EXPERIMENTS ON THE MIXED HERBAGE OF PERMANENT MEADOW. 299 
As, in the ordinary practice of rotation on arable land, most of the constituents of the 
straw of wheat and barley, which are in the first instance removed from it, are in due 
course returned to it, the eventual loss of constituents to the land by the growth of 
such crops will be more nearly represented by the amounts in the grain alone, than by 
those in the total produce, corn and straw together. In the case of the hay crop the 
return of constituents is by no means so regular, and the figures show how very variable 
may be the amount of them in a given weight of the crop, according to the supply of 
them in the soil, or by manure. Thus, whilst there is more nitrogen in a given weight 
of the hay grown without manure than with farmyard manure, there is one-and-a-half 
time as much phosphoric acid, and more than one-and-three-quarters time as much 
potass, in the hay grown by farmyard manure than in that without manure. On the 
other hand, there is more lime, more magnesia, much more soda, and more sulphuric 
acid, but less silica, and much less chlorine, in a given weight of the unmanured than 
of the manured produce. In spite of these variations the mean of the two gives a 
composition agreeing very fairly in essential points with the average deduced by 
E. Wolff from the results of 39 ash-analyses by different experimenters. 
Assuming as the basis of comparison the mean composition of the manured and the 
unmanured hay, it is seen that a fairly good crop will remove about one-third more 
nitrogen than the grain of a fairly good crop of wheat or barley, and practically the 
same amount as the total produce, grain and straw together, of either of the corn 
crops. 
Of phosphoric acid, the hay crop will remove somewhat less than the grain alone, 
and only about two-thirds as much as the total produce of wheat or barley. 
Of potass, the assumed average hay crop will remove five or six times as much as 
the grain of either the wheat or the barley, and nearly twice as much as the total 
produce, corn and straw together. 
Of lime, soda, sulphuric acid, chlorine, and silica, the hay will remove many times 
more, and of magnesia much more, than either the wheat or the barley grain. Of 
lime, soda, sulphuric acid, and chlorine, the hay will also remove much more, and 
of magnesia more, than both corn and straw together. Of phosphoric acid and silica 
alone, will the total produce of the corn crops remove more than the hay crop. 
To sum up the most important points: it is quite obvious that, in the soil in 
question, which it should be remembered is a loam with a clay subsoil, the effect 
of the application of a complex manure such as dung, supplying as it doubtless does 
much more of all the mineral constituents than the crop takes up, is in a striking 
degree to increase the assimilation of potass ; notably also that of phosphoric acid, 
and to some degree that of silica; much more chlorine was also taken up. In fact, 
as will be shown further on, the supply by manure of potass has a more marked effect 
on the quantity, and on the botanical and the chemical character, of the herbage of 
the hay crop, than that of any other of the mineral, or ash-constituents. If these few 
illustrations relating to the composition of the crop be borne in mind, the results 
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