On the Groicth of Barley by different JSIanures, Sj-c. 513 



have clearly shown that they have an influence, fluctuating ac- 

 cording to season, exhaustion, amount employed, and other cir- 

 cumstances. It is, however, entirely inadmissible to attempt to 

 draw any conclusions as to the influence of the state of combina- 

 tion of the nitrogen, or of the effect of substances supplied with 

 it, from the comparison of the results of experiments in which 

 unequal quantities of niti'ogen are employed to a given area, or 

 which were made indiscriminately 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, 

 andj above all, in unequal quantities in different seasons. But 

 Baron Liebig founds his arguments upon the influence of the 

 varying cliemical combination of nitrogen, and upon the compara- 

 tive effects of ammoniacal salts used alone, or in admixture with 

 other constituents, upon experiments Avitli nitrogen in these dif- 

 ferent states, made indiscriminately with different quantities of 

 nitrogen to a given area, and in different seasons. 



He compares together on this point — the increase by the use of 

 sal-ammoniac alone, for one year, 1843, with that during three other 

 years (1844, 1845, and 1846), by sal-ammoniac and phosphates 

 applied in the first and third years only, and with that during 

 the same three years (1844, 1845, and 1846) by guano applied 

 only in the iifst (1844). The amounts of nitrogen supplied to a 

 given area were also widely different. They were respectively 

 70'3 parts when the sal-ammoniac was used alone, 176 parts when 

 it Avas used witli phosphates, and only about 15 parts when the 

 guano was employed. Nor is anything said of the influence oi 

 the varying seasons ; to which his authority, Mr. Kuhlmann, calls 

 particular attention. In this way, the increase being first calcu- 

 lated for a fixed amount of nitrogen in manure in each case, 

 Baron Liebig arrives at the following varying result of the given 

 amount of nitrogen as attributable to different states of combina- 

 tion, or to admixture with other manurial constituents : — 



NITROGEX IN MAXURE. | ™'i'^f'' °' 



100 parts in the form of Sal-ammoniac j 2,439 parts of Hay. 



,, „ „ Sal-ammoniac with phosphate of)' An.n- 



lime J ' ' " " 



„ „ ., Guano 1 1G,460 „ 



No reader of this Journal will require to be told, that the 

 results of about 70 parts of nitrogen to a given area in the form 

 of sal-ammoniac alone in one year (1843) — of about 176 parts in 

 the form of sal-ammoniac with phosphates applied partly in 1844 



