On the Rain and Drainage - Waters at Rotkamsted. 
41 
The Rape-cake (Plot 19) and farmyard-manure (Plot 2) are 
both applied to the land in the autumn ; in each case the 
drainage-waters are richest in nitrates in the winter. Nitrifica- 
tion, however, proceeds far more slowly with these organic 
manures than in the case of ammonium-salts, the amount of 
nitrates lost by drainage even in a wet winter is thus much 
less considerable. The rape-cake yields more nitric acid to the 
drainage-water than the farmyard-manure, and, when oppor- 
tunity is given for accumulation, the amount of nitric acid may 
become very considerable, as in the case of the drainage-waters 
of February 16 and 17, 1880, when the nitrogen as nitric acid 
amounted to 33"0 per million for Plot 19. This considerable 
production of nitric acid from rape-cake is a proof, if one were 
needed, that the nitric acid in soil is not produced, as is some- 
times asserted, solely from animal matter or ammonium-salts. 
Table XLVIII. — Niteogen as Nitrates iu Dkainage-Waters from 
Broadbalk Field at different Seasons of the Year, Average of 
Three Years (November 1878-October 1881). 
Plot. 
Nitrogen as Nitrates per Million of Drainage- Water. 
Nitrogen 
per Acre 
per inch of 
Drainage. 
Whole Year. 
Spring 
Sowing to 
end of May. 
June to 
Harvest. 
Harvest to 
Aurumn 
Sowing. 
Autumn 
Sowing to 
Spring 
Sowing. 
AVhole 
Year. 
lbs. 
2 
o 
G 
1 
4 
G 
0 
9 
5 
7 
5 
1-70 
3&4 
0 
0 
I 
4 
8 
5 
0 
3 
9 
0-88 
5 
•> 
9 
0 
2 
4 
8 
5 
5 
4 
2 
0-95 
6 
14 
7 
0 
7 
6 
0 
5 
4 
5 
4 
1-22 
7 
27 
1 
1 
4 
7 
3 
5 
4 
6 
8 
1-54 
8 
28 
2 
4 
0 
13 
5 
7 
5 
9 
3 
210 
9 
50 
4 
9 
1 
15 
0 
7 
8 
12 
5 
2-83 
10 
31 
6 
11 
4 
12 
7 
6 
9 
10 
7 
2-42 
11 
25 
8 
5 
8 
9 
0 
7 
7 
9 
0 
2-04 
12 
22 
6 
3 
7 
8 
0 
7 
1 
7 
9 
1-79 
13 
26 
4 
1 
9 
7 
3 
G 
7 
7 
G 
1-72 
14 
31 
6 
3 
4 
8 
1 
7 
5 
8 
5 
1-92 
15 
6 
7 
2 
9 
7 
5 
28 
1 
19 
3 
4-37 
16 
3 
3 
0 
1 
5 
3 
5 
6 
4 
5 
1-02 
17 &/Amm. 
29 
7 
1 
8 
6 
6 
5 
5 
7 
1 
1-61 
18 \Min. 
1 
5 
0 
3 
5 
6 
5 
5 
4 
3 
0-97 
19 
3 
7 
0 
5 
7 
7 
14 
0 
10 
4 
2-35 
In Table XLVIII. is given a summary view of the nitrogen 
as nitric acid present in the drainage-waters of the various plots 
at different seasons of the year, based on the analyses made at 
Rothamsted during the last three years. The figures are of 
great interest ; they should not, however, be taken as more than 
indications of the general truth. This is especially to be 
