on Permanent Meadow Land. 
243 
increase of nitrogen in the produce by tlie use of it in manure 
is supposed to be represented by so mucli only as was over and 
above that yielded by the mineral manures alone, there would 
then appear to be only about the same proportion of the sup- 
plied nitrogen recovered as when the nitrogenous manures were 
used alone, and the increase of nitrogen then calculated over that 
in the unmanured crop. Thus, taking, as supposed, the yield of 
nitrogen by the mineral manures alone as the basis of tlie calcu- 
lation, the increase obtained by the super-addition of the 400 lbs. 
of ammoniacal salts will have returned only 30 per cent. ; that 
by the 400 lbs. of ammoniacal salts, and 2000 lbs. of sawdust,, 
only 24"1 per cent. ; that by the 400 lbs. of ammoniacal salts and 
2000 lbs. of cut wheat-straw, only 28'8 per cent. ; and that by 
the 800 lbs. of ammoniacal salts, 35 5 per cent., of the sup- 
plied nitrogen. In regard to the fact, that there appears to be a 
larger proportion of the supplied nitrogen recovered (35"5 per 
cent.) when the extravagant amount of 800 lbs. of ammoniacal 
salts per acre was employed, it may be stated that tlie result is 
due to an extremely high percentage of nitrogen in the produce, 
and not to a favourable proportion of increase. The larger 
return of the supplied nitrogen is, therefore, though an apparent, 
yet only a questionable advantage. Adopting the same mode of" 
calculation as above, the addition of nitrate of soda to the mineral 
manures gave a less favourable r3sult than that of ammoniacal 
salts. When 41 lbs. of nitrogen were employed in the form of 
nitrate, there were only 17"7 per cent. ; and when 82 lbs. of 
nitrogen were so provided, there were only 21 "2 per cent, of the- 
supplied nitrogen recovered in the increase. 
But, reckoning, as has been shown it would be more pi'oper to- 
do, that the whole of the nitrogen obtained by the conjoint action 
of the mineral and nitrogenous manures beyond that yielded 
roithout manure, has probably been due to that artificially sup- 
plied, the proportional return in the immediate increase then, 
appears to be much greater. On this mode of estimation, the 
400 lbs. of ammoniacal salts (with mineral manure) have re- 
turned in the increase 50-5 per cent. ; the 400 lbs. of ammoniacal 
salts and 2000 lbs. of sawdust (with mineral manure) 43"5 pei" 
cent. ; the 400 lbs. of ammoniacal salts and 2000 lbs. of cut wheat- 
straw (with mineral manure) 46'5 per cent. ; the 800 lbs. of am- 
moniacal salts (with mineral manure) 45 8 per cent. ; the 275 lbs. 
of nitrate of soda (with mineral manure) 59"9 per cent. ; and th& 
550 lbs. of nitrate of soda (with mineral manure) 42'3 per cent ^ 
of the nitrogen supplied in the manure. 
Taking the average of the results just quoted, there were about 
48 per cent, of the supplied nitrogen recovered in the immediate 
increase of the hay-crop, when the nitrogenous manure was asso- 
R 2 
