Aug,' 1, 1902.] Supplement to the '* Tropical Agriculturist." 
Ui 
But there are always associated with sand 
and clay (or, to use their scientific names, 
silica and hydrated silicate of alumina) certain 
impurities which are of the utmost importance, 
and it is to these impurities, Tiz,, potassium 
magnesium, calcium, iron, &c., derived from 
the original rocks from which the soils were 
formed) that the plant must look for its mineral 
food. 
Sand and clay are the ingredients which form 
the bulk of soiis. Lime or limestone is useful 
as supplying an element of plant food, but it also 
aids in the decomposition of organic matter, and 
thus helps to prepare the nitrogenous food of plants. 
Limestone generally contains as impurities plios- 
phates or sulphat* of lime, magnesia, &c., which 
are valuable as plant food, while it also has the 
effect of keeping soils in a friable (i.e., in an easily 
worked) condition. Humus or decayed organic 
matter is very important from a chemical point 
of view. As a mechanical agent it keeps soil 
open which would otherwise be stiff and gives body 
to lifht soils, while it is also an absorber and 
retainer of moisture. The ultimate products of 
the decomposition of humus are carbonic acid, 
ammonia and water, all yaUiable ngents in the 
nutrition of plants. A soil wholly composed of 
organic matter is as you well know |au unsatis- 
factory one for the cultivator. 
I have already given you an idea of what 
a typical soil should be, and it should be 
the aim of every cnltivator to bring his soil 
as near as possible to this type. Of the four 
most important ingredients of plant food (the 
available supply of which is liable to run short) 
viz., nitrogen, phosphoric acid, potash and lime : 
nitrogen is at its highest in peaty soils and at its 
lowest in sandy soils ; phosphoric acid is found 
most in a clay soil and least in a sandy soil ; 
potash is at its highest in clay and lime in 
calcareous soils, while both are very deficient in 
sandy soils. 
We have to look upon the bulk of soil as the 
element in which the roots of plants live— as 
fish live in water — and travel aboul in search 
of food and moisture. The actual nutriment 
is present in comparatively very small propor- 
tions, as will be seen from the following statement 
showing the percentage composition of a loamy 
soil :— 
* Organic matter and loss on heating 5*07 
Oxide of Iron 
3-63 
Alumina 
3-51 
Carbonate of Lime 
1-48 
Sulphate of Lime 
•34 
Magnesia 
•42 
Potash 
•30 
Soda 
•01 
Phosphoric acid 
•10 
Insoluble Silicates and Sand 
85-14 
100-00 
Containing Nitrogen 
•23 
^C[ual to ammouia . • 
•19 
THE AGRICULTURAL OUTLOOK IN 
SOUTH AFRICA. 
Mr, W, Willcooks, c.m.g , m.i.c.e., in a report 
on irrigation in South Africa addressed to II. E. 
Lord Milner remarks that the permanent develope- 
ment of the country will depend on irrigation and 
irrigation alone. The Colony, itis said, has remained 
strangely stationary, apart from the develope- 
ment of its gold, diamond and coal mines. Fifty 
years ago it was a j)astoral country importing 
cereal and dairy produce and even hay from 
foreign countries ; and it is the same to-day. 
Half a century ago it needed a farm of 5,000 acres 
to keep a family in decent comfort, and things are 
not altered since then. This is the picture drawa 
by the writer of the report. Except in the. south- 
west corner of Cape Colony, we are told, agri- 
culture has scarcely been attempted except on the 
most primitive lines and on insignificant areas. 
Farmers trek from the high velt to the low velt 
and back again with the seasons. And the reason 
of this want of developement of the agricultural 
resources of the country is said to lie in the 
fact that the rainfall of the three colonie?, 
with the exception of the south-west corner, 
is uncertain and erratic : it is constant 
and heavy in autumn, which is followed by 
a severe winter without any moisture in the air. 
As Mr. Willcooks pithily puts it — when rainfall is 
wanted it is not there, when it is not wanted it 
is invariably present ! For countries so situated 
the only possible means of developement lie, he 
thinks, issterageof water and irrigation. If these 
countries are ever to develope their immense 
agricultural wealth, we are told that they must be 
proclaimed a semi-arid region, and legislation 
framed accordingly. 
Mr. Willcocks goes on to refer to liis experience 
in the Indian and Egyptian Irrigation Departments, 
and points to the immense benefits derived from 
irrigation in these countries and in Italy. Referring 
to the Transvaal he remarks : — There the mineral 
wealth is extraordinarily great, but it is exhaust- 
ible — some say in 50, some in 100 years. It 
would be a disaster indeed if none of the wealth 
were devoted to the developement of agriculture. 
If the companies working the various mines 
were by decree required to devote a percentage 
of their gain to the execution of irrigation works, 
then when the mineral wealth of the county had 
disappeared, its agricultural resources would have 
been put on such a solid basis that the country 
will not have to fall from the height of prosperity 
to the depth of poverty. " The permanent deve- 
lopement of the agriculture of South Africa will 
depend on Iriigation and Irrigation alone." 
The plea is a strong one, and the prospect it 
hints at is bright, and we have no doubt 
that the wise men at the head of the new adminis* 
trfttion will not lose sight of the possibilities 
which irrigation can secure for the country. 
— 
BETEL CULTIVATION IN INDIA. 
In cultivating betel in the Madras Presidency 
the land is first planted with SesOania </randi- 
flora (Siu, liaturumurunga), and the cuttings o| 
