56 On the Rain and Drainage - Waters at Rothamsted, 
increases considerably, and that in the drainage increases pro- 
portionally more, with each increase of nitrogen in the manure. 
But if the amounts in the produce and drainage without am- 
monium-salts (Plot 5) be deducted from those with ammonium- 
salts, there is, so reckoned, a very large and increasing amount 
of that supplied unaccounted for in either crop or drainage. 
The next six columns of the Table show" the amounts of 
nitrogen in the crop, and estimated in the drainage, on six 
plots, each receiving 86 lbs. of nitrogen annually as ammo- 
nium-salts, in one case without anj- mineral manure, and 
in the others with different descriptions of mineral manure, 
for the whole period of 30 years or more. The amount of 
nitrogen annually removed in the crop is 32-7 lbs. with the- 
ammonium-salts alone, and gradually increases with the ad- 
dition of the different mineral manures until it reaches 46"2 lbs. 
with the ammonium-salts and the most complete mineral 
manure. The estimated amount in the drainage, on the other 
hand, is the highest, 43*2 lbs., with the ammonium-salts alone, 
and the lowest with the ammonium-salts and the complete 
mineral manure, namelv, Sl'O lbs. The amounts in the crop 
and drainage respectively, are indeed, in the two cases, to a 
great extent complementary. Thus, with the ammonium-salts 
alone, there are, in crop and drainage together, 75*9 lbs., made 
up of 32'7 lbs. in crop, and 43"2 lbs. in the drainage ; and,, 
with the ammonium-salts and mixed mineral manure, there are 
in crop and drainage 77'2 lbs., but made up of 46*2 lbs. in the 
crop, and of 31 lbs. in the drainage. The intermediate plots- 
also show upon the whole the less in the drainage the more 
there is in the crop. 
The general result is that with the same amount of am- 
monium-salts and the complete mineral manure, there is- 
the maximum amount of nitrogen per acre in the crop and 
the minimum amount in the drainage ; but with the am- 
monium-salts without mineral manure, there is the minimum 
amount in the crop and the maximum amount in the drainage. 
Again, with the six very different conditions as to mineral 
manure, there is upon the whole the less accounted for in crop 
and drainage together, the less the amount in the crop, and the 
greater the actual amount in the collected drainage. There is. 
in fact, as before, though more in the drainage, more entirely 
unaccounted for the greater the excess over the demands of the 
crop ; whilst, with the more favourable conditions of growth in 
regard to mineral supply, and the more nitrogen taken up in 
the crop, the total amount in crop and drainage the more nearly 
approximates to the ami)unt annuallv supplied in manure. 
Plot 7 is some exception to this ; but there is reason to believe 
