On the GroivtJi of Barley hy diffcreid Manures.^ ^-c. 517 



removed no silica. So that, besides the excess of other mineral 

 constituents, there was an accumulation durins: 10 years of avail- 

 able silica. Yet with all this unusual accumulation of the 

 necessary mineral constituents, the residue of nitrogen unre- 

 covered in the increase of turnip crop — amounting as it did in 

 some cases to more than the largest dressing we ever applied in 

 one year to a corn crop — gave us, where there was the largest 

 amount thus unrecovered, during 3 successive years of barley, an 

 average annual increase of only 5f bushels of corn, and between 

 oOO and 400 lbs. of straw, per acre. On the other hand, the 

 addition of fresh nitrogen, in the form of salts of ammonia and 

 nitrate of soda respectively, gave at once an increase of 33 and 35 

 bushels of corn, and 4903 and 5531 lbs. of straw. And although 

 the addition of the fresh nitrogen in the form of ammoniacal 

 salts yielded an increase of 33 bushels of corn and 4903 lbs. of 

 straw, which together would contain only about half the nitrogen 

 supplied in the manure, yet the remaining half, notwithstanding 

 the still enormous excess of previously supplied mineral consti- 

 tuents, gave in the succeeding year only 6| bushels increase of corn 

 and 64G lbs. of straw. Are we then to conclude, that, under the cir- 

 cumstances stated, the supposed large residue of nitrogen supplied 

 to the turnips, was inefhcient only for the want of available mi- 

 nerals ? — and that the striking effects of the newly supplied lesser 

 amounts of nitrogen were chiefly due to the action of the acids of 

 the ammoniacal salts and of the soda of the nitrate, in rendering 

 available the otherwise locked up mineral constituents within the 

 soil? The utter inefhciency of even a liberal direct supply of 

 mineral constituents, to recover, in the second crop of wheat after 

 nitrogenous manures, more than an insignificant proportion oi 

 the supplied nitrogen not recovered in the first, has been forcibly 

 illustrated in a former paper. 



This brings us to a consideration of the experimentally ascer- 

 tained proportion of nitrogen used in manure, which has been 

 recovered in the increase of crop obtained. Before recording 

 our own direct evidence on the point, as illustrated in the experi- 

 ments with nitrogenous manures on barley which form the chief 

 subject of this paper, it will be well to say a few words on some 

 evidence and reasoning recently put forth on the subject by 

 others, in this Journal. 



In the article already alluded to (Jour. Roy. Ag. Soc, vol. 

 XVII., Part I.), Baron Liebig adduces evidence and arguments 

 to shovr, that, when the necessary mineral constituents are mixed 

 with the nitrogen in manure, there is no deficiency, but a yain of 

 nitrogen in the increase of crop. Assuming the increase of hay 

 in Kuhlmann's experiments to contain 1 per cent, of nitrogen, 

 Baron Liebig states that, where ammoniacal salts were used alone^ 

 there was an apparent loss of four-fifths or three-fourths of the 



VOL, XVllI. 2 M 



