MnucJtcslcr Memoirs, Vol. Iviii. (19 14), No. 6. 5 



the last half-century or more and had received the same 

 manurial treatment every year. The soil was taken fresh 

 from the field, added to such a volume of water as would 

 produce a mixture of 2C kilos dry soil and 35 kilos water, 

 left for a da)- and the solution filtered off. Pure lines 

 (to secure uniformity) of wheat and barley were grown in 

 these solutions, ten plants of each being grown in the 

 solution from each soil, and the solutions were renewed 

 fortnightl}- to ensure that the food supply was always 

 adequate. In order to confine the problem to the mineral 

 constituents only of the soils, the same amount of nitrate 

 of soda was added to each solution. From the outset, 

 growth proceeded much more vigorously in some solu- 

 tions than in others, the best plants being those growing 

 in the solutions from the soils that had been continuously 

 manured. 



Table I. gives the average yield during the last ten 

 years on the plots from which the soils were taken. 

 Table II. gives the average weight of the wheat and 

 barley plants growing in the solution, while the diagram, 

 Text-fig. I, shows a comparison of the growth in the 

 solution with that in the field. 



There can be no mistake about the significance of 

 these results : the growth in the solutions is strictly 

 parallel to the growth in the same soils in the field, if an 

 allowance is made for the nitrogen supplied to the solution 

 from the unmanured soil, which receives no nitrogen in 

 the field. The growths are such as would be expected 

 from the known history of the plots, and do not agree 

 with the idea that all soils yield solutions of the same 

 nutritive power. 



The solutions themselves were next analysed with the 

 results set out in Table III., where also the analj'ses of 

 the soils are added for comparison. The composition of 



