on Permanent Meadoio Land. 563 



mixed mineral manure gave more than three times as much 

 increase as the ammoniacal salts alone, and four times as much 

 as the mineral manure alone. The average annual produce, 

 by the mixture of the ammoniacal salts and mineral manure, 

 amounted in fact to within less than a hundredweight of 3 tons 

 of hay per acre, by the side of 1 ton 4 cwts. per acre on the 

 continuously unmanured land. 



Now, this produce, by the mixed mineral manure and ammo- 

 niacal salts (Plot 10), consisted almost exclusively of Grami- 

 naceous plants. There was scarcely a clover, or any other 

 Leguminous plant, to be found upon the plot. The action of the 

 mineral manures, in this conjunction with ammoniacal salts, was 

 not therefore to yield increase by aiding the development of 

 Leguminous plants, as was the case when the same mineral 

 manures were used alone. The mineral manure has now acted 

 by supplying, within the reach of the plants, a sufficiency of 

 certain mineral constituents, to enable the Graminaceous plants to 

 appropriate, and turn to the account of growth, a much larger 

 portion of the artificially supplied nitrogen than they could do 

 when the ammoniacal salts were used alone. In fact, there were 

 1 ton 4^ cwts. per acre per annum more Graminaceous hay 

 grown when the artificial supply of nitrogen was accompanied by 

 a liberal artificial supply of certain mineral constituents, than 

 when it was not so accompanied. 



It has been shown that the mineral manures had little or no 

 effect in increasing the assimilation of nitrogen by the Meadow 

 Grasses, when that constituent teas not artificially supplied. On 

 the other hand, they very considerably aided that assimilation, 

 when available nitrogen was artificially supplied. It has also 

 been shown that the addition to the mixed mineral and nitro- 

 genous manure of a large quantity of sawdust — a substance rich 

 in carbon — did not further increase the produce. In fact, neither 

 did the sawdust (whether alone or in admixture) seem to aid the 

 solution of mineral constituents by the evolution of carbonic 

 acid ; nor did this possible source to the plant of carbonic acid 

 itself seem to have been of any avail. The addition to the 

 mixed mineral and ammoniacal manure, of an equal weight of 

 cut wheat-straw instead of sawdust (Plot 12), was equally without 

 effect with that of the latter substance. Indeed, notwithstanding 

 the large amount of mineral constituents, and especially of sili- 

 cious compounds, contained in the cut wheat-straw, as compared 

 with the sawdust, there was, whether compared with the produce 

 by the mixed mineral and nitrogenous manure, or with that by 

 the mixed mineral and nitrogenous manure and sawdust, an 

 average annual deficit of 4 to 5 cwts. of first-crop hay, where 

 the cut wheat-straw was employed. The plot with the cut wheat- 



