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Focus
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| Olives: The Fruits of Partnership |
Ashraf
Tubeileh, Francis Turkelboom, Adriana Bruggeman and
Richard Thomas |
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| Olive plantation on marginal land in Khanasser valley, Syria. |
The trees produce olive oil for family use and for sale, and turn marginal land into a useful resource. But as cultivation expands into marginal environments, farmers are facing problems that have not been addressed before. ICARDA and its partners are using a bottom-up, participatory approach to find solutions.
In Syria, the number of olive trees has increased by 50% during the last decade. Much of this expansion has taken place in sloping and arid areas. The Khanasser valley in northern Syria is a typical example. Annual rainfall is only 220 mm, and highly variable. In the 1980s, a few irrigated olive orchards were established in the flat areas of the valley, supported by an unsustainable exploitation of groundwater. Plantations expanded into the shallow, stony soils of the footslopes; and by 2003, the number of olive trees in the western part of the valley (with the steepest slopes and poorest soils) contained over 550 trees per square kilometer. Today, most olive-growing households have 100-150 trees, and orchards are still expanding. The trees require irrigation, so groundwater is pumped in huge quantities – even though sustainable extraction rates in the valley are barely sufficient to sustain a person's daily needs.
Olives are a vital part of the local economy – so is water. How to balance development versus resource conservation? ICARDA researchers first organized a group of 16 farmers to discuss the problems they faced. They identified water shortages and drought as the most serious. A participatory research program was then launched with a few olive growers to study possible interventions for improving water-use efficiency and drought resilience.
Researchers, extension staff and farmers worked together to devise a three-fold strategy – variety and site selection, water management, and soil management. Potential solutions were identified (including refined versions of traditional methods), and then tested through an integrated, farmer-led program of field experimentation.
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| Dry summer, shallow soil. The tree survives because the soft limestone material placed around the trunk retains moisture. |
Most farmers in Khanasser valley prefer the Zeiti variety for its high oil content and rapid initial growth and production. But Zeiti is sensitive to water stress and some olive pests. Staff from Syria's Olive Research Department worked with farmers to examine the characteristics of different olive varieties in the valley – and soon found better alternatives.
Two varieties, Qaisi and Sorani, were clearly more drought-tolerant, able to survive and produce good yields even without supplemental irrigation. ICARDA and the Olive Research Department developed extension leaflets on these varieties, and adoption is growing.
... and where to grow them
Before the project began, most farmers were planting olive trees in the flat areas of the valley, which are generally cultivated with barley. Farmers were encouraged to focus expansion on stony slopes, which were originally covered with rangeland vegetation but have been degraded due to uncontrolled grazing. These lands involve low opportunity costs, and are suitable for water harvesting. Carefully cultivated, they could generate income while helping to arrest degradation.
Water harvesting
Farmers in the Middle East have harvested rainwater for centuries. The project built on this traditional knowledge by introducing simple, easy-to-build 'micro-catchments'. Participatory experiments with farmers showed that micro-catchments increased soil moisture by 10-15% percent up to early July, just before the peak summer period began. Water harvesting also improved water and nitrogen contents in leaves, and the growth rate of tree trunks.
Limited irrigation
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| Hardy wild olive trees, found throughout the Mediterranean, could provide genes for improving stress tolerance. |
Mulching methods
Another traditional farming technique is stone mulching – the soil around the tree trunk is covered with stones to reduce evaporation losses from the soil surface. In northern Syria, farmers spread white (calcareous) soil or chalky limestone fragments under the tree canopy, especially in red or heavy soils. They believe this reduces soil cracking and soil temperatures in summer, and conserves moisture.
Project experiments showed how farmers could get better results by using basalt stone mulch instead of chalky limestone. Basalt mulch was more efficient in conserving soil moisture; and trees with basalt mulch had better water status, better nitrogen levels, and higher fruit yields.
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farmer's contribution: Insert subsurface irrigation A farmer in Khanasser, who saw his neighbors trying to devise new irrigation methods, suggested an innovation he had seen being used in olive groves in very dry parts of Tunisia. Place a stone pocket or gravel layer 40 to 70 cm underground, in or around the root zone of each tree. Take a 10-cm diameter PVC tube, and insert it
vertically into the stone pocket. Apply irrigation water into the tube, so that it goes directly to the deeper roots. For even better results (especially for old trees), use two or more tubes per tree, with the gravel layer or stone pocket arranged in a circle or crescent around the tubes. |
Field experiments
helped refine this technique. For example, irrigation in the tree
basin, without inserts, resulted in lateral water losses. Irrigation
partly into the basin and partly into the tubes increased
soil moisture content across all soil profiles below 15 cm. Irrigating entirely through the inserts resulted in higher moisture content in the profiles below 30 cm with almost no gain in soil moisture in the top layer – enhancing deep root proliferation and disfavoring superficial roots. |
The key: farmer participation
The key element in the project was farmer participation. In addition to these field experiments – planned, conducted and evaluated jointly by farmers, researchers and extension staff – regular extension meetings were held to improve farmers' practical skills in olive grove management. These included training sessions on pruning, pest management and grafting.
The project has demonstrated how olives can be produced sustainably and profitably, even in marginal environments, by combining drought-tolerant varieties, low-cost soil and water management methods, and genuine farmer participation. The farmers of Khanasser valley are reaping the fruits of this partnership.
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| Ashraf Tubeileh is a Post-doctoral Fellow, Francis Turkelboom (f.turkelboom@cgiar.org) is Soil/Conservation/Land Management Specialist, Adriana Bruggeman is Agricultural Hydrology Specialist, and Richard Thomas is Desertification/Land Management Specialist at ICARDA. |
© 2008 International Center for Agricultural Research in the Dry Areas (ICARDA).
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