THE FARMER'S MAGAZINE. 



370 



absolutely inoperative, while the acid has acted exactly 

 like saltpetre itself and like ammonia." 



As to the general question here at issue, "it cannot 

 for a moment be denied that the state of combination of 

 the nitrogen in our nitrogenous manures, or their ad- 

 mixture with other substances, has some share of in- 

 fluence on the result. We have clearly shown that they 

 have an influence, fluctuating according to season, ex- 

 haustion, amount employed, and other circumstances. 

 It is, however, entirely inadmissible to attempt to draw 

 any conclusions as to the influence of the state of com- 

 bination of the nitrogen, or of the eff"ect of substances 

 supplied with it, from the comparison of the results of 

 experiments in which unequal quantities of nitrogen are 

 employed to a given area, or which were made indis- 

 criminately in the same or in different seasons. Every 

 one, at all conversant with field experiments, will have 

 been early impressed with the very varying proportional 

 effect from one and the same manure, if used in different 

 quantities in the same season, in even equal quantities in 

 different seasons, and above all, in unequal quantities in 

 different seasons. But Baron Liebig founds his argu- 

 ments upon the influence of the varying chemical com- 

 bination of nitrogen, and upon the comparative effects 

 of ammoniacal salts used alone, or in admixture with 

 other constituents, upon experiments with nitrogen in 

 these different states, made indiscriminately with dif- 

 ferent quantities of nitrogen to a given area, and in 

 different seasons." 



M. Kuhlmann indeed, upon whose results Baron 

 Liebig founds his arguments, called particular attention 

 to the influence of the various seasons in which bis ex- 

 periments were made. The following statement must 

 further show, that the experiments cited were quite in- 

 comparable on the point in question. Thus, Baron 

 Liebig compares with one another the results of about 

 701b8. of nitrogen to a given area in the form of sal- 

 ammoniac alone in one year (1843); of about 17G 

 parts in the form of sal-ammoniac vnth phisphaies, 

 applied partly in 1844 and partly in 1846 and the in- 

 crease of produce taken over the three years, 1844, '5, 

 and 'G ; and of about ;15 parts of nitrogen in the form 

 of guano applied only in one year (1844), and the in- 

 crease taken over that and two succeeding years ; and 

 upon the comparison thus made, ho founds conclusions 

 as to the effects of the different states of combination of 

 the nitrogen in the manures, or on that of its admixture 

 with other constituents. But, besides the experiments 

 above alluded to, in which Kuhlmann applied about 15 

 parts of nitrogen to a given area in the form of guano, 

 he made another, side by side, with the same guano, but 

 with double the quantity, yielding therefore 30 parts of 

 nitrogen to the same area. The result was, that where 

 the smaller quantity of nitrogen was used, 72 per cent, 

 more increase was obtained for a given amount of ni- 

 trogen than with the larger ; yet, it was the action of 

 the smaller quantity of guano applied in one year, and 

 acting over three, which Baron Liebig selects to contrast 

 with the large amount of nitrogen applied in different 

 seasons in other manures, attributing the difference in 

 result to the action of the associated mineral constituents 



in the guano. In another of Baron Liebig's illustra- 

 tions on the same point, although 74.^lb8. more nitrogen 

 were supplied with phosjiliaten than were given without 

 them, he attributes the increase of produce in the one 

 case over that in the other, to the addition of the phos- 



Further, Baron Liebig explains the efficacy of a 

 fresh supply of salts of ammonia, when a still unre- 

 covcred supposed residue of nitrogen from previous 

 applications would be without effect, by supposing that 

 the mineral constituents have been exhausted by the 

 action of that portion before supplied which had been 

 active, and that by the action of fresh salts fresh 

 mineral constituents were set free from the soil, and 

 thus the conditions restored for the supplied nitrogen 

 to become effective. How far such an exjilanation is 

 probably correct, may perhaps be judged of by the 

 results which have been recorded on the growth of 

 barley after ten years of turnips differently manured, 



" During the growth of the ten turnip crops, some 

 of the plots had received every year enormously more 

 of all the mineral constituents of the barley crop, except 

 silica, than the turnips removed. The latter removed 

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

 constituents, there was an accumulation during ten 

 years of available silica. Yet with all this unusual ac- 

 cumulation of the necessary mineral constituents, the 

 residue of nitrogen unrecovered 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 three successive years of 

 barley, an average annual increase of only of bushels of 

 corn, and between 300 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 re- 

 spectively, gave at once an increase of 33 and 35 bushels 

 of corn, and 4,903 and 5,531 lbs. of straw. And al- 

 though the addition of the fresh nitrogen in the form of 

 ammoniacal salts yielded an increase of 33 bushels of 

 corn and 4,903 lbs. of straw, which together would con- 

 tain only about half the nitrogen supplied in the 

 manure, yet the remaining half, notwithstanding the 

 still enormous excess of previously supplied mineral 

 constituents, gave in the succeeding year only GJ bushels 

 increase of corn and GIG lbs. of straw. Are we then to 

 conclude, that, under the circumstances stated, the sup- 

 posed large residue of nitrogen supplied to the turnips, 

 was inefficient only for the want of available minerals ? 

 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 in- 

 efficiency 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 of the supplied nitrogen not recovered in 

 the first, has been forcibly illustrated in a fornu r paper." 



By the concurrent testimony of field experiments of 



