496 



Agricultural Chemistry — Turnips, 



their botanical alliances; and distinctions between the necessary 

 conditions of artificial supply of certain constituents have been 

 made, which are inconsistent with the dictates of experience, and 

 equally so with those to which we are led when other circum- 

 stances besides the (nevertheless important) botanical distinctions 

 are brought into consideration. The varying quantitative reliance 

 upon the atmosphere and the soil of different natural families of 

 plants constitutes indeed a most interesting and important point of 

 study, and the principles upon which the natural system is founded 

 may derive essential confirmation from chemical researches ; but 

 in referring the varying agrictdtural value of different plants to 

 the functional characters of the several natural orders to which 

 they belong;, it must always be first decided that the natural aim 

 and tendency of the plant and order are favoured by our methods 

 and objects of cultivation, and that the agricultural value of the 

 plant is in no way dependent on a monstrous or artificial develop- 

 ment at variance with that of its individual health and reproduc- 

 tive tendencies. 



The cultivation, habits and uses of the turnip are well suited to 

 form a contrast to those of our grain crops ; and the plant itself 

 may, to some extent, be taken as the type of the green or fallow 

 crops, a main effect of which is the preparation of the soil for the 

 after-growth of corn. The essentially artificial condition which is 

 induced in the cultivation of the turnip plant, for feeding and 

 manuring purposes, is most strikingly illustrated by the effect of 

 climate and manures upon the quantity and composition of the 

 produce. 



We shall now proceed to discuss in detail the results of experi- 

 ments which have been in progress in the field and in the labora- 

 tory for several years, and which were undertaken with the view 

 of elucidating some of the general effects of rotation. From the 

 commencement of the inquiry it has been our wish to avoid, as 

 far as possible, the bias of any of the conflicting opinions which 

 have of late years been put forth upon the important subject 

 under examination, and it will be our endeavour, as we proceed in 

 our Report, impartially to lay before our readers such results of 

 direct experiment as will enable them to form their own estimate 

 of the soundness of any views which we may advocate or adopt. 



At the outset, however, it may be well to caution the agricul- 

 turist against expecting what we by no means presume to exhibit. 

 The object of the experiments has not been the production of 

 immense crops, but to trace, as far as we were able, the real con- 

 ditions of growth required by the turnip, and to distinguish these 

 from those of the crops to which it is to a great extent subservient. 

 To attain our object it will be necessary to speak of amounts of 

 produce vv^hich may at first sight excite the ridicule of those who 



