On the Growth of Barley by different Manures, Sfc. 515 



the other manures, attributing the difference in result to the 

 action of the associated mineral constituents. 



After adducing (with some other) experimental evidence of 

 this kind, Baron Liebig says : — 



" By the use of the phosphate of lime, the effect of the ammonia iu sal- 

 ammoniac was almost doubled. By the action of the substances which in 

 guano accompa^iy the ammonia, the effect of the latter was made seven tunes 

 greater than that of the same quantity iu the shape of sal-ammoniac alone." 



He also adds as a general conclusion, that — 



" Since the effect of a manure is not proportional to the quantity of nitrogen 

 it contains, it will be easily rmderstood why the value of a manure cannot be 

 estimated \>j its percentage of nitrogen." 



It will be instructive to examine a little further Baron Liebig's 

 reasoning upon experimental evidence. Further illustrating the 

 action of the mineral constituents, he says : — 



" Kuhlmann had manured a portion of his field in 184:4 with a mixture of 

 666 lbs. of sal-ammoniac, along with phosphate of lime, and had obtained an 

 excess of produce =^ 12,172 lbs. of hay per ^hectare. In the same year the 

 portion manured with 500 lbs. of sulphate of ammonia (without phosphate 

 of lime) yielded an excess =: 3488 lbs. of hay. The former, therefore, yielded 

 2| times more excess of j)roduce than the latter." 



Here, be it observed. Baron Liebig compares the effect of 176 

 lbs.* of nitrogen loith plwsphates, with that of 101^ lbs.* icitliout 

 phosphates, to illustrate the influence of these phosphates. He 

 says : — 



" By the addition of phosphate of lime to the ammoniacal salt the effect 

 of the latter was augmented : there were obtained in all 8684 lbs. of hay 

 more than by the use of ammoniacal salts alone. Now, in this excess, which 

 is equal to 2'i times the whole excess obtained by the ammoniacal salts alone, 

 there were contained 2J times more silica, and 2J times more potash, than 

 would have been removed from the soil ivithout the tise of phosphate of lime 

 along ivith the ammoniacal salts ;\ and the soil was rendered necessarily by 

 so much the poorer iu these coustituents." 



Thus then, although there were 74i lbs. more nitrogen supplied 

 with the phosphates, Baron Liebig attributes the 8684 lbs. of 

 increase to the addition of the phosphates. But he continues : — 



" This great loss of indispensable coustituents could not be without influence 

 on the subsequent crops. The field which in 1844 had been manured with 

 500 lbs. of sulphate of ammonia had no manure in 1845, and received, in 

 1846, 500 lbs. of the same ammoniacal salt. The result was as follows : — 

 The same quantity of phosphate of lime and sal-ammoniac, which in 1844 

 had yielded a jiroduce higher by 8684 lbs. than that of the field manured 

 with sulphate of ammonia alone, yielded, in 1846, 3592 lbs. of hay. The 

 field manured ivith sulphate of ammonia alone yielded, in 1846, 3726 lbs. of 

 hay ; that is, 124 lbs. (134) more than the other. The same manures which 



* We here take the composition as given by Kuhlmann for the pure salts, as 

 Baron Liebig has done the same. Kuhlmann states, however, that a deduction 

 of 5 per cent, should be made for -water and impurity. 



t The italics are our own. 



