My last column included
a photo of an underweight baby. The sadness of this malnourished
child is a cry to the soil, for it is the soil that feeds the mother
and the mother that feeds the child. Our health ultimately depends
on the health and fertility of the soil we steward.
Traditional agriculturists understand that soil is the most important
aspect of crop support. The earth nurtures plants just as a mother
nurtures her child. Reliance on synthetic fertilizers, on the other
hand, sacrifices soil (the mother) by seeking to feed the crop (or
child) directly. Feeding the mother will automatically care for
In talking about composting to extension agents in Ghana, my goal
was to include scientific information while concentrating on practical,
traditional African composting methods. Composting aligns well with
traditionally held values in Ghana, and I emphasized that it was
an honored task, practiced by their forefathers.
As we assembled our compost pits, we enlisted the help and support
of the neighboring villagers. When we finished, we gathered in a
circle around the pile and I asked the participants to join hands.
Be grateful for a kind mother who nurtures grateful hearts; this
feeds our soul. Show your gratefulness to the source of life by
recognizing Earth as the Mother and taking care of Her. We promised
to share the bounty of the compost.
Then I asked each participant to press his or her hand into the
pile. This represented how each of us had put their hands and hearts
into this project. The hand is the gateway to the heart when our
labor represents our heartfelt emotions. These sentiments feed the
living compost on the nonphysical level.
Tropical soils: Challenges and opportunities
As I mentioned last time, about two-thirds of the world's tropical
soils are red acid soils, notoriously low in plant nutrients. In
Ghana, red acid soils constitute about 80 percent of the soil base,
and farmers complain that it is getting harder and harder to wrest
productivity from the land. Improving agricultural productivity
in Ghana and other tropical areas clearly depends on improving management
of red acid soils.
reasons to make and use compost
Dr. Paul shared his motivations for composting as part
of his presentation on the importance of soil health
and composts role in maintaining this health.
In a previous column I wrote about the ‘terra preta do Indio,’
or Indian black soils. These intriguing soils are derived from red
acid oxisols and ultisols, the oldest and generally least fertile
of all soil families. Unlike their parent soils, however, the Indian
black soils are extremely productive, and demonstrate the great
potential for transforming red acid soils by increasing their soil
organic matter content. Although we see eroding and deteriorating
soils in many parts of the world, we can take heart because not
only can this be stopped, it can even be reversed under what appear
to be the most limiting of conditions.
This is the essence of Robert Rodale’s concept of regenerative
agriculture. Regenerative agriculture is partly inspired by Sir
Albert Howard’s experience working with impoverished red acid
tropical soils in British colonial India. Modern windrow composting
is a variation on the "Indore Compost Method," refined
by Sir Albert from ancient Indian composting practices. In Africa,
we need to go beyond sustainable agriculture because with the present
poor resource base we will not be able to feed the growing population
just by being sustainable. Instead, we need to re-capacitate or
regenerate soils, farms, and communities. Sir Albert called this
the Law of Return--we must feed the soil properly if it is to feed
The Rodale Institute® farm in Kutztown, Pennsylvania, was founded
on worn-out agricultural soils that have now been regenerated. Through
organic farming methods such as the use of compost, cover cropping
and rotations we have not only sustained a thin, perishable soil
layer but built it to a point where we routinely surpass neighboring
Some soil scientists dismiss acid red tropical soils as being incorrigibly
unproductive. But these soils do have valuable qualities: in general,
they are deep, well drained and can be worked with machinery shortly
after heavy rains. Just as we cannot afford to have children left
behind in their educational experience, we definitely need to "leave
no soil behind" in the effort to support our growing world
From an agricultural development perspective, the question should
be: How do we most effectively convert acid red soils into black,
fertile soils? To a large extent, the answer is, by boosting organic
matter levels through the use of compost.
Organic matter neutralizes constraints of acid
Red acid soils exhibit both low fertility and potential toxicity
to plants. An acid red soil lacking in soil organic matter can solubilize
large amounts of metals, notably aluminum and manganese. When these
metallic ions dominate the soil solution, they block the absorption
and activity of essential nutrients such as calcium, resulting in
reduced yields or even crop failure.
Increasing soil organic matter can solve both of these problems together.
Native clay and humic materials both have an overall negative electrostatic
charge, so they are mutually repellant. Organic matter overcomes this
repellency by forming a stabilized product of native clay and humic
material, bridged together by polyvalent, positively charged ions
such as aluminum, iron, manganese and calcium.
||"Organic matter works to expand the
nutritional support potential of the soil, fostering more optimum
As the organic matter and clay complexes form, aluminum ions are
pulled out of the soil solution. Once aluminum is captured in an
insoluble complex of clay and organic matter, calcium absorption
and movement in the plant roots and tops is no longer impeded.
Besides eliminating nutrient interference, soil organic matter
itself serves as a rich source of nutrients for plant growth. Organic
matter works to expand the nutritional support potential of the
soil, fostering more optimum plant growth. It also allows more water
to penetrate the soil and remain there to be taken up by plants.
A soil optimized in organic matter helps protect plants from periodic
|High aluminum levels
in soil make it difficult for plants to put down healthy
When plants develop aluminum toxicity in an acid soil environment,
they look like someone cut off their root tips. The condition is
called terminal deficiency because it affects the outermost cells
and tissues. Blossom-end rot in tomatoes is a form of terminal deficiency.
(In humans the effects of insufficient calcium are as dramatic as
in plants--the breakdown of bone structure called osteoporosis.)
Tip necrosis due to insufficient calcium can result from the use
of ammoniated fertilizer or prevented by calcium fertilization.
Acidity from ammoniated fertilizers drives aluminum ions into solution,
interfering with calcium uptake and movement in plants. Adding calcium
can take aluminum out of solution and serve as a direct source for
plant nutrition. Calcium salts provided to the plant through foliar
applications, however, will have no effect on root health, because
calcium only moves upward within plant tissue.
Calcium plays many crucial roles in plant physiology, including
bridging and linking cells by interacting at cell walls and membranes.
Water availability, in turn, is critical to the movement of calcium
within plants--fluctuating water stress predisposes plants to blossom-end
rot. Soil organic matter, with its ability to buffer water fluctuations,
plays an important role in preventing water stress.
Although a calcium salt solution can remedy both aluminum toxicity
and calcium deficiency, calcium salts cannot help soil percolate
or hold water the way organic matter does. Knowing this, we can
understand aluminum toxicity as an induced calcium deficiency that
can be resolved by organic matter. Organic matter is the bulwark
of soil, maintaining both proper moisture availability and aeration.
No chemical salt can substitute for these functions.
From all of these perspectives, soil improvement with optimized
organic matter makes sense. Salts can in some instances remedy the
symptoms of soil infertility, but they provide none of the long-term
benefits of increased soil organic matter.
Black organic matter is the real green revolution
Conventional ammoniated fertilizers exacerbate existing soil acidity.
Ammoniated fertilizer does not feed soil organic matter but instead
stimulates decomposition, resulting in lower soil organic matter
content. The nitrogen component of conventional fertilizer has no
duration from season to season and requires similar or greater applications
for every crop, every season.
|"Compost improved soil organic matter
and nitrogen levels while simultaneously lowering nutrient losses
to ground and surface water."
The Rodale Institute's Compost Utilization Trial compared the effects
of fertilizer, raw manure and compost on crop productivity, soil
health, and environmental quality. Interestingly, although all approaches
were equally effective in optimizing crop productivity, compost
was the only approach that also improved soil health and environmental
quality. Compost improved soil organic matter and nitrogen levels
while simultaneously lowering nutrient losses to ground and surface
water. Compost also increased crop nutrient content. Fortunately,
composting is a traditional technology practiced throughout the
In Africa there is little infrastructure to support widespread
liming and other conventional agriculture approaches by small farmers.
As a result, concentrating on fertilizer “solutions”
leads to the problem Ghana's small farmers complain about: poor
soils becoming worse.
Raising soil organic matter opens the soil texture, allowing both
air and water to penetrate and stimulating soil microbial life.
In The Rodale Institute Farming Systems Trial, we have found that
improved soil organic matter levels can increase water penetration
by as much as 50 percent. This contributes to the ability of plants
to make do on limited water supplies. In many developing areas,
including northern Ghana, water is not optimized and improving the
soil is the best way to stabilize crop productivity.
As natural materials, soil organic matter and compost are very
complex in their composition and action. This complexity intrigues
and confuses scientists. There is no formula for humic material;
rather it exists as a mixed class of an infinite number of compounds,
representing a wide array of biological products from diverse organisms
and defying chemical definition.
"Man no be God"—and neither is
|Paul Hepperly and
the group of Ghanaian extension agents brought together
by Farm Serve, a program of Opportunities Industrialization
In the Western scientific method, a lot of emphasis is given to
how things work, their mechanism of action. The biological processes
at work in organic agricultural systems, however, are much more
complex than the simple actions of chemical salts.
If we limit ourselves to interacting only with things we completely
understand, we are left with a poor set of tools indeed. Often,
the things we do not understand are more powerful than the things
we do understand.
Many Western scientists simply do not want to deal with things
they don’t understand. Traditional knowledge allows for a
more humble approach, basing practice on experience even when the
mode of action is not completely understood.
It would be most unfortunate to select technologies of lesser potential
because we believe we understand them better. Rather than take that
limited track, we should put more effort on traditional processes,
which offer more even though they are less well understood.
Western technology is extremely powerful, but it should complement
indigenous knowledge, not replace it. Western scientific methods
need to be tempered by ethics, or the technological result will
ultimately be sterile.
Modern insecticides and fertilizers are examples of sterile technologies.
Both are also extensions of war technologies. The fact that we understand
precisely how they work does not obscure the fact that they were
designed to kill. We need values to reverse the problems we have
created with such technologies.
One of my favorite things I saw while I was in Ghana was a sign
on the side of a passenger van that read, “Man no be God.”
When man uses technology in self-serving and destructive ways, he
takes an ignorant and egotistical approach.
An unfortunate side effect of scientific endeavor is egoistical
thinking. Frequently, we know less about our actions and how they
affect natural balances than we think. As we eliminate pesky insects,
for instance, we also eliminate pollinators and other beneficial
Basing our crop production systems on poisons and attempting to
replace the soil life force with simple chemical salts are perfect
examples of science and technology running amok.
The Hippocratic Oath enjoins physicians to "first, do no harm."
Agronomists and other crop advisors should observe a similar rule.
Even many advocates of chemically intensive agriculture now understand
that substantial damage is being done to the environment.
It is better for us to work with nature and be aware of its greatness.
By casting life as the enemy, we set up a conflict against ourselves,
for we are part of the web of life. In truth, we will "win"
only if nature prevails, and we fall short of our goals.
composting for soil improvement in northern Ghana In the first
of this series, Paul describes a three-week volunteer effort to
help West African villagers learn about organic farming methods