on Permanent Meadow Land. 567 



carbonic acid, or of other products of decomposition, more readily 

 than that of either of the substances just mentioned. But the 

 farmyard manure contained, besides carbonaceous substance, a 

 large amount of both mineral constituents, and of ammonia, or 

 nitrogen in some form. It has been seen, too, that these latter 

 substances, when used without carbonaceous matter, gave greatly 

 increased crops of hay. Under these circumstances, we can 

 hardly hesitate to attribute the main effects of the farmyard 

 manure upon the hay crop, rather to the conjoint action of its 

 mineral and nitrogenous constituents than to its enormous bulk of 

 carbonaceous substance. 



That the mineral constituents of the dung had their share of 

 effect, would appear from the fact, that the Leguminous herbage 

 was moderately luxuriant on the dung plot, and that those of the 

 Grasses were the most developed which were increased in their 

 proportion to the rest by the artificial mineral manures. And 

 again, that the nitrogen also of the dung was effective, may be 

 judged, not only from the general development of the Grami- 

 naceous plants under its use, but from the fact of a like fullness 

 in the proportion of the Grasses in jiowering and seeding stem, as 

 where ammoniacal salts were employed in conjunction with the 

 mixed mineral manure. It would appear, however, that a much 

 less proportion of the whole nitrogen supplied to the land was 

 active, when it was provided in the form of farmyard manure, 

 than when in that of ammoniacal salts. There would, in fact, be 

 considerably more of nitrogen applied per acre in the 14 tons of 

 farmyard manure, than in the 400 lbs. of the mixed ammoniacal 

 salts. Nevertheless, the encouragement of the Leguminous plants 

 was much greater, and that of the Graminaceous ones much less, 

 where the farmyard manure was employed, than where the 

 400 lbs of ammoniacal salts, together with the mixed mineral 

 manure, were used. 



That the less produce by the farmyard manure, than by the 

 mixed mineral manure and 400 lbs. of ammoniacal salts, was due 

 to a deficiency of available nitrogen, notwithstanding the large 

 actual amount of it in the dung, would appear from the fact, that 

 on the employment of 200 lbs. of ammoniacal salts in addition to 

 the farmyard manure (Plot 17), there was a further average 

 annual increase of 8f cwts, of hay per acre. Still, even with this 

 addition, there was about ^ a ton less of hay annually than where 

 the " mixed mineral manure" and the 400 lbs. of ammoniacal salts 

 were applied. 



The evidence regarding the action of the farmyard manure 

 goes to show, that, though it is doubtless a very complete and 

 important restorer of both the mineral constituents and the 

 nitrogen required to repair the exhaustion of this most greedy 



