Agricultural Chemistry — Tiimipsi. 



551 



of nitrogen usually found in the cultivated turnip-bulb may be 

 nearly doubled by means of ammoniacal manures, and since we 

 have stated that the feeding value of a crop may to some extent 

 be measured by its percentage of nitrogen, it might be supposed 

 that we should be led strongly to advocate the use of such ma- 

 nures in the growth of the turnip. Our field experiments have 

 already shown, however, that this would be a one-sided inference 

 from these departmental results ; and when we come to make 

 some general application of our varied evidence to practical and 

 economic agriculture, the true position and bearing of the dif- 

 ferent branches of the question will be indicated. 



We regret that we have not as yet a sufficient number of deter- 

 minations of nitrogen in the turnip leaf to enable us to decide 

 satisfactorily whether the percentage be as clearly dependent upon 

 the supply by manure as in the case of the bulb ; the vigorous 

 leaf being, however, highly vascular, and containing much of the 

 still circulating unassimilated food derived from the soil, we might 

 anticipate it would be so ; but, on the other hand, if we look at 

 the bulb as a reservoir of matters which are in excess so far as the 

 natural seed-formxing tendencies are concerned, we might expect 

 the less artificial organs, the leaves, would be more constant in 

 their composition. The following results will not assist us much 

 in deciding these questions ; they are, however, not without in- 

 terest :- — 



Percentage of Nitrogen in flie Dry Matter of Norfolk White Turnip Leaf. 





Plot Numbers. 



Description of Manures. 



Dried 



at 

 212°. 



Specimen 

 dried be- 

 low 200°, 

 and Nitro- 

 gen calcu- 

 lated upon 

 lully dried 

 Substance. 







1 



Farm-yard dung . 



3-24 



3-60 







2 



Unmanured . , 



4*22 



4-35 





Here are given the results obtained from specimens of leaf, in 

 one instance dried fully at 212^ in the water bath, and in another 

 dried much below that temperature ; the percentage of nitrogen in 

 this case being calculated upon the fully desiccated substance. 

 The fact before alluded to, that succulent specimens frequently 

 lose nitrogen at 212°, is thus illustrated; in one instance there is 

 a defect of 0 • 36, and in the other of 0 • 13. We have met with a 

 similar result with other succulent substances. 



It v/ill be remembered that the turnip-leaf was found to contain 

 a proportion of dry matter more than half as large again as the 

 bulb ; and it is seen that in the case of the dung specimen the dry 



2 o 2 



