566 Report of Experiments with different Manures 



raging that of the Graminaceous plants, or Grasses. The increase 

 of action when the mineral constituents were added to the nitrogen 

 in the form of the nitrate, was, therefore, as in the case of their 

 addition to the ammoniacal salts, not to be attributed to their 

 enabling Graminaceous plants to take up more nitrogen from 

 natural or unaided sources, but to their supplying, within a 

 limited range of the soil, the mineral constituents requisite for 

 the efficient action upon the collective and assimilative processes 

 of the plants, of the nitrogen artificially supplied. It will be 

 shown, on a future occasion, that the percentage of nitrogen in the 

 dry substance of the hay, grown both by ammoniacal salts alone, 

 and by nitrate of soda alone, was comparatively very high — in 

 fact, considerably higher than when the mineral manures were 

 also employed, whereby the Graminaceous produce was much 

 increased. So far then as there was an excessive amount of 

 nitrogen, in the form of elaborated nitrogenous vegetable com- 

 pounds, where the supplied nitrogen was liberal — the mineral 

 constituents in defect — and the growth restricted thereby — it was 

 that there was a relative deficiency in the formation of the non- 

 nitrogenous vegetable substances. 



Attention has now been called to the annual amount of hay 

 obtained both without manure, and by the use of certain indi- 

 vidual, or classified constituents of manure. In this way, some 

 information has been acquired as to the manurial requirements 

 for the growth of a heavy produce of the crop in question. Let 

 us now examine — what were the effects upon the hay crop of that 

 complex substance — Farmyard manure ? And, bearing in mind 

 the facts already brought to view, in regard to the action of certain 

 individual inanures, let us endeavour to form a judgment as to 

 which of the constituents, or classes of constituents, of farmyard 

 manure, its effects upon the hay crop are mainly, or at any rate 

 characteristically, due. 



The annual application of 14 tons of farmyard manure per 

 acre, gave, over the three years, an average annual produce of 2 

 tons \ cwt. of hay, = 16j cwts. per acre per annum more than 

 the unmanured plot. Tliis increase by farmyard manure is 

 greater than that by either the mixed mineral manure alone, or 

 the ammoniacal salts alone ; but it is less than half tlie increase 

 obtained when these two descriptions of manure were used con- 

 jointly. This increase of 16^ cwts. of hay per annum, by the use 

 of 14 tons of dung is, it will be seen, little more than 1 cwt. of 

 hay for every ton of the manure employed. 



It has been seen that carbonaceous substance, whether applied 

 in the form of sawdust or of cut wheat-straw, had little or no 

 effect upon the hay crop. It is probable that the carbonaceous 

 substance of the dung would yield up its carbon in the form of 



