704 WHEAT. 
From this table we may learn that the straw and chaff | 
of a given amount of crop (on the average of this year) 
remove from the soil together very little more than 
half the phosphoric acid contained in the grain—at 
the same time, however, requiring twice as much 
potash. The quantity of silica removed in the 
whole produce is very considerable, 2 cwt. of this 
substance being required for a very moderate crop. 
The addition of silicate of potash to the land must be 
tolerably liberal if itis wished to supply by its means 
the silica required for the wheat crop. A compari- 
son of columns 3 and’4 will show us that, weight for 
weight, wheat chaff contains three times as much 
silica and phosphoric acid as the straw; and although, 
from the quantity of mineral matter it contains, and 
the woody nature of its vegetable substance, it may 
not be so nutritious a food for animals as the straw, 
the manure into which it is converted must be re- 
garded as much more valuable than that produced 
from the latter. 
‘¢ We may fairly conclude that, in round numbers, 
an average crop of wheat would remove from the 
soil in the grain, straw, and chaff per acre, 
84 lbs. 
20 lbs. 
4 lbs. 
of silica. 
of phosphoric acid. 
of sulphuric acid. 
8 lbs. of lime. 
6 lbs. of magnesia. 
1 lb. peroxide of iron. 
23 lbs. of potash. 
13 Ib. of soda. 
Of these substances three may be considered as non- 
essentials: these are, the lime, the peroxide of iron, 
| and the soda, all of which, if the plant requires 
them, it may readily obtain from almost any soil. 
To supply the other ingredients in the form of ma. 
nure of mineral composition alone, we must employ 
an alkaline silicate, phosphate of lime, and a salt of 
magnesia. The silicates of potash and of soda, as 
they are manufactured for agricultural purposes, are 
compounds of very varying constitution. Of silicate 
of potash, the average amount required for the sup- 
| ply of 84 Ibs. of silica would probably be about 2 or 
2} ewts. It is plain that the quantity of potash re- 
quired by the crop is small when compared with that 
which would be added in the requisite dose of sili- 
cate of potash. We would therefore recommend 
silicate of soda as a more economical method of sup- 
plying this mineral ingredient of plants. The potash 
must then be applied in another form. The total 
phosphoric acid of the wheat crop would be furnished 
in 8 ewt. or 1 cwt. of unburnt bones; the magnesia 
by 40 lbs. of sulphate of magnesia (Epsom salts ;) 
and the potash by about 35 lbs. of carbonate (pearl- 
ash,) or 50 lbs. of nitrate (saltpetre;) but this last 
| addition will be unnecessary if silicate of potash be 
employed: the necessary top-dressings will then be — 
24 ewt. silicate of potash, 
1 ewt. of crushed bones, 
40 lbs. sulphate of magnesia. 
Taking into consideration, however, the very gra- 
dual solution of the phosphate of lime of bones, it 
| would no doubt be better to adopt another form of 
top-dressing for wheat. The following would per- 
haps be a better application :— 
2 ewt. of silicate of soda, 
1 ewt. of bones dissolved in 
4. ewt. of oil of vitriol, 
40 lbs. of sulphate of magnesia, and 
35 lbs. of carbonate of potash. 
The bones should be dissolved in the acid previously 
diluted with an equal measure of water: when they 
become thoroughly broken down, the sulphate of 
magnesia and carbonate of potash should be added, 
WHEAT-FLY. 
and the whole well stirred and left at rest for twenty- 
four hours. At the end of this time the mixture 
would in all probability be found sufficiently dry, 
when broken. up, to be distributed by the hand; it 
might otherwise be mixed with ashes or mould, in 
order to attain the proper condition. We have al- 
ready remarked, that of the total silica required by 
the wheat, three-fourths belong to the straw, the 
remainder being found in the chaff and grain. On 
the other hand, by far the largest proportion of 
phosphoric acid is appropriated by the grain. Rea- 
soning upon these facts, we should endeavour, as far 
as possible, to supply the several ingredients at the 
time when they are wanted. ‘Two-thirds of the sili- 
cate of soda and one-third of the prepared top-dress- 
ing might be applied to the young plant very early 
in the spring; the remainder of both should be re- 
served and applied as late as practicable, in order 
that they may be at the command of the plant as the 
ear fills and the straw and chaff strengthen. In many 
soils, such as stiff clays, and in all localities where 
the soil is formed from granitic or other primary 
rocks, the addition of silicates will be an unneces- 
sary outlay of money; but the other mixture is com- 
paratively inexpensive, and would always more than 
remunerate the farmer, if not in the wheat, &t least 
at some other period of the rotation. The advan- 
tage of the method of application here proposed 
mainly consists in the use of soluble phosphates, such 
as those of potash and magnesia, which are produced 
when the materials before mentioned are mixed to- 
gether; for this purpose, however, the employment 
of sulphuric acid to dissolve the bones is indispensa- 
ble. It is quite probable that such a top-dressing, 
from its solubility and tendency to absorb moisture, 
would take effect when the season is too dry to allow 
of other applications being made with advantage. But 
the same solubility will cause its earlier removal 
from the land by rains and drainage, unless the pre- 
caution be taken of applying it at intervals, as we 
have suggested.” See the articles Flour, STarcu, 
Breap, GLUTEN, GRAIN, and STRAW. 
Sinclair’s Hortus Gramineus Woburnensis.—Lou- 
don’s Hortus Britannicus.—Host’s Icones et Descrip- 
tiones Graminum Austriacorum.—Lawson’s Agricul- 
turist’s Manual.— Catalogue of the Highland Society’s 
Museum.—Parmentier’s Traité sur La Culture des 
Grains.—Von Thaer’s Principes Raisonnes d’ Agri- 
culture.—Low’s Elements of Agriculture. — Buel’s 
Farmer’s Instructor.—Baxter’s Library of Agricul- 
ture.—Brown’s Treatise on Rural Affairs.—Trans- 
actions of the Bath and West of England Society.— 
Communications to the Board of Agriculture.—Mar- 
shall’s County Reports.—Farmer’s Magazine.— Quar- 
terly Journal of Agriculture.—Transactions of the 
Highland Society. —Journal of the Royal Agricultural 
Society of England.—Useful Knowledge Society’s 
Farmer’s Series.—Arthur Young’s Works.—Museum | 
Rusticum.—Mill’s Husbandry.—Dickson’s Husban- | 
dry of the Ancients. —Magazine of Natural History.— | 
Boussingault’s Rural Economy.—Sir John Sinclair’s | 
General Report of Scotland.— Burroughs on the 
Cultivation of White Crops.—Blathie on Mildew — 
Liebig’s Chemistry of Agriculture. — Rev. Edwin 
Sidney’s Blights of the Wheat.—Johnston’s Lectures 
on Agricultural Chemistryx—Rham’s Dictionary of 
the Farm. 
WHEAT-FLY. Any one of several insects 
which feed on wheat. The chief is the Cecido- 
mya tritici, popularly called the wheat-fly par 
excellence, or the wheat-midge ; another of some 
interest is the Oecidomyia destructor, popularly 
called the Hessian fly or the American io | 
midge; and a third is the Chlorops pumilionis, 
Fc 
