504 



Agricultural Chemistry — Turnips. 



Were we to look at the results of this Table with a purely agri- 

 cultural eye, the column of acreage weight of bulb would be suf- 

 ficient to guide our judgment as to the efficiency of the various 

 manures ; but since the object of the experiments is rather to pro- 

 vide a key to the requirements of the turnip than to afford exact 

 examples of manuring, other items than that of the actual acreage 

 results obtained must be taken into consideration in forming an 

 estimate respecting the nature of the conditions which cultivation 

 should be calculated to supply. Manures, indeed, cannot be re- 

 garded only as containing certain constituents convertible into the 

 substance of the crops, but also as agents acting beneficially or 

 otherwise according to the form or combinations in which they 

 are supplied, and their adaptation to soil and season. Thus it is 

 known that the casualties and tendencies to disease or prevalence 

 of insects often prove more destructive to the young turnip-plant 

 under high farming, when the soil abounds in animal and vege- 

 table matter, than when it is deficient in such substances ; and the 

 number of plants per acre may by such causes be so greatly re- 

 duced as to show a better acreage yield under bad than under 

 liberal cultivation. The number of plants per acre must not 

 therefore be overlooked in considering the results of the Table. 

 The average weight of bulb may also be taken as to some extent 

 indicating the relative effects of different conditions of growth. 

 Where we have an increased average weight, as well as a large 

 number of plants, both agency and sujjply have been favourable 

 to the requirements of the plant; and although the efficiency of 

 either of them is dependent on that of the other, it may as a 

 general fact be assumed that a high number of plants indicates a 

 favourable condition, and a large average weight a favourable 

 amount of supply. Bearing in mind these considerations, we have 

 given in the last column of the Table the estimated acreage yield, 

 calculated from the actual average weight of bulb, and supposing 

 a uniform number of plants per acre, namely, 19,360, or 4 in a 

 square yard. Such an arrangement would give about 12^ inches 

 from plant to plant along the rows, and may be taken as affording 

 a more just view of the effects of the manures, independently of 

 the contingencies arising from the manner of their application. 



In reference to the results of this first season it must further be 

 remarked, that the previous course having been wheat, clover, 

 wheat, the peculiar exhaustion of the soil would be that induced 

 by corn-cropping ; and if there be any truth in the opinions which 

 we have given elsewhere on this subject, this would imply a defi- 

 ciency of nitrogen relatively to other constituents, so far as the 

 future growth of wheat would be concerned ; and it would appear 

 from the amounts of produce without manure during the three 

 seasons, as already given, that in some important respects the con- 



