Int. J. Water, Vol.
Copyright © 2010 Inderscience Enterprises Ltd.
Re-coupling the carbon and water cycles
by Natural Sequence Farming
Natural Sequence Farming Coordinator,
c/-Post Office Hardys Bay,
New South Wales 2257, Australia
Baramul Stud via Denman,
New South Wales 2328, Australia
Abstract: The techniques of Natural Sequence Farming (NSF) were developed
during hands-on management of degraded farmland in the Upper Hunter Valley
region of Australia. Early settlement of the continent by people with European
cultural assumptions disrupted established interactions of water, soil, and plants
resulting in lost fertility. Moreover, agricultural practices such as clearing,
burning, ploughing, draining, and irrigation, have implications for global
warming. Soils hold twice as much carbon as the atmosphere, and three times
as much as vegetation. But carbon in exposed soil oxidises releasing CO2 into
the atmosphere. NSF is designed to restore ecosystem functions by re-coupling
the carbon and water cycles.
Keywords: restoring landscape function; NSF; natural sequence farming;
water and carbon cycles; plants as heat valves; climate change.
Reference to this paper should be made as follows: Norris, D. and Andrews, P.
(2010) ‘Re-coupling the carbon and water cycles by Natural Sequence
Farming’, Int. J. Water, Vol.
Biographical notes: Duane Norris is Co-ordinator of the Natural Sequence
Farming movement in Australia. He holds degrees in Agricultural Science
and Sustainable Landscape Management from the University of Sydney, has
worked on rainforest ecology in Papua New Guinea and North Queensland, and
is currently engaged in writing a national syllabus on Natural Sequence
Farming for farmers, natural resource managers and landcare practitioners.
He co-edited the Conference Proceedings: Natural Sequence Farming:
Defining the Science and the Practice (2006), and has authored numerous
papers and blogs for the Natural Sequence Farming Forum.
Peter Andrews pioneered the conservation technique known as Natural
Sequence Farming (NSF). He lives in the Upper Hunter River region of
New South Wales, Australia, and developed his systematic analysis of how the
Australian landscape functions while working as a farmer and horse breeder.
Currently, he applies NSF principles in landscape consulting, and specialises
Re-coupling the carbon and water cycles by Natural Sequence Farming 387
in the restoration of degraded land, vegetation, and water systems. His aim is to
bring local ecosystems up to fertility levels existing at the time of European
settlement. He has authored two books on the NSF approach: Back from the
Brink (2006) and Beyond the Brink (2008).
1 Farming or mining carbon?
Loss of carbon from the land has been going on since the European settlement of
Australia began and today, according to one paper, these landscapes contain only
one-tenth of the amount of carbon they had 200 years ago (Wells and Prescott, 1983).
Moreover, it has been estimated that soils that once contained carbon matter 4000–10,000
years old, are now holding carbon that is only two years old. For when a farmer takes
cattle to market around 6% of land productivity has been removed by animal grazing,
and another 4% is lost to the atmosphere by oxidation from de-vegetated land (Andrews,
2006, p.116). This suggests that 90% of regenerative capacity remains. But most likely
only 20% of carbon matter is held each year, the rest being eroded and leached into the
sea by fast-running water flows (Ripl, 2010).
Whatever is in soil that makes it fertile has been put there by plants (Lal, 2009;
Andrews, 2006, p.32). Carbon is critical to soil health and plant fertility, but it is lost
through oxidation when a ploughed paddock is left fallow. More carbon is released when
grassland and trees are cleared. However, when vegetation is allowed to break down,
even if it is weedy cover, the carbon content of the soil is raised and growing conditions
improve. Plants make soil. Soil is sand and clay with plant material added. Careful water
management, planting, and mulch farming, can control this loss, but to be effective, land
management techniques must replicate the unique geographic logic of a continent.
The roles of water, plants, and soil in maintaining a landscape are each part of a complex
historically evolved system of interlocking cycles; a naturally occurring ‘design’ that is
fundamentally controlled by plants, in ways that is often beyond the capacity of humans
to fully comprehend.
The environment runs on energy and plants are the means of generating and
accumulating that energy. The primary environmental function of a plant is to extract
carbon from carbon dioxide in the air by photosynthesis. The green-surface area of a
landscape represents the ‘extractive and manufacturing’ capacity of that landscape,
and plant leaves, using the energy of the sun, mix carbon with water making sugars that
the plant needs to grow. Everything in the landscape including human food and energy
for human use depend on this process. The more a rainforest accumulates energy, the
greater diversity of plant species can live off the energy. Burn a forest and the energy
dissipates as carbon gas, so fewer plant and animal species can survive there.
Plants moderate the water cycle as well as the carbon cycle and serve as a bridge
between the two aspects of landscape productivity, regulating their interchange. Plants
have been termed ‘heat valves’ because of their evaporative cooling function, a process
described by Pokorný et al. (2010). Plants stabilise the distribution of water and carbon
on the Earth’s surface, and by physically slowing the movement of water, plants prevent
landscape entropy through loss of carbon matter in soil and debris to the sea. This is what
it means to speak of the coupling of hydrological and carbon cycles. As active managers
of natural functions, plants are neither an inconvenience to humans, nor a passive
388 D. Norris and P. Andrews
convenience – as implied in the political phrase ‘carbon sink’. The coupling of the water
and carbon cycle by plant transpiration and atmospheric evaporation is the largest transfer
of energy on the planet.
Natural Sequence Farming (NSF) is based on the restorative management of
biological functions such as these, and observations in the Australian context indicate that
the accelerated fertility decline of agricultural landscapes is brought about by deeply
gouged stream beds. Stream incision increases the erosive energy of water, leading to soil
and nutrient loss, reducing the capacity of a floodplain to hold water, lowering
underground water table reserves, and resulting in loss of wetland habitat within a valley.
NSF techniques use ponding and overflows from segmented reed beds to reduce stream
incision, so restoring flood plain sedimentation, ecological health, and retaining carbon
in the ground (Erskine, 1999).
2 Human impacts in Australia
Australia is a land of extremes. In terms of climate, it ranges from tropical to temperate.
Its weather patterns fluctuate from drought to ‘big wet’. In terms of landscape, it ranges
from rain forests to deserts. It has the oldest landscapes in the world, and it also has the
youngest. Indeed, given the highly erosive nature of the continent’s landscape,
an Australian floodplain may be no older than the last flood. Moreover, Australia’s
landscape is enormously dependent on biodiversity, one reason being that the land was
not occupied by humans until relatively recently. The arrival of Aboriginal peoples was
only 60,000 years ago, not long in geological time.
Prior to the arrival of Aboriginals, the Australian landscape supported a very different
kind of forest mix. In those areas of the continent that were forested the plant mix was
made up of palms and other Gondwana-like rainforest trees, gymnosperms including
conifers like Araucaria, and a variety of species including eucalypts. Human impacts,
first from Aboriginal communities, and then from European colonisers of the land, would
bring an end to this biodiversity. Today, eucalypts make up 90% of Australia’s forest,
since they have been better able to regenerate after fire and other environmental impacts
than almost any other plant (Singh et al., 1981; Andrews, 2006, p.150).
Archaeological evidence suggests that before Aboriginal peoples were living on
the Australian continent, the landscape rarely burned. The natural burn cycle may have
been as much as 300 years apart. Once human habitation was established, the burn cycle
appears to have shifted to every two or three years and this had a profoundly
transformative effect. Later, early European explorers would describe how Aborigines
burned vast tracts of land at a time while hunting, since animals fleeing from a bushfire
were easier to spot and kill. Burning also replaced old, dry vegetation with fresh,
green re-growth attracting kangaroos and other edible animal species (Hughes, 1981).
Other burns may have been accidental, since people carried fire sticks everywhere
(Cary et al., 2003). Forests that once covered much of Australia’s inland were almost
entirely destroyed. The destruction of vegetation in turn, very likely caused the
disappearance of mega-fauna. Finally, burning had another devastating effect. Without
vegetation to renew and sustain the topsoil, it was readily blown or washed away
exposing the clay layer beneath. The arrival of Europeans introducing inappropriate farm
practices and hoofed animal stock further reduced both biodiversity and soil cover.
Re-coupling the carbon and water cycles by Natural Sequence Farming 389
By the time Europeans arrived in Australia in the late 1700s, the landscape was
already in decline. Even so, by today’s standards it was still relatively rich in fertility.
One indication of this is the speed at which introduced animals like sheep, rabbits, rats,
and mice, multiplied. Within a few decades these numbered tens of millions. By 1891,
barely a century after farmers settled, Australia’s sheep population totalled 106 million
(Cathcart, 2009). A decade later there was severe drought across more than half the
continent. This was called the Federation Drought after the federation of Australian states
in 1901, although it really began in the mid 1890s and was at its worst in 1902. During
this drought, sheep numbers halved; but a little over 20 years later, they were 100 million.
All this is a measure of the health of the environment. Since then, intensive farming has
taken a heavy toll on Australian farmland and its fertility is poor. The continent is now
subject to encroaching desertification (Williams and Saunders, 2003). Australian farming
practices can be described as ‘mining carbon’.
Deserts throughout the world are a result of human intervention. In Europe, however,
these effects have been masked by the resilience of landscapes there. In Australia,
anthropogenic effects are magnified by extremes of climate as well as by the introduction
of cattle, goats, and camels. The eminent limnologist Professor Wilhelm Ripl from the
Technical University of Berlin has commented that if land managers in Australia learned
the lessons of this landscape, they would become international leaders in understanding
how the global environment functions (Ripl-Andrews, Personal Communication, 2005).
Australia is a laboratory for the world.
3 Observing the land: Peter Andrews’ story
As I explain in Back from the Brink (Andrews, 2006), my training is not a scientific one.
NSF is a practice that has developed from close observation and respectful interaction
with the land. I started out as a sheep farmer and racehorse breeder, and my interest in
land was driven by practical considerations. I wanted healthier, faster horses, and came to
realise that they had a better chance, if they grazed on paddocks with plenty of
biodiversity. This was quite a revelation to me at the time, and so I set out to find out
more about the inner workings of the landscape. I soon discovered that biodiversity
was only one of the vital keys to animal health and landscape sustainability. I next
moved on to investigate the formation of in-ground water reserves. Each of these
factors – biodiversity and inground water – is generally ignored by Australian farmers,
few of whom bother to maintain biodiversity on their land. To the contrary, many spend a
large part of their working lives applying artificial fertilisers, which act like a dose of
caffeine to the soil, leaving it exhausted afterwards. Others try to eliminate the weedy
growth that could help provide their land with functional stability and fertility.
Even fewer farmers make an effort to understand the movement and storage of water
below the earth’s surface.
An important scientific question arises from all this: If Australia’s landscape is poor
today as a result of human intervention, why was it fertile before humans arrived?
How did the continental ecosystem run so successfully for millions of years? My initial
assumption was that the answer to this should help reinstate the natural processes that
once kept the Australian environment and climate functioning. Finding the answer would
be a matter of reading clues in the landscape and working out how they related to each
other. I also cross checked my immediate observations with the historical record provided
390 D. Norris and P. Andrews
by early explorers. What I learned was that the Australian landscape had evolved by
sustaining itself with in-ground water. And that this hydrological process, through the
mediation of plants, balances the carbon cycle (Field, 2004).
This is how the system worked – and in some respects it is quite counter intuitive to
people educated to scientific premises imported from Europe and America. The explorer
Mitchell (1831), said that in Australia under natural conditions, water entered
higher-ground through a system of cracks, and sandy, gravelly, ‘recharge areas’.
This water was stored in the layer of clay that underlies much of the Australian continent.
On the plains, water travelled in creeks and rivers, but paradoxically these were elevated
above the surrounding land and formed more like ponds (Eyles, 1977). A true flood plain
was what its name suggests: a plain that was periodically flooded.
The rivers and creeks were not as seen today; they had not gouged out or excised
a channel that moved water quickly across the plain. Indeed, explorer Charles Sturt
commented that they are not rivers as in England, but more like channels adjoining broad
wetlands some 50 miles across (Sturt, 1828–1831). After a rain event, whenever there
was enough water in the system, the shallow rivers would spill out of the wetlands
and spread water across the plain on either side (Figure 1). It was these floods that slowly
soaked the flood plains. Australia has never had enough rainfall to drench the land
Figure 1 Courtesy Peter Andrews, Back from the Brink (2006, p.177)
Australia’s flood plain system, as it evolved, was too brilliant a system of water
management to have been humanly invented. Each flood plain typically consisted of
a chain of separate plains. If you were to have flown over an ancient flood plain system
from top to bottom, you would have seen that the valley housing the flood plain
alternately opened out to a wide expanse and narrowed to a relatively small channel, thus
dividing the flood plain into segments. These segments were arranged in steps, each a
little lower than the one before. At the bottom of each step, perched above the step below,
was a wetland full of reeds and other vegetation.
How did these wetlands originate? My hunch is that in many cases, the formation of
wetlands was triggered by a heavy dump of mulch that trapped other debris and
sediment beginning a build-up of carbon matter. Once the wetlands were established,
Re-coupling the carbon and water cycles by Natural Sequence Farming 391
water flowing down the system would be checked by reeds and have the erosive energy
taken out as it entered one of these wetlands. The clay was deposited where it was
trapped by plants so building new fertility. The ecological functioning of the flood plain
stands in marked contrast to the rapid erosive movement of water through an incised
4 The natural water cycle
In 1975 I took over a horse stud named Tarwyn Park in the Bylong Valley, a few hours’
drive north west of Sydney. The stud was located on an ancient flood plain, although the
stream that once supplied the plain with water now ran along the bottom of an eroded
channel and hardly ever flooded. I set about reinstating, in miniature, a simulation of the
old flood plain system as it once operated in Australia. Using a bulldozer and tractor,
I developed a stepped system with a small wetland at the bottom of each step, and
I installed pipes and channels to ensure the plain on either side of the stream was
In 1997, local and overseas scientists visited Tarwyn Park to assess the work I had
done. Among them was Haikai Tane, chief planner for Australia’s biggest river system,
the Murray-Darling, and Wilhelm Ripl from Berlin. I shared my conclusions about the
role of hydrology in the Australian landscape generally, and at Tarwyn Park,
in particular. Tane came up with an excellent description of the system, naming it a
broad-acre example of step-diffusion hydroponics (Andrews, 2006). Hydroponics is a
method of plant cultivation in which plants grow without soil, either in water with
dissolved nutrients, or in an aggregate material like gravel or sand, through which
nutrient solution flows. It is the second type of hydroponics that Tane had in mind when
he likened Tarwyn Park to a giant hydroponic system.
By my analysis, broad-acre step-diffusion hydroponics is what used to happen in the
Australian landscape generally. Water moved down from higher country through a series
of flood plain steps, diffusing through each wetland and filling the ground with water
laden with nutrients (See Figure 2). The further the water moved down, the richer in
nutrients it became. The plants grew and flourished in this slowly moving in-ground
water, just as they would in a hydroponic system. Today, human intervention makes the
Australian river system into a plumbing and drainage system. Water now runs down
gouged creek and riverbeds as if down a pipe, leaving the land on either side dry
The original flood plain system performed an essential function that was peculiar to
Australia: it ensured that sediment and fertility was filtered and thus retained on the land,
not washed out to sea. It is reasonable to surmise that, while inland Australia was still
forested and inland flood plain systems were still functioning efficiently, Australia’s
coastal strips were vegetated with sea grasses and mangroves, thanks to carbon leaking
from the inland. The coastal strip would have been trapping sand then, rather than losing
it, thus providing an evolving landscape rather than a degrading one.
It was streams that formed the flood plains. Most likely reeds growing densely on low
ground blocked the flow of the water and forced it onto higher ground. In ancient
Australia reeds grew in abundance almost everywhere (White, 2000). One of the most
widespread varieties is Phragmites australis known as ‘common reed’. English colonials
referred to it as elephant grass. This plant generally grows to a height of about three
392 D. Norris and P. Andrews
metres, although in some locations it can be three times as tall as that. The important
thing is that reeds grew in the lower, wetter, fertile areas. Typically, Australia alternates
between long, dry periods and short, very wet periods, so water usually comes in a rush.
When there was little or no flow, water would trickle through a reed bed. When the water
came in a rush, however, it would not be able to get through the reed bed, so it would
pond behind it. When the pond grew big enough, the water would escape by flowing
around the outside of the reed bed, which meant the water was now on higher ground.
This was a self-sustaining process, for once water was redirected to the high ground it
leached fertility from the soil there.
Figure 2 Courtesy Peter Andrews, Back from the Brink (2006, p.177)
The remains of elevated river and creek beds are an observable feature of the Australian
landscape. If you drive from Sydney to Bylong, you get views of the Hunter River
winding through the countryside, contained by its banks, but several metres above land
on either side. A river or creek flowing in an elevated channel above the surrounding
country is a sign of a healthy landscape, not just in Australia but everywhere. In any
landscape that is regarded as pristine, the water body is elevated at the level of the trees.
Conversely, where a river flows through a deeply incised channel, like the Zambesi River
in Africa, or the Colorado River in the USA, it is likely to be running through a desert.
Tane has noted similarities between this perched drainage system and representations
of floodplain ecosystems found in traditional Aboriginal artwork (Tane, 1997). The
segmented system of flood plains, with each step separated from the next by a narrow
channel guarded by a reed bed could work only if all parts did. As soon as one part of the
system failed to function, the whole system failed. However, as soon as farmers
introduced industrial agriculture and hoofed animals, the system failed – reeds were
poisoned or ploughed out, eaten or trampled. Australia’s indigenous animals are soft-
footed, a fact that was vital to the survival of the ancient flood plain system. Soft-footed
animals do not damage vegetation; hard-footed animals introduced for commercial
purposes do. Where reed beds had previously controlled the flow of water from one flood
plain step to the next, water now roared through and erosion began. Head-wall cuts began
running backwards, undermining watercourses. Without reeds to moderate flow, water
flowed quickly through the lower land. The old watercourses on higher ground were
Re-coupling the carbon and water cycles by Natural Sequence Farming 393
abandoned, although the ridges they formed still wind across the countryside, relics of a
time when plants managed the Australian landscape.
5 Environmental breakdown
The demise of the flood plain system was one of two environmental disasters to have
afflicted Australian landscapes. The other was the destruction of trees on high ground.
At countless locations around the country, trees on high ground were cut down or
otherwise destroyed, with the result that under-storey plants protected by trees
disappeared too. It was the fertility generated by trees and under-storey plants on high
land that fed the country below, including swamps, with nutrients. On average, trees shed
about one seventh of their mass each year, which means that a single tree standing in a
field with a mass of, say, 300 tons, can contribute up to 20 tons of mulch to that field
each year (Walter Jehne, Personal Communication, 2010).
The contribution of soil nutrients by a forest is considerable, and on high ground
these nutrients under force of gravity, work their way to the land below. Swamps then
process the sugars and other carbon matter that have seeped down, and when the next
flood comes these are spread over the landscape. Without trees and under-storey plants
existing above, swamps are starved of nutrients and become exhausted. In the absence of
native plants, weeds can be used temporarily to help reinstate this repair. This is not ideal,
but at least weeds help restore metabolic functions in the landscape, without which
metabolism, no plant will survive long.
In Australia, the destruction of native forests along the continent’s East Coast appears
to have had another serious consequence: it put an end to the so-called ‘biotic pump’
effect that previously ensured there was a net daily movement of moist air from the ocean
to the land. As a result, eastern Australia is markedly drier than it used to be. The ‘biotic
pump’ theory (Makarieva and Gorshkov, 2010) argues that a heavily forested coastal
strip is cooler than the ocean because during the day the forest fills with transpired water
vapour. When this vapour condenses, a lowered pressure in the forest attracts moist
onshore winds, creating an upward thermal thrust of moist air and inland rainfall.
Australian research suggests that desert areas in North Queensland are the effect of
rainforest clearing on the coastal strip (McAlpine et al., 2007; Shiel and Murdiyarso,
2009). This scientific observation is consistent with the cultural memory of local
Australia is not the only place in the world with environmental problems like these.
European scientists are equally concerned about landscape changes. For instance, where
spruce trees once grew at 15,000 feet, they are now struggling to grow above 3000 feet,
the reason being that it is now too cold above 3000 feet for the young spruces to survive.
Since forests in the high country have been thinned out, there are no longer enough trees
to moderate the temperature at night, and the young trees cannot cope with the extreme
cold (Lovelock, 2005). People cut down trees in high country for timber, not realising its
consequences for landscape in the low country where they lived. Trees are huge
accumulators of carbon fertility. They attract birds and insects, which leave droppings;
they attract sheep and cattle, which leave their dung; and they drop leaves and other
debris which produce fertility too. Biochar should never be considered a substitute for
natural biomass in the soil. Biochar is a burnt, inert, dead compound; one that may house
microbes in a wet climate, but will do nothing for a dry landscape.
394 D. Norris and P. Andrews
6 Hands-on solutions
The term NSF confuses some people, and most of the confusion is over the word
‘sequence’. People ask: what sequence do you have in mind? In Europe, the sequence by
which the landscape operates is seasonal. In Australia, the sequence is not nearly so
regular and it is not determined by seasons. The basic factors that control this landscape
are the carbon processing green surface area of plants and the water cycle, operating
together in an interrelated sequence of processes. The event that sets the sequence in
motion is rain. The key principle is re-coupling of the carbon cycle with the hydrological
cycle, which together have the capacity to promote landscape fertility, on the one hand,
and to moderate climatic extremes through evaporation, on the other.
Contouring the land, that is, building a bank along the line of a contour and creating
a channel behind it, is one restorative NSF technique. It enables a farmer to control the
landscape hydrology and use it to advantage. It helps distribute nutrients across the land
as far as contour channels extend. Essentially, it is a water management and fertility
management system. A farmer who contours is really installing a wetting cycle in the
landscape, mirroring the ecological cycle that existed earlier. This achieves mechanically,
what plants once achieved naturally. Humans cannot do it as well as plants did,
but certainly, contouring solves some of the landscape problems that Australians must
deal with, fertility and salinity foremost among them.
The Australian landscape flourished for millions of years operating under a system
that, notwithstanding extremes of climate, ensured the continent’s sustainability.
But currently, it is a landscape in decline. Too many Australian farmers are wedded to the
idea that they can clear and then spray a paddock ready for cropping, that is, kill
everything growing there, and that nature will stand still until the crop is sewn months
later. Fertility is lost as long as that paddock is bare, and the landscape is depleted every
day as the sun burns away non-living plant matter; or wind blows it away; or water
washes it away. Obviously Australians cannot turn the clock back 100,000 years to
recreate the continent existing before humans started disrupting it. This would
mean retrieving the millions of tons of material that have been eroded out of the land
and carried to the sea. The natural regulating mechanisms that used to exist, most
notably wetlands, cannot be replaced. It is possible, however, is to reinstate the
functionality of the ancient landscape with processes that simulate the systems which
were active long ago.
The authors would like to thank Professor David Mitchell of Charles Sturt University for
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