Experimental Crops at Rotliamsted. 
123 
safely be assumed that the dry matter of the crop at tlie time 
of the experiment would be under rather than over 2 tons 
per acre, which, at the rate of 300 parts to 1, would only 
account for an exhalation of 600 tons of water per acre. 
Further, since there was such a great difference in the per- 
centage of moisture in the two cases at the lowest depth taken, 
it is only reasonable to conclude that the difference extended 
lower still. 
To conclude, in reference to these particular experiments, it is 
clear that we have in the facts adduced sufficient evidence, and 
a striking illustration, of the enormous extent to which, in a time 
of drought, our crops may rely upon the supplies of moisture 
previously stored up within the soil. At the same time it 
cannot fail to be recognised how dependent must be the result 
upon the character of the soil and the subsoil with which the 
farmer may have to deal. 
Summary, and General Observations. 
Leaving detail, it will be of interest to summarise the results 
illustrating the difference of effect of the drought of the past year on 
the different crops, and also to bring together those relating to the 
amount of water retained by the soils and subsoils of the different 
fields, under the various conditions as to season, manuring, and 
cropping. 
It has been already said that although the summers of both 
18G8 and 1870 were seasons of drought, yet, chiefly owing to the 
facts that the deficiency of rain commenced later, and the tem- 
peratures ruled higher in 1868, there was in reality considerable 
difference in the characters of the periods of growth of the two 
seasons, and in their consequent effects upon the different crops. 
To save space, however, we will confine attention here to the 
effects on the different crops of the more continued drought 
of 1870. 
Table XI. shows the average annual produce obtained, under 
selected conditions as to manure, of hay, of wheat, and of barley ; 
also the produce of each in 1870, and the deficiency compared 
with the average. In the case of the hay, the average is taken 
over 15 years, and in that of wheat and barley over 19 years. 
For simplicity of comparison, the produce is, for all three crops, 
given in lbs. ; and the figures relating to wheat and barley repre- 
sent the total produce, corn and straw together — which, of course, 
more clearly indicates the total amount of vegetable growth, com- 
pared with that of the hay, than the records of corn and straw 
separately would do. 
