Aloe Vera Living Barriers Cape Verde - Barreiras Vivas de Aloevera (Portuguese)

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1 Aloe Vera Living Barriers Cape Verde - Barreiras Vivas de Aloevera (Portuguese) It is a technique which uses the structure of a cross-slope barrier of Aloe vera to combat soil erosion by decreasing surface wash and increasing infiltration. Aloe vera is a durable herbaceous plant which is planted in the form of living barriers to recover degraded slopes on the Cape Verde Islands. The plants are closely planted along the contour to build an efficient barrier for retention of eroded sediments and superficial runoff. The living hedges of Aloe vera stabilize the soil, increase soil humidity by improving infiltration and soil structure. Groundwater is recharged indirectly. Soil cover is improved, and thus evaporation and erosion reduced. Implementation is relatively simple. The contour lines are demarcated using a water level. Seedlings are planted along one line at a distance of cm between plants; spacing between the rows varies between 3-5 m according to the slope. The technology is applied in subhumid and semi-arid areas, on steep slopes with shallow soils, a poor vegetation cover and high soil erosion rates. These areas are generally used by poor subsistence farmers for rainfed agriculture with crops such as maize and beans, which are considered inappropriate for such slope angles. On slopes steeper than 30% the living barriers are often combined with stone walls (width cm; height cm). The plants stabilize the stone risers, making this combined technology one of the most efficient measures for soil erosion control on the Cape Verde Islands. The herbaceous plant is well adapted to the local biophysical conditions and to the land use system: it can be grown with any crop, is available for any farmer, establishment and transport are simple, its green leaves are not palatable for livestock, the plant is extremely resistant to water stress and grows on any bioclimatic zone on the island. Furthermore, Aloe is known for its multiple uses in traditional medicine. left: Aloe vera living barriers are often combined with stone walls to enhance the erosion control on steep slopes (Photo: Hanspeter Liniger) right: Aloe vera in an agroforestry farming system (Photo: M. Moemedi) Location: Ribeira Seca catchment Region: Santiago Island, Cape Verde Technology area: 71.5 km 2 Conservation measure: vegetative Stage of intervention: rehabilitation / reclamation of denuded land Origin: Developed externally / introduced through project, Land use type: Cropland: Annual cropping Grazing land: Extensive grazing land Climate: semi-arid, tropics WOCAT database reference: T_CPV006en Related approach: Compiled by: Jacques Tavares, INIDA - Instituto Nacional de Investigação e Desenvolvimento Agrário Empresa Date: Contact person: Jacques Tavares, Instituto Nacional de Investigação e Desenvolvimento Agrário (INIDA) Classification Land use problems: - Low productive land, shallow soil depth, loss of soil by runoff water, reducing its thickness and fertility (expert's point of view) Low productive land, weak and thin (land user's point of view) Land use Climate Degradation Conservation measure Annual cropping Extensive grazing land rainfed extensive grazing land semi-arid Soil erosion by water: loss of topsoil / surface erosion, gully erosion / gullying Vegetative: Grasses and perennial herbaceous plants

2 Stage of intervention Origin Level of technical knowledge Prevention Mitigation / Reduction Rehabilitation Land users initiative Experiments / Research: years ago Externally introduced Agricultural advisor Land user Main causes of land degradation: Direct causes - Human induced: soil management, overgrazing Direct causes - Natural: droughts, other natural causes, Steep slopes: Low vegetation cover accelerates the runoff Indirect causes: poverty / wealth, education, access to knowledge and support services Main technical functions: - reduction of slope length - improvement of ground cover - improvement of topsoil structure (compaction) - stabilisation of soil (eg by tree roots against land slides) - increase of groundwater level / recharge of groundwater - sediment retention / trapping, sediment harvesting - increase of biomass (quantity) Secondary technical functions: - control of raindrop splash - reduction of slope angle - increase of surface roughness Environment Natural Environment Average annual rainfall (mm) Altitude (m a.s.l.) Landform Slope (%) > 4000 mm mm mm mm mm mm mm mm < 250 mm > <100 plateau / plains ridges mountain slopes hill slopes footslopes valley floors flat gentle moderate rolling hilly steep very steep Soil depth (cm) >120 Growing season(s): 90 days(august to October) Soil texture: medium (loam) Soil fertility: medium Topsoil organic matter: medium (1-3%) Soil drainage/infiltration: medium Soil water storage capacity: high, low Ground water table: 5-50 m Availability of surface water: poor / none Water quality: poor drinking water Biodiversity: low Tolerant of climatic extremes: seasonal rainfall decrease, wind storms / dust storms, floods, decreasing length of growing period Sensitive to climatic extremes: seasonal rainfall increase, droughts / dry spells If sensitive, what modifications were made / are possible: Aloe vera it is resistant to lack of water because of their physiognomy and anatomy, but can not resist a big drougth Human Environment Cropland per household (ha) < ,000 1,000-10,000 >10,000 Land user: Individual / household, medium scale land users, Leaders / privileged, men and women Population density: persons/km2 Annual population growth: > 4% Land ownership: individual, titled, Diocese Land use rights: leased Water use rights: communal (organised) Relative level of wealth: average 3% of the total area is owned by average land users Importance of off-farm income: : Access to service and infrastructure: moderate: health, technical assistance, employment (eg off-farm), market, drinking water and sanitation, financial services; high: education, energy, roads & transport Market orientation: subsistence (self-supply)

3 Technical drawing Aloe Vera Living Barriers on slope of more than 60%. The soil accumulated behind the barrier can reach depths of 55 cm. (Jacques Tavares) Implementation activities, inputs and costs Establishment activities - Demarcation of contour lines, using water levels - Collection of Aloe Vera plants (Aloe vera grows naturally on upper slopes and in depressions) - Planting Establishment inputs and costs per ha Inputs Costs (US$) % met by land user Labour % Equipment - tools % Agricultural - Plants % TOTAL % Maintenance/recurrent activities - Replanting of Aloe vera to fill gaps in life barriers (very rare, survival rate is over 95%) - Vegetative control: removal of Aloe vera plants that are invading cropland (maize, peas) between the life barriers Maintenance/recurrent inputs and costs per ha per year Inputs Costs (US$) % met by land user Labour % TOTAL % Remarks: The labour used in this technique consists of individuals from poor or very poor rural communities who come to work in search of an income with a payment of 250 Escudos per day. Labour inputs for implementation are rewarded by project: individuals of poor communities receive a salary of 3.3 US$ per day. Plants are collected locally; their value on the market would be around 3-4 US$ per plant. Establishment costs do not include labour-intensive construction of stone risers (supportive measure). Maintenance costs are borne by land users. Assessment

4 Impacts of the Technology Production and socio-economic benefits reduced risk of production failure increased crop yield Socio-cultural benefits improved cultural opportunities improved conservation / erosion knowledge improved food security / self sufficiency Ecological benefits improved harvesting / collection of water reduced surface runoff improved soil cover increased biomass above ground C increased water quantity increased soil moisture Off-site benefits Production and socio-economic disadvantages loss of land Socio-cultural disadvantages Ecological disadvantages Off-site disadvantages increased water availability Contribution to human well-being / livelihoods Aloe vera is used in traditional medicine, and is also used in personal hygiene. Benefits /costs according to land user Benefits compared with costs short-term: long-term: Establishment slightly negative very positive Maintenance / recurrent neutral / balanced very positive The structure does not require costly maintenance, it is simply controlling the spacing of the barrier (vegetative control) and punctual replanting. Acceptance / adoption: 95% of land user families (380 families; 9% of area) have implemented the technology with external material support. 5% of land user families (20 families; 1% of area) have implemented the technology voluntary. There is little trend towards (growing) spontaneous adoption of the technology. Concluding statements Strengths and how to sustain/improve Weaknesses and how to overcome Recover the degraded land and increase the production The vegetation of the area between the barriers will make the recovery and protection of the soil layer is stronger Stabilizes the soil making it more resistant to the impact of the rain water Sedimentation behind the barriers is favored along the time due to the continued growth of the plant Aloe vera Reduction of the production area, which is occupied by bands of Aloe vera Annual vegetative control within cultivated area and by cutting Aloe vera plants growing outside the living barriers, using it more economically Improves the thickness of the soil leaving it stronger and more productive The mineral and organic matter retained behind the lines of Aloe vera will promote an increase in the thickness of the soil, improving also the volume of water retained in the soil, resulting in better root development. Therefore, the process of soil formation is best done.

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