turn enhance soil structure, water
infiltration and root penetration.
Chemical cycles in soil, such as the
carbon and nitrogen cycles, are
driven by microorganisms. When
soils are regarded as a biologically
active system, one can understand
that soil disturbance by tillage
would disrupt the normal activity of
microorganisms.
According to the FAO definition, CA
systems should involve minimum or
low levels of soil disturbance using
no-tillage and direct seeding. If soil
is disturbed, the disturbed area
should be no more than 15 cm
wide, or less than a quarter of the
total cropped area. For instance, if
practices such as strip tillage are
followed, the tilled area should be
less than 15cm wide, or the undisturbed area between the strips
should be more than 75% of the
total cropped area. The same principles apply for tine planters.
Organic soil cover
Another key management practice
which form part of conservation
agriculture, is residue management
and/or cover crops. Residue retention in the long-term can improve
soil structure, nutrient cycling and
could be an effective measure of
weed control. Moreover, it protects
the soil from erosion, prevents
Crop rotation have a direct
influence on the soil life. A
diversity of crops in rotation
through years add a different quality of soil organic
matter and active C to the
soil. Cultivate at least three
crops in rotation to reap the
most benefits.
evaporation and retains water. A
moist soil environment supports
microbial functioning and therefore
supports processes enhancing soil
quality. Residue retention also buffers soil temperature fluctuations. A
bare soil in the Western Cape can
easily reach 60ᵒC on a normal summer’s day, and may even become as
hot as 80ᵒC under certain conditions. Most beneficial soil microorganisms cannot survive such extreme temperatures. When soil is
covered with organic material such
as crop residue, mulch or a living
cover crop, the soil is prevented
from heating to such extremes.
During the planting season, these
processes facilitate faster adaptation to optimum planting conditions and protect the seed from
temperature and moisture extremes. The FAO specifies that a soil
area of which less than 30% is covered (measured immediately after
planting), is not considered as CA.
Crop rotation
Crop rotations hold in many benefits. One of the biggest essential
benefits is that it helps to control
many soil borne-disease problems,
such as sclerotinia and black-leg in
canola. Although not always the
case, rotations also can also help
control insects and weeds. Crop
rotation is one way to spread the
workload during the season and
therefore reduce the risk associated
with drought or wet conditions,
and pressure from pests or diseases.
One of the main beneficial effects
of including a leguminous crop in
cereal and/or canola rotations is to
reduce N inputs in the subsequent
grain crop. Crop rotation can therefore improv e crop yield potential.
Crop rotation also have a direct influence on the soil life. A diversity
of crops in rotation through years
add a different quality of soil organic matter and active C to the
soil. This, in turn, support a diversified soil microorganism population.
A diverse soil life will enhance the
system’s resiliency. These advantages can be substantial. It may
provide a basis for a profitable
cropping systems.
The FAO specifies that crop rotation
should involve at least 3 different
crops. However, repetitive cropping
is not an exclusion factor, for instance a wheat-wheat-canola-barley
-system could still be classified as
CA, although there are two subsequent years of wheat production.
To summarise, CA could be applied
to all agricultural systems and land
uses. It could also be locally
adapted to practices followed in a
specific situation. Therefore, exter-