On the Bain and Drainage - Waters at Rothamsted. 
57 
that the drainage results for that plot are somewhat too low, 
and perhaps those of Plot 14 rather too high. Indeed, the total 
amount in crop and drainage is less for Plot 7 with ammonium- 
salts (in most years sown in the autumn) and the mixed mineral 
manure, than for Plot 9 with nitrate of sodium (always sown 
in the spring) and the mixed mineral manure on one-half 
onlv of the plot. With these differences there is on Plot 9 even 
rather more recovered in the crop, and there is more also in the 
drainage. 
Finallv, in these estimates for the thirtv years, with much better 
average seasons, and much more nitrogen recovered in the crops, 
but with mostly autumn sowing, and generally rather more 
nitrogen in the drainage from the ammonia-plots, there is con- 
siderably more accounted for in crop and drainage together, 
than over the two seasons of spring sowing, and excessive 
drainage. The estimated amounts in the drainage were, 
indeed, over the two years, greater, or about equal, with defec- 
tive mineral supply and defective growth accordingly, but they 
were less under the more favourable conditions of growth than 
over the thirty years. 
It will be seen that in the foregoing comparisons of the 
amounts of nitrogen in the total crop and drainage with the 
amounts supplied in manure, no account is taken of the small 
quantity (say 2 lbs. per acre per annum) supplied in the seed, 
and the very much larger quantitv contributed by rain and con- 
densation from the atmosphere, and by the soil itself ; nor of 
how much, if any, is retained by the soil. 
Assuming that the crop and drainage of the plots receiving 
nitrogen in manure have received the same amount from other 
sources as Plot 5 without such manure, the amounts in the 
crop and drainage respectively, of that plot, have been deducted 
from the amounts for the other plots, and the result is given 
in the middle division of the Table. The amounts so deducted 
are, for crop 20*3 lbs., for drainage 12 lbs., together 32"3 lbs. 
Reckoned in this way, a very large amount of the nitrogen 
supplied by manure appears unaccounted for in crop and drain- 
age. The quantities so unaccounted for amount, as shown in 
the bottom line of the Table, to from 40 to 50 per cent, of the 
total amount supplied ; and with 86 lbs. of nitrogen in manure 
they range from 34'4 lbs. to 42'4 lbs. per acre per annum. The 
figures further show that, with the best conditions of mineral 
manuring and of growth, 30*1 per cent., or less than one-third of 
the supplied nitrogen, is recovered in the increase of crop, and 
that 221 per cent, have appeared in the drainage. Compared 
with this result there is, yvith the 400 lbs. of ammonium-salts 
alone, only 14 4 per cent, reckoned to be recovered in the 
