 



Poor sandy soil (clay 4-5,|sand 89.6 per 100) 



takes up from the above -- ... 2.43 



Ammonia in one gallon of liquid-manure, 



provided by Mr. Mechi 3.36 



Mr. Mechi's very stiff clay soil ; clay 76, saud 10 

 per 100, takes up from the liquid-manure 

 provided by Mr. Mechi 1.81 



Potash and phosphoric acid are also taken up in part 

 by the soils, while part passes off in the liquid ; but 

 generally the clays have taken up more than the lighter 

 soils of both of these. 



Dr. Voelcker says : " It will be noticed that none of 

 the four soils used in the experiments had the power of 

 absorbing completely the whole of the ammonia, potash, 

 or phosphoric acid contained in the liquid." I may, 

 however, here draw attention to the fact that a little less 

 than half the ammonia — about 3-7ths— has been taken 

 up by the clay soils of Cirencester, and with Mr. 

 Mechi's clay soil, with a solution very much weaker ; so 

 that there is only 1-lOth of the ammonia in a gallon 

 which there is contained in the other mixture. One- 

 half, or rather a little more than one-half, namely 1.81 

 grain out of 3.36 grains, has been retained in the soil, 

 the rest passing off in the liquid. 



It would I think be an interesting question to solve 

 what, in the use of large amounts of liquids in contact 

 with soils, can be expected to be retained of the manure 

 in those liquids; what the proportion of ammonia, &c., 

 which is retained in the soil in the case of Edinburgh 

 or Milan, by analysis of the liquid pussed off as well as 

 passed on to the land. Or would the vegetation on the 

 ground produce a difTerent effect to that produced by 

 the plain soils unmixed with herbs in Dr. Voelcker's 

 experiments.' It is singular, too, that the money-value 

 of the crops taken off fields largely irrigated, to which 

 I first alluded, were also half of the money-value of the 

 ammonia, &c , in the liquids passed through the land. 



From these experiments I think it will be seen, if the 

 land is so underdrained that the liquid readily percolates 

 that from good soils, we shall get more than from poor 

 sandy soils ; and receive what we gain upon a more con- 

 centrated area. 



It has been said that there is little value in sewage ; 

 that it is not much better than an equal amount of 

 water. Now, this is true in respect to market-gardening 

 and arable land crops ; but is it true in respect to grass- 

 land ? It is said that in these large dosings of sewage 

 for grass we should gain our advantage from the loater ,- 

 that water alone is known to produce upon some grass- 

 lands very great eftects, but that it depends upon the 

 land suiting the water, or the water suiting the land. 

 OT do we know that land can take up in an available 



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