550 



Agricultural Chemistry — Tu7'nips. 



that the supply of a top-dressing of rape-cake to this otherwise 

 exhausted plot, raises the acreage produce of bulb from 13j cwts. 

 to 7J tons, and the average weight of bulb from less than 2 to 

 nearly 11 oz., and notwithstanding the nitrogenous supply of the 

 rape-cake, we have, with its large provision of carbonaceous sub- 

 stance, the percentage of nitrogen reduced from 3*31 to 2*17. 

 In the 3rd column, where there is added to the natural supplies 

 of soil and season nitrogen, but no carbon, we had an evidently 

 unhealthy condition ; for the acreage produce, the size of bulb, 

 and the number of plants, were all less than where there was no 

 manure whatever. Again, with these unfavourable circumstances 

 of growth we have a very large percentage of nitrogen ; less, in- 

 deed, than in the unmanured bulbs, but considerably higher than 

 when rape-cake alone was used. In the 4th column we have the 

 same supply by manure of carbon and nitrogen as in column 2, 

 with the addition, however, of the nitrogen as in column 3, and 

 we find, as in other cases, that although the actual supply of 

 nitrogen is greater than in column 3, it being proportionally less, 

 the percentage in the bulb is reduced. 



In the third line the standard manure is rape-cake, the extra 

 dressings being, as usual, a further addition of rape-cake, of am- 

 moniacal salt, or of both. Comparing the percentage of nitrogen 

 by the drilled rape-cake, as in column 1, with that by farm-yard 

 dung, we find that the rape-cake gives the highest, and we would 

 suppose the proportion of nitrogen to carbon would be greater. 

 In column 2 the amount of rape-cake being greater, the per- 

 centage of nitrogen is greater : the supply of nitrogen to that of 

 carbon is not, however, greater than in column 1 ; but we have 

 before seen that a full quantity of rape-cake, without extra mineral 

 manure, is not conducive to the most healthy growth of the 

 turnip-bulb; nor indeed would the carbon so supplied be so 

 completely and rapidly available as the nitrogen. The addition 

 of ammoniacal salt in column 3 raises the percentage of nitrogen 

 from 2-23 to 2-80, and in column 4, as compared with column 2, 

 from 279 to 3-00. 



We have made other determinations of nitrogen in turnip-bulb, 

 with a view to some more special points, but as we cannot discuss 

 them in this paper without extending our remarks to an undue 

 length, we shall defer notice of them until a future occasion. 

 The results already given are moreover, we think, sufficient to 

 aid our estimation of the characters of the turnip as a food and 

 rotation crop. 



An important fact elicited is, that within a certain range, which 

 indeed is wider than has generally been supposed, the organic 

 com.position of the turnip bears a very direct relation to that of 

 the manures by which it is grown. It is seen that the proportion 



