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sustainable agriculture & desertification

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  • adamhenne
    ... Desert ... drought. ... uncertainty ... sis.org.uk/desertification.php
    Message 1 of 1 , Mar 27, 2002
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      >Subject: [HEALTHE] fwd: Sustainable Agriculture Pushing Back the
      >Date: Mon, 25 Mar 2002 22:24:30 -0800
      >Sustainable Agriculture Pushing Back the Desert
      >Desertification - land degrading into desert - is often blamed on
      >mismanagement and misuse of land. Local people are allegedly guilty
      >of over-farming, over-grazing and allowing their populations to
      >exceed the environment's capacity. <mailto:ching@...>Lim Li
      >Ching contests this myth, describing how local farmers in arid Africa
      >are using innovative means to farm productively without destroying
      >the environment, and highlights some criteria for sustainable
      >If you wish to see the
      >document with references, please consider becoming a member or friend
      >of ISIS. Full details <http://www.i-sis.org.uk/membership.php>here
      >Debates concerning natural resources often pivot on a 'received
      >wisdom' about environmental change and people's role in this process.
      >In the case of the environment, the received wisdom is that people
      >invariably degrade natural resources. Outsiders, perceiving
      >environmental change as degradation, blame local land-use practices.
      >The dominant idea about desertification has been that dryland
      >environments are rapidly degraded by a combination of natural and
      >human factors. Desertification is defined as the degradation of
      >drylands, involving loss of biological or economic productivity and
      >From the 1930s, the blame was laid largely on the land use practices
      >of farmers and herders, and on increasing populations. This was
      >reinforced in the late 1970s and early 1980s, culminating in the UN
      >Conference on Desertification in 1977. Some scientists were uncertain
      >about the causes and extent of desertification, and expressed concern
      >at the lack of long-term data. Despite that, the Conference ended by
      >stating that desertification was threatening 19% of the earth's
      >surface, and that this threat came from increased intensity of land
      >use, overgrazing and inappropriate irrigation, exacerbated by
      >Such claims were reiterated by the UN Environment Programme, which
      >was the driving force for the UN Convention to Combat Desertification
      >(UNCCD), which entered into force in 1996. The rationale for the
      >Convention is that "over 250 million people are directly affected by
      >desertification, and some one thousand million (or one billion) are
      >at riskS. Over the past two decades, the problem of land degradation
      >in dryland regions has continued to worsen".
      >Yet, evidence has been mounting that some of these assertions are
      >unfounded. Most received wisdom on 'desertification' and 'land
      >degradation' assumes an equilibrium environment with linear
      >development. Thus, observations of expanding desert at certain
      >periods and certain locations are extrapolated as ongoing, even
      >accelerating, desertification.
      >For instance, work in northern Sudan that estimated the desert edge
      >had shifted 90-100 km southwards in 17 years, is often cited. Whilst
      >the period and location of the study was limited, it produced
      >widespread understanding that "the whole southern Saharan edge" was
      >expanding at a rate of 6 km a year. These results were later
      >In the first instance, there are in effect three related but distinct
      >phenomena - drought, dessication and dryland degradation - that have
      >been conflated in the term 'desertification'. On a continuum, these
      >have increasing time-scale effects and decreasing potential for
      >In particular, drought pulses are now seen as a key driving force of
      >dynamic ecological systems - droughts lead to variability in
      >ecosystem process and productivity, not its decline. And in many
      >cases, what was assumed as dryland degradation is actually a result
      >of drought, and can reverse quickly under normal rainfall.
      >Additionally, data from dry years were often compared with that from
      >wet years, ignoring longer-term climatic cycles. This led to an
      >interpretation of a decline in productivity, rather than a variation
      >in the response of natural vegetation or crops to soil moisture
      >The new understanding is that arid and semi-arid areas are
      >non-equilibrium environments, characterised by high levels of
      >temporal and spatial variability and therefore, are unpredictable and
      >uncertain. The critical indicator is a high coefficient of variation
      >in rainfall (30% or more). Rainfall doesn't follow regular patterns,
      >at least not in the short-term, and it affects variability of
      >patterns and amount of vegetation.
      >This dynamic conception of drylands is underpinned by changes within
      >ecological thinking - the 'new ecology' - that have suggested that
      >nature is in a state of continuous change. It contests conventional
      >ecology, which depicts nature as tending toward stability, with
      >notions of 'carrying capacity' and assumptions of a stable climax at
      >equilibrium i.e. if the carrying capacity is exceeded, deterioration
      >The 'new ecology' also involves a conception of historical time. Land
      >that appears 'degraded' may have already been that way long before
      >farming or grazing. Researchers might erroneously associate degraded
      >land with destructive human activity while knowing little of a
      >place's environmental history.
      >Dynamic ecological systems mean that ecological drivers are external
      >in dryland environments, and hence not necessarily subject to
      >density-dependent events. Instead, human livelihood adaptations in
      >these environments are very specialised; people are in reality
      >raising meat and crops under ecologically sound conditions.
      >New research reveals that in many of the poorest African countries
      >along the Sahara's edge, in Nigeria, Niger, Senegal, Burkina Faso and
      >Kenya, integrated farming, mixed cropping and traditional soil and
      >water conservation methods are increasing per capita food production
      >several fold, keeping well ahead of population growth.
      >For example, the use of sheep manure for fertiliser has allowed
      >increased yields for farmers in Kano, Nigeria. Additionally, planting
      >leguminous crops increases nutrient levels in the soil by fixing
      >nitrogen from the air. Integration of crops and livestock enhances
      >nutrient cycling - legumes and manure return to the soil what crops
      >take out.
      >A 4-year study in eastern Burkina Faso found that despite declining
      >rainfall since the late 1950s and increasing populations, there is no
      >evidence of land degradation connected to human activities nor a
      >decline in food productivity. Conversely, yields of many crops have
      >risen. The study found no proof of soil fertility decline over 30
      >Farmers have not achieved environmental sustainability through a
      >capital-intensive or high-tech path. In Burkina Faso, the increased
      >yields of sorghum, millet and groundnuts is hardly attributable to
      >increased external inputs, because these crops receive little
      >fertiliser and are largely based on hand hoe cultivation.
      >Farmers have a rich repertoire of soil and water conservation
      >technologies, such as crop sequencing, crop rotation, fallowing,
      >weeding, selective clearing, intercropping, appropriate crop &
      >landrace selection, adapted plant spacing, thinning, mulching,
      >stubble grazing, weeding mounds, paddocking, household refuse
      >application, manure application, crop residue application and compost
      >pits. They use many mechanical practices too.
      >Perhaps more important than the practices is the selective way they
      >are used, which vary with different field types, allowing optimal
      >adjustment of limited labour and inputs to the requirements of
      >different crops and soils. If land becomes limited, farmers do not
      >need to invent new management systems; they apply these soil and
      >water conservation practices more intensively, and only when and
      >where needed.
      >High local population densities, far from being a liability, are
      >actually essential for providing the necessary labour to work the
      >land, dig terraces and collect water in ponds for irrigation, and to
      >control weeds, tend fields, feed animals and spread manure. As
      >population densities increase, farmers intensify their cooperation
      >systems, grouping to tend each other's fields at busy periods,
      >lending and borrowing land, livestock and equipment, and swapping
      >seed varieties.
      >People thus invest heavily in creating and maintaining social
      >networks, such as land networks, labour networks, women's natal
      >networks, cattle networks, technology networks and cash networks.
      >Furthermore, in Maradi district in southern Niger, where repeated
      >droughts have wrought environmental damage, farmers have been
      >fighting back, and have actually reversed desertification. This is
      >also true of Machakos (renamed Makueni) district in Kenya. In the
      >1930s, British colonial scientists condemned the eroding, bare hills
      >of the drought-prone area to environmental oblivion. This narrative
      >was consistently reproduced in the 1950s and 1970s. Yet, while there
      >have been droughts, the hills are greener, less eroded and more
      >productive today than before, despite a fivefold population increase.
      >The local Akamba people had responded to the droughts by switching
      >from herding cattle to settled farming, giving them incentive to work
      >the land effectively.
      >"This is no high-tech breakthrough, nor a result of Western aid
      >programmes". A major reason for the overestimation of land
      >degradation is the underestimation of local farmers' abilities.
      >This demonstrates the importance of relying and building on local
      >people's knowledge and practices. Many external interventions have
      >usurped and undermined local systems of decision-making and resource
      >management. It's time to turn the received wisdom on its head, and
      >learn from local communities, instead of blaming them wholesale for
      >land degradation.
      >In light of all this evidence, a 'new realism' now exists about
      >desertification, which gives climatic variation equal footing with
      >human activities, as a cause. The UNCCD now takes care to point out
      >the reversibility of drought, the influence of climatic variation,
      >and recognises that the causes of desertification are complex, as is
      >the human-environment relationship.
      >Policies need to appreciate the inherent uncertainty in science.
      >'Opportunistic management', i.e. seizing opportunities to evade
      >problems, working within complex systems, adapting to instability and
      >exploiting environmental instability, is needed for dynamic
      >Dynamic ecological theory does not replace conventional theory but is
      >more appropriate in some contexts, such as in dryland ecosystems.
      >Environmental complexity doesn't lend itself to simple, linear or
      >reductionist technological fixes. Ecosystems are dynamic wholes and
      >sustainable agriculture works in tandem with these (see Box), as
      >local farmers in Africa are showing.
      >Sustainable agriculture
      >makes best use of nature's goods and services by integrating natural,
      >regenerative processes e.g. nutrient cycling, nitrogen fixation, soil
      >regeneration and natural enemies of pests
      >minimises non-renewable inputs (pesticides and fertilisers) that
      >damage the environment or harm human health
      >relies on the knowledge and skills of farmers
      >promotes and protects social capital - people's capacities to work
      >together to solve common management problems
      >depends on locally-adapted practices to innovate in the face of
      >contributes to public goods, such as clean water, wildlife, carbon
      >sequestration in soils, flood protection and landscape quality
      >If you wish to see the
      >document with references, please consider becoming a member or friend
      >of ISIS. Full details <http://www.i-sis.org.uk/membership.php>here
      >This article can be found on the I-SIS website at
      >The Institute of Science in Society <http://www.i-sis.org.uk/>
      >PO Box 32097,
      >London NW1 OXR
      >Tel: 44-20-8731-7714
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