increasing the resilience of dryland agro-ecosystems to...

Increasing the Resilience of Dryland Agro-ecosystems to Climate Change

Richard J Thomas, Eddy de Pauw, Manzoor Qadir, Ahmed Amri, Mustapha Pala,

Amor Yahyaoui, Mustapha El-Bouhssini, Michael Baum, Luis Iñiguez and Kamel Shideed

International Centre for Agricultural Research in the Dry Areas (ICARDA)

P.O. Box 5466, Aleppo, Syria

Corresponding author’s E-mail: [email protected]

Introduction

The current debate on climate change, its impacts on socio-ecological systems and the role of agriculture has

shifted from an emphasis on how to mitigate the effects of increasing greenhouse gas (GHG) emissions to how

to prepare and adapt to the expected adverse impacts. This follows the recognition that the climate is already

changing as a result of mankind’s activities and there is little that can be done to prevent further increases in

atmospheric concentrations of GHG in the short term (Henson, 2006). There is much debate on what are the

likely tipping points where irreversible changes will occur in the earth’s ecosystems (Schellnhuber et al., 2006;

Stern 2007). In addition the linkages between climate change, land degradation and loss of biodiversity are

increasingly viewed as highly interactive, requiring more holistic frameworks and approaches in order to solve

common problems (MEA, 2005). These converging viewpoints lead to an increased focus on sustainable land

management and development whereby incomes of the poor can be increased but not at the expense of the

natural resource base and the environmental services they provide. A recent scientific workshop distilled the

problem of sustainable land management down to a need to maintain a protective biological surface cover

(living plants or mulches), good soil structure to allow gas, water and nutrient exchanges between soils and

plants and adequate levels of soil organic matter and their soil-inhabiting organisms (TAA, 2007). These

measures would also reduce the GHG emissions associated with food production This biophysical perspective

needs to be combined with a socio-ecological perspective whereby the driving forces behind land use decision

making are clearly understood in terms of the socio-economic context and the asset base of the land users (i.e.

the use of the sustainable livelihood perspective and the principles of physical, human, social, financial and

natural capitals (Bebbington, 1999). Sustainable land management includes the utilisation and conservation of

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An Open Access Journal published by ICRISAT________________________________________________________________________________________________________

SAT eJournal | ejournal.icrisat.org December 2007 | Volume 4 | Issue 1

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genetic diversity. This diversity has played a key role in past adaptation to climate change and should be a

starting point for strategies to overcome the negative effects of climate change on crop and animal production.

Genetic resources held in national and international genebanks have been used effectively to develop varieties

adapted to existing and arising biotic and abiotic stresses. Therefore in situ and ex situ conservation of within

and among species diversities and functional types along with habitat protection will continue to be required for

adaptation measures.

From this brief introduction it is clear that strategies for adaptation to climate change will need to embrace

different sectors, support development and will be interdependent, requiring collaboration amongst multiple

stakeholders, ranging from resource managers to policy makers. There is a need to be more proactive rather than

reactive and to focus first on measures that achieve multiple goals, i.e., that address not only the impacts of

climate change but also other stresses such as land degradation or desertification. In this brief review we

highlight such measures that are being developed by the International Centre for Agricultural Research in the

Dry Areas (ICARDA) for the world’s non-tropical drylands.

The impact of climate change on dryland agro-ecosystems

For drylands with low inherent levels of biological productivity, coping with climate change presents particular

problems. The world’s drylands cover over 40 % of the global terrestrial area and house more than 2 billion

inhabitants MEA, (2005). The world’s poorest people live in these areas and they will be hit hardest by the

adverse effects of climate change. The effects will manifest themselves not through increased temperatures per

se but rather via changes in hydrological cycles characterised by both increased droughts and paradoxically,

increased risks of flooding.

Key impacts of climate change and climate variability on dryland agro-ecosystems include;

1. Reductions in crop yields and agricultural productivity with subsequent threats to the food security of

dryland countries.

2. More erratic rainfall patterns and difficulties in determining timings of sowing and harvesting, and the

selection of suitable crops with varying durations.

3. Reduced availability of water in already water scarce regions coupled with extreme rainfall events with

increased loss of water via run off, etc.

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4. Complete loss of crops resulting from extreme events such as prolonged droughts and torrential rains.

5. Slow pervasive loss of soil fertility through loss of soil carbon from erosion and higher decomposition

of soil organic matter as a result of higher temperatures, reduced soil moisture and moisture storage

capacity.

6. Lower livestock productivity from heat dissipation and reduced availability of feed and fodder.

7. Alterations in pest and disease risks for both crops and animals (and humans) as temperatures increase.

8. Changes in agro-ecologies and the threats from new invasive plant and animal species.

9. Reduction of biodiversity of key crop species through habitat change and loss.

10. Increased vulnerability of pastoralists because of erratic rangeland production, through shifts in rainfall

patterns and loss of vegetative land cover.

These impacts will further constrain the livelihoods of rural communities in dry areas resulting in greater

poverty, reduced livelihood opportunities and increased rates of migration. It is clear from the above that there is

an urgent need to improve the management of natural resources (land, water and biodiversity) and the ability of

populations to prepare for, and respond to, future climate conditions.

ICARDA’s role in climate-proofing dryland agro-ecosystems

ICARDA has been working to help poor farm communities cope with dryland conditions for over 30 years.

Together with partners in over 50 countries and especially the National Agricultural Research Systems (NARS),

new technologies and tools have been developed and disseminated in order to raise agricultural productivity,

increase farm incomes and conserve and manage natural resources in the harsh and variable environments that

characterise drylands. ICARDA’s work focuses on the non-tropical dryland regions of the world as shown in

Figure 1.

The non-tropical dry areas occupy some 4 billion hectares or 25% of the world’s land area, and are home to 28%

of the global population – over 1.7 billion people. About 16% of this population lives in chronic poverty; and

the problem is particularly acute in marginalized rainfed agricultural areas. Poverty and food insecurity are

exacerbated by depletion or poor management of natural resources (especially water, soil and biodiversity) and,

in most countries, by rapid population growth. Social, political, and economic constraints are also pervasive.

Appropriate enabling policies, effective institutions and investment are often lacking. In many areas women are

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not adequately empowered, thus their full potential contribution to sustainable agriculture remains untapped.

Economic poverty, as well as resource poverty, lead to under- or unemployment, which often then drives

migration.

In addition the non-tropical drylands of Central and West Asia and North Africa are the main centres of

diversity of crops and livestock that are of global importance such as wheat, barley, lentil, chickpea, several feed

legumes and fruit trees, sheep, goats and camelids. Landraces and wild relatives of these crops and animals

continue to form the basis of the livelihoods of those dependent on agriculture.

An initial task has been undertaken to identify important vulnerabilities or ‘hot spots’ in non-tropical drylands

where climate variability is already a major problem. Figure 2, taken from the IPCC 4th Assessment Report

Summary for Policy-Makers (IPCC, 2007), shows the likely temperature increases in the periods 2020-2029

(left) and 2090-2099 (right). These projections indicate that, whereas in the near future the increases are likely to

be moderate and affect mostly the northern hemisphere, at the end of the 21st century, they will be severe and

have global impact.

Whereas the IPCC SPM Report does not provide information on changes in precipitation patterns between the

recent past and near future, the end of the century is also likely to be affected by major changes in precipitation.

The comparison of Figure 3 with Figure 1 indicates that the non-tropical drylands countries and regions that can

expect substantially lower precipitation include Mexico, the Mediterranean, Central Asia, southern Africa, and

the west and eastern coastal belts of Australia.

The CWANA region (North Africa, West Asia, Central Asia and parts of the Horn of Africa) is the largest

contiguous block of non-tropical drylands. There is ample evidence of hotspots of vulnerability to climate

change in this region.

Figure 4 shows the coefficient of variation of the maximum NDVI for the period 1982-1999, which is an

indicator of the fluctuations in agricultural or natural biomass, which do not result from land use change and are

related to current climatic variability.

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The colors in orange and red express where the variability is the highest. As the CV of the maximum NDVI

expresses the response of the vegetation biomass to climatic fluctuations, it is an impact indicator and hence

evidence of the presence of ‘hot’ or ‘cool’ spots in different parts of CWANA.

The map shows several current hot spots:

• North Africa, from Morocco into Tunisia

• The Sahel, from Mauritania into Sudan, Eritrea, northern Ethiopia and turning south into Somalia

• The Fertile Crescent, from Jordan, Syria, Iraq, turning southeast into Khuzistan province in southern

Iran

• The foothill zone north of the Tien-Shan and Pamir Central Asia mountain ranges

• The rangelands in the north of Central Asia

All these areas are already currently characterized by multiple stresses that include severe droughts, degradation

of land, water and vegetation resources, and sometimes famines. Figure 3 indicates that of the 5 CWANA

hotspots of current climatic variability the following are likely to have a drastic reduction in winter

precipitation:

• North Africa, from Morocco into Tunisia

• The Fertile Crescent, from northern Syria, Iraq, Khuzistan and southern Iran and a side branch to

northern Iran along the Alburz mountain range

According to Figure 3, the Alburz mountain range in northern Iran will have a reduction of both winter and

summer precipitation. Yet, much of Central Asia will have a significant increase in winter precipitation. At the

same time, summer precipitation is likely to decrease, especially where it matters most: on the central Asian

mountains of the Tien-Shan and Pamirs, resulting into reduced streamflows into the irrigated areas of

Uzbekistan, Turkmenistan and southern Kazakhstan, where most of the people live.

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Within each of these hot spots there are a number of compounding factors that may lead to a potentially fast

impact of climate change:

• Already high and growing populations

• Persistent reliance on income from agriculture; off-farm income unstable due to political and

socioeconomic factors discouraging investment into industry and services

• Dwindling water resources due to overuse and lack of appropriate policies to protect or use them

efficiently

• High levels of biodiversity but under threat by global warming.

Figure 5 shows the population densities in the CWANA region and its surroundings. Within North Africa, the

Fertile Crescent and the southern rim of Central Asia population densities may match those of western Europe,

but the growth rates are much higher.

From current climatic variability and population densities and projected trends of future climate change and

population growth, two ‘red’ hot spots (the ‘Maghreb hot spot’ and the ‘Fertile Crescent hot spot’) and one

‘orange’ hot spot (the southern edges of Central Asia and the ‘Silk Road hot spot’) can be identified. These

regions can be used to study the impacts of climate change on agro-ecosystem functioning and provide valuable

lessons for other areas that will be similarly affected in the longer-term future. Similar but more detailed studies

are required to develop plausible predictions of local impacts as the current models tend to operate at greater

scales (regional and global) that are not particularly useful for any one locality. This remains a great challenge

for developing countries that lack the appropriate know how and human capacity.

Developing solutions

ICARDA’s work that contributes to ecosystem resilience, mitigation of, and adaptation to climate change is

summarised in Table 1. ICARDA’s approach to climate change builds on technologies and

research/development methods that have proved successful in these environments. The aim is to strengthen the

adaptive capacity of communities, and the resilience of farming systems – in short, mitigation plus adaptation.

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ICARDA does this in various ways (see Table 1 for details):

• Better understanding of climate change processes, ecological impacts, and factors influencing them.

• Better characterization of rural poverty by combining financial indicators such as farm income with

natural resource degradation (as a measure of environmental poverty).

• Conservation and sustainable use of dryland agrobiodiversity.

• Better adapted varieties, improved cropping systems, more efficient use of natural resources.

• Technology options for livelihood diversification and income generation.

• Studying local coping strategies, and drawing lessons for wider application.

• Examining trade-offs: for example, will policy reform on water (in order to improve overall

productivity) reduce water access for the poor?

Some examples of ICARDA’s work are presented below.

Conservation, characterisation and utilization of genetic diversity

ICARDA’s genebank holds more than 131,000 accessions of cereals, food and feed legumes, and forages

including cultivated varieties, landraces and wild relative species. More than 50% of the conserved genetic

resources originated from the drylands of the CWANA regions. Most of these holdings are geo-referenced

allowing a better targeting of germplasm for use in changing environments. A large part has been characterized

agronomically under different biotic and abiotic stress selection pressures in collaboration with partners. On-

going work is developing sub-sets of these collections targeting different abiotic stresses including heat and

drought tolerance. To date only a limited number of accessions are used by international and national breeding

programs, mainly to derive resistance to diseases and pests, to improve grain quality and broaden the genetic

base, indicating that potential exists to prospect further for important traits. At ICARDA, several promising

lines, with good tolerance to drought are derived from interspecific crosses for barley and wheat. Wild relatives

of different crops have sustained recurrent droughts and heat cycles which allowed natural selection against

these stresses and therefore could hold valuable genes for these stresses. ICARDA’s approach to this work on

drought tolerance in barley for example, is two-pronged. Firstly efforts made on direct selection for grain yield

under varying conditions of farmers’ fields indicate the importance of traits such as growth habitat, early growth

vigour, plant height under drought, long peduncle and short grain-filling duration (Baum et al., 2007). The

second approach is the use of molecular markers for drought tolerance through the identification of quantitative

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trait loci (QTL) in studies on the agronomic performance in drought stressed environments. These studies

revealed that the wild progenitor of cultivated barley, Hordeum vulgare spp. spontaneum is a source of tolerance

to extreme levels of drought through developmental genes involved in flowering time and plant stature (Baum et

al, 2007). Efforts are continuing on the exploitation of these genes from wild barley.

New research using DNA marker techniques and GIS tools will allow better gene prospecting mainly for

improving tolerance to drought, heat and other stresses such as the UG99 virulent race of stem rust in cereals.

More germplasm enhancement activities will be undertaken targeting the use of wild species in different gene

pools of cereals and legumes. Based on GIS layers, new collection missions will need to be organized to areas

with high potential for finding drought and heat tolerant accessions.

ICARDA, through the implementation of a GEF-UNDP funded project on the conservation and sustainable use

of dryland agrobiodiversity in Jordan, Lebanon, Palestine and Syria, developed an holistic approach for

promoting in situ/on-farm conservation of dryland agrobiodiversity. This included the search for added-value,

alternative sources of income, institutional and policy options targeting the improvement of the livelihoods of

the custodians of local agrobiodiversity. The results of socio-economic surveys in the eight targeted areas

showed that traditional agriculture based on landraces of field crops and fruit trees, natural rangelands and local

breeds of livestock only contributes to approximately 50% of the total farm income. The remaining half is

derived from government salaries and retirements, remittances and other non-agricultural incomes.

Landraces of crops and local breeds of small ruminants (Iñiguez, 2005, 2006) and South American camelids

continue to be used by farmers because of their better adaptation to harsh conditions including droughts and

extreme temperatures, their appreciated qualities and the expanded demand. This conservation and sustainable

use of such valuable biodiversity and its associated knowledge is needed to increase productivity while

sustaining natural resources and for the development of added-value and alternatives sources of income with

better opportunities for marketing local products. Eco-tourism, food processing, dairy production and other

initiatives were introduced to local communities and NGOs as part of this holistic approach and successful

examples of improvement of livelihoods have been documented in Lebanon, Palestine and Syria. Many under-

utilized species. e.g., Hawthorn (Crataegus spp.), Sumac (Rhus coriarius), wild pistachios (Pistacia spp..), wild

almonds, (Amygdalus spp.) and several species with medicinal and aromatic values with good adaptation to

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harsh conditions can contribute to the diversification of farming systems and sources of incomes for people who

have to cope with climate change.

Dynamics of pests and diseases

Diseases and insect pests are major biotic stresses of economically important crops in the non-tropical dryland

areas. Increased temperature and erratic rainfall patterns have an impact on the spatial and temporal distribution

and proliferation of insects and pathogen populations and will alter host-parasite interactions and thus will

require new integrated pest management strategies. Global climate changes have far-reaching consequences on

crop diseases and insect pests in these areas. A rise in temperature for example would contribute to an increase

in the number of generations for insects such as the Russian wheat aphid (a major pest of wheat and barley in

dryland areas) and several virus-transmitting aphid species. Resistance genes will lose their effectiveness under

high temperature regimes; for instance, resistance genes in wheat for Hessian fly are particularly vulnerable

(Khalifi et al., 1996; El Bouhssini et al., 1999). Similarly, the severity of diseases such as Fusarium wilt of

chickpea will increase and pathogen strains would become more virulent as is the case with yellow rust of

wheat. The change of rainfall patterns such as more late-season rains will result in more severe Aschochyta

blight infection on chickpea pods and Fusarium head blight on wheat.

ICARDA develops technologies to address biotic constraints on important crops in marginal dryland areas with

a view to improving crop productivity and farmers’ income, but this work now has to take cognisance of the

impact of climate change on current IPM strategies. The immediate solutions include:

• Careful monitoring of disease and pest damage, including associated pathogen and insect populations.

This would be the first step in a strategy to understand and deal with the effect of global climatic

changes as they occur. The acquired knowledge would provide tools to enhance resistance/tolerance to

biotic stresses, which would lead to improved IPM and sustained crop productivity.

• Development of prediction models for insect pests and disease outbreaks.

• Studies on the expression of resistance/virulence genes under different temperature regimes, and the

identification and use of resistance genes that are stable under high temperature regimes.

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Conservation agriculture

Conservation agriculture (CA) is defined by FAO as agriculture that maintains and improves crop yields and

resilience against drought while maintaining the biological functioning of the soil (FAO, 2002). Others have

defined it more broadly to mean the integration of natural resources management with sustainable and economic

agricultural production (Dumanski et al., 2006). Notwithstanding these different perspectives CA has much to

offer resource poor farmer’s attempts to cope and adapt to climate change. It involves minimal soil disturbance,

maintaining land cover either through plants or mulches, ensuring good soil structure to allow adequate

exchanges of gases, nutrients and water and maintaining and/or increasing the levels of soil organic matter and

thereby carbon sequestration, and more diverse crop rotations. Benefits include savings in labour, time, fuel and

machinery wear; more timely sowing; higher yield potential, and less erosion. Thus CA is an example of a

mitigation-adaptation strategy to cope with climate change. ICARDA’s work in this area focuses on

conservation cropping based on the principles of improving the soil, efficient and effective use of crop

production inputs such as water, fuel, fertilizer and pesticides, including labor and optimizing profits by

employing all improved agronomic practices as an integral part of production systems (Pala et al., 2007).

An example from this work is the effect of zero-tilled direct sowing compared to conventional and conservation

tillage in durum wheat/lentil legume rotations. The tillage treatments studied over a 5-year period were;

1) Conservation tillage by ducks-foot (10-12 cm) for wheat and conventional deep tillage by mouldboard

plough (25 cm) for lentil phase of the rotation (shallow-deep tillage system),

2) Conventional deep tillage by mouldboard plough (25 cm) for both phases of the rotation (deep-deep

tillage system),

3) Conservation tillage by ducks-foot (10-12 cm) for both phases of the rotation (shallow - shallow

tillage system),

4) Zero-till direct drilling with residue remaining on soil surface, and

5) Zero-till direct drilling with residue removed for livestock feed.

Rainfall was above average for 3 of the 5 years (2001/02, 2002/03 and 2003/4) and below average for the

2004/05 and 2005/06 seasons. Results of both grain and straw yields are presented in Table 2 for the 5-year

period. The recommended conservation tillage (shallow-deep) practice gave highest wheat yields compared to

other tillage systems with little or no differences in lentil gain yields although lentil straw yields were greatest

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under zero-till direct sowing. Zero-till gave good but not best results in terms of yields. However zero-till does

appear to be more economic when cost-benefits are considered (Table 3). These results demonstrate the

potential of conservation agricultural practices that will help both mitigate climate change and improve

adaptation to climate variability. Current work is testing these options in Jordan, Iran, Morocco, Sudan, Turkey

and Central Asia (Pala et al., 2007 and references therein).

ICARDA’s work on the introduction of cereal-legume and other crop rotations has demonstrated the potential of

increasing soil organic matter (Thomas et al., 2006). As nitrogen and phosphorus are the most common nutrient

deficiencies in dryland soils particular attention has been given to their interactions with water deficiency.

Research has shown that under more favourable moisture conditions responses to N are more critical for yield,

whereas under drier conditions responses to P are higher (Pala et al, 2007).

Although a particular challenge in dry lands because of the lower biomass production, it has been shown that

maintaining even small amounts of crop residues on the soil surface helps retain precious soil moisture.

ICARDA is working on CA in Syria and Central Asia and has shown the benefits of minimum- and zero-tillage

over deep-tillage systems, especially in terms of increases in crop yields and soil organic matter, water use

efficiency and net revenue. When combined with crop rotations including legumes additional beneficial effects

are observed on soil quality, N-fertilizer use efficiency and water use efficiency in the system (Pala et al., 2007).

ICARDA will continue to explore the potential of CA in drylands paying particular attention to

- new higher value crop rotations with high yielding drought and pest resistant varieties that include

oilseeds, medicinal and pharmaceutical crop options,

- shorter duration and earlier sowing varieties to increase the options for changing climates,

- Better weed management,

- Potential of combining supplemental irrigation and water harvesting.

Improved management of water resources

Climate change will have large effects on the hydrological cycles in drylands with less total rainfall, drier soils

but with increased risks of floods from increased frequency and intensity of storm events (IPCC, 2007). Many

dryland countries are highly dependent on snow fall and snow melt for water supplies. Increasing global

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temperatures will increase the ratio of rain to snow, decrease the length of the snow pack season and increase

the rate and intensity of spring season snowmelt thus altering the amounts of water and the timing of its

availability for farming practices (Gleick et al., 2001). A given % reduction in rainfall has been shown to have a

proportionately greater reduction on groundwater recharge in semi-arid areas (e.g., Sandstrom, 1995). This will

add to the costs of groundwater extraction and in coastal areas result in salt intrusion into aquifers. These

predictions when taken together resulted in the recognition that water demand management and institutional

adaptation are key factors to increasing system flexibility and adaptation to climate change (IPCC, 1996). A part

of the solution to reduce water demand is the need to improve the water productivity of drylands, meaning

increasing the ratio of net benefits from agriculture, forestry and fisheries to the amount of water needed to

achieve those benefits (IWMI, 2007). There are two types of water productivity; physical water productivity

defined as the ratio of the amount of agricultural output to the amount of water used and economic productivity

defined as the value derived per unit of water used.

ICARDA’s work has focused on some of the demand-side biophysical and socio-economic options such as

improving water productivity and water use efficiency and changing land use practices. Major research

achievements have been reported elsewhere (Oweis and Hachum, 2003 and references therein) on water use

efficient techniques such as supplemental irrigation for rainfed farming, rainwater harvesting in drier

environments, efficient on-farm water management through deficit irrigation and changing cropping patterns

and cultural practices.

An example of this work is shown in Table 4 that builds on the finding that with only 50% of full supplemental

irrigation (SI) yields are reduced by just 10-15% allowing substantial water savings or the potential to bring

more land into production with the same amount of water. The results in Table 4 were obtained over a 6-year

period on farms which were divided into four 1 ha treatment plots. These were rainfed, irrigation with normal

farmer practice, irrigation with no moisture stress (full SI) and irrigation with 50% of full irrigation

requirements (Deficit SI). The key finding was` that under rainfall conditions during 1994-2000 a farmer could

produce 33% more grain from the deficit SI practice compared with full irrigation.

There are now many practices available to improve water productivity including supplemental irrigation, deficit

irrigation, more efficient storage, delivery and application of water, modern irrigation technologies such as drip

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and sprinkler systems, soil water conservation and tillage practices and better synchrony of water and inorganic

and organic nutrient supplies. The adoption of these techniques needs better enabling policies and institutional

environments that offer incentives to producers and resource managers and that society is willing to accept and

pay for. New water resource allocation tools and methods are required in order to guide policies towards more

effective water use at different scales from the field/farm to the watershed. An example of these is a study on

on-farm water use efficiency by ICARDA that showed that farmers actually over-irrigate their crops by by 20-

60% (Shideed et al., 2005). This modelling tool can help farmers better allocate available water from a crop

yield and economic perspective.

To improve the adoption of promising technologies increased emphasis is now given to community involvement

and co-management between local communities and external agents such as researchers, government extension

and non-governmental organizations (Brooks, 2002). This approach is likely to bring significant benefits to the

rainfed sector that occupies 80% of the world’s cropland and produces as much as 60% of the world’s cereal

grains (IWMI, 2007). The effects of climate change on this sector will be particularly important as the

communities that inhabit these rainfed lands are usually the poorest and the most vulnerable to the expected

adverse effects on agricultural productivity. Another aspect of reducing water demand is the reuse of wastewater

for agriculture from the agricultural, domestic and industrial sectors. Notwithstanding the need to ensure health

and quality aspects of waste water use from contaminants such as salts, metals, metalloids, residual drugs,

organic compounds, endocrine disrupter compounds, active residues of personal care products and/or pathogens,

there is added benefit from its use as waste water generally has higher levels of nutrients than groundwater. For

example, ICARDA and IWMI assessed the production, treatment, and reuse of wastewater in the Aleppo region

in the Euphrates–Aleppo Basin. A comparative benefit-cost analysis revealed that the return on wheat irrigated

with wastewater was double the return on wheat irrigated with groundwater. For each US dollar invested in

wheat irrigated with wastewater the return was US$5.31. Wheat irrigated with groundwater returned US$2.34

for each dollar invested. Wheat irrigated with wastewater gave higher yields because of the wastewater’s high

nutrient content. Farmers also saved on the costs of fertilizer (US$95 ha) and pumping.

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Amelioration and management of salt affected soils

The Intergovernmental Panel on Climate Change (IPCC, 1998) predicts that rising sea levels will accelerate

saline water intrusion and increase the problem of salt-prone land and water in arid and semi-arid regions and

coastal zones. In addition, reliance on salt-prone waters — generated by irrigated agriculture or pumped from

aquifers — seems inevitable for irrigation (Bouwer, 2002; Qadir et al., 2007a,b). Similarly, salt-affected soils,

which occur within the boundaries of at least 75 countries, will have to be used for agriculture.

Currently at least 20% of the world’s irrigated land (> 50 million ha) is salt-affected and/or irrigated with waters

containing elevated levels of salts (Ghassemi et al., 1995). Land degradation caused by salinity and sodicity has,

for example, increased steadily over the last few decades in the northwest plains of the Indo-Gangetic Basin in

India and Pakistan and in China’s Yellow River Basin. Salt- and irrigation-induced land degradation is also

occurring in the Aral Sea Basin in Central Asia. The environmental changes in the basin are considered to be

some of the largest caused by humanity in recent times. Other examples of such degradation exist elsewhere in

the world (Qadir et al., 2006).

As the agricultural use of salt-prone land and water resources increases, exacerbated by climate change, their

sustainable use for food and feed production will become a more serious issue. In the future, sustainable

agricultural systems using these resources should have good crop production with adverse environmental and

ecological impacts minimized (Qadir and Oster, 2004). This will require a comprehensive approach to soil,

water, and crop management. The foci will need to be on the amelioration of new lands, rehabilitation of salt-

affected lands generated by past irrigation practices, improved productivity per unit of water used, and

environmental protection.

The work of ICARDA reveals that crop and water management play a pivotal role in the amelioration and

management of salt-affected soils and reuse of saline water for irrigation. Water conservation and drainage

water reuse and disposal can improve management of agricultural drainage water. Depending on the salt content

and type, salt-prone waters can be used directly, in cyclic mode with freshwater or in blended form, but careful

management is required to sustain productivity. Appropriate rates of fertilizer application or by building organic

matter in the soil can help mitigate the adverse effects of salinity. Crop-based management of salt-affected soils

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has shown to be advantageous in several ways: (1) accrued financial or other benefits from crops grown during

soil amelioration and management, (2) increase in soil aggregate stability and creation of macro-pores that

improve soil hydraulic properties and root proliferation, (3) greater plant nutrient availability in post-

amelioration soil because of added organic matter, (4) sequestration of carbon in post-amelioration soil, and (5)

environmentally feasible and productive use of otherwise marginal and degraded soils.

Productivity enhancement of salt-prone land and water resources through crop-based management has the

potential to transform them from an environmental burden into an economic asset. Research efforts have led to

the identification of a number of field crops, forage grasses and shrubs, aromatic and medicinal species, bio-fuel

crops, and fruit-tree and agroforestry systems, which are profitable and suit a variety of salt-prone environments.

Several of these species have agricultural significance in terms of their local utilization on the farm. Therefore,

crop diversification systems based on salt-tolerant plant species are likely to be the key to future agricultural and

economic growth in regions where salt-affected soils exist, saline drainage waters are generated, and/or saline

aquifers are pumped for irrigation. However, such systems will need to consider the following issues:

Monitoring water quality at the farm, watershed, and basin levels,

Improving productivity per unit of salt-prone land and water resources,

Protecting the environment and mitigating the adverse effects of climate change through carbon

sequestration,

Involving farmers in the most suitable and sustainable crop diversifying systems to mitigate any

perceived risks,

Evaluating the socio-economic aspects of the farming communities relying on the use of salt-prone

land and water resources.

ICARDA has done pioneering work on the management of a unique kind of salt-affected soils, i.e. soils

containing elevated levels of magnesium, which are greater than calcium. Elevated levels of magnesium in soils

result in severe structural degradation that leads to lower infiltration rates and hydraulic conductivities. These

effects are similar to those observed in sodium dominated soils (i.e., sodic soils) that are characterized by

structural instability resulting in poor crop growth. High-magnesium soils occur in several parts of the Aral Sea

Basin in Central Asia with more than 30% of the irrigated area in southern Kazakhstan having excess levels of

15



magnesium with exchangeable magnesium percentages in the range of 25-45%, and in some cases, as high as

60%. When magnesium dominant soils are plowed they characteristically form massive clods that impede the

flow of water down furrows and across irrigated fields resulting in poor water distribution (Figure 6). The

problem is compounded where magnesium concentrations are higher than calcium in irrigation water. Southern

Kazakhstan is a typical example where excess levels of magnesium are present in both the soil and irrigation

water. Consequently, there has been a gradual decrease in cotton (Gossypium hirsutum L.) yields in the area.

Farmers rely heavily on this crop for their livelihoods and hence a decline in productivity has a significant

impact on the profitability of their farming enterprise. Similarly, yields of winter wheat (Triticum aestivum L.)

are negatively affected by this soil related problem.

High-magnesium soils can be brought back to their original productive state by increasing the levels of calcium

to counteract the deleterious effects of magnesium. This is accomplished through the application of a source of

calcium to the soil in sufficient amounts. Gypsum or phosphogypsum are often used as a calcium source.

Gypsum (CaSO4·H2O) is a mineral, which is found in sedimentary environments. Phosphogypsum is a by-

product from the production of phosphoric acid from rock phosphate (apitite), which is used in the production of

phosphate fertilizers. Phosphogypsum is widely available in Kazakhstan and could be used to enhance the

productivity of high-magnesium soils the area and elsewhere in Central Asia at an affordable cost to the farmers.

Phosphogypsum can be applied in winter before snowfall or after plowing the field for seed-bed preparation. In

low rainfall years, incorporation of the applied phosphogypsum by harrowing the field is recommended in order

to reduce the risk of the material being blown away due to strong winds that are common in the region. Snow

melt and rainfall in winter season accelerate the dissolution rate of phosphogypsum and concentrations the

calcium in the soil. This is followed by the replacement of magnesium from the cation exchange complex by

calcium as a result of mass action. The replaced magnesium is leached to depth in the profile by the application

of an excess irrigation or rainfall. In ameliorated soils, water and air movement is improved along with

increased root penetration, seedling emergence, decreased runoff and erosion. Such changes have a positive

effect on water use efficiency as well as the activity of plant roots that ultimately enhances crop growth and

yield.

In addition to mitigating the deleterious effects of magnesium, phosphogypsum application improves nutrient

availability status of the soil. ICARDA studies have shown that an application of 4.5 t ha–1 increased phosphorus

16



(P2O5) levels in the top 0.2 m soil layer from 82 kg ha–1 to 106 kg ha–1, indicating an increase in phosphorus

levels by 29%.

There was a substantial increase of 62% in phosphorus levels (from 87 kg ha–1 to 141 kg ha–1) in the same soil

depth after application of phosphogypsum at the rate of 8 t ha–1. At the 0.2-0.4 m soil depth, the percent

increase in phosphorus levels was 18 and 28% for the 4.5 and 8 t ha–1 phosphogypsum treatments, respectively.

There was also a small increase in potassium levels (3-5 %) in the soil after the application of phosphogypsum

to the soil.

Studies carried out by ICARDA under field conditions reveal the beneficial effects of the amendment

application on the yield of cotton. There were improvements in germination, and bud and boll formation, all of

which contributed to an increase in crop yield (Figure 7). Cotton yield in the control plots (1.4 t ha–1) was almost

half of the yield harvested from phosphogypsum treatments. There was a 93% increase in cotton yield from the

phosphogypsum treatment (4.5 t ha–1) over the control. In the case of the 8.0 t ha–1 treatment, cotton yields

increased to 114% over that harvested from control plots. The enhancement in cotton yield in the

phosphogypsum treatments was due to the improved levels of calcium in soil solution and on the cation

exchange complex, which improved the ionic balance and physical properties of the soil. The increase in

phosphorous levels in the soil also helped improve the phosphorous nutrition of the plants. The yield responses

observed in the first year were similar in subsequent years indicating a persistent effect.

The beneficial effects of phosphogypsum in enhancing the productivity winter wheat and cotton on high-

magnesium soils have also been demonstrated on farmers’ fields. The determination of an appropriate rate of

phosphogypsum for a high-magnesium soil is a crucial step. This depends on the initial level of magnesium in

the soil that needs to be reduced to a critical level to restore the soil to a productive state.

The effects of phosphogypsum applied to a high-magnesium soils may last for several years. Studies done by

ICARDA have shown that under conditions where high-magnesium waters are used to irrigate the post-

amelioration soils, the levels of magnesium tend to increase and that of calcium gradually decrease 4-5 years

after the initial application. These conditions underscore the need for further application of phosphogypsum to

17



maintain the magnesium concentrations at desirable levels in order to ensure sustained and profitable crop

yields.

Policy and socio-economic aspects of natural resource management

Increasing the resilience of agro-ecosystems often implies improving or at least maintaining the natural resource

base. Resource poor land users however are forced to exploit their natural capital in order to make a living and

frequently do not have access to inputs to replace the resources used. While there are some ‘win-win’

technologies such as multi-storied agro-forestry systems that can satisfy on the one hand the short-term demands

of farmers for produce at local scales, and on the other the longer-term demands of national and international

communities for tourism, biodiversity, and reduction of GHG emissions, in general land users will deplete the

natural resource base and thus increase the vulnerability of their agro-ecosystems to climate change. Such

situations require policy and economic interventions to close the gap between the goals of resource poor land

users and those of society at large regarding measures to mitigate and adapt to climate change (Izac, 1997).

Realising this paradox there has been increasing interest in the concepts of compensation or payments for

environmental services. Enthusiasm for these ideas is growing rapidly as we move beyond the Kyoto protocol

and the Clean Development Mechanism and with the opening up of voluntary carbon trading markets (Taiyab,

2006). Compensation for ecosystem services (CES) is a payback for any human induced action or effect that a

group or individual generates to the benefit of the environment, which in turn can be used by third parties such

as communities, private sector and governments (Global Mechanism, 2007).

A major challenge in implementing these schemes for the non-tropical drylands is the fact that the majority of

the land is rangeland with common pool or open access characteristics thus making it difficult to determine who

are the beneficiaries and whether or not there are sufficient institutional, policy and legal frameworks in place to

operate such schemes (Dutilly-Diane et al., 2007). Currently most schemes involve forestry or agro-forestry on

owned land where it is relatively easy to value the ecosystem benefits. Operating these schemes on common

pool resources is one of our greatest challenges as the potential benefits in terms of C sequestration, water

quantity and quality and biodiversity are large, e.g. C can be accumulated at initial rates of 0.9 – 1.9 Pg y-1 if

degraded drylands can be rehabilitated (Lal, 2000). Putting values on ecosystem services is an urgent topic in

order to convince policy makers of the need for greater investments in the protection and enhancement of the

18



natural resource base. Current government decision making needs to build in concepts of future risk from

climate change to a nation’s economic and environmental welfare (Homer-Dixon, 2007).

Other potential policy options have been reviewed elsewhere (Dietz et al.2004, Hazell, 2004, Thomas, 2007).

Worthy of mention is the need to consider crop and weather insurance schemes and the development of better

climate data bases and drought early warning systems.

ICARDA has examined the enabling policy environment requirements to enhance the uptake of natural resource

management technologies in drylands (Shideed et al., 2007). The results suggest that even when there is a

promising option such as the introduction of Opuntia cactus /Atriplex spp. alley cropping that increases barley

and biomass production, reduces animal feed costs, maintains livestock production during drought, improves

soil organic matter and reduces soil erosion, there is still a need for incentives from outside to stimulate

technology adoption because rates of return to farmers were not high enough to trigger technology adoption in

these harsh and high risk environments. This reinforces the need to find additional incentives such as the

proposed CES schemes described above.

Conclusions

ICARDA’s research benefits not only small-scale farmers, but also governments, the global scientific

community, and international development initiatives. The work on the conservation, characterisation,

utilisation and development of better adapted crops that are drought and salinity tolerant and which will tolerate

changing biotic stresses will contribute to food production and security and help cope with changing climate

conditions. Work on conservation agriculture is producing more robust production systems that are more

efficient in water and nutrient use while at the same time sequestering more carbon in soils. Agro-ecological

characterisation is helping to identify regions where climate change is already occurring and can support

increased preparedness for both beneficial and detrimental effect of climate change. The ability to work across

disciplines using an integrated approach to natural resource management (Campell et al., 2006) will facilitate the

required research on multiple stresses and their effects on social and ecological systems. In particular the

relationships between land degradation and climate change will be tackled through inter-disciplinary studies.

New areas for research include;

19



• Carbon trading/offset schemes (CDM, voluntary markets, mitigation-adaptation offsets)

• Payment for environmental services and valuation of natural resources, linked to carbon trading/offset

schemes.

Any proposed adaptation mechanism or climate proofing will need to consider the following interacting factors;

• the local agro-ecological conditions,

• the crop-livestock production system,

• the assets of households and villages including labor constraints, access to markets and technology and

land tenure,

• the political and institutional setting including existence of community organizations, access to national

and international markets, conflicts of natural resources, presence or absence of incentives for a better

enabling environment.

ICARDA’s work will continue to focus on increasing our understanding and enhancing the adaptive capacities

of both dryland communities and the national agricultural research systems (NARS) that serve them.

20



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25



Figure 1. Non-tropical drylands of the world (ICARDA, 2007).

26



Figure 2. Projected surface temperature changes for the early and late 21st century relative to the period

1980–1999. The left and right panels show the Atmosphere-Ocean General Circulation multi-Model

average projections for the B1 (top), A1B (middle) and A2 (bottom) SRES scenarios averaged over

decades 2020–2029 (center) and 2090–2099 (right)

27



Figure 3. Projected changes in precipitation for the period 2090-2100 (source: IPCC, 2007)

28



Figure 4. Response and vulnerability to climatic fluctuations 1982-1999. Celis et al., 2007

29



Figure 5. Population densities in the CWANA region and its surroundings:

CIESIN and CIAT.2005. Gridded Population of the World Version 3 (GPWv3)

30



Figure 6. Formation of massive clods after plowing in a high-magnesium soil that has a negative impact

on hydraulic properties and water flow rate

31



Figure 7. Cotton yield as affected by different rates of phosphogypsum application (0, 4.5, and 8.0 t ha–1)

on a high-magnesium soil in southern Kazakhstan

0

1

2

3

4

Con

trol

4.5

t/ha

8.0

t/ha

Con

trol

4.5

t/ha

8.0

t/ha

Con

trol

4.5

t/ha

8.0

t/ha

Con

trol

4.5

t/ha

8.0

t/ha

2001 2002 2003 2004

Treatments

Cot

ton

yiel

d (t/

ha)

32



Table 1. ICARDA’s contribution to ecosystem resilience, mitigation and/or adaptation to climate change?

Research activity Ecosystem resilience Mitigation of climate change

Adaptation to climate change

Conservation, characterization and sustainable use of genetic diversity and plant improvement for tolerance to abiotic stresses (extreme temperature, droughts, flooding, salinity)

Understanding of functional biodiversity and ‘keystone’ species will help maintain ecosystem functions and resilience

Increased C sequestration, reduced GHG emissions from farms and natural habitats In situ conservation of adapted biodiversity

Better targeting of germplasm to specific environments

Collection and use of commercially promising and/or underutilized plants

More efficient water use

Introduction of new commercial species with low water requirements, to increase livelihood options

Dynamics of pests and diseases under changing climates; plant improvement for biotic stresses

Less reliance on pesticides and herbicides

IPM options will reduce vulnerability to changes in pathogen distribution

Better control, improved prediction of pest and disease infestations

Role of livestock and rangelands in buffering climate change

Less overgrazing, more sustainable extraction

Increased C sequestration in rangeland soils and biomass

Increased drought preparedness

Diversification of livelihoods, including new crop-livestock options

More sustainable production systems

Increased C sequestration, reduced GHG emissions

Wide range of production system options

Conservation agriculture and crop rotations

More robust cropping systems will conserve natural resource base

Increased C sequestration, lower energy requirements

Wide range of production system options

Improved water-use efficiency, water allocation

Conservation of water resources will help maintain environmental services

Reduction of GHG emissions from soils

Production systems adapted to climate variability, especially water scarcity

Water quality monitoring, improved management of marginal-quality water (treated wastewater, saline water)

More sustainable water use, maintenance of environmental services

Increased biomass production and C sequestration

Production systems sustained despite of the use of marginal-quality water

Improved soil management and soil fertility

Increased soil organic matter will increase agro-ecosystem resilience

Increased soil C sequestration

Higher soil organic matter will reduce risk crop failure from floods, drought

Amelioration and management of salt-affected soils

Salinity mitigation will increase productivity and ecosystem health

Increased soil C sequestration

With improved crop productivity, amelioration will slow down loss of arable land; in certain cases amelioration will bring back the degraded soils to a highly productive state

Policy and socio-economic aspects of co-management of water resources

Enabling environment for more sustainable production practices

Enabling environment for more sustainable production practices and enhanced uptake and impacts of improved technologies

33



Research activity Ecosystem resilience Mitigation of climate change

Adaptation to climate change

Studying local coping strategies, drawing lessons for application to other areas

Increased range of adaptation strategies used by resource poor land users

Understanding trade-offs between development and climate change

Improved ecosystem management

Improved ecosystem management for long term sustainability

Identifying hot spots most vulnerable (food security, poverty, environmental sustainability) to climate change

Improved decision making on crop management based on better and more widely available climate information

Better matching of adapted germplasm to climate variability, reduced GHG emissions

Adaptation strategies focused on most vulnerable regions. Improved climate information used to refine coping/adaptation strategies

34



Table 2. Mean grain yields of wheat and lentil from the different types of tillage and zero-till direct sowing, (Mean for 2002-2006)

Mean Crop Yields (t/ha) Tillage practices

Wheat grain

Wheat Straw

Lentil Grain

Lentil Straw

1. Conservation (Shallow-Deep) tillage 3.96 6.73 1.15 1.48 2. Conventional (Deep-Deep) tillage 3.85 6.05 1.14 1.69 3. Conservation (Shallow-Shallow) tillage 3.58 5.61 1.10 1.48 4. Zero-Till direct sowing (Residue left)

3.29

5.13

1.07

1.81

5. Zero-Till direct sowing (Residue removed) 3.33

5.83

1.12

1.83

SE (+/-) (significant for WGY, WSY and LSYat p<0.01; NS for LGY)

0.09

0.21

0.05

0.06

35



Table 3. Net benefit of the different types of tillage and zero-till direct sowing, Tel Hadya Research farm (Mean for 2002-2006 periods for 5 years)

Net return (SL/ha)

Tillage practices Wheat Lentil

W-L rotation System

1. Conservation (Shallow-Deep) tillage 32368 6739 19554 2. Conventional (Deep-Deep) tillage 29946 7707 18827 3. Conservation (Shallow-Shallow) tillage 27188 7436 17312 4. Zero-Till direct sowing (Residue left)

25538

8778

17158

5. Zero-Till direct sowing (Residue removed)

30347

9509

19928

US$ = 50.5 SL

36



37

Table 4. Wheat-grain production scenarios for 4 ha farms with various strategies of supplemental irrigation in Syria Management strategy Rainfed

(342 mm) Farmer’s practice

Full SI Deficit SI

Total water applied (m-3) 2980 2220 1110 Grain yield (t ha-1) 1.8 4.2 4.4 4.2 Water productivity (kg m-3) 0.53 0.70 1.06 1.85 Possible 4 ha farm production if water is non-limiting (t)

7.2 16.7 17.8 16.6

Possible 4 ha farm (t) production under limited water (50% of full irrigation assumed to be available)

7.2 10.8 12.5 16.6

Adapted from Oweis and Hachum, 2003.



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