Strategies to sustain productivity of olive groves on steep slopes in the northwest of the Syrian Arab Republic

Abstract

In the marginal Mediterranean areas of the northwest of the Syrian Arab Republic, land degradation is a serious problem, particularly on vulnerable agricultural land. The traditional land-husbandry practices have not kept pace with the intensification and expansion of olive production into steeper areas. In these areas, soil erosion by water and tillage is widespread, especially where the soil is left bare as result of intensive clear-tillage and where no land-conservation measures are applied. These conditions are prevalent in the northwestern hills of the Syrian Arab Republic.In 1997, a small research project was started in Yakhour, a typical olive-producing village in the area. The aim was to develop, test and refine options for better land management that have the potential to stabilize and increase the productivity of the olive groves. The research followed a farmer-participatory approach that involved a large part of the community for selection of options and conducting controlled on farm experiments with farmer consultation. Socio-economic studies and a survey of the land-users’ perceptions of land degradation and constraints for the adoption of land-conservation measures confirmed that the land users were aware of the serious degradation of their agricultural land. Rainfall simulation studies revealed the high erodibility of the soils in the area.In association with the farmers, two different comprehensive packages of soil- and water-conservation measures were designed for the olive groves. One was an “agronomic package” designed to increase vegetation soil cover (by vetch intercropping), reduce soil disturbance (by minimizing tillage), and enhance soil structure (by incorporating organic materials) and short-term chemical soil fertility (by application of mineral nitrogen, phosphorus, and potassium). A second “structural package” was based on designing and building earthen, semi-lunar-shaped water-harvesting bunds. This package was applied in addition to the first package. Emphasis was placed on those soil- and land-management practices that reduce soil erosion and help restore soil fertility. After five years, the conservation measures had led to a marked improvement in the soil in terms of fertility, organic carbon content, and structure stability, while soil and nutrient losses had been reduced. The improved soil parameters were associated with a marked increase in olive productivity of 25–75 percent. As a result of the close cooperation with the villagers, the suitability of the measures to reduce soil erosion was successful and vetch intercropping has expanded in the village.