KECOVERY OF NITROGEN IN CHOP 113 



supplied in Manure. In view of the large amounts of nitrogen 

 applied in the manures, it is important to consider what 

 proportion of each of the different nitrogenous compounds 

 is recovered in the crop. 



If the soil has suffered no loss of nitrogen, then the whole 

 of the nitrogen removed in the crop must have been derived 



TABLE XLIE. Mangolds. Relation between the Nitrogen recovered 

 in Crop and that supplied in Manure. 



* Average for 21 years, omitting 1876-7, 1885, 1895, 1901-2. 

 t Average for 22 years, omitting 1876-7, 1885, 1901-2. 

 j Percentage calculated from 9 years, 1878-82, 1897-1900. 



from the manure, and on that assumption the percentages 

 given in the table above are calculated. In calculating the 

 amount of nitrogen recovered each year no account has been 

 taken of the leaves, because they are returned to the soil and 

 their nitrogen is not removed from the land ; if both leaf and 

 root were taken into account the recovery of nitrogen for any 

 single year would be very much greater ; indeed in some 



seasons when a big crop is grown more nitrogen is removed in 



H 



