724 
Supplement to the "Tropical Agriculturist." [April i, 1890. 
that admit of cultivation, the quantity contained in 
them is very often insufficient for the healthy growth 
of certain crops. Therefore if lime be applied to 
such soils it naturally increases their fertility. On 
soils of this kind the striking effects of lime is best 
seen when the soil contains in abundance all the 
other essential elements of fertility with the excep- 
tion of lime. Lime not only acts directly as a manure, 
but increases the other materials necessary for the 
growth of crops. In most cases the beneficial influence 
of lime is due to its chemical action in the soil. Lime 
preserves clay in an "open" condition, thus makiDg 
heavy soils friable and pervious to water. It also 
promotes the decomposition of vegetable matter and 
the formation of nitrates. A soil whose fertility has 
been impaired by an excess of organic matter can 
be rendered fertile by a large dose of quicklime. 
In some soils that are infested with insects an appli- 
cation of lime destroys them entirely at little expense. 
When applied in large quantities to clay land, it 
opens and loosens the clay and gives it a certain 
amount of porosity, and as a consequence it brings 
about further improvement by exposing a larger extent 
of surface to the action of the atmosphere. The 
quantity of lime applied to the soil varies with the 
purpose it is intended to serve. If lime is applied 
to destroy an excess of organic matter a large dose 
will be necessary, but when a soil is naturally defi- 
cient a far smaller dose will be sufficient. For ob- 
taining the fullest effects of lime, small doses at 
short intervals are very effective. Where the opposite 
course is adopted there is considerable waste and a 
gradually diminishing effect, as the natural tendency 
of lime is to sink down into the subsoil. A certain 
quantity of lime is dissolved and removed by drainage 
water, and the remainder in a few years sinks below 
the cultivated depth, or chemical changes take place 
which render it effete. On arable land, the plough 
for a season or two brings it back to the surface, 
but after a time it gets beyond the depth of the 
plough and is lost. This strong tendency of lime to 
sink into the subsoil shows us that when liming 
we should not plough the lime in, but keep it as 
near the surface as possible. The land should be 
ploughed first, then the lime spread and simply har- 
rowed in; Burnt lime is much more powerful in its 
action on vegetable matter than chalk or marl, it 
Bhould be used with discrimination Jest the humus 
of the soil be unduly diminished. Heavy clays or soils 
rich in humus are those most benefited by burnt lime. 
In reclaiming peat-bogs lime is of the highest value. 
The acid humic matter of the peat is neutralised by the 
lime, and the conditions are made suitable for the oxida- 
tion of the nitrogenous organic matter and the 
formation of ammonia and nitrates. The general effect 
of lime is to render available the plant food already 
in the soil without itself supplying any significant 
amount. Vegetable remains under peculiar circum- 
stances refuse to decay, and accumulate to 1 n injurious 
extent. This kind of vegetable matter is generally 
found in undrained or badly drained land. To remove 
this sour humus, lime is generally employed, which 
by acting upon the insoluble vegetable matter hastens 
its decay, and " sweetens, the laud" for by decay these 
materials furnish carbonic acid and other useful food- 
materials for plants. The lime thne converts a noxious 
ingredient into a source of fertility. Lime economises 
the use of potash ; for certain crops, where potash 
is not abundant in the soil, have to some extent 
the power of utilizing lime in its place. Lime also 
improves the quality of grain, grasses, and other 
crops, the finer grasses on certain lands refusing to 
grow until the land has been limed. It hasten 8 
the maturity of crops and checks the growth of 
moss and weeds in the soil. The effect of lime on 
the mechanical texture of many soils is also great. 
It pulverizes and lightens strong soils, at once im. 
proving their drainage and rendering them more easily 
tilled. It also improves the texture of light soils — 
provided an overdose be not applied — even when they 
contain but little organic matter. The avidity of 
lime for moisture added to the chemical changes 
brought about by it, have the effect of increasing 
the absorptive and retentive power of soils to a 
considerable degree. A deep soil requires a heavier 
dressing of lime than a shallow one, and deep till- 
age will call for larger applications than where the 
cultivation is shallower. A sandy soil requires less 
than a heavy clay, and 3oils poor in vegetable 
matter require less than soils which are rich in or- 
ganic matter. A small quantity of lime will have greater 
effect on drained land than a larger dose on wet or 
undrained land. Lime slakes best and quickest when 
laid down in small heaps and slightly covered with 
fine soil. This saves refilling and recarting. The heaps 
should be put down at equal distances apart so that 
when the lime is slaked, it could be spread out easily. 
There should not be too much magnesium carbonate 
present in a limestone, as it is considered less valuable 
for agricultural purposes. As I have said before, 
it is best to apply lime in small doses at short in- 
tervals rather than large doses at lcug periods, as 
Darwin has shown us that the action of earthworms tends 
to bury it. The weight of lime per bushel varies from 
75 lb. to neariy 1 cwt. according to the particular kind. 
The better it is burnt the lighter it is comparatively 
Pure varieties of limestone yield a little over 11 cwt. 
of burnt lime per ton. Lime should be applied as a 
rule to soils containing much clay or humus; not in 
close contact with nitrogenous manures such as dung 
or guano, as it sets free the ammonia, which is 
liable to escape into the air. But lime, since it Bets 
free plant food, tends to exhaust the soil, and " lime 
withe ut manure, will make both farm and farmer poor.''" 
The following are the chemical chaDges which lime 
passes in its application to land : — 
1st OaOOs. Pure limestone rock, calcium car- 
bonate before burning. 
