Nitrogen Recovered, and not Recovered, in Hay Crop. 195 



the next growing season had commenced. Table XL VIII. 

 shows, for plot 3 (unmanured) and plot 2 (farmyard manure 

 eight years, unmanured twelve years) : 



1. The calculated average amounts of soil, free from stones, 

 and free from moisture expelled at 100 C., in pounds per 

 acre, for each layer of 9in. down to a depth of 54in. ; 



2. The percentage of nitrogen in the dry mould of each 

 9in. layer, as determined by the soda-lime method ; 



3. The calculated nitrogen per acre in pounds ; 



4. The difference in amount between the two plots. 



The foregoing results as to the accumulation of the nitrogen 

 of the manure within the soil, adopted on the basis of the 

 determinations to the total depth of 54 inches, may be 

 discussed in connection with the figures given below in Table 

 XLIX. 



TABLE XLIX. ESTIMATED NITROGEN SUPPLIED IN THE MANURE, 



RECOVERED IN THE INCREASE OF THE HAY CROP, DETERMINED AS 



BESIDUE IN THE SOIL, AND NOT RECOVERED IN EITHER THE INCRKASE 



OR THE SOIL, TO THE DEPTH OF 54 INCHES. 



In interpreting these figures it is necessary to bear in mind 

 the uncertainty in the estimate of the amount of nitrogen 

 supplied in the manure ; the difficulty in determining how 

 much of the nitrogen of the produce was derived from that 

 supplied ; the possible natural difference, apart from the 

 influence of manure, in the soils and subsoils of the respective 



o 2 



