1851. 
THE CULTIVATOR. 
229 
Mixing Plaster and Manure. 
It has been recommended to mix plaster with animal 
or putrescent manures, for the purpose of preventing 
the waste of fertilizing substances. The theory is, that 
the sulphuric acid of the plaster unites with the ammo¬ 
nia of the manure, forming sulphate of ammonia—that 
the ammonia thus combined or fixed, is preserved from 
loss, and when applied to the soil, being soluble, is taken 
up as food to crops. 
This mode of using plaster, according to the testimony 
of those who have adopted it, has been decidedly bene¬ 
ficial in many cases. Of late, however, we have heard 
of some cases where the use of plaster appeared to pro¬ 
duce a very different effect from that above described. 
A writer in the Richmond Whig, with the signature of 
“ T. S. IV ; (supposed to he Thos. S. Pleasants, Esq., 
of Petersburgh, Va.,) states that he has recently taken 
some pains to “ investigate the matter,” and thinks he 
has obtained “ a number of important facts.” His in¬ 
vestigations related chiefly to mixing plaster with guano. 
He says— 
il The result was. that in nearly every case the action 
of guano was impaired by the addition of plaster, very 
much in proportion to the quantity of plaster employed. 
When mixed together in anything like equal propor¬ 
tions, the effect of the guano was entirely destroy¬ 
ed. In one or two instances, when plaster had been li¬ 
berally used with stable manure, the effect was equally 
injurious.” 
Now if these results have been produced'—results so 
different from those generally attributed to the use of 
plaster—it becomes important to understand the causes 
which have produced them. And to illustrate the sub¬ 
ject, it will be interesting and useful to refer to some ex¬ 
periments reported by Mr. Pusey,* in the Journal of 
the Royal Ag. Soc. for 1850. The following relates to 
some of his trials with gypsum: 
11 Ammonia was escaping largely from the litter of a 
farm-yard, as could be perceived by the common test 
of holding near the surface, paper dipped in spirits of 
salt, which turn sthe invisible fugitive into a white opaque 
steam of sal-ammonia. A whole bushel of gypsum was 
strewed over a few square feet of the yard. The test 
showed that the escape of ammonia was uncnred.” 
Mr. Pusey states also that he had used plaster in his 
stables, but they were not “ sweetened.” He thinks 
Boussingault has thrown light on this subject. 
‘ 1 He says that gypsum in solution, as in a laboratory 
experiment, does act as desired, but that in a state of 
moist powder , the gypsum is indifferent towards am¬ 
monia; nay more, that in that state the law of affinity 
is reversed, and that carbonate of lime, chalk, decom¬ 
poses sulphate of ammonia, actually unfixes it. To ex¬ 
plain this contradiction he quotes Berthollet and the 
following singular law. If two saline solutions, con¬ 
taining between them an insoluble salt, be mixed, that 
insoluble salt will be formed: but if two salts, contain¬ 
ing between them a volatile salt, he mixed in a moist 
pulverulent state, the volatile salt will be produced. 
Thus sulphate of lime and carbonate of ammonia in 
solution, produce carbonate of lime insoluble, leaving 
sulphate of ammonia, which is soluble though not vola¬ 
tile. But carbonate of lime mixed with sulphate of 
ammonia, in a state of moist powder, acting by an op¬ 
posite interchange, produce carbonate of ammonia, a 
volatile salt, and sulphate of lime. The following dia¬ 
grams will show at a glance the contrary changes. 
* “ Progress, of Agricultural Knowledge during the last Eight 
Years. By Ph. Pusey, M. P.” 
Solutions mixed. 
Sulphate of Lime ( Sul P huric acid -^Sulphate of Ammonia. 
G >'P sum .(Lime, 
Carbonate of Am-j Amrnoni ^' 
mou * a .( Carbonic acid___H_ Carbonate of Lime— 
Insoluble. 
Moistened Powders mixed , 
Carbonate oflime ( Carbonic acid -—.Carbonate of Ammo- 
-CHk.} Ume . ~ ™-toUu«e. 
Sulphate of Am- ( Ammonia- 
mouia.( Sulphuric Acid--.Sulphate of Lime. 
Mr. Pusey concludes, therefore, that gypsum must be 
in a state of solution to fix ammonia, and to bring it into 
solution, requires, he states, 500 times its own weight 
of water. It is stated by chemists, however, that gyp¬ 
sum may be dissolved in a much less amount of water, 
when mixed with chloride of ammonia; and the solu¬ 
bility of gypsum when mixed with manure, is probably 
increased by the ammonia which the manures contain. 
If this reasoning is correct, it seems to explain the causes 
of failure above alluded to. in regard to the mixture of 
gypsum with guano. From the want of sufficient mois¬ 
ture, the carbon of the guano united with the lime of 
the gypsum, and the sulphuric acid not uniting with the 
ammonia of the guano, the ammonia became volatile 
and escaped. 
The ammonia in guano has a great tendency to be¬ 
come volatile, when the guano is in a dry state, and 
hence, when it has been sown on the surface of the soil 
during very dry weather, there have been frequent com¬ 
plaints of its inefficiency. The escape of ammonia from 
stable or yard manures also takes place chiefly when the 
manure is dry. It is greatest when the manure heats 
or burns—'the carbon, with which the ammonia had been 
united being consumed and the ammonia set free. This 
loss might he greatly increased by mixing with the 
manures, while in a dry state, any substance which 
should render the ammonia more volatile. 
Irrigation in Switzerland. 
The following account of the mode of irrigation prac¬ 
tised in Switzerland, was communicated for the Journal 
of the Royal Agricultiiral Society , by Mr. Jenkinson, 
who collected the information in a personal visit to that 
country. 
The system of irrigation appears to have been prac¬ 
tised in Switzerland as early as the fourteenth century, 
and has doubtless been so extensively introduced owing 
to the dryness and rarity of the atmosphere; but on ac¬ 
count of the variety of the position of the various can¬ 
tons, there are some modifications in the management 
of water meadows. 
In the Canton of Aargau, which contains some of the 
best land in Switzerland, the meadows are irrigated with 
water alone, where the nature of the ground admits of 
its application. My informant, M. Jean Herzog of Aa- 
rau, told me that the water they apply possesses the 
most fertilizing qualities—that it is of a peculiarly soft 
nature—and that he has at times observed a kind of 
soapy or oily (savoneuse) substance floating over the 
meadows when they are in water. When the streams 
are increased by the melting of the winter snows, the 
water loses its efficacy, but when thickened with rain, 
their efficacy is increased. Also when the water is suf¬ 
fered to flow over too large an extent of land, its virtue 
is invariably diminished. M, Herzog also informed me 
