198 
THE CULTIVATOR. 
JuNU 
1. Clover. 
2. Wheat. 
3. Oats. 
4. Beans. 
5. Peas. 
6. Carrots. 
7. Potatoes. 
8. Mangel Wurzel. 
9. Corn. 
10. Ruta-baga, 
11. Turneps. 
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The burned lime used, should be slaked by exposure 
to the air: when reduced to powder it will be partly in 
the state of hydrate and partly of carbonate of lime; as 
carbonic acid sufficient for the wants of plants exists in 
the soil and air, I propose that carbonates of lime, soda, 
and ammonia, should be tried with the sulphates, with 
a view to determine how much of the extra growth of 
the plants is due to the action of these substances, and 
how much to the sulphuric acid. By a comparison of 
the produce of the different patches of any one plant, 
we may be enabled to conclude whether gypsum acts 
chiefly by means of its lime, its sulphuric acid, or its 
power of fixing ammonia. 
A comparison of the produce of all the plants, will in¬ 
dicate whether gypsum acts differently on different 
plants growing under the same circumstances, and 
whether it is probable that other substances may be used 
with greater profit than gypsum, in certain localities. 
The advice of a professional chemist would be required 
as to the quantities of these substances to be used, and 
how they should be applied; it will be necessary, I ap¬ 
prehend, to consider what quantity of each would be re¬ 
quired to afford an equal quantity of sulphuric acid; 
what is the degree of solubility, and the tendency to form 
fresh compounds when in contact with the soil. 
A consideration of this subject, suggests another inte¬ 
resting inquiry, viz: how can gypsum be most advanta¬ 
geously applied to plants? One might have supposed 
that it would have been of little moment whether it was 
worked into the soil previous to sowing, orstrown on the 
plants early in the spring, or if there was any difference, 
it would be in favor of the former practice, as by that 
means the gypsum would be more thoroughly mixed 
with the soil, and be useful to the plants from the com¬ 
mencement of their growth. The experience of farmers, 
however, points to a different result, and seems to indicate 
a peculiarity of action not yet understood, and which, 
therefore, requires to be cleared up by experiment. 
Many have supposes that gypsum exercises the great¬ 
est influence when strown upon the plants in spring; 
some, indeed, consider that it increases the growth of 
plants in proportion to the length of time it remains on 
the leaves, and that if rain falls immediately after it is 
applied, it produces little or no effect. Cuthbert John¬ 
son says —“ he has noticed that the weather, at the time 
of spreading gypsum, has a very material influence on 
the result of the experiment. Its effects are never soon 
apparent when sown in dry weather, but if the season 
is damp, so that the powder adheres to the leaves and 
stalks, the effect is immediate.” This, he says, has been 
observed in England and the United States. It is also 
#aid to be a well known fact with the sanfoin growers of 
Berkshire, the clover cultivators of Surry and Kent, and 
to the growers of lucerne in Essex and Middlesex. 
In other instances, I find it has proved of great use to 
wheat, when strown on the plants in spring, and it is 
said to produce immense crops of peas, if applied when 
the plants are “ looking up.” At Well wood, in Ayr¬ 
shire, gypsum and salt were strown on a mixed crop of 
oats, beans, and peas, which, by some means had been 
much injured. The effect is described as like magic; the 
plants assumed a deeper color, and grew wonderfully. 
On the same farm, a similar dressing was applied to a 
portion of a crop of beans when coming into flower. 
The beans at the time were very weak, but they ultimate¬ 
ly became as good a crop as other portions to which ma¬ 
nure had been earlier applied. 
Again, it is said in British Husbandry, that gypsum 
never appears to produce better effects than when it has 
been laid upon red clover already so far grown as that 
the leaves nearly cover the soil, “ for there seems no 
doubt that it acts with the greatest force when it adheres 
to them, and that the longer it remains upon them the 
better.” 
These observations derive great support from a com¬ 
parative experiment made by Professor Korte, who 
found that gypsum applied to clover, at different peri¬ 
ods, produced the following results: 
Undressed, 100 lbs. 
Top-dressed the 80th of March, 132 lbs. 
“ “ 13th of April, 140 lbs. 
“ “ 27th of April, 156 lbs. 
Thus the benefit derived seems to have been in propor¬ 
tion to the extent of the foliage on which the powder 
could he spread. The plants most advanced in growth 
when the gypsum was applied, having, with the same 
materials, accomplished the most work in the least time. 
It is, doubtless, of importance to ascertain by further 
comparative experiments, whether gypsum is invariably 
most efficient when it remains some time on the leaves; 
and if so, what is the cause of this special influence. Does 
the gypsum act immediately on the plant, while in con¬ 
tact with the leaves, or does it acquire some property by 
being exposed to the air, which afterwards renders it 
more efficient when mixed with the soil? Gypsum, 
when spread on the floors of stables, is known to purify 
the air by abstracting ammonia, and it is not improbable 
that gypsum may, in like manner, attract ammonia from 
the atmosphere, when exposed thinly on the leaves of 
plants. It would in that case prove a more efficient ma¬ 
nure. If a small quantity only of ammonia exists in a 
soil, and if there were present, vegetable mould and other 
matters to prevent its escape, then gypsum would pro¬ 
bably act by means of its sulphuric acid and lime only; 
but if before entering the soil, the gypsum had abstracted 
a certain quantity of ammonia from the air, the soil 
would obviously become richer in this essential food of 
plants. But if this is not the reason why gypsum is 
more efficient when strown on the leaves of plants, is it 
probable that leaves have the power of disengaging and 
absorbing the sulphuric acid and water of the powdered 
gypsum? As sulphuric acid is an essential constituent 
of those plants to which gypsum is generally most use¬ 
ful, may not the presence of sulphuric acid in the plant, 
in a more concentrated form, and greater abundance 
