after
explained.

[What is a sandy soil? A clay soil? A loamy soil? A marl? A
calcareous soil? A peaty soil?]

As the following names are used to denote the character of soils, in
ordinary agricultural description, we will briefly explain their
application:

A _Sandy soil_ is, of course, one in which sand largely predominates.

_Clay soil_, one where _clay_ forms a large proportion of the soil.

_Loamy soil_, where sand and clay are about equally mixed.

_Marl_ contains from five to twenty per cent. of carbonate of lime.

_Calcareous soil_ more than twenty per cent.

_Peaty soils_, of course, contain large quantities of organic matter.[P]

[How large a part of the soil may be used as food by plants?

What do we learn from the analyses of barren and fertile soils?]

We will now take under consideration that part of the soil on which
depends its ability to supply food to the plant. This portion rarely
constitutes more than five or ten per cent. of the entire soil,
sometimes less--and it has no reference to the sand, clay, and vegetable
matters which they contain. From analyses of many fertile soils, and of
others which are barren or of poorer quality, it has been ascertained
that the presence of certain ingredients is necessary to fertility. This
may be better explained by the assistance of the following table:

---------------------------+--------------+-------------+----------
In one hundred pounds. | Soil fertile | Good | Barren.
| without | wheat soil. |
| manure. | |
---------------------------+--------------+-------------+----------
Organic matter, | 9.7 | 7.0 | 4.0
Silica (sand), | 64.8 | 74.3 | 77.8
Alumina (clay), | 5.7 | 5.5 | 9.1
Lime, | 5.9 | 1.4 | .4
Magnesia, | .9 | .7 | .1
Oxide of iron, | 6.1 | 4.7 | 8.1
Oxide of manganese, | .1 | | .1
Potash, | .2 | 1.7 |
Soda, | .4 | .7 |
Chlorine, | .2 | .1 |
Sulphuric acid, | .2 | .1 |
Phosphoric acid, | .4 | .1-1/2 |
Carbonic acid, | 4.0 |