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Desember 2014
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Conservation agriculture tour
to the USA
– a reflection and key messages
F
rom 23 to 29 June this year, the 6th World Congress on
Conservation Agriculture (WCCA) took place in Winnipeg,
Canada and gave nearly 400 participants from 51 countries,
including a South African delegation of nine (six officials and
three producers), the opportunity to learn from and network with
an international gathering of agricultural experts on conservation
agriculture (CA).
According to the WCCA, agricultural production systems are
not sustainable unless they are profitable, and CA holds the key
to building and maintaining healthy soils and profitable farming
systems.
After the conference, a three and a half day Dakota no-till tour took
delegates through the heart of no-till farming areas of the north
Midwestern USA. Delegates heard from producers who have been
practicing no-till crop production for over two decades.
According to the United States Department of Agriculture (USDA),
managing to obtain soil health can be accomplished by:
Disturbing the soil as little as possible.
Growing as many different species of plants as can practically
be done.
Keeping living plants in the soil as often as possible.
Keeping the soil covered all the time.
Manage more, disturb less
Tilling the soil is the equivalent of an earthquake, hurricane,
tornado and forest fire occurring simultaneously to the world of soil
organisms. Simply stated, tillage is bad for the soil.
Physical soil disturbance is destructive and disruptive to soil
microbes and creates a hostile, instead of hospitable, place for them
to live and work.
The soil may also be disturbed chemically or biologically through
the misuse of inputs, such as fertilisers and pesticides. This disrupts
the symbiotic relationship between fungi, micro-organisms and
crop roots. By reducing nutrient inputs, we can take advantage of
the nutrient cycles in the soil to supply crop nutrients and allow
plants to make essential associations with soil organisms.
Diversify with crop diversity
Sugars made by plants are released from their roots into the soil
and traded to soil microbes for nutrients to support plant growth.
The key to improving soil health is assuring that the food and energy
chains and webs include as many different plants or animals as
practically possible.
Biodiversity is ultimately the key to the success of any agricultural
system. Lack of biodiversity severely limits the potential of any
cropping system, resulting in the increase of disease and pest
problems. A diverse and fully functioning soil food web provides
nutrients, energy and water cycling that allows a soil to express its
full potential.
Grow living roots throughout the year
There are many sources of food in the soil that feed the soil
food web, but there is no better food than the sugars exuded by
living roots.
Soil organisms feed on sugar from living plant roots first. Next, they
feed on dead plant roots, followed by above-ground crop residues.
Lastly, they feed on the humic organic matter in the soil. Healthy
soil is dependent upon how well the soil food web is fed. Providing
plenty of easily accessible food to soil microbes helps them cycle
nutrients that plants need to grow.
Keep the soil covered as much as possible
Soil should always be covered by growing plants and/or their
residues, and soil should rarely be visible from above.
Soil cover protects soil aggregates from “taking a beating” from
the force of falling raindrops. A mulch of crop residues on the soil
surface suppresses weeds early in the growing season giving the
intended crop an advantage. They also keep the soil cool and moist
which provides a favourable habitat for many organisms that begin
residue decomposition by shredding residues into smaller pieces.
Observations during the CA tour
to the USA
General observations
Producers visited in North (ND) and South Dakota (SD) have a long-
term view or vision to:
build natural resources (soil), which is their big concern or focus
(not yield); and
cut down on external inputs as far as possible.
As Mr Gabe Brown from The Brown Ranch, near Bismarck (ND), said:
“We must remove all synthetic fertilisers to be truly sustainable,
which will require very high levels of soil health.” Some producers
in the USA have indeed managed to remove synthetic fertilisers for
many years.
ON FARM LEVEL
World Congress / CA
Conservation agriculture
Definition of soil health:
The continued capacity of the
soil to function as a vital living
ecosystem that sustains plants,
animals and humans.
Soil Renaissance Plan, USDA
HENDRIK SMITH,
CA facilitator, Grain SA