AGRICULTURAL PROGRESS AND EXPERIMENTS. 579 
of plants; or it may be that in some cases the 
process has to be repeated before its good effects 
are yielded, or that the subsoil ought only to 
be encroached upon gradually. The condition, 
again, of the subsoil cannot but be an important 
factor in determining the success or failure of 
the operation. It goes without saying, for 
instance, that a clayey subsoil ought not to be 
stirred when it is wet. One kind of subsoil is 
likely to require one kind of treatment, and 
another another. When so great an advantage 
as enabling the soil to take in more water is 
attached to the practice, we ought certainly to 
ascertain what the conditions are under which 
it is successful, as well as what can be done to 
make it successful under other conditions. For 
a study of this important subject to be at all 
satisfactory, it is necessary for the experiments 
to be comparative, and that they should be made 
in many different kinds of soils and subsoils. 
(2.) The disposition of dead vegetable matter in the 
sou.—That this should be made the subject of 
experimental investigation has been suggested 
to me as well by the apparent importance of the 
subject, as by the fact that the different 
methods of ploughing which are practised in 
India and England dispose of the surface vege- 
tation so differently ; and that while our climate . 
more nearly resembles that of India, in our 
practice we follow the English method. The 
Indian plough, which has stood the test of very 
long usage, and has probably been in use from 
time immemorial, is furnished with nothing of 
the nature of a mouldboard, and makes no 
attempt to cover the vegetation and crop-residues 
which are on the surface. It leaves them where 
it finds them, or at the most covers a very small 
proportion of them, and then only lightly. The 
result is that practically none of the crop-residues 
or weeds which are on the surface go to add 
to the humus content of the soil. They simply 
remain on the surface until they are burnt up 
(oxidised) by exposure to the sun and air, or are 
blown away. It is hardly surprising, therefore, 
that the agricultural soils of India have been 
found to be relatively very poor in humus. It 
