Oil the Growth of Barleij hy different Manures, Sfc. 489 



classification, and are thus assumed to represent about equal 

 annual supplies of nitrogen to the crop, this assumption must 

 only be taken with the qualifications above stated. 



In addition to the nitrogen we have of coui'se in the nitrate 

 its soda, in the ammoniacal salts sulphuric acid and chlorine, and 

 in the rape-cake not only a considerable amount of carbon-yield- 

 ing organic matter, but also a considerable amount of the mineral 

 matters of the seeds from which the cake is made. The rape- 

 cake, at least, must therefore be considered as providing, not only 

 available nitrogen, probably in larger quantity than the other 

 combinations, but minei'al matters also. And it will, besides 

 hese, yield a constant supply of carbonic acid, or other carbon 

 products of transformation of its organic substance. 



Besides the nitrate, the salts of ammonia, and the rape-cake, 

 each used alone, the mixture of the ammoniacal salts, and also 

 the rape-cake, were each used in conjunction with the respective 

 mineral manures before described — namely the " mixed alkalies,^' 

 the superphosphate of lime, and the mixture of the two. 



Here, where the nitrate of soda was used in the larger quantity, 

 as also where it was used in smaller amount (Experiment 7), it 

 followed a mixture of sulphate of potash and superphosphate of 

 lime, applied in the first year of the experiments (1852), but not 

 since. What portion of the indicated superiority of the nitrate 

 over the ammoniacal salts, whether used in the larger or the 

 smaller quantity, may be due toj^his fact, unfortunately cannot be 

 determined. On this point it may be noticed, that it was only 

 in the later years of the experiments that the ammoniacal salts 

 fell short of the nitrate in result. It was, therefore, only after an 

 unusual exhaustion of the annually available minerals of the soil, 

 by taking off a series of corn crops highly manured with available 

 nitrogen, that the nitrate, following after supplied minerals, showed 

 its superiority. Where the larger quantities were used, the 

 average annual excess both of corn and straw by the nitrate over 

 the ammoniacal salts was, however, considerably less than where 

 the smaller amounts were employed. Again, as the nitrate in the 

 larger quantity, gave almost identically the same average annual 

 amounts both of corn and of straw as the rape-cake with its equal 

 or larger amounts of nitrogen and abundant minerals, and as the 

 equivalent amount of ammoniacal salts approaches nearer in result 

 to the nitrate, and to the rape-cake with its minerals, than did the 

 ammoniacal salts to the nitrate when used in smaller quantity — 

 both of course, then, requiring much less minerals from the soil 

 — we must judge, that part of the indicated superiority of the 

 nitrate is really due to greater rapidity of its action ; by which, 

 both the underground and aboveground feeders of the plant were 



