INTRODUCTION. 



15 



TABLE I. — List of the Rothamsted Field Experiments. 



1 Including one year fallow. 



2 Including one year wheat, and five years fallow. 



3 Including four years fallow. 4 Including two years fallow. 



6 Clover, twelve times sown (first in 1848) ; only eight crops, four very small ; 

 one year wheat, five years barley, twelve years fallow. 

 6 Including barley without manure three years, 1853-55. 



It is obvious that the results of field experiments with the 

 individual crops, conducted as above described, must of them- 

 selves throw much light on the characteristic requirements of 

 the particular crop under investigation, whilst those of the ex- 

 periments on the growth of crops in an actual course of rotation 

 will serve to confirm and control those obtained with the indi- 

 vidual crops, and will in their turn receive elucidation from the 

 results with the individual crops. Then, again, the results of 

 the experiments on the application of different manures to the 

 mixed herbage of grass-land — which includes, among others, 

 members of the botanical families that contribute some of the 

 most important of our rotation crops — may, independently of 

 their value in reference to the special objects for which they 

 were undertaken, be expected to afford interesting collateral 

 evidence in regard to the requirements of individual plants 

 when thus grown in association, instead of separately year after 

 year, or in rotation, as in the other series of experiments. Ob- 

 viously, too, the chemical, and in some cases the botanical, 



