Page 9 - Our Land

OUR LAND 9
It can take anything from several decades to 1 000 years
to grow a centimetre of topsoil and healthy soil is vital to a
resilient, food-secure country, writes Mandi Smallhorne
High-potential arable land by province
he dust storm that engulfed the Kraft
family on the national road as they
drove home from their holiday in the North West
Free State in January 2016 was so thick 1%
they couldn’t see 2m in front ahead of 4%
Tthem; they were forced to pull into a
garage and wait it out.
The dust clouds barrelling across the parched
province’s fields, which should have been green with
mealies at least waist high, were reminiscent of 21%
scenes from the Dust Bowl disaster in the US during
the 1930s.
Back home in Johannesburg, the Krafts’ neighbour,
a soil scientist, showed them the red dust that had 46%
settled on his patio: “That’s Free State fines,” he said,
using a term for a kind of topsoil.
THE LIFE UNDER US 22%
Topsoil is the top layer of the soil – it can be
anything from centimetres to metres deep – in which
life happens; the roots of plants burrow deep, 5%
sending out fine, furry side branches that interact Mpumalanga
with bacteria, insects and fungi in the soil. These are
the living creatures that break down organic matter Limpopo
(such as manure) and minerals, and enable the plant
to feed on them. Source: Bureau for Food and Agricultural Policy
Under natural conditions, this dense matting of
roots and microorganisms also stabilises the soil, and Arable soils for rain-fed agriculture
the spongy nature of good, healthy topsoil soaks up
rainfall, reducing the risk of floods, retaining water (in areas that are dependent on rainfall)
just where plants need it and boosting the storage of
groundwater. High potential
One other vital service that healthy topsoil Moderate potential
performs is that it is full of carbon. Hendrik Smith, a Marginal potential
soil scientist at Grain SA, says organic carbon, is “the
fabric of healthy soils”. So there is a win-win
equation here – if we can store more carbon in our
soil, we will have healthier and more resilient soil,
and we will also be acting to counter climate change.
When human activities disturb the soil, via actions
such as overgrazing, land clearing or continuous
monoculture cropping, the topsoil becomes very
susceptible to water and wind erosion, says Garry
Paterson, a soil scientist at the Agricultural Research
Council’s (ARC’s) Institute for Soil, Wind and Climate.
And when, as happened in the Free State from 2014
to last year, you add to the mix a prolonged drought
and high temperatures that desiccate plants and suck
all moisture from the soil, conditions are ripe for the
dense dust storms the Krafts saw. 0 2 50 500km
Storms whip up the precious topsoil and can
deposit it far away (during Dust Bowl storms in the Source: Bureau for Food and Agricultural Policy Graphics24 for farmers to protect the soil.
Midwest, topsoil travelled half a continent across the
US to land in thick layers on ships in the New York
Harbour). 12
LOSING THE LIFE
Topsoil is life; it is what grows our food, whether
in the form of the plants we eat or the plants that THE PERCENTAGE OF
feed our livestock. It can be considered a SA’S LAND THAT IS
nonrenewable resource and, under natural conditions,
it can take anything from several decades to 1 000 SUITABLE FOR CROP PRODUCTION
years to grow a centimetre of topsoil.
Smith says we are losing it much faster than it is
produced naturally to windstorms, erosion and other
land uses. 13
In South Africa, it’s often said we lose 13 tons of
topsoil per hectare of mealies harvested, but that’s a
raw average. Paterson says losses range from five tons THE NUMBER OF TONS, AS A RAW
to 25 tons in some of the more fragile areas.
“If you look at satellite photos after heavy rains, AVERAGE, OF TOPSOIL WE LOSE FOR
you can see brown stains spreading out into the EACH HECTARE OF MAIZE HARVESTED
ocean – that’s silt and minerals washed down our
rivers.”
We don’t have much land to play with in the first
place. Of the approximately 1.2km 2 million that is 70
South Africa, only 12% is suitable for crop production
– and less than a quarter of that (22%) is high-
potential arable land. THE PERCENTAGE OF SA’S
Water is the main constraint. Paterson says there is
good soil for agriculture in parts of North West and LAND THAT IS ONLY SUITABLE FOR
the north-western Free State, but very little available LIVESTOCK AND WILDLIFE GRAZING
water.
Close to 70% of our land area is suitable only for
grazing, be it for wildlife or livestock.
Quite a significant chunk of land that is good for 26
farming could be considered precarious, either in
Mpumalanga, where it lies over highly desirable
underground coal seams, or in rapidly urbanising THE PERCENTAGE OF HIGH-POTENTIAL
areas. Paterson points out that, “although it’s the
smallest of the provinces, Gauteng has the highest ARABLE SOIL LOST TO MINING AND
percentage of good soils”. At present, however, there’s PROSPECTING IN MPUMALANGA BY 2012
still good open farming land on the outskirts of
Gauteng worth preserving – towards Bapsfontein or
Vereeniging and Carletonville, for instance.
Eastern Cape According to a Bureau for Food and Agricultural
Policy pilot study back in 2012, 46.4% of our high-
Free State potential arable soils are in Mpumalanga.
1% “The potential loss of maize production to current
mining activities and activities in the near future
amounts to 284 844 tons per annum. A further 162 736
tons of maize could be lost from the prospecting
Gauteng areas that in future could also be transformed,” the
authors wrote, calculating that this could, over time,
push the price of mealies and mealie meal up
significantly.
Mpumalanga can be seen as food security
insurance for South Africa because it is resilient to
drought – and a changing climate means we’ll be
seeing more droughts. The sad news is that “high-
potential soils that are mined will never be
rehabilitated”.
At the time the study was done, Mpumalanga had
KwaZulu- probably already lost about 26% (225 217ha) of its
Natal high-potential arable soils to mining and prospecting.
And it can’t really be restored.
“It’s like putting a wedding cake in a tumble drier
and then trying to make use of what comes out,”
Graphics24 says Paterson.
Contrary to earlier beliefs, you can’t replace topsoil,
and the damage done by opencast mining to the
water table compounds the overall damage to
agricultural potential.
WHAT WE CAN DO
If our soil is so crucial and so hard won, is there
anything we can do to save it? Yes, as it happens,
quite a lot.
First, we can use the extensive information that is
available from the ARC and other organisations to
assess the land we’re considering buying or using – is
agriculture feasible, and what kind? Would mining or
development destroy good soil?
Secondly, we can demand more responsibility and
accountability from our government. Mining-affected
communities, environmental social justice activists
and even mining companies themselves have all
demanded more stringent application of laws and
regulations pertaining to the environment. Civil
society should understand that this could affect our
food and water security too, and join them.
Thirdly, we can suggest that government tighten up
on laws such as the Conservation of Agricultural
Resources Act to include some kind of duty of care
Finally, we can get behind organisations like the
ARC and Grain SA in supporting the application of
conservation agriculture.
This is a method of farming that does not plough
up the land, tearing the topsoil; instead, it drills into
the topsoil to drop individual seeds into relatively
undisturbed soil. It keeps a layer of mulch or growing
plants on the land at all times and it looks to
diversify farms, running livestock and planting a
range of crops instead of just one.
Conservation agriculture not only preserves soil
from erosion, it also actively grows topsoil, and
that is something we are going to need in a
precarious future.
SOIL SAVIOUR
Cocky Mokoka invested in a no-till plough in 2007
and switched his entire 1 000ha farm in the Vaal area
to conservation agriculture, with 300ha under crops
and livestock running on the rest.
“The secret is a cover crop,” he explains.
This prevents evaporation of precious moisture and,
if you choose the right cover crop, it can fix nitrogen
in the soil, reducing your need for chemical
fertilisers.
“And you need to plant diverse crops. You need to
move away from this mono, mono, mono,” he adds,
referring to huge swathes of land all under a single
crop in regimented rows.
Initially, it’s expensive to invest in the machines,
but, after a few years, your input costs start to
drop (less fertiliser, herbicides, pesticides and even
diesel for your equipment) and your soil springs back
to life.
The little community of microorganisms and
insects starts doing its job again, the soil retains
water better, it stashes away carbon and the whole
ecosystem becomes more resilient.
. This article is part of a series on climate and
food security. It was made possible with the support
of the African Academy of Sciences