Healthy Soils e-Brochure v9 Farmacy - Page 4

The Healthy Soils Concept
Good soil health is fundamental to agricultural productivity and sustainability.
Although soil health is predominately seen as a function of biological activity,
it is influenced by the dynamic interactions that occur between the physical,
chemical and biological components of the soil.
Chemical components
Biological components
Physical components
The impact soil chemistry has on
the development of plant microbe
interactions is particularly important.
During its conversion from plant
and animal residues to humus, soil
organic matter has a direct impact
on soil health.
The physical properties of a soil are
determined by the balance between
sand, silt and clay particles, which
results in texture and these particles
combine with organic matter to form
soil aggregates.
For example, limestone soils tend to
be rich in calcium and be alkaline, so
restricting the uptake of phosphorus
and manganese. This can reduce
root mass and limit root exudate
production, reducing both microbial
activity and response to microbial
growth promotion.
Soil chemical properties also regulate
microbial growth rates directly
through nutrient availability and will
affect the rate at which microbes
release available nutrients.
Fresh organic material provides a
food source for macro-organisms
such as earthworms, which mix
partially decomposed organic matter
with minerals as it passes through
them, creating channels for air and
water movement in the process.
Microbes thrive in worm casts
converting organic matter to available
nutrients and humus.
This results in increased soil fertility
and yield potential. Humus also
provides a long-term source of
energy and nutrients for beneficial
fungi and bacteria.
The size and distribution of these
aggregates determines soil structure,
which directly affects the movement
of air and water through the soil
profile. This affects biological
activity, root development, crop
establishment and tolerance to
environmental stress.

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