370 
MESSRS. J. B. LAWES AND J. H. GILBERT ON THE RESULTS OF 
farmyard-manure plot, especially in the later years, has not been very strikingly 
different ; and the difference may, for our present purpose, be summed up in the 
statement that there was, on the manured plot, a higher percentage, and a considerably 
larger quantity per acre, of gramineous herbage ; a considerably lo tver percentage, and 
a smaller amount per acre, of leguminous herbage ; and lastly, a rather lower percentage, 
but a somewhat larger actual amount, of miscellaneous herbage. 
With the greater proportion of gramineous and less of leguminous herbage in the 
produce by the farmyard-manure, there was a considerably lower, and a decreasing, 
percentage of nitrogen in it; but there was a higher percentage of total mineral matter. 
Of lime, magnesia, soda, and sulphuric acid, there was more, and of potass, phosphoric 
acid, chlorine, and silica, very much more, removed per acre from the farmyard-manured 
than from the continuously unmanured plot. The percentages of lime, magnesia, soda, 
and sulphuric acid, were, however, all lower in the dry substance of the produce by 
the farmyard manure ; but those of potass, phosphoric acid, chlorine, and silica, were 
not only in very much larger actual amount, but in higher percentage in the produce 
of the manured plot; and (excepting chlorine) this was so even in the later years. It 
is clear, therefore, that there was a greater or less available residue of all the mineral 
constituents, and more especially of potass, phosphoric acid, and silica, many years after 
the cessation of the application of the manure. 
It is obviously a matter of very great interest to consider at what rate, and in what 
proportion, the several constituents of the farmyard manure which were not recovered 
during the years of the application, have been so since, and what prospect there is of 
their final total recovery ? These are questions which will be considered more in detail 
in the chemical section of our report, but a few general observations on the subject 
seem to be called for in this place, to enable us to form any just conception of the 
character of the agricultural results. 
We have sufficient analytical data on which to found a pretty correct estimate of 
the amounts of nitrogen, and of the several mineral constituents, removed in the crops 
during the separate periods; but we have not any such sure basis for the estimation 
of the amount of the same constituents contained in the 112 tons of farmyard manure 
applied per acre to the plot during the eight years. We are obliged, therefore, to 
adopt the best estimate we can of the constituents supplied in the manure, founded 
on much data, both synthetic and analytic, relating to the subject, and a careful con¬ 
sideration of them. The result must obviously be only approximative, but it is doubt¬ 
less sufficiently so to give considerable value and importance to its general indications. 
Of nitrogen, it is estimated that the farmyard manure will, on the average, contain 
0‘64 per cent., and therefore that 200‘7 lbs. were applied per acre per annum ; or, in all, 
1606 lbs. in the eight years. The total produce removed, during the eight years of the 
application, about 29 per cent, as much nitrogen as is thus estimated to be supplied in the 
manure. During the next six years about 20 per cent., and during the last six of the 
20 years about 10 per cent, more, were removed, making in all about 59 per cent. 
