I.] ROTHAMSTED 9 



In particular, these views on the nutrition of plants 

 and the part played by the nitrogenous nianures, did 

 not commend themselves to John Bennet Lawes, a 

 young Hertfordshire landlord who had recently come 

 into possession of the family estate of Rothamsted, near 

 St Albans, and had already begun to try manurial 

 experiments on a small scale. In 1843 the experiments 

 took more systematic form and Lawes obtained the 

 services of Joseph Henry Gilbert, a chemist who had 

 worked under Liebig at Giessen, to conduct them, 

 thus inaugurating the field trials which have continued 

 without a break to the present day. The immediate 

 result of the Rothamsted experiments was to demon- 

 strate the necessity of a supply of combined nitrogen, 

 the yield being in fact roughly proportional to the 

 amount of combined nitrogen added as manure. If 

 only the mineral constituents of the ash were supplied, 

 the crop fell away rapidly as soon as the reserves of active 

 nitrogen in the soil had become exhausted. Lawes, 

 Gilbert, and Pugh further repeated, with great exacti- 

 tude, a series of laboratory experiments initiated by 

 Boussingault, and demonstrated that the ordinary plants 

 of the farm were incapable of utilising the free nitrogen 

 of the atmosphere, but only took up nitrogen in a 

 combined form from the soil or the manure. Lawes 

 and Gilbert were fiercely attacked by Liebig ; but as far 

 as his views can be extracted from his writings, there 

 was no very great difference between the opinions held 

 by the rival parties. Liebig laid the chief stress on 

 the need for the mineral manures, whereas the latter 

 investigators were more concerned to demonstrate the 

 importance of nitrogen. Liebig also seems to have 

 thought that the leafy crops, like clover or roots — the 

 so-called restorative crops — could gather nitrogen from 

 the atmosphere and dispense with any supply in 



