seed and seedling emergence.
CA impact
Conventional farming practices around the
world has unfortunately been the culprit when
it comes to poor soil and water preservation.
This is due to improper soil use, practising
monoculture and the reliance on tillage tools.
These inadequate technologies, not adapted
to site specific needs, leaves the soil bare and
pulverized, exposing the soil to be carried
away by heavy rains. This ultimately results in
a gradual loss of soil and soil fertility, leaving
the land unproductive. Eroded, unproductive
and abandoned land, as well as the signs of
desertification across the world, is a silent
testimony.
The question now is, how do we turn this
around? Can it be reversed? The answer is yes
and lies in the implementation of the three
CA principles: low soil disturbance, residue
retention and diversity through crop rotation.
When the soil is covered by living plants and/
or plant residue, the plant biomass absorbs
the impact energy of raindrops and the drops
brake up into smaller droplets, which flow
gently to the soil surface and here it infiltrates
into porous and undisturbed soil. In this way
the sealing-off of soil pores is prevented,
erosion is minimised and even eliminated.
Once disturbance of the soil is limited, soil
structure can be rebuilt through the build-
up of soil organic matter and carbon. The
aim is to rebuild the soil structure, which we
eliminated through tillage, in such a way that
the porous aspect is returned. Think of it as
building an apartment complex underneath
your feet. Just like an apartment consist of
rooms of varying sizes, soil has larger and
smaller pores or spaces where water can
AgriKultuur |AgriCulture
be stored. This stored water, along with the
cover provided by the biomass, prolongs the
effective use of water by crops, especially
in drier climates, drive the soil biology and
some much more positive outcomes driving
productivity. The effectiveness of infiltration
and water holding capacity will increase over
time as organic matter increases in the soil.
Research conducted in Brazil showed that the
percentage of soil covered with plant residues
is the most important factor that influences
water infiltration into the soil. They showed
that soil with a 100% cover accepted nearly all
the water from a rain simulator delivering 60
mm/hour, but in the case of bare soil, between
75 and 80% of the water was lost as runoff.
Other researchers also obtained similar results
(Derpch, 2004).
Conclusion
Soil erosion is not only caused by water,
but wind also plays a huge role. Just think
about the dust storms seen in the Free State.
Conservation Agriculture, using no-till or zero
till, offers the most effective and affordable
way to control soil erosion and ultimately
achieve sustainable agriculture.
References
Derpsch, R., 2004. Understanding the process
of Soil Erosion and Water Infiltration. Special
Publication. No-till on the Plains Inc.
Lal, R., 1982. Management of clay soils for
erosion control. Tropical Agric., 59 (2). 133 –
138.
Meyer, L.L. & Mannering, J.V., 1967. Tillage and
land modification for water erosion control.
Amer. Soc. Agric. Eng. Tillage for Greater Crop
Production Conference. Proc. Dec. 11-12, 1967,
58- 62.
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