were started in 1848, the experiments on Roots have been continued 

 on the same field since 1843, and on the same plan since 1856. The 

 grass plots began in 1856, and the rotation experiments in 1848. 



It is impossible to exaggerate the importance of continuing the 

 experimental plots at Rothamsted without any change, as nowhere 

 else in the world do such data exist for studying the effect of season 

 and manuring upon the yield and quality of the crop, and for 

 watching the progressive changes which are going on in the soil. 

 Year by year these plots are found to throw light upon new problems 

 in Agricultural Science ; in all directions they continue to provide 

 material for investigations upon points which were not contemplated 

 in the original design of the experiments, so that it is impossible to 

 forsee when and how they will not become useful and provide 

 indispensable material for the solution of problems undreamt of at 

 the present time. 



The maintenance, however, of the old data throws a heavy burden 

 upon the Experimental Station. There are 210 plots, and every 

 year 243 samples have to be taken with proper precautions and put into 

 store for future reference. In addition there are made 486 determin- 

 ations of dry matter, 243 of ash, 170 of nitrogen, 50 of phosphoric 

 acid, and 24 of potash, also 180 determinations of nitrates, etc., in 

 rain and drainage waters, and 17 botanical analyses of hay. This 

 does not include examinations of soils, the complete grass separations, 

 and other extensive series of determinations which are made at longer 

 intervals. All the above determinations however are part of the 

 necessary routine which must be completed before any new investi- 

 gations can be undertaken. 



It should be remembered that the object of the Rothamsted 

 experiments is to ascertain " how the plant grows," and only 

 indirectly to find the most paying method and manuring ; hence 

 both the nature and the quantities of material applied are not to be 

 taken as indicating the manures which should be used in practice. 



