492 
Report of Experiments on the Growth of Wlieat. 
The following Table (see page 493) shows, side by side, the 
average annual produce obtained, without manure, by the " mixed 
mineral manure" alone, by 400 lbs. ammonia-salts alone, and by 
the " mixed mineral manure" and 400 lbs. ammonia-salts together — 
1. During 8 years (1856-63) in the experimental field in 
which the results recorded in this paper were obtained. 
2. During the same 8 years in an adjoining field, after several 
wheat crops had previously been taken without manure. 
3. During 3 years (1852-54) at Holkham, in Norfolk, on a 
soil described as a light, thin, and rather shallow, brown sand- 
loam, but resting upon an excellent marl containing a large 
quantity of calcareous matter, and which had grown wheat in the 
preceding year with the same manures, and white turnips ma- 
nured with farmyard dung and guano (of which both tops and 
roots were removed), in the year preceding the wheat. 
4. Over 4 years (1856-59) at Rodmersham, Kent, on a soil 
described as a mixed clay, upon a chalk subsoil lying from 4 to 
6 feet below the surface, and which had grown — in 1853, turnips 
manured with 2 cwts. of guano and 3 cwts. of superphosphate of 
lime per acre, the crop being fed on the land; in 1854, barley; 
and in 1855, beans with stable dung. 
The coincidence of the results obtained in the two fields at 
Rothamsted is most striking ; and when the known differences in 
the condition of the comparable plots in the two cases are taken 
into consideration, even the differences, such as they are, only 
afford additional evidence of the consistency of the indications. 
Thus, in Broadbalk field, the mineral manure alone succeeded 
heavy dressings of nitrogenous manure, whilst in the other it did 
not ; and, accordingly, there is rather more produce in the former 
than in the latter. Again, the ammonia-salts had, in Broadbalk 
field, been used alone for several years on the same plot prior to 
the period taken into the calculation ; and hence, with the greater 
exhaustion of mineral constituents in its case, there was rather 
less produce. The results without manure, and with the mixed 
mineral manure and ammonia-salts together, are so nearly identical 
in the two cases as to call for no remark. 
The Holkham soil and subsoil were totally different in character 
to those at Rothamsted ; the condition at the commencement as 
affected by recent manuring was rather higher, and two of the 
seasons over which the averages are taken were unfavourable, and 
one very favourable for the wheat crop. With these great differ- 
ences of circumstance in almost every particular, we still find, as 
at Rothamsted, very little increase by mineral manure alone, con- 
siderably more by ammonia-salts alone, and more still by mixed 
mineral manure and ammonia-salts together. 
The Rodmersham soil and subsoil Were more nearly allied in 
