Dominica’s national motto “Après Bondie C’est La Ter” meaning “after God is the land” highlights the importance of the land (the soil) to Island. The amount of precious top soil eroded by the torrential rains during the Erika disaster may never be quantified or featured among all we have lost. Nonetheless, losses incurred due to landslides and soil erosion and the subsequent impact on communities and livelihoods highlight the need to elevate the importance of soil and land use management in Dominica.
The 68th United Nations General Assembly declared 2015 as the International Year of Soil. A primary objective was to raise awareness among civil society and decision makers of the profound importance of soils for human life. As a non-renewable resource, its preservation is paramount for food security and our sustainable future.
Soils are not merely parcels of uniform materials. Instead, they are units with characteristics that change vertically downwards through different layers and horizontally in every direction. Therefore, to describe a soil it is not sufficient to only look at the surface, a vertical cut or boring must be made and the different layers from the surface to the parent material (underlying rock) carefully examined.
The soils of Dominica were classified by Mr. David Lang over 40 years ago. His work provides general descriptions of the major soil types, soil forming processes and includes several important recommendations for land use planning and agricultural development. Mostly, the soils are formed by the weathering of volcanic rock. The weathering process results in the formation of clays and secondary minerals. However, the unique properties of the respective soil types are based on the underlying rock and as influenced by environmental factors, rainfall patterns, topography, vegetation and the extent of weathering.
The physical and chemical characteristics of our soils, suitability for agriculture and other land uses are largely dependent on the type and quantity of clay they contain. For example, soils along the west coast between Jimmit and Tarreau dominated by Smectite clay minerals are noted for their shrinking and swelling properties. They shrink and crack considerably when dry and expand when wet. This activity is responsible for the cracks and movement frequently observed in the paved roads in that area. The Smectoid clays differ from soils on the north east, around Marigot, which are dominated by Kandite clay minerals. Kandoid clays are generally highly weathered (older), appear reddish to red-brown, are well-drained and better suited for agricultural development.
Several studies have investigated the mechanics of landslides in Dominica. The steep slopes, high rainfall and high water holding capacity of our soils are some of the factors that predispose many parts of the island to landslides. While heavy rainfalls are common in Dominica, it is the prolonged precipitation at high intensities, as occurred with Erika, which is capable of causing serious destruction from landslides.
Efforts to rebuild Dominica must be focused on building resilience and adapting to climate change impacts. Soil conservation and land use planning based on available technologies and the findings and recommendations generated from scientific studies (most of which already exist) should guide policy decisions and inform activities at the farm and community levels. We must also rely on the practical experience of individuals who have continued in the traditions of our forefathers, by stabilizing slopes with deep rooting crop and forest trees, bamboo and vetiver strips and who willingly adopt the approach that some extra work now can set the foundation for a sustainable future.
Davidson Lloyd (PhD)