PDC LESSON 4.4 SOIL – HOW THICK IS YOUR TOPSOIL
PERMA COURSE AGRO-ECONOMY
PDC LESSON 4.4 SOIL – HOW THICK IS YOUR TOPSOIL
Are there any differences in colour and texture?
Mottled grey and rust brown streaks in the lower
horizons indicate leached acid soils and possible drainage problems.
Brown and red colours are from oxidised iron, a result
of acidity. Absence of horizons may indicate a very deep topsoil or a good
organic content.
Layers of different coloured clays are commonly found
in tropical soils.
Looking at your plant profile, how deep do the roots
penetrate?
How far down can you find worm tunnels or other
visible creatures? Note the depth of any compacted layer or hardpan were roots
end abruptly. (This is often found in soils that have been commercially farmed because
of much ploughing.)
The key component of soil vitality is the movement of
water, soil life, organic matter, air, and nutrients between the topsoil and
sub soil. The nature of the boundary between the two should be uneven, gradual
with channels made by plant roots well into the subsoil. If you can see that
then you have good dirt.
Text from the roots, Elisabeth Ferkonia
(Aus.) PDC studied with Bill Mollison,
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