196 



The Eoihamsted Grass Experiments. 



plots ; and also the unavoidable range of error in the 

 sampling of, and determinations of nitrogen in, the soils, and 

 the calculation of such data into quantities per acre. Taking 

 into account the figures relating to the first, second, and 

 third depths only that is, only so far as the manured soil 

 shows more nitrogen than the unmanured the result as to 

 accumulation and loss of nitrogen will stand as shown in 

 Table L. 



TABLE L. ESTIMATED NITROGEN SUPPLIED IN THE MANURE, 



RECOVERED IN THE INCREASE OF THE HAY CROP, DETERMINED AS 



EESIDUE IN THE SOIL, AND NOT RECOVERED IN EITHER INCREASE 



OR SOIL, TO THE DEPTH OF 27 INCHES. 



It is then practically beyond doubt that only a com- 

 paratively small proportion of the nitrogen supplied in the 

 farmyard manure was recovered in the increase of crop ; that 

 there was a considerable accumulation of it within the soil ; 

 and that there was also a very considerable amount so far 

 unaccounted for. 



Such a result would seem to require some confirmation, 

 and this is not wanting. The great practical importance of 

 the subject now under discussion renders it desirable to 

 notice somewhat fully this confirmatory evidence. Among 

 the experiments at Eothamsted, wheat has been grown year 

 after year on the same land from 1843-4 up to the present 



