1836.] 



FARMERS' REGISTER, 



587 



causes an evaporation, by which the bulk of the 

 manure is much diminished, yet its power is 

 thought to be thus increased. This apparent di- 

 minution in bulk has indeed been too much insisted 

 on by the opponents of rotten dun";, as proof of its 

 decrease in value; for, although the size of the 

 heap thus evidently becomes smaller, yet its cubi- 

 cal contents are, by its condensation, increased in 

 weight.* Alter about six weeks it assumes a 

 saponaceous, greasy appearance, in which soli 

 and sappy state, when neither fresh nor too rotten, 

 but in the medium between those states, it is gen- 

 erally applied to the land by the best farmers. 

 When very rotten, its effect is more immediate 

 and powerful; but when only moderately rotted, its 

 effect, though more gradual, is found to be more 

 durable. 



On this subject of evaporation, which has justly 

 engaged so much of the attention of scientific ag- 

 riculturists, we, however, add the following ex- 

 tracts from the work of Von Thaer, whose prac- 

 tical knowledge cannot be too highly appreciated. 

 He savs, that not only does theory teach us, but 

 during his own experience he has had frequent oc- 

 casion to observe, that it is hurtful to remove farm- 

 yard manure while it is in a high degree of fer- 

 mentation; for, according to all appearance, an es- 

 sential portion of the most active substances of 

 which it is composed are evaporated when exposed 

 to the air while that process is going on. But, be- 

 fore the fermentation has arrived at its height, or 

 after it has passed, the dang does not seem to lose 

 anything by exposure to the air; or, at least, no- 

 thing but what it regains by some other means. 



That an evident advantage attends the spread- 

 ing of fresh strawy dung upon the surface of the 

 soil during ihe winter, and leaving it there in that 

 state until the spring ploughing (it being, at the 

 same time, well understood that no declivity of 

 the land allows of its being washed away by the 

 rain) — for this method of covering the ground oc- 

 casions it to absorb the juices of the dung, and 

 thus renders it not only friable to work, but ex- 

 tremely productive: so much so, that the straw has 

 been afterwards raked off the land at the close of 

 the season, and yet the soil has appeared as much 

 improved, as that in which the whole of the litter 

 had been buried — an effect which is also apparent 

 in meadow ground which has been similarly treat- 



* The weights of putrescent manures will depend 

 much upon the progress of their decomposition at the 

 time, as well as the proportion of moisture which, from 

 accident or particular treatment, they may contain. 

 From an experiment on the subject, recorded in the 

 Farmer's Magazine, we learn that the comparative 

 weight of the following substances was as follows: — 



cwt. or. lbs. 



One cubical yard of garden-mould 10 3 25 



Ditto of water 15 7 



Ditto of a compost of earth, weeds, lii 

 and dung, that had lain nine months, ami 



been turned over 14 5 



if new dung 9 3 IS 



Ditto of leaves and sea-weeds 9 7 



Thus a cubic yard of water is to that of newdungnear- 

 ly as 3 to 2.— vol. xiv. p. 162. Von Thaer calculates 

 the weight of a cubic foot of any strawy farm -yard 

 manure at only about 4G lbs.; while one which has been 

 partly decomposed will weigh from 56 to upwards of 

 60 Pas. without being compressed. Pnneipes Rahon- 

 nes d'Jgriculturc, torn. ii. p. 32S. 



ed. Not alone has this occurred in many such in- 

 stances; but in others, in which both long and 

 short dung have been spread upon land already 

 sown with tares and peas, and though left there 

 during vegetation, have produced the most bene- 

 ficial effect upon the crops, especially when sown 

 late, and applied to ordinary land of a light and 

 warm nature; but what appears more extraordina- 

 ry, and difficult to explain — the land which has 

 been thus managed has evinced a decided superi- 

 ority in the subsequent crops over ground on which 

 even a larger quantity of dung had been regularly 

 [ loughed in. 



That, as one proof of this, in the spring of 1808, 

 rape was sown along with clover upon a poor soil, 

 and was afterwards covered with fresh dang: in 

 the autumn of 1809, the clover-ley was broken up, 

 and rye was sown; the crop of which in the fol- 

 lowing year was distinguished by its superiority 

 over that of an adjoining field which had been 

 dunged upon a summer fallow. Indeed, after a 

 number of comparative experiments, made by 

 himself as well as by other farmers, it appeared to 

 him beyond all question— however incredible it 

 may seem to those who have not also tried its ef- 

 fects—that dung which has already passed the ex- 

 treme point of fermentation, not only loses nothing 

 by being exposed upon the land, even during the 

 summer, but even gains. The evaporation may, 

 indeed, be not so great as it is generally supposed; 

 for although it is true, that when the clung is 

 carted out and spread, it then effects the air with 

 a strong musky smell, yet there is no mode of 

 avoiding that; and even if there were, the vapor 

 which is thus diffused is so tenuous, light, and ex- 

 pansive, that doubts may be entertained whether 

 the quantity of sap which is thus evaporated can 

 be very considerable, as, after a short period, the 

 dung does not exhale any odor. According to the 

 experience of M. Thaer, a docs not lose in weight; 

 and he remarks, that, if laid during a few weeks 

 upon a summer fallow, a number of young plants 

 of a very vivid green will be seen to spring up, 

 even upon spots which have not. come into contact 

 with the dung; which proves that its fertilizing 

 properties were spread around, even before it had 

 been buried in the soil* 



We have thus entered at large into this discus- 

 sion, because we consider it important to throw 

 every light upon the subject of which it may be 

 susceptible; and it besides contains some strong 

 reasons for the application of long dung. 



There are, however, many fanners who persist 

 in the use of* over-year muck, or that which has 

 been kept perhaps a twelvemonth, or more, until 

 it is completely reduced to a palp, in which state it 

 is very commonly applied io turnips. It thus loses 



*Principes Raisonnes d'Agriculture, torn. ii. p. 315, 

 §600. It is difficult to ascertain the precise degree of 

 evaporation arising from fresh dung; but, by an ex- 

 periment made by the Rev. St. John Priest, Secretary 

 to the Norfolk Agricultural Socii ty, in the presence of 

 Mr. Curwen, of Workington, it was found that steam 

 was evaporat id by a piece of ; Id under 



a laro-e glass during a quarter of an hour, in the month 

 of October, at the rate of about 1 A cwt. per acre. Sur- 

 vey of Buckinghamshire^. 274. 



This indeed, appears a large amount within that 

 soace of time; but, bad the i been longer 



continued, it would have been much diminished, and 

 would, no doubt, in a short time, have entirely ceased. 



