May 1, 1902.] Supplement to the Tropical Agricultiitht.'" 
787 
THE ADVANTAGES OF MULCHING. 
[The appended lecture was delivered by Dr. 
Lehmon, Agricultural Chemist, Mysore, before 
the United Planters' Association, and clearly 
explains the advantages of a practice too little 
adopted in countries subject to drought. The 
lecture is reproduced in Bulletin No. 2 of the 
Department of Agriculture Mysore, entitled 
"Notes on Coffee Cultivation,' which in Dr. 
Lehman strongly recommends mulching instead of 
digging round the bushes.— Ed. A.M.'] 
The subject is a very large one, but I shall only 
touch on four of the most important points. These 
ore : — 
(1) The tendency to preserve the soil moisture. 
(2) The tendency to prevent the formation of 
a crust on the surface. 
(3) The tendency to preserve the soil in a loose 
and open condition and retarding the 
growth of weeds. 
(4) Allowing the rain to enter the soil more 
easily and preventing the surface washing. 
The tendency to preserve the soil moisture. — As 
•we nil know, the top layers of soil are generally 
the driest, while those below are gradually in- 
creasing ill moisture till the level of the sub-soil 
water is reached. Of course, shortly after rain 
thia order will be partially reversed, but this will 
only be for a very short time. In mulched soils 
this is not, however, the case, as Wollney, in his 
elaborate experiments conducted near Munich, has 
clearly pointed out. He, for one found that, even 
after ten days of dry weather, the surface soil, 
under a mulch of about an inch of coarse, strawy 
manure, had still considerably more moisture near 
the surface that at a depth of four feet. Compared 
with unmulched soil, the differences are also very 
striking ; especially in the first four inches of soil, 
as it contained 13 per cent more water than that 
not mulched. At a depth of two feet there were 
still 2 per cent in favour of the mulched soil and 
at three feet a little more than 1 per cent. The 
above is an average of several experiments ; and 
numerous others conducted at different places 
on different soils and with different mulches gave 
similar results ; boards, stones, straw and leaves 
were among the mulching materials used. Avery 
loose surface soil also acts as a mulch, but on the 
one hand, it is not nearly so efficient as leaves 
and, on the other, it would soon become compact 
again. Nevertheless, one of the objects of cul- 
tivation is to provide this partial and temporary 
mulch ; for in most localities the application of 
the only other practical mulching materials, viz., 
straw or leaves, would prove a rather expensive 
operation. Since part tf the object of cultivation 
is to form a mulch to retain soil moisture, mid as 
a mulch of leaves would perform this object much 
better than cultivation, mulching may replace 
part of the cultivation. The more thoroughly we 
study the subject, the more convinced of this fact 
will we become. I need not enter into the 
theories advanced for the facts obtained by ex- 
periments notwithstanding that they have been 
proven beyond a doubt. It is surprising how the 
soil moisture will vary in adjacent portions of 
soil only a few feet or a few inches apart. You 
may have noticed yourselves that under a eovering 
of leaves only a few feet square the soil may be 
moist to the very surface, while just beyond this 
covering the soil is perfectly dry to the touch for 
perhaps two feet or more from the surface. The 
shade under which coffee is grown has also a 
tendency to preserve the soil moisture. But tlie 
mulch of leaves from the shade trees will be at 
least quite as effective in this respect as the trees 
themselves. 1 should not like to make any remark 
which might induce any of you to lessen your 
shade ; but it is just possible that after extensive 
experiments have been made, it would be found 
possible to replace part of the shade by a mulch 
of leaves. As far as soil moisture goes, a mulch 
and shade trees work in the same direction. 
Properly speaking, I ought to give a brief account 
of the functions of the water in the soil to show 
how far the preservation of soil moisture is an 
important factor. But as every one knows that a 
liberal supply of moisture (not stagnant water) is 
absolutely necessary, I need not speak of it further 
at present. Of course, it is possible to have too 
much water in the soil. But as a mulch will in 
no wise interfere with the drainage, and as the 
coffee soils do not appear to have an excessive 
water-holding power, it is not likely that the 
mulch will retain much of that which would act 
injuriously to the coffee. But it would tend to 
keep the water near the surface, whore the 
larger portion of the roots are — at seasons when 
without it these po?:tion8 of the soil would be too 
dry. Of course, experiments will have to prove 
in how far the wintering of coffee is desirable or 
necessary, and it will depend upon the lesults of 
those whether it would be desirable or not 
to retain the mulch through the hot and rain- 
less season. Some planters have noticed that 
coffee does apparently better on stony soil than on 
adjacent fields which are not stony. It would be 
premature to say that this was due to the stones 
ou-the surface forming a partial mulch. But that 
stones act similarly to a mulch (though not nearly 
so effectively) has been proved. And that the 
crops are sometimes injuriously affected by re- 
moving them has also been noted by observant 
farmers both in England and in Germany. 
Preventing the formation of a puddled surf ace. — 
The ease with which the surface soil becomes 
puddled in some parts of the State is very marked. 
Few of us realize, I believe, what a drawback this 
really is to plant growth. Frequently you must 
have noticed that plants are growing very poorly 
indeed if there is only a thin crust on the surface of 
th e soil. Unfortunatelj', I do not remember having 
seen any accurately conducted experiments which 
would indicate the extent of the injuries done by 
the crust. But T. B. Terry and other practical 
agriculturalists claim to have more than doubled 
some of their crops by always stirring the soil 
after every shower of rain as soon as it was 
sufficiently dry, so as to break the crust as soon 
after it had formed as possible. To do this on 
any of your estates would be impossible. But a 
mulch which would break the force of the rain or 
drip at the surface would prevent this crust for- 
mation to a v«ry large extent, if not altogether, 
The rain water after percolating through the 
mulch has not sufficient force to move any large 
