Experiments an the Growth of Wheat. 
31) 
at Rothainsteil, and elsewhere, • regarding tli'; character of the 
manures required for the increased growth of wheat on land 
under the ordinary conditions of cropping and cultivation in 
our rotations. They are, moreover, perfectly consistent Avith the 
experience of common practice on the point. 
It is worthy of remark that after the land had been well 
dunged, and grown a crop of beans, the greatest increase, 
especially of corn, obtained in the first year was where the 
manure was the most nitrogenous. Thus, the ammonia-salts 
alone, the guano, and the rape-cake, each gave 4 to 5 bushels' 
increase of dressed corn ; whilst the mineral manure, and the 
mineral manure and ammonia-salts together, gave only about 
1 bushel. The ammonia-salts alone also gave rather more in- 
crease of straw than any of the other manures — more even than 
the mixed mineral manure and ammonia-salts together. The 
produce of the unmanured plot in the second and succeeding 
years showed, however, that the condition of the land had then 
become reduced ; and it is, therefore, from the average results of 
each of the different manures taken over a series of years, that 
we shall be able best to judge of the character of the exhaustion 
induced by the growth of the wheat crop in that particular soil. 
It is proposed to make a few comments : first, on the produce 
during the four years of the application of the manures ; secondly, 
on that of the two years after the cessation of the manuring, 
showing the influence of the residue of the manures previously 
applied ; and then on the total amount of increase obtained in 
the six years by the different manures. 
Plot 1. Unmanured. — As already observed, the produce with- 
out manure was, in the first year, about 32^ bushels of dressed 
corn and nearly 43 cwts. of straw. In the five succeeding years 
it was, respectively, 25;^, 24f, 19f, 7;^, and 15|^ bushels of dressed 
corn, and about 22 J, 24, 2>0^, 14^, and 16^ cwts. of straw. But, 
a part only of this great reduction in the produce Avas due to the 
reduction of the condition of the land as affected by previous 
manuring ; for, as already said, in the last two years of the experi- 
ments the seasons were unfavourable and the land had become 
somewhat foul. Excluding the first year, the average produce 
of the next three years was 23 J bushels of dressed corn, and 
25|^ cwts. of straw ; and the average of the five years, without 
manure, that is, excluding the first year and including the last 
two unfavourable seasons, was IS^- bushels of dressed corn and 
21^ cwts. of straw. Here at Rothamsted (Herts) where Avheat 
had been grown without manure for a dozen previous conse- 
cutive years, the average pioduce of the same five seasons was 
16 bushels of dressed corn and 14|^ cwts. of straw, or 2^ bushels 
of dressed corn and 7 cwts. of straw less than at Rodmersham 
