14 The History of a Field neioly laid doivn to Permanent Ch-assi 
is probable that some of the deficiency may be due to the roots 
being more exhausted after the removal of a second crop in 
September, than in January after no removal by mowing since 
the preceding summer. The amount of nitrogen in the roots 
at the two periods will be considered further on. 
The amount of water varied comparatively little in the six 
samples taken in January 1879, but more, with the less actual 
quantities, in the five samples of 1888. 
Lastly, as to the fine soil free from water, the variation in 
the amount in the different samples has obviously some relation 
to the amount of stones; but, taking the average, the 1879 
samples represent 2,008,584 lbs., and the 1888 samples only 
1,908,978 lbs., or, as has been said, about one-twentieth less. 
The significance of this difference will be seen as we proceed. 
Two or more determinations of nitrogen were made in each 
separate sample, in each of the two years, and also in a mixtiu-e 
of the six samples of 1879, and of the five of 1888. The follow- 
ing Table (V.) gives the mean percentage of nitrogen in each 
separate sample, and in the mixture for each year. It also gives 
the amounts of nitrogen per acre, in lbs., to the depth of 9 inches, 
calculated from these percentages, and the actual weights of soil in 
each case, as given in the preceding Table, and, for convenience, 
repeated in the first two columns of the Table below. 
Table V. — Nitrogen per Cent., and per Acre, in the Surface- 
Soils TO the Depth of 9 Inches, in January 1879, and 
September 1888. 
Samples 
Fine soil (dry) per acre 
Nitrogen 
Per cent. 
Per acre 
1879 
1888 
1879 
1888 
1879 
1888 
No. 1 
„ 2 
„ 3 
„ 4 
5 
., 6 
Mean . . ) 
Mixture . J 
Mean of mean ) 
and mixture J 
lbs. 
2,062,523 
1,989,629 
1,981,921 
2,108,068 
1,951,038 
1,967,724 
lbs. 
1,798,008 
1,824,246 
1,861,122 
2,059,114 
2,002,402 
per cent. 
0-1975 
0-2013 
0-2112 
0-1942 
0-2048 
0-2051 
per cent. 
0-2477 
0-2388 
0-2614 
0-2380 
0-2255 
lbs. 
4,073 
4,005 
4,186 
4,094 
3,997 
4,015 
lbs. 
4,454 
4,356 
4,865 
4,901 
4,515 
2,008,584 
1,908,978 
0-2024 
0-2057 
0-2423 
0-2405 
4,062 
4,132 
4,618 
4,591 
0-2041 
0-2414 
4,097 
4,604 
Referring first to the 1879 results, the percentage of nitrogen 
is not widely different in the different samples. The highest is 
0-2112 per cent, in sample 3, and the lowest 0-1942 in sample 4. 
