Sustainable rice production in african inland valleys

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Sustainable rice production in African inland valleys: Seizing regional potentials
through local approaches
Article  in  Agricultural Systems · January 2014
DOI: 10.1016/j.agsy.2013.09.004
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Rodenburg et al., 2014. Sustainable rice production in African inland valleys: seizing regional potentials through local approaches. Agricultural Systems 123, pp 1-11.
– 1 –
This paper has been published in Agricultural Systems. Please cite this paper as:
Rodenburg, J, SJ Zwart, P Kiepe, LT Narteh, W Dogbe, MCS Wopereis, 2014. Sustainable rice
production in African inland valleys: seizing regional potentials through local
approaches. Agricultural Systems 123, pp 1-11.
The original document can be found at:
http://dx.doi.org/10.1016/j.agsy.2013.09.004
Review
Sustainable rice production in African inland valleys:
seizing regional potentials through local approaches
Jonne Rodenburga1
Sander J. Zwartb
,
Paul Kiepea
,
Lawrence T. Nartehc
,
Wilson Dogbed
,
Marco C.S. Wopereisb
a
Africa Rice Center (AfricaRice), East and Southern Africa, Dar es Salaam, Tanzania, P.O. Box 33581
b
Africa Rice Center (AfricaRice), Cotonou, Benin, 01 BP 2031
c
Food and Agriculture Organization of the United Nations (FAO), Viale delle Terme di Caracalla 0153, Rome, Italy
d
Savanna Agricultural Research Institute (SARI), P.O. Box TL 52, Tamale. Ghana
1
Corresponding author: Tel. +255 222780768; +255 688425335; j.rodenburg@cgiar.org (J. Rodenburg)

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ABSTRACT
With an estimated surface area of 190 M ha, inland valleys are common landscapes in Africa. Due to
their general high agricultural production potential, based on relatively high and secure water
availability and high soil fertility levels compared to the surrounding uplands, these landscapes could
play a pivotal role in attaining the regional objectives of food security and poverty alleviation. Besides
agricultural production, i.e. mainly rice-based systems including fish-, vegetable- fruit- and livestock
production, inland valleys provide local communities with forest, forage, hunting and fishing resources
and they are important as water buffer and biodiversity hot spots. Degradation of natural resources in
these vulnerable ecosystems, caused by indiscriminate development for the sole purpose of agricultural
production, should be avoided. We estimate that, following improved water and weed management,
production derived from less than 10% of the total inland valley area could equal the total current
demand for rice in Africa. A significant part of the inland valley area in Africa could hence be
safeguarded for other purposes.
The objective of this paper is to provide a methodology to facilitate fulfilment of the regional
agricultural potential of inland valleys in sub-Saharan Africa (SSA) such that local rural livelihoods are
benefited and regional objectives of reducing poverty and increasing food safety are met, while
safeguarding other inland-valley ecosystem services of local and regional importance. High-potential
inland valleys should be carefully selected and developed and highly productive and resource-efficient
crop production methods should be applied. This paper describes a participatory, holistic and localized
approach to seize the regional potential of inland valleys to contribute to food security and poverty
alleviation in sub-Saharan Africa. We analyzed over a 100 papers, reference works and databases and
synthesized this with insights obtained from nearly two decades of research carried out by the Africa
Rice Center and partners. We conclude that sustainable rice production in inland valleys requires a step-
wise approach including: 1) the selection of ‘best-bet’ inland valleys, either new or already used ones,
based on spatial modelling and a detailed feasibility study, 2) a stakeholder-participatory land use
planning within the inland valley based on multi-criteria decision making (MCDM) methods and using
multi-stakeholder platforms (MSP), 3) participatory inland-valley development, and 4) identification of
local production constraints combining model simulations and farmer participatory priority exercises to
select and adapt appropriate practices and technologies following integrated management principles.
Key words: lowlands, wetlands, integrated crop management, water management, biodiversity,
participatory approaches, sustainable development, weeds, soil fertility, land use planning

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1. INTRODUCTION
Inland valleys can be defined as seasonally flooded wetlands comprising valley bottoms (fluxial) and
hydromorphic fringes (phreatic) but excluding river flood plains (Figure 1; Table 1). With an estimated
land area of 190 M ha (FAO, 2003) inland valleys are abundantly available in Africa and serve a multitude
of ecosystem functions. Inland valleys, in particular the valley bottoms - bas-fonds, fadamas, inland
swamps in West Africa; mbuga in East Africa and vleis, dambos, mapani, matoro, inuta or amaxhaphozi
in Southern Africa according to Acres et al. (1985) - generally have a high agricultural production
potential due to their relative high and secure water availability and soil fertility (Andriesse et al., 1994).
The hydromorphic slopes of the inland valleys are often used for dryland rice and cash crops like cotton,
while the upper slopes, with lower groundwater levels (Figure 1), are often grown by high value fruit
trees, like mangos and cashew nut, and fodder crops (Balasubramanian et al., 2007), and the crests by
maize or sorghum (e.g. Lawrence et al., 1997). The ground cover provided by these trees and crops on
higher parts of the slope reduces soil run-off towards the hydromorphic slopes and valley bottom (e.g.
de Ridder et al., 1997; Rodenburg et al., 2003). The only major food crop that can be grown under the
temporary flooded conditions of these valley bottoms is rice (e.g. Andriesse and Fresco, 1991).
Depending on the species (O. sativa or O. glaberrima), sub-species (japonica or indica) and cultivar, this
crop can be grown along the upland – lowland continuum (e.g. Saito et al., 2010). The development of
inland valleys into rice-based production systems, can be accomplished with relatively small-scale
technologies that would require moderate investments (Roberts, 1988). For this reason, inland valleys,
comprising such huge and yet largely unexploited area, are strategically important for the development
of the African rice sector (e.g. Sakurai, 2006; Balasubramanian et al., 2007).
Figure 1. Schematic landscape presentation of rice production environments along the upland – lowland
continuum, and their hydrological regimes (Adapted from: Windmeijer and Andriesse, 1993)

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Table 1. Rice growing ecosystem characterization (water supply, agro-ecological zone and main
biophysical production constraints); inland valleys may cover the whole range from hydromorphic
fringes to irrigated lowlands.
Sources: Andriesse et al. (1994); Kiepe (2006); Thiombiano et al. (1996); Wopereis et al.(2007).
Wetlands, such as inland valleys, are particularly important assets for the rural poor as they can fulfil
many services (Turner et al., 2000). Apart from agricultural production, these ecosystems supply local
communities with a range of goods, including hunting, fishing, forest and forage resources (e.g. Roberts,
1988; Scoones, 1991; Adams, 1993) and they are local hot-spots for biodiversity (Chapman et al., 2001).
As different inland-valley ecosystem functions may conflict with agricultural objectives, and because
there are large area-specific differences in development suitability and risks, indiscriminate
development should be avoided (McCartney and Houghton-Carr, 2009). Ecosystem functions of inland
valleys, such as biodiversity and water buffering, are affected when inland valleys are used for
agriculture. Where developments are implemented without proper impact assessments, they can
negatively affect local livelihoods and environments (e.g. Whitlow, 1983). Indeed, aligning food
production with biodiversity conservation is an important future challenge for agronomic and
environmental research (Verhoeven and Setter, 2010). Following the above, the central aim of this
paper is to develop an approach to fulfil the regional agricultural potential of inland valleys in sub-
Saharan Africa (SSA) such that local rural livelihoods are benefited and regional objectives of reducing
poverty and increasing food safety are met, while safeguarding other inland-valley ecosystem services of
local and regional importance.
A number of useful frameworks have recently been proposed to characterize wetlands for their
agricultural and ecological potentials in order to make informed decisions on their use (e.g. McCartney
and Houghton-Carr, 2009; Kotze, 2011; Sakané et al., 2011). As a step forward compared to earlier
methods specifically targeted to inland valleys, such as the ones proposed by Andriesse and Fresco
(1991) and Andriesse et al. (1994) that were primarily based on biophysical and land use
characterizations, these approaches combine biophysical with socio-economic characteristics. The next
step forward is to integrate these characterizations in a comprehensive methodology, supported by
appropriate tools, that runs from selection of the most suitable inland valley for agricultural production
to the actual development and eventually to sustainable management practices. Such methodology
should also provide guidelines on how to ensure participation of local stakeholders in all these stages.
The current paper, focussing specifically on sustainable realization of the inland-valley potential for rice-
based production systems, attempts to do just that, as we believe that for the sustainable development
Ecosystem Upland Hydromorphic fringes Rain-fed lowland Intensified lowland Irrigated lowlands
Main water
supply
Rainfall Rainfall + water table Rainfall + water
table + unregulated
floods
Regulated floods Full irrigation
Agro-ecological
zone
Guinea savannah –
humid forest
Guinea savannah –
humid forest
Sudan savannah to
humid forest
Sudan savannah to
humid forest
Sahel to humid
forest
Main biophysical
production
constraints
Drought, Weeds,
Pest & Diseases, P
and N deficiency,
Soil erosion, Soil
acidity
Drought, Weeds, Pest &
Diseases, P and N
deficiency, Soil erosion
Soil acidity, Iron toxicity
Drought/flooding,
Weeds, Pest &
Diseases, P and N
deficiency,
Iron toxicity
Drought/flooding,
Weeds, Pest &
Diseases, P and N
deficiency, Iron
toxicity
Weeds, Pest &
Diseases,
Salinity/Alkalinity, P
and N deficiency,
Iron toxicity

– 5 –
of these ecosystems, the site selection, land use planning and design, development and resource
management should follow a participatory, integrated and systematic approach. We aim to provide a
framework for such an approach based on a review of the literature and insights obtained from recent
research carried out by the Consortium for the Sustainable Use of Inland Valley Agro-Ecosystems in Sub-
Saharan Africa (short: Inland Valley Consortium, IVC) and its convening organization, the Africa Rice
Center (AfricaRice). The IVC, composed of twelve West-African national agricultural research systems
and a number of international (AfricaRice, IITA, ILRI, IWMI, FAO, Worldfish and CORAF) and advanced
research institutes (CIRAD, Wageningen University), was founded in 1993 with the objective to develop,
in concerted and coordinated action, technologies and operational support systems for the intensified
but sustainable use of inland valleys in Sub-Saharan Africa.
2. CURRENT INLAND VALLEY USE
2.1. Drivers for inland valley use
There are no reliable figures about the percentage of the total inland valley area (190 M ha)
currently under rice production in sub-Saharan Africa. Andriesse et al. (1994) were only able to provide a
rough estimate for this area in West Africa (10-25%) and this estimate includes inland valleys in peri-
urban areas that are mainly used for vegetable production due to proximity of markets (e.g. Erenstein,
2006; Erenstein et al., 2006). The share of inland valley area under rice or rice-based production systems
in the whole of Africa, hence including the central, eastern and southern parts, is expected to be much
lower. Inland valleys are, however, increasingly used for agricultural production, partly driven by the
drought spells in the 1970’s (e.g. Niasse et al., 2004), and following declining soil fertility in the uplands
due to unsustainable farming practices (Windmeijer and Andriesse, 1993). Valley bottoms and
hydromorphic fringes generally have higher water availability and higher soil fertility levels compared to
upland soils (e.g. Andriesse et al., 1994; van der Heyden and New, 2003), even though soil fertility is still
often suboptimal to sustain high crop productivity. Rice yields in rain-fed upland rice systems in SSA are
currently around 1 t ha-1
(e.g. Rodenburg and Demont, 2009) and production years should be followed
by 3-7 years of fallow to maintain soil fertility and control pests, diseases and weeds (e.g. Becker and
Johnson, 2001a). With good management, inland valley rice can produce 5-6 t ha-1
without the need for
such unproductive fallow periods required in the uplands (Wakatsuki and Masunaga, 2005).
Global changes have also given a new impetus to inland valley development. While there are a
number of conflicting projections with respect to the severity, timing and geographic distribution of
future wetting and drying (e.g. Cook and Vizy, 2006; Hoerling et al., 2006; Biasutti et al., 2008), model
forecasts suggest changing and increasingly variable precipitation patterns in Africa resulting in less rain
in the Sahel (Giannini et al., 2008) and more in the equatorial zones (Christensen et al., 2007). A secure
harvest from a wetland produced crop becomes of invaluable importance in the increasingly dry and
unreliable agricultural environments (e.g. Scoones, 1991; Sakané et al., 2011). However, because of the
sensitivity of inland valley systems to changes in quantity, quality and frequency of water supply, climate
change also poses an hydrological threat to these ecosystems, requiring adaptive management
strategies (e.g. Erwin, 2009).

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Besides the aforementioned biophysical assets, inland valley development also has a clear economic
driver. About 10 million tonnes of milled rice, approximately 40% of the annual regional consumption, is
imported into Africa (mainly from Asian countries) each year, worth about US $5 billion (Seck et al.,
2010; 2012). Regional production has, however, increased steeply since the early 2000s due to a
declining availability of global rice stocks for export, and consequently an increase in regional farm-gate
prices from an estimated average US $285 per tonne in 1999 to US $564 per tonne in 2009 (Based on
available data from 20 rice-producing countries in sub-Saharan Africa; FAO, 2010). These significant
price changes have encouraged many small-scale farmers to take up rice production, as reflected in an
increased inland valley use (e.g. Sakurai, 2006).
2.2. Multi-functional character of inland valleys
Apart from their importance for agriculture, mainly rice and maize production and horticulture
(Sakané et al., 2011), inland valleys have essential ecosystem functions such as biodiversity
conservation, water storage, local flood and erosion control, nutrient retention and stabilization of the
micro-climate (Adams, 1993; Wood et al., 2013). These environments are also used for recreation and
tourism and for retrieving clay and sand for crafts and construction, and for collection and use of forest,
wildlife, fisheries and forage resources and they contribute to local cultural heritage (Dugan, 1990;
Adams, 1993). Inland valleys are important locations for local communities to collect non-agricultural
plant resources, and rural people generally recognize useful plant species and dispose knowledge on
their use, abundance and collection places (Rodenburg et al., 2012).
Due to their multifunctional character, inland valleys are attractive for exploitation and therefore
vulnerable to degradation. The economic opportunities of inland valleys have been widely recognised
and investments have indeed been made to make these areas better accessible and profitable.
Indiscriminate development of these vulnerable environments will however lead to degradation of the
natural resources they harbour, and thereby jeopardize their unique and divers ecosystem functions
(e.g. Dixon and Wood, 2003). The trade-off between conservation of natural resources and agricultural
land use is particularly critical in African wetlands (e.g. McCartney and Houghton-Carr, 2009; Wood et
al., 2013) and therefore, any development activities in such ecosystems need to be planned with care
and should only be implemented when participation of the local users is guaranteed. Until recently, the
importance of wetland functions for local communities have, however, often been ignored in policy
planning (Silvius et al., 2000; Wood et al., 2013). Understanding the use and management of ecosystem
functions by local communities would be the first necessary step to generate recommendations for their
sustainable use (Rodenburg et al., 2012). Different ecosystem services do not necessarily conflict. For
instance, agricultural fields can be considered as important locations to find useful non-cultivated plants
too (Rodenburg et al., 2012). Farmers recognize the useful weed species during weeding and leave them
untouched or keep them apart after uprooting (see references in: Rodenburg and Johnson, 2009) and at
field clearing useful species (predominantly trees) are often maintained (e.g. Leach, 1991; Madge, 1995;
Kristensen and Lykke, 2003). In fact this is a common strategy to cope with declining forests (Shepherd,
1992). Other strategies, observed by Rodenburg et al. (2012) around inland valleys in Togo and Benin,
include the establishment of a community garden with useful species and the conservation of a small
community forest. These observations show that local communities depending on natural resources in

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and around inland valleys are able to exploit these landscapes synergistically, balancing agricultural
production with biodiversity conservation, use and management.
3. CONSTRAINTS TO DEVELOPMENT AND USE OF INLAND VALLEYS IN AFRICA
3.1. Development constraints
Inland-valley utilization efforts are driven by the aforementioned environmental and economic
motives but mired by health and cultural constraints. Traditionally, inland valleys were not often used
for agricultural production purposes in Africa (Adams, 1993; Verhoeven and Setter, 2010). This is partly
because inland valley bottoms are difficult to manage and they are also often associated with water-
borne diseases such as malaria (e.g. Plasmodium falciparum, P. malariae, and P. ovale), river blindness
(onchocerciasis; vector: Onchocerca volvulus, source: Wolbachia pipientis), bilharzia (schistosomiasis;
Schistosoma haematobium and S. mansoni) and sleeping sickness (trypanosomiasis; Trypanosoma brucei
or T. brucei rhodesiense) (e.g. Gbakima, 1994; McMillan et al., 1998; Yapi et al., 2005). And even
controlling such diseases is no guarantee for profitable (agricultural) exploitation of these environment,
due to counteractive policies (e.g. unfavourable tax regulations, cheap food imports) and the lack of
suitable technologies (McMillan et al., 1998).
Many water management infrastructures built in the 1970’s have been abandoned. Such failures are
thought to have resulted from the lack of local community participation during selection, design and
planning of the developments (e.g. Dries, 1991; Maconachie, 2008), or because traditional local land-
tenure arrangements were overlooked (Brautigam, 1992). In the 1960’s and 70’s many irrigation scheme
developments in West Africa were funded by public investment corporations and development projects.
The Benin-China Cooperation, for instance, developed a total of 1,400 ha inland valleys and flood plains
into medium-sized (25-150 ha) irrigation schemes by equipping them with water retention structures,
irrigation and drainage canals, inlets and outlets, cofferdams and small bridges. Most of these irrigation
schemes are currently under-utilized or abandoned. One of the exceptions is the irrigation scheme of
Koussin-Lélé, where farmers grow rice on 106 ha developed land using gravity irrigation. A comparison
between this scheme and the nearby mostly unutilized schemes of Bamè and Zonmon (33 and 84 ha
respectively) showed that careful selection of the valley and local stakeholder participation in planning,
design, implementation and use of the developments are prerequisites for successful development
efforts (Djagba et al., 2013).
The socio-economic environment in inland valleys is highly variable and complex. Inland valley
exploitation is also often complicated by unfavourable land tenure arrangements (e.g. Thiombiano et al.,
1996; Fu et al., 2010; Oladele et al., 2010) or prohibiting customary beliefs. Land tenure arrangements
vary between locations and range from ownership by states to ownerships by individuals. The most
common ways in which farmers in inland valleys in Africa acquire ownership over land is through
inheritance, marriage, or through renting, lease or sharecropping (Oladele et al., 2011). When farmers
lack stable land ownership the incentive for longer-term investments is usually low and this in turn is
likely to have a negative effect on productivity and sustainable resource management. Farmers working
in the inland valleys do often not possess the rights over the land and are therefore not always
benefiting from inland-valley development investments. Land tenure arrangements also often affect
gender relations. Land is mostly owned by men but cultivated by women, in particular when the value of

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the land is low due to, for example, low soil fertility or lack of control over water. Upon development,
when the value of the land is raised, men can claim their rights again. Such social constructions should
be considered when inland-valley development projects are designed that aim at benefiting the poor
and empowering disadvantaged groups like women. In the Pegnasso inland valley in south-east Mali, for
instance, the French Development Cooperation deliberately opted for a partial rather than a complete
development (Abdoulaye Hamadoun, personal communication). The logic was that large investments
would increase the land value whereby women, using the land prior to the development, would risk
losing access, and would not benefit from the project. The modest improvements (a small water
retention structure, one central inlet and bunded plots) enabled farmers to make better use of the
available water for a prolonged period of time and thereby increase rice productivity. As rice production
in this inland valley is locally mainly the responsibility of women the project succeeded in its mutual goal
to benefit the community while strengthening the position of women.
As inland valleys in Africa are socio-economically and biophysically diverse and complex (Sakané et
al., 2011) the development of these landscapes for crop production requires a flexible and careful
approach (e.g. Andriesse et al., 1994), with actively participating stakeholders.
3.2. Production constraints
Estimated actual rice yields in inland valleys across Africa (1.4 t ha-1
according to Rodenburg and
Demont, 2009) are much lower than the attainable yield, i.e. the potential yield limited by the available
water and nutrients in a given environment (Rabbinge, 1993), achieved under optimal management
conditions (5-6 t ha-1
according to Wakatsuki and Masunaga, 2005). Based on a survey among rice
scientists in eight countries in West Africa weed competition, poor soil fertility and diseases, were
classified as the three most important biophysical production constraints, responsible for these low
actual yields in inland valleys (Thiombiano et al., 1996; Table 1.).
Dominant weeds in inland valley rice are grasses like Echinochloa spp. and Oryza spp. (wild rice),
sedges such as Cyperus spp. and a variety of broad-leaved weeds like Sphenoclea zeylanica, Ludwigia
spp. and Heteranthera callifolia (Rodenburg and Johnson, 2009). Another emerging problem in inland
valleys across Africa, in particular the ones with poor water control, is the parasitic weed Rhamphicarpa
fistulosa (Rodenburg et al., 2010) causing crop yield losses in infested farmers’ fields to exceed 60%
(Rodenburg et al., 2011). Other important biotic production constraints in inland valleys are diseases
such as Rice Yellow Mottle Virus (RYMV), leaf blast, bacterial leaf blight and brownspot. RYMV, endemic
to Africa, is transmitted by beetles (order Coleoptera, family Chrysomelidae) and can lead to total yield
losses ranging from 5 to 100% in rain-fed lowland rice in Africa (Kouassi et al., 2005). Pests such as
insects (e.g. African rice gall midge, stem borers and rice bugs) and rodents and birds can also cause
significant yield losses (Balasubramanian et al., 2007). African rice gall midge, common in both West and
East Africa, damages rice tillers causing up to 65% yield loss (Nacro et al., 1996). It should be emphasized
that none of these pests and diseases is restricted to inland valleys alone. If these ecosystems are to be
put under production, however, one should find effective ways to deal with them.
Low soil fertility is a general production constraint in inland valleys despite enrichment caused by
soil deposition of silt and fine clay factions through runoff from the surrounding uplands (Ogban and
Babalola, 2003) increasing the exchangeable bases (Kyuma, 1985), calcium and magnesium (Fagbami et

– 9 –
al., 1985) and phosphorus contents (Ogban and Babalola, 2003). Soil fertility in these environments is
often far from optimal for sustainable and profitable crop production. While soil fertility varies across
agro-ecological zones (Issaka et al., 1997), studies on soil fertility in inland valleys across West Africa
revealed low to very low levels of nitrogen, available phosphorus, pH, CEC and total carbon (Issaka et al.,
1996), deficiencies in micro-nutrients like sulphur and zinc (Buri et al., 2000) and poor clay mineralogy
(Abe et al., 2006). A commonly associated problem with low soil fertility in inland valleys is iron toxicity
(Becker and Asch, 2005; Audebert and Fofana, 2009). This is a complex nutrient disorder caused by
excessive iron in the soil solution under the specific but typical water-logged conditions of rain-fed and
irrigated lowlands, in particular inland valleys (Narteh and Sahrawat, 1999). Direct and indirect effects of
iron toxicity can lead to 40 to 45% rice yield reductions in lowlands but this can be mitigated by effective
water and soil fertility management and by selecting tolerant cultivars (Audebert and Fofana, 2009).
Lack of inputs, credits, water control and labour, were the most important institutional and socio-
economic constraints mentioned in the survey of Thiombiano et al. (1996). These constraints are all
inter-related and also closely related to the main biophysical constraints. Most farmers working in inland
valleys in Africa are resource-poor subsistence farmers (Balasubramanian et al., 2007). Such farmers
generally have limited financial means and monetary surpluses (e.g. Ismaila et al., 2010) and they would
need credits to purchase inputs. Indeed, for resource-poor rice farmers, the financial means or level of
credits often determines the level of inputs, such as fertilizer (Donovan et al., 1999), necessary to
alleviate the negative effects of biophysical production constraints. Without access to credits, inputs are
difficult to obtain and labour inputs will have to increase to avoid crop losses. This labour trade-off is
most obvious in weed control. Weeding is by far the most time-consuming practice in rice cultivation in
inland valleys and the time can be significantly reduced when farmers have access to herbicides (e.g.
Lawrence and Dijkman, 1997) or, presumably, when they have control over water, as flooding is one of
the most effective weed control practices (e.g. Rodenburg and Johnson, 2009).
4. TOWARDS SUSTAINABLE INLAND VALLEY DEVELOPMENT AND EXPLOITATION
While regional food security is an important goal, and agricultural production from already exploited
as well as new inland valleys can contribute to this, the selection, development and exploitation of these
environments should be approached with care. Not all inland valleys are necessarily suitable for crop
production (e.g. Kotze, 2011; Sakané et al., 2011). Crop production derived from the valleys that are
suitable, would be enough to contribute significantly to the region’s food security, in particular when
ways are employed to increase productivity and resource-use efficiency. The remainder of the valleys
should be safeguarded for non-agricultural ecosystem services such as pastoralism, biodiversity and
wildlife sanctuaries and natural (excess) water buffers. To illustrate this, if the regional average rice
yields in inland valleys could be raised by only 1 t ha-1
through improved water and weed management
(as shown by Becker and Johnson, 2001b), the current total continental rice production and imports
could hypothetically be covered entirely by production from only 9.1% of the estimated total land area
of these landscapes in Africa (Table 2), and hence more than 90% could be conserved. Future increases
in rice demand should be accounted for by a further increase in productivity. In reality significant rice
production is also derived from other rice growing environments, such as uplands and river flood plains

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(Balasubramanian et al., 2007; Seck et al., 2012), hence the 90% of inland valleys that could be saved for
other purposes, can be considered as a lower limit.
Table 2. Estimated inland valley area (and percentage) needed to cover the total paddy demand of Africa,
calculated as a sum of total rice import and production (based on 2010 figures), assumed that mean productivity
can be increased by at least 1 t ha
-1
following improved water and weed management
Estimated figure Calculation
Milled rice import in Africa (2010) 10 M t
Conversion rate paddy-milled rice 0.6
Equivalent paddy quantity of imported rice in Africa (2010) 16.7 M t 10 ×
1
0.6
Paddy production in Africa (2010) 24.7 M t
Total paddy demand in Africa (2010) 41.4 M t 16.7 + 24.7
Current productivity 1.4 t ha
-1
Productivity (paddy) increase with improved water and weed
management
2.4 t ha
-1
Inland valley area needed for total paddy demand in Africa 17.25 M ha
41.4
2.4
Total inland valley area in Africa 190 M ha
Share of total inland valley area in Africa needed to cover total
paddy demand
9.1 % 100 ×
17.25
190
Sources: Becker and Johnson (2001bb); FAO (FAO, 2003, 2012); Rodenburg and Demont (2009); Seck et al. (2010).
Indeed, such a strategy requires systematic approaches and methodologies for 1) characterizing and
selecting the ‘best bet’ - most suitable and least-risk - inland valleys for agricultural development to
avoid investment failures or unnecessary destruction of wetlands, 2) participatory multi-stakeholder
land use planning within the inland valley, 3) designing, implementing and evaluating the ‘best-fit’ –
locally adapted and communally managed - water management development infrastructure and 4)
optimizing - and locally adjusting - crop management practices for increased (rice) productivity.
Proposed tools for each step are summarized in Table 3.
4.1. Selecting suitable inland valleys
The selection and characterization of suitable inland valleys is of vital importance for successful
agricultural development interventions. This accounts both for new, unexploited valleys as well as for
valleys that are already (partly) used for crop production. Suitability depends on a wide range of socio-
economic and bio-physical factors that require investigation before proceeding to following steps.
Pioneering work on assessing inland valley systems and their potential for development has been
conducted by Andriesse et al. (1994) who proposed a comprehensive agro-ecological characterization

– 11 –
on four levels: ‘macro’ (1:1,000,000-1:5,000,000), ‘reconnaissance’ (1:100,000-1:250,000), ‘semi-
detailed’ (1:25,000-1:50,000) and ‘detailed’ (1:5,000-10,000). At the first level (macro), the major agro-
ecological zones are distinguished based on the length of the growing period. They are then sub-divided
into agro-ecological units and sub-units at the ‘reconnaissance’ level. This subdivision is based on
information on lithology, hydrology, soils and climate using Geographic Information System (GIS) tools
(e.g. Narteh et al., 2007) and land use statistics retrieved from national sources and rapid rural
appraisals. This methodology was further elaborated by Thenkabail et al. (2000) who used various
spatial data sets of soil, cropping seasons, roads, population density, discharge and rainfall data in
combination with maps on land use and inland valleys classified from satellite images. Each of the spatial
layers was given a certain weight based on expert knowledge, and by summing these weights inland
valleys with high potentials were identified. This approach of spatial modelling was later repeated for a
research area in Ghana (Gumma et al., 2009). Experts outlined bio-physical, technical, socio-economic
and eco-environmental indicators that affect the potential for development. But data scarcity for the
indicators as well as the debatable justification for the quantification of the weights make the
methodology inaccurate and subjective. Random Forests (RF) procedures, a classification method based
on a decision-tree, may provide an alternative for the aforementioned methods as it does not require
prior knowledge or assumptions about the relationships of, or interactions between, the variables and
distribution of the data (Breiman, 2001). Random Forests procedures were successfully applied to assess
the potential for paddy rice cultivation in Laos using predictors on topography, climate, accessibility and
demography and poverty (Laborte et al., 2012).
Remote sensing or remote-sensing derived products have been used to map inland valleys. Simple
image classification has been used in Benin (Thenkabail and Nolte, 1996), Ghana (Gumma et al., 2009)
and Cote d’Ivoire (Thenkabail et al. 2000) to classify images with good results. Thenkabail and Nolte
(1996), Gumma et al. (2009), and Chabi et al. (2010), identified inland valleys using the normalised
difference vegetation index (NDVI) determined from satellite images, and a slope map generated by GIS
software using a digital elevation map. Cloudy conditions are, however, prevalent in most regions and
this inhibits the implementation of such methodologies on national or regional scales. Recently,
AfricaRice developed an automated mapping procedure based only on information from a digital
elevation model, which is globally available at a spatial resolution of 30 meters. This standardized
methodology is currently being implemented and validated for the entire West-African region (Zwart
and Linsoussi, personal communication). Such spatial modelling tools are helpful in the first necessary
assessment of availability, suitability and locations of inland valleys and will save project developers or
policymakers valuable time and resources.
However, the application of spatial modelling, using GIS and remote sensing, can only provide an
indication for the development potential of inland valleys. Soil fertility and soil depth are of great
importance for this purpose as well, but information on such soil characteristics are not widely available
in maps with sufficient detail and cannot be derived with remote sensing techniques. Alongside
biophysical and agronomic assessments, socio-economic variables such as availability of markets,
extension services or social customs are important to assess which valleys can be developed for
agriculture (e.g. Narteh et al., 2007) and many of these can simply not be mapped and must therefore
be assessed using terrain surveys and feasibility studies.

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Table 3: Essential steps and tools for selection, planning and implementation of sustainable inland valley
development.
The Working Wetland Potential (WWP) index (McCartney and Houghton-Carr, 2009) is a
comprehensive assessment tool that can be implemented at the valley scale to assess its suitability for
agricultural development. It consists of assessments on: 1) the ecological potential, 2) the social and
economic importance, 3) the agricultural suitability and 4) the environmental and socio-economic risks
involved in the actual development. The product of ‘suitability’ and ‘risk’ scores based on these
assessments results in the WWP index which provides an indication of the agricultural use-potential of
an ecosystem. The ‘best-bet’ inland valleys for rice production should score high on (agricultural)
production and marketing potential and low on environmental and social risks, and preferably also low
on other ecosystem functions such as biodiversity. Hence a thorough assessment of the valley’s
economic value for local communities, including direct, indirect and non-use benefits is required
(Scoones, 1991) as well as an environmental systems analysis of upstream - downstream impacts from
developments.
Step Proposed tools Purpose Key references
1. Selecting suitable inland valleys Remote sensing/GIS analysis/spatial
modelling
To identify inland valleys and assess
development potential at national level
(Thenkabail and Nolte, 1996;
Thenkabail et al., 2000)
Random Forest method To assess agricultural potential (Laborte et al., 2012)
Detailed agro-ecological survey To determine the suitability for
agricultural development
(Andriesse et al., 1994)
Working Wetland Potential index
(WWP)
To determine the suitability for
agricultural development
(McCartney and Houghton-Carr,
2009)
2. Participatory land use planning Multi-criteria decision making
(MCDM) such as the WWP
To collect decision criteria from key
stakeholders
(Raj, 1995; McCartney and
Houghton-Carr, 2009)
Multi-stakeholder platform (MSP) To reach a workable compromise
between stakeholders’ interests
(Warner, 2006)
3. Designing, implementing and
evaluating best-fit water
management
Rapid pre-development diagnostics
(DIARPA)
To assess inland valley water dynamics
to select the best-fit intervention
(Lidon et al., 1998)
Participatory Learning and Action
Research for Integrated Rice
Management (PLAR-IRM)
To guide farmer participatory inland
valley development for improved water
management to acquire ownership over
the development structures
(Wopereis et al., 2007)
Simple, Participatory Inland Valley
Development Approach
To guide farmer participatory inland
valley development for improved water
management
(Worou, 2013)
Irrigation performance assessment To monitor and improve productivity
and sustainability of irrigations systems
(Dembélé et al., 2012)
4. Optimizing crop management
practices
Sawah system development (SSD) To improve water, nutrient and weed
management to raise crop productivity
(Abe and Wakatsuki, 2011)
Participatory Learning and Action
Research for Integrated Rice
Management (PLAR-IRM)
To create farmers’ awareness, identify
local production constraints and locally
available solutions to solve them
(Wopereis et al., 2007)
Modelling (e.g. ORYZA, EPIC, farm
household models)
To prioritize production constraints,
analyse management options and guide
decision making
(Lansigan et al., 1997; Boling et al.,
2007; Laborte et al., 2009; Worou et
al., 2012)

– 13 –
In conclusion, a two-step approach is advocated. First, spatial modelling and analysis at national or
sub-national level should provide the location of the inland valleys and a first indication of the potential
for development. Second, a detailed feasibility study (we propose the aforementioned Working Wetland
Potential – WWP - index) must be implemented using field and farmer surveys to assess the true
potential for development of the selected inland valleys.
4.2. Participatory land use planning
After site selection, an inventory of land uses should be followed by the actual land use planning
within a valley. For this step to be successful, active participation of all important stakeholders is
required (e.g. Perfecto and Vandermeer, 2008; Del Amo-Rodriguez et al., 2010). Here, multi-criteria
decision making (MCDM) methods could be practised in recognition of the insight that stakeholders are
likely to base decisions on more than just one criterion (e.g. Raj, 1995). The earlier mentioned WWP
index, which principally is an MCDM method, can again be used to evaluate the potential of different
agricultural activities within the valley and to find synergies, or at least compromises, between different
ecosystem services (McCartney and Houghton-Carr, 2009). Preferably all local stakeholders, including
local authorities and politicians, should play a role in the land use planning within a selected inland
valley and find consensus on the directions to take. To facilitate this process so-called multi-stakeholder
platforms (MSP) could be created. This is perhaps the most challenging part of the approach, as getting
all stakeholders around the table has proven difficult in some situations (Warner, 2006) and reaching
consensus among a wide ranging group of stakeholders with different interests, might be another
considerable hurdle to take. The outcome such MSP processes should aim for would be to reach a
compromise between economic, social and environmental gains and risks and the identification of hot-
spots for specific ecosystem services within the inland valley under consideration. The make-up of such
a compromise would of course depend on the specific values local stakeholders place on the services
that the ecosystem provide them with, relative to alternative income sources and interest (McCartney
and Houghton-Carr, 2009). The MSP process should lead to a detailed strategic plan for the local land
use of a specific inland valley, with areas designated for agricultural production and areas that are
maintained or managed to fulfil other ecosystem functions. This should result in the sort of spatially and
temporally mixed, land use forms that were earlier proposed by Dixon and Wood (2003) and assumed to
be inherently environmentally and socially sustainable.
4.3. Designing, implementing and evaluating best-fit water management
After these first two, rather difficult and time-consuming, steps of inland-valley selection and
participatory planning, the actual development, mainly consisting of clearing of vegetation and
construction of irrigation and drainage structures to increase water control, can start. As much as
possible this work should involve the future beneficiaries of the development to enable them to acquire
ownership. Information on the extent of participation in the development work provided by an
individual stakeholder can be used to guide plot partitioning once the inland-valley development is
finalized. Personal time investments at these stages will also ensure user-commitment to future
management and maintenance of the infrastructure and thereby benefit the sustainability of the inland-
valley production system. In the Blétou valley in south-west Burkina Faso, for instance, an IVC project
installed a contour-bund system consisting of small water retention bunds along the contour lines. A

– 14 –
community-participatory development approach was used, whereby plots were distributed among
farmers, according to their participation in the construction of these water-management structures
(Youssouf Dembélé, personal communication). The active participation of farmers in the construction
reduced the costs of the investment and, more importantly, provided them with ownership. The plots
were assigned in a participatory manner following each individual’s contribution to the work. This
resulted in fair distribution of the plots based on group consensus, respecting individual time
investments and disregarding gender or age.
Clearly, every inland valley is unique in terms of biophysical and socio-economic characteristics and
there is no ‘off-the-shelf’ technology with a broad and indiscriminate application range. Technologies for
inland valleys must be locally adapted. For instance, the regulation of water – e.g. to control flooding,
optimize irrigation, conserve water for late-season use - requires a design that takes local conditions
into account. Various physical factors, such as the size of the catchment area, the valley morphology and
soil texture (determining hydrological behaviour) need to be considered for the design of the most
suitable water management system. This requires a thorough diagnostic study on the spatial and
dynamic water movements within the valley (Wopereis et al., 2007) followed by in-depth discussions
with stakeholders (preferably through a multi-stakeholder platform) to ensure full buy-in of the
community and to make sure that land tenure issues are identified and solved beforehand. Inviting local
politicians and villages chiefs in such multi-stakeholder platforms is imperative in this respect as they
often have the responsibility or power to allocate land to land users. Discussions on the land and water
development options that could be put in place should also consider consequences for water availability
for downstream users.
The first steps towards improved water management in inland valleys in Africa will be the
construction of main and secondary drainage pathways and outlining, bunding and levelling of individual
fields with minimal soil movement. A valley with a slight slope will result in fairly large bunded fields,
whereas a valley with a steep slope will lead to more ‘terraced’, bunded fields. The introduction of such
very simple water management structures will already lead to substantial yield gains (1-2 t ha-1
),
especially if accompanied with good crop management practices (e.g. Becker and Johnson, 2001b; Toure
et al., 2009). For this type of partial water control structures, that can be developed entirely by farmers
themselves, Worou (2013) developed a useful guide.
To raise rice productivity with improved water control, relevant modules of the curriculum for
Participatory Learning and Action Research (PLAR) for Integrated Rice Management (IRM) can be
implemented. PLAR-IRM was developed by AfricaRice and partners, based on the insight that a locally
adapted and integrated approach is required to increase rice productivity in inland-valley production
systems in Africa (Wopereis and Defoer, 2007). It is essentially a farmer participatory, step-wise
approach to put inland valleys under rice production using good agricultural practices (Defoer et al.,
2004; Wopereis et al., 2007). Farmers involved in the Japanese funded SMART-IV project implemented
by AfricaRice and partners in Togo and Benin obtain very good results in inland valley settings,
introducing relatively simple, low-cost water management structures (drainage canal development,
bunding, levelling) that can be constructed and maintained totally by farmers themselves. Use of power
tillers, while not essential at the first stage, can substantially speed up land development once farmers
are familiar with the technique.

– 15 –
If full water control is targeted, five main water management systems for inland valleys can be
envisaged: 1) the traditional random-basin system, 2) the central-drain system, 3) the interceptor-canal
system, 4) the head-bund system and 5) the contour-bund system (for technical details see: Oosterbaan
et al., 1987; Windmeijer and Andriesse, 1993; Windmeijer et al., 2002). Lidon et al. (1998) developed a
diagnostic interactive tool called DIARPA (‘diagnostic rapide de pré-aménagement’; Eng.: rapid pre-
development diagnostics) which works as a decision tree and helps to assess the ‘best-fit’ type of
intervention at a given location and a given level of investment, with the purpose to optimize
agricultural production with limited hydraulic risks. While the technicalities of the choice of the water-
control design and parts of the actual implementation of the development may be beyond the resource-
poor farmers’ capacities and expertise, we again stress the importance of involvement of farmers in the
activities that can be carried out by them to gain the aforementioned necessary ‘ownership’ over the
water-control structures. Moreover, the proper functioning, management and maintenance of the
water-control structures requires the actual users (i.e. the farmers) to understand the basic principles.
After completion of the water management structures, a performance evaluation, similar to the one
suggested by Dembélé et al. (2012), should be carried out on a seasonal basis to enable farmers to make
necessary adjustments and thereby further improve water productivity. This requires farmer training
and facilitation.
4.4. Optimizing productivity and profitability
Following the selection of the inland valley, the land use planning within the selected inland valley
and the development of that part of the inland valley designated for agricultural production, the last
step is to establish and optimize crop production within these designated areas. At this stage, a set of
local constraints need to be tackled in order to benefit from the inherent inland-valley production
potential. Simulations with physiological crop models (e.g. ORYZA), and multi-criteria models (e.g. EPIC,
farm household models) can be used to analyse productivity and sustainability of cropping systems, or
to quantify effects of different stresses on crop yield, and as such they can provide a decision support
tool to improve management on the crop, farm or inland valley level (e.g. Lansigan et al., 1997; Boling et
al., 2007; Laborte et al., 2009; Worou et al., 2012).
Following water management, key factors for raising productivity in inland valleys are weed and soil
fertility management (Wopereis and Defoer, 2007) and pest and disease control (Table 1). However the
order of importance of production constraints needs to be locally assessed for each inland valley. The
data collected during the aforementioned detailed characterization should be helpful in this respect.
Such characterizations in turn can guide the selection of technology interventions (e.g. Sakané et al.,
2011). The aforementioned PLAR-IRM curriculum also provides a very useful method to identify key
production constraints, as well as locally researchable issues. PLAR-IRM further stimulates farmer
experimentation in order to test ‘what works best’ under the given local (biophysical and socio-
economic) conditions, using an integrated management approach. The available modules of the PLAR
curriculum provide guidelines for such approaches from which facilitators and farmers can tap to
improve the local productivity. Through integrated water, soil fertility and weed management in inland-
valleys, rice yields can increase considerably. Bunding, puddling (if possible) and levelling for instance,
facilitates water management and decreases weed competition - as many weed species are not well
adapted to permanently flooded conditions (e.g. Kent and Johnson, 2001) - and generally increases

– 16 –
nutrient use efficiencies, in particular in well-drained fields. These relatively simple technologies have
shown to increase rice yields by 40%, and reduce weed infestation by 25% across agro-ecological zones
(Becker and Johnson, 2001b; Toure et al., 2009). Bunding, levelling and puddling (mainly to improve
water management) is also proposed through Sawah system development (Abe and Wakatsuki, 2011) a
labour-intensive approach which basically promotes the aforementioned contour-bund system
combined with good agricultural practices. Further yield improvements can then be attained by using
improved rice cultivars. For instance, some cultivars of NERICA (New Rice for Africa) adapted to lowland
conditions have an inherent high weed competitiveness (Rodenburg et al., 2009) and a high yield
potential (Sié et al., 2008). Following such investments in crop productivity increases, one should also
aim at reducing post-harvest losses due to birds, insects and rodents, mainly by shortening the time
between crop maturity and harvest and storage and by improving transport and grain storage facilities
(e.g. Yusuf and He, 2011). Finally, conducive policies ensuring good prices for producers on the local
market, are imperative for profitable agricultural exploitation of inland valleys (e.g. McMillan et al.,
1998).
5. CONCLUSIONS – REGIONAL POTENTIALS, LOCAL APPROACHES
Tapping the regional potential of inland valleys in sub-Saharan Africa requires development of high-
potential and low-risk areas that are yet unexploited, as well as improvement of already used areas,
through development of water management structures and the use of improved crop management
technologies. We propose a step-wise and locally-adaptable stakeholder-participatory approach for site-
selection, land-use planning, water management design and implementation and crop management, to
realize this, while maintaining other important ecosystem functions of these landscapes. A number of
approaches, tools and technologies have been developed over the past three decades that contribute to
achieving this. We propose: 1) the selection of ‘best-bet’ inland valleys, whether unexploited or already
used, based on spatial modelling and analysis at national or sub-national level (using GIS and remote
sensing tools) followed by more detailed typologies using the Working Wetland Potential (WWP) index,
2) a stakeholder-participatory land use planning within the inland valley based on the earlier
characterizations (notably the WWP index) and using multi-stakeholder platforms (MSP), 3)
participatory inland-valley development (e.g. clearing, levelling and construction of water management
structures) following guidelines developed by Worou (2013), relevant modules of the Participatory
Learning and Action Research (PLAR) curriculum and the pre-development diagnostic tool DIARPA
followed by regular performance assessments of the water-control system, and 4) identification of local
production constraints combining model simulations and farmer participatory priority exercises (e.g.
PLAR), to select and adapt appropriate management practices and technologies following principles of
Integrated Rice Management (IRM). While there is some experience with the first and the last two steps
of this approach no published evidence exists yet showing that the second step (e.g. formation of MSPs
for detailed strategic planning) indeed results in the desired sustainable use of inland valleys in Africa.
Future research and development projects, like some of the current ones carried out by AfricaRice and
partners, should test and fine-tune such approaches.
We conclude that it is essential to use systematic analyses approaches for the selection of ‘best-bet’
inland valleys for rice production as only a fraction of the available inland valleys in Africa would need to

– 17 –
be used for agricultural production in order to attain regional self-sufficiency in rice. The remaining
inland valleys could then be safeguarded to fulfil other ecosystem services. However, for this strategy to
be effective, an environmental impact assessment should be compulsory before any development takes
place. Conservation regulations and monitoring and evaluation mechanisms need to be established to
help protecting those inland valleys that are either too vulnerable (e.g. to soil and water degradation or
social conflicts) or too valuable (because of other ecosystem functions such as biodiversity) for
agricultural development. Selection of ‘best-bet’ production valleys should be based on both biophysical
and socio-economic criteria and be broadly supported by the local communities depending on them.
The same approach is proposed for the identification of locations within the inland valley that should be
used for crop production and those that should continue to fulfil any other ecosystem function. This
again requires involvement of local stakeholders. Following these steps, the actual development is the
next challenge. The right choice of water-management system is of pivotal importance and this depends
largely on the valley morphology and the local soil and hydrological characteristics. Development and
implementation of such water management systems and the agricultural production practices following
such development should not negatively impact the water quality and availability downstream. For the
actual crop production, high-yielding and stress-resilient lowland rice cultivars and locally adapted and
integrated crop management practices are required. Harvesting technologies and post-harvest facilities,
for drying, threshing, milling, storage and transport should also be included in inland-valley
development plans.
For the sustainable realization of the regional potentials offered by inland valleys in Africa, full local
stakeholder participation is required in all stages, ranging from decision-making to development and
implementation. This should result in consensus on the selection and land use plans of inland valleys
and the implementation of broadly supported interventions and flexible, locally adaptable, and cultural
and socio-economical acceptable solutions to the numerous constraints encountered in inland valleys in
this region.
Acknowledgements
The insights herewith presented have resulted from work of the Inland Valley Consortium (IVC) and
the Africa Rice Center (AfricaRice) and partners. We are indebted to all those who have contributed to
this work over the past decades. This paper is dedicated to our respected colleague Youssouf Dembélé,
who passed away so untimely and unexpectedly. For many years he contributed invaluably to research
and development of inland valleys in West Africa.
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