Category: Slope steep

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Vegetative Lines

Vegetative lines involve the planting of lines of vetiver grass following the contour lines, along stream banks and roadsides, to create a hedge. These hedges act like semi-permeable barriers, aimed to hinder surface erosion as they slow down run-off and retain sediments picked up by excess rainwater. This setup improves water infiltration and helps to increase the ground moisture level. Their root systems also help stabilise the soil and prevent further soil erosion. Thus this provides increased stabilisation of embankments, gully erosion, roads and slopes. Furthermore, water runoff and soil runoff reductions are observed, at around 57% and 80% respectively.

Vetiver grass can grow on slopes of > 50% and can be planted on a high variety of soils (red latosols, black cracking vertisols, roadside rubble, C-horizon gravels, laterites, sodic, and saline soils). Furthermore, vetiver grass is resistant to different types of climatic conditions: rainfall from 600mm to 6000 mm /year and extreme temperatures of -14°C to 55°C, and could survive several months submerged in water. Vetiver grass can support high levels of toxicity by manganese, aluminium and other metals and high levels of soil acidity, salinity, alkalinity, and acid sulphate conditions. All in all, they provide great solutions as they are non-invasive, fire resistant, and regrow quickly and be used as mulch and fuel (vetiver energy value is 55% the energy value of coal). Finally, vetiver grass is very efficient in stabilising Semi-Circular Bunds, Eyebrow Terraces or Negarim.

Very similar to the intervention described above is the so-called “Vegetative lines with cactus”. This intervention is based on the same principle as the Vegetative lines with vetiver grass, but it is suitable for drier environmental conditions (0 – 600mm). Like some other interventions, over time, this type of intervention can lead to the formation of terraces due to tillage and water erosion between the hedges.

This Grass Barrier Strips video offers useful insights into the principles behind vegetative lines and how vegetation can slow runoff and protect soil.

Below is a step-by-step instructional video showing how to establish this type of vegetative barrier in the field.

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Fanya Chini

Similar names: Retention trenches, infiltration trenches

The name Fanya chini means “throw it downwards” in Kiswahili. It consists of trenches and earthen ridges facing downslope. This intervention aims to reduce soil erosion by breaking down long slopes into smaller sections. Thus, the speed of runoff will decrease, and water can infiltrate into the soil between the bunds. This will result in a reduction of nutrient leaching and increased water availability for crops. Fanya chini is common in areas with 300-600 mm of annual rainfall on 1-25% slopes. It is suitable for all types of relatively permeable soils (e.g. alluvial, red, laterite, brown, and shallow and medium black soil). Still, it doesn’t work very well with clayey soils or vertisols as these are not permeable.

One of the main benefits of Fanya chini is that it limits soil erosion from water runoff, and simultaneously improves water retention in the soil and increases water availability for crops. Furthermore, an increase in yield is observed, as well as improved soil fertility.

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Fanya Juu

Similar names: Terracing, Retention Trenches, Infiltration Trenches

The Fanya Juu technique is an agricultural practice that involves creating ridges along the contour lines of sloping land. The name Fanya Juu means “throw it upwards” in Kiswahili and is very similar to Fanya Chini as it consists of terrace bunds and ditches along the contour. This technique rapidly spread during the 1970s and 1980s and it is well known throughout Eastern Africa. The goal of Fanja Juu contour bunds is different depending on the environmental conditions of the areas within which they are applied. Their aim in semi-arid areas is to harvest and conserve rainfall, whereas, in sub-humid zones, contour bunds are constructed to discharge excess runoff. However, their main purpose is to prevent water and soil loss and to make conditions more suitable for plants to grow. 

Fanya Juu is suitable for slopes of 5-20%, similar to the ones that characterise Fanya Chini interventions. The species most often used in drier zones are Pennisetum Purpureum (Napier grass or Uganda grass) and Panicum Coloratum (also known in southern Africa as “white buffalograss”) and the harvest can be used as fodder for livestock. Fruit trees (e.g. citrus or bananas) can be planted either immediately above the embankment or below the ditch, where runoff tends to concentrate.

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Eyebrow Terraces

Similar names: Banquettes, Boomerangs, Terraces, Stone Bunds, Eyebrow Systems, Eyebrow Basins.

Eyebrow Terraces are a form of microcatchment water harvesting system. They are handmade micro basins, in the shape of an eyebrow, and are often made from soil and stones. Their main goal is to facilitate vegetation growth on steep slopes by collecting runoff water from a small catchment area and having it infiltrate the soil. This way, it is stored in the root zone and will be available for crops. They are usually situated on hillsides and can be used on up to 50% of slopes. The steeper the slope, the more the bunds have to be reinforced with stones. Eyebrow Terraces work well in areas characterised by 200-600 mm of annual rainfall. Reinforcing Eyebrow Terraces with stones on steep slopes makes them more resistant to the increased water speed caused by the slope. Instead, they can be some metres apart. After completion, the pit uphill from the eyebrow may fill with sediments and soil, thereby giving rise to terraces.

Some of the main advantages of Eyebrow Terraces are that they reduce the risk of flooding, while simultaneously increasing the on-site conversion of water through the facilitation of filtration. Furthermore, the intervention improves the yields in the area, by increasing the soil organic content, as sediments are trapped in the terraces.

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Farmer Managed Natural Regeneration

Similar names: treecovery, natural regeneration, tree-based regeneration, Kisiki Hai

Natural regeneration is a biological process that can be assisted and managed by farmers and landowners to increase the recovery of native ecosystems and their functions. Usually practised on wooded agricultural land, Farmer Managed Natural Regeneration (FMNR) is an approach that aims to increase the number of trees by protecting, managing and pruning existing tree and shrub stumps and roots to create the optimal conditions for them to flourish and germinate seeds again. 

An advantage of FMNR is the freedom that farmers have in implementing and adapting this technique to their specific landscape. Farmers can make decisions based on their knowledge and experience and choose which tree species they want to target, for example, fruit trees. Farmers can also select which species they want to save or remove during the pruning process, as well as when and what preferred tree density they want.

Learn the four steps of FMNR in the below instruction video:

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Tree planting

Similar names: reforestation, afforestation, planting saplings, planting seedlings

Tree planting is a technique whereby tree seedlings are transplanted for a variety of different purposes (such as forestry, land reclamation or landscape restoration). One can refer to the tree planting technique with the name of afforestation or reforestation. Afforestation indicates that the area being planted has not been recently forested. Reforestation means the area being planted was forested in the recent past. In the field of landscape restoration, tree planting is a means to tackle soil erosion thereby reducing the risk of floods and landslides. Tree leaves protect against rainfall: by intercepting raindrops, tree leaves slow down their fall and reduce their erosion power. Tree roots, on the other hand, serve as an anchor for soil, especially on sloping terrains. Planting trees also contributes to the prevention of soil erosion by improving water infiltration in the ground, so that water runoff will be reduced. Lastly, trees play an important role in restoring degraded lands, because they prepare the soil for future crops by providing it with organic matter through dead leaves and by creating good conditions through the roots.

Tree planting initiatives provide several economic benefits, such as income from wood, fuel, and non-timber forest products, as well as cost savings and job creation. Social benefits include clearer tenure security, community engagement, and a sense of shared responsibility for the environment. These initiatives also serve as educational platforms, raising environmental awareness among community members, especially youth. Additionally, they improve air quality and help preserve traditional knowledge related to native tree species and their uses.

NOTE: If the main desired outcome is to restore a forest, tree planting should only be implemented where the adoption of cheaper and more time-efficient interventions such as Assisted Natural Regeneration (ANR) or Farmer Managed Natural Regeneration (FMNR) are not possible. 

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Conservation Agriculture

Similar names: No-Tillage Agriculture, No-Till Farming, Zero Tillage, Zlimate-Smart Agriculture

The Conservation Agriculture approach is a system of managing agricultural lands based on certain farming practices. It aims to achieve sustainable production through minimizing soil disruption, while preserving soil quality and improving its biodiversity. Indeed, the main goal of Conservation Agriculture is to tackle land degradation and increase efficiency in the use of water and nutrients. For this reason, this technique works well with degraded agro-ecosystems as it helps in the restoration of resources, and to increase profits and food security. Beside the conservation of soil structure and fertility, this practice plays an important role in preventing soil erosion caused by machineries, especially in hilly and mountainous areas.

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Mulching

Similar names: Covering, Groundcover, Topping, Blanket Mulching

Mulching involves applying a layer of material to the soil surface mainly in order to improve soil health and enhance plant growth. Either organic or inorganic materials can be used as mulch. Mulching simulates a natural forest environment. In a natural forest, soil is covered by leaves and organic material, and it is rich in living organisms that recycle nutrients. Mulch can be composed of a wide variety of materials (see method of application) and has a number of potential uses. It is an especially helpful technique in climactic zones with high evaporation rates. 

The physical and ecological benefits of Miyawaki are numerous. Firstly, the layer of mulch helps retain soil moisture by reducing the soil’s exposure to direct sunlight and preventing evaporation. Mulching is also effective at stifling weed growth by physically impeding their growth and stopping their access to sunlight needed for photosynthesis (amongst other mechanisms of weed prevention such as allelopathy with certain Mulching materials). Other benefits of Mulching include that it helps prevent soil erosion, is an effective means of regulating soil temperature by acting as insulation and improves the fertility and structure of soil (especially organic Mulching). Please refer to the conditions section for information on potential problems with Mulching so as to ensure the best chances of successful implementation.

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Gully Rehabilitation Stem Cuttings

Similar names: Gully Plugging with Stem Cuttings, Check Dams from Stem Cuttings, Brushwood Check Dams, Live Check Dams

Gully Rehabilitation Stem Cuttings is an intervention that “plugs” particularly active gullies and streams by building Check Dams made of Stem Cuttings to control erosion and runoff. These living barriers are efficient in slowing down runoff water and stopping sediment buildup in the gullies. Field research has proven that they work well in soils of sandy/loamy texture, where the performances of these dams are greater than ones made of stone dams due to rooted poles and the stabilised root system of the living barrier.

Stem Cuttings involve taking sections of woody stems from suitable plants and inserting them into the soil in a gully or erosion-prone area. These stems will develop roots and grow into new plants, helping to stabilize the soil and prevent further erosion. Stem Cuttings are cost-effective and environmentally friendly, promoting natural vegetation growth, and enhancing biodiversity, and ecosystem health. They also provide erosion control once established, preventing further degradation of the gully.

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Tree Islands

Similar Names: applied nucleation, cluster planting, Assisted Natural Regeneration, Tree Island Planting

Tree islands, also known as “applied nucleation” or “cluster planting”, are a forest restoration technique that combines tree planting and natural regeneration. The primary goal of tree islands is to restore degraded landscapes by accelerating natural forest regeneration. It involves the strategic planting of small clusters of trees (“tree islands”), creating focal points for ecosystem restoration and accelerating natural regeneration in between the islands. They enhance natural forest recovery, rely on animal species for the dispersal of native tree seeds, and promote high levels of native biodiversity. 

The tree islands act as biodiversity hotspots, improving soil fertility, water retention, and microclimate, creating resilient ecosystems. They increase the availability of tree seeds and attract seed dispersers. They also provide shade, suppressing sun-loving plants that can overgrow in the area,  leaving no space for trees to establish. By creating tree islands, a base is offered from which the forest can re-establish itself and grow back much faster than conventional natural regeneration approaches.

Overall, tree islands represent an innovative and promising approach to forest restoration, offering a sustainable method for accelerating the recovery of temperate, tropical, and subtropical forests. It is a cost-effective forest restoration technique that uses only about 20% of the trees that would be needed for a whole forest plantation of the same area. This makes it more accessible and the structure more natural.

When implementing this intervention in a certain area, it is best to involve the community. It can even become a community-driven initiative, with community members working on the implementation, monitoring, and maintenance of the tree islands. This enables them to play an active role in local forest regeneration.