for Twenty Years in succession on the same Land. 373 
For twenty years in succession on tLe same land, an annual 
expenditure of less than 3/. per acre in artificial manures has 
yielded an average produce of 6 quarters of dressed barley, of 
good quality, and nearly 1^ ton of straw. Any practical farmer 
can estimate what would be the additional expense upon the 
crop, in the way of rent, cultivation, harvesting, bringing to 
market, Sec ; and, having done so, the result will doubtless show 
a considerable profit. 
The soil at Rothamsted is more suitable for wheat than it is 
for the growth of barley after roots, as is the common practice of 
the locality ; but the facts show that it will nevertheless grow 
large crops, of good quality, under favourable circumstances. 
Indeed, it may be laid down as a general rule, applicable to the 
country at large, that, on the heavier soils, full crops of barley of 
good quality may be grown with great certainty after a preceding 
corn crop, under the following conditions : — 
First of all, it is essential that the land be got into good tilth. 
It should be ploughed up when dry, as soon as practicable after 
the removal of the preceding crop. In the spring it should be 
prepared for sowing by ploughing or scuffling as early in March 
as possible, if sufficiently dry. 
The artificial manure employed should contain nitrogen, as 
ammonia or nitrate (or organic matter), and phosphates. 
From 40 to 50 lbs. of ammonia (or its equivalent of nitrogen 
as nitrate) should be applied per acre. These quantities would 
be supplied in — 
1^ to 2 cwts, of sulphate ammonia, or 
If to 2^ cwts. of nitrate of soda. 
With either of these there should be employed — 
2 to 3 cwts. mineral superphosphate of lime. 
Of late years the composition of Peruvian guano has been so 
variable and uncertain, that it is quite impossible to estimate 
how much of it would be required to supply nitrogen equal to 
from 40 to 50 lbs. of ammonia. It is impossible, therefore, under 
such circumstances, to recommend it. If, however, the agents of 
the Peruvian Government were to manufacture their guano into a 
substance of uniform quality, and to guarantee to deliver it of a 
stated composition, it would be quite otherwise ; and, as the guano 
itself contains phosphates, if the ammonia required were pur- 
chased in that form, superphosphate need not be also employed. 
Rape-cake is also a good manure for barley. From 6 to 8 cwts. 
would supply about as much nitrogen as would be equal to from 
40 to 50 lbs. of ammonia. But, a smaller proportion of the 
nitrogen of rape-cake, than of sulphate of ammonia, nitrate of 
soda, or Peruvian guano, will be effective within a given time. 
In the experiments at Rothamsted about 9 cwts. of rape-cake 
per acre per annum, gave an average annual produce, over 14 
2 C 2 
