Agricultural Chemistry. 457 
of increase. In the following Table (HI.), we have the result of 
this experiment; namely, that on plot 21, which, with those on 
plots 7 and 22, given on either side of it, will illustiate the point 
in question : — 
Table III. — Selection of Eesults of Expermieiits on Turnips. 
I'roduce of Bulb per Acre. 
Years. 
Plot 7. 
i Cwt. vSulphate Ammonia, 
in 1843. 
3 Cwts. ground Apatite, in 
1844. 
12 Cwts. Gypsum, in 1845. 
Afterwards Unmanured. 
Plot 21. 
Superphosphate of Lime, 
ill lt'43-ri-5. 
Afterwards Unmanured, 
Plot 22. 
Superphosphate of Lime, 
cvenj Year. 
Norfolk Whiles. 
■ 1S43 
1844 
1845 
184G 
1847 
, 1848 
Tons. Cnts. 
G 18i 
3 1 
5 13| 
2 Hi 
1 0^ 
Tons. Cwts. 
11 14^ 
7 3i 
13 2J 
1 5i 
3 17 
6 7i 
Tons. Cwls. 
12 3^ 
12 13f 
1 18 
5 11 
10 11 
Swedes. 
■ 1849 
1850 
1851 
I 1852 
0 2A j 0 15f 
4 C| 8 0 
3 10 6 7i 
14 2 15^ 
3 15 
11 9 
10 161 
8 9i 
Totals . . 
28 8^ 
61 9 
85 If 
Means . . 
3 3i 
G 3 
8 lOi 
Plot 21 received in all, during the first three years of the 
experiment, about 800 lbs. of bone-earth, or its equivalent in 
apatite (mixed with sulphuric acid) ; and from that time it was 
unmanured. And since the whole produce of the ten years 
would only remove from tlie land, say one-third, of the phos- 
phoric acid added in the first three years, it is obvious that there 
must have remained in the soil a large residue of the supplied 
phosphate, for the seven crops grown since the application of the 
manure. 
Plot 22 had also large amounts of superphosphate of lime 
supplied to it during the first three years ; and after that time 
it received eveiy year 160 lbs. burnt bones, mixed with 120 lbs. 
of sulphuric acid of sp. gr. 1*7. 
Plot 7, having had a small quantity of ammonia-salts in 
1843, 3 cwts. of apatite in 1844, and 12 cwts. of gypsum in 
1845, yielded, in 1840, without manure of any kind, so small a 
crop as not to be w orth weighing ; and this plot 7 was after- 
wards continuously unmanured. 
It is seen that, during the first three years of the experiment, 
plots 21 and 22, being both manured liberally with superphos- 
