58' On the Rain and Drainage - Waters at. Rotliamsted. 
increase of crop, and 36'3 per cent, found in the drainage. The 
results for the plots with the partial mineral manures are inter- 
mediate between these two extremes. 
The next question is — whether there is any accumulation of 
the nitrogen of manure within the soil which may account for 
some or all of the large amount otherwise unaccounted for ? 
In 1865 careful samples of the soil were taken from eleven of 
the differently-manured plots in the Experimental Wheat-field. 
The samples were taken from eight places on each plot, and in 
each case to three depths of 9 inches, or in all to a depth of 
27 inches : and the eight samples of the same depth were mixed 
together. In no case were less than three determinations of 
nitrogen made in these mixed samples, and in some four or 
more. The following Table (LIV.) shows the mean per- 
centage of nitrogen in the dry mould (that is, excluding stones 
and moisture) in the mixed samples of the first 9 inches of 
depth for each of the eleven plots, tt also shows the calculated 
amounts of nitrogen per acre (reckoning 2,300,000 lbs. of dry 
mould to the depth of 9 inches), and the amounts on the other 
plots more or less than on Plot 5. 
Table LIV. — Mean Percentage, and Quantity per Acbe, of 
Nitrogen in the Surface Soil (9 inclies deep) of Selected Plots 
in the Experimental Wheat Field. 
Samples Collected October 1S65. 
Nitrogen in Dry Mould. 
Plots. Jtanuies per Acre i^er Annum. 
2 I 14 tons Farm-yard Manure 
3 I Uniuanured 
6a I Mixed Mineral Manure 
7rt ' Mixed Min. Manure and 400 lbs. Arum. -salts .. 
9a ' Mixed Min. M;in. and 550 lbs. Nitrate of Sodium 
lOo j 400 lbs. Amm. -salts, alone (1845 and since) 
11a 1 400 lbs. Anim.-sults and Superphosphate 
12a ' 400 lbs. Anim.-salts, Superplios. and Sulpli. Soda. 
13a ] 400 lbs. Am. -salts, Superphos. and Sulpli. Potass. 
14o 1 400 lbs. Amm. -salts, Superphos. and Sulpb. INIag. 
16a ' 800 lbs.* Amrn. -salts and Mixed Min. Manure 
Per 
Cent. 
Per 
Acre. 
I Per Acre, 
+ or- 
Plot .>>. 
Per cent. 
0-18821 
0-1090 
o-uiol 
0-1230 
0-1232 
|0-1]08 
0-1171 
0-1208 
I0-I2O6 
0-1197 
0-1264 
lbs. 
4329 
2507 
2574 
2829 
2834 
2548 
2G93 
2778 
2774 
2753 
2907 
lbs. 
-f- 1755 
I- 67 
L 255 
l-f- 260 
26 
-I- 119 
+ 204 
-t- 200 
-f 179 
-f 333 
These determinations of nitrogen relate to the condition of 
the plots after all had been under experiment for 22 years in 
succession. The unmanured and the farmyard-manured plots 
had been subject to the same treatment from the commencement. 
* To 1864 inolusivp, but none in 1805, or since. 
