the Progress of Enc/JisJi Agriculture. ^21 = 561 
lonths than during- the periods of the active growth of plants, 
'he fertility of land, it may further be observed, is more readily 
napaired by the loss of nitrogen by drainage than by the removal 
1 that manner of those mineral matters which are food to 
lants. 
It follows from this, as a natural consequence, that much 
lore nitrogenous food must be applied to the land, and in good 
ractice is always used, than would be necessary to produce a 
iven increase in the crop, if all the nitrogen could be recovered 
lercin. 
Again : this investigation clearly shows that when nitrogenous 
rganic matters are applied to the land in the shape of farmyard- 
lanure, or of organic refuse matters, they suffer decomposition, 
nd arc gradually resolved into ammonia compounds, which are 
taincd by the soil for a limited period, and are finally oxidised 
ito nitrates. Farmyard-manure thus yields a more constant 
nd gradual supply of nitrogenous food than nitrate of soda, 
hich, unless consumed by the crop to which it is applied, is 
asted to a large extent by drainage. 
In accordance with the teachings of modern chemistry, the Farmyard- 
lost advanced farmers in England apply to the land farmyard- manure.wh^n 
lanure, fresh from the stables or cattle-sheds, if possible, in * 
atumn or winter. The manure then has ample time to become 
itten, and by degrees the nitrogenous constituents of the manure 
e transformed into nitrates, of which there will be a ready 
ipply in spring when vegetation makes a fresh start. 
Peruvian guano and similar ammoniacal manures, when used 
r winter-wheat, as a rule are applied in England in autumn 
ther before the wheat is sown, or after it is fairly above ground. 
the land is rather light, the best farmers prefer to top-dress Artificials, 
eir wheat with guano, soot, or other ammoniacal manures early 
spring. Probably the end of February, or beginning of 
arch, is the best time for the application of ammoniacal top- 
essings. 
Since the price of nitrate of soda has been so moderate as 
has been of late years, its consumption in England has greatly 
creased, and most English farmers are quite alive to the fact 
at nitrate of soda is not retained in the land for more than one Nitrate of soda 
owing season, and that it is liable to be washed out of it '^^{J^f'^^^^ 
rain. Speaking generally, nitrate of soda is applied in most season, 
irts of England towards the end of March as a top-dressing 
r wheat or barley, either by itself, or in conjunction with 
mmon salt for wheat, or in conjunction with superphosphate 
r barley and oats. 
With the remarkable increase of our knowledge, which has 
ken place since 1860, of the physiological and chemical effects 
