Category: Aridity: Humid

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Stone Lines

Similar names: Cordons pierreux, stone bunds.

Stone lines are stones grouped in the shape of a line and placed along contours. The stones can be of different sizes. The goal of these lines is to conserve the soil and reduce runoff, as they are used to slow down water runoff and break its velocity. Hence, they increase infiltration and retain sediment and seeds to make water and nutrients available for crops. Stone lines are most suitable for water harvesting on slightly sloping plains (up to 5%) in semi-arid regions. For slopes starting from 5%, stone bunds can be used (see Eyebrow Terraces).

Stone lines are an easy and cheap intervention if stones are available in the immediate surroundings. This intervention is widely used in Africa, both in dry and humid areas. Moreover, stone lines are often used in combination with Zai Pits intervention for the rehabilitation of degraded and crusted lands. It is applied in semi-arid areas, on sandy and loamy soils where the slope is lesser than 5%. A great example can be seen in Niger, where the combination of the two techniques is applied to capture runoff, making infiltration more efficient and improving nutrient availability. The pits have a diameter of 20-30 cm, and a depth of 20-25 cm and are spaced about 1 m apart in each direction. Stone lines are spaced 20-25 m apart on slopes of 2-5%. With this layout, stone lines are usually quite small, three stones wide and only one stone high, and they are placed by hand along the contour lines. Very often grass grows between the stones leading to a greater infiltration and helping the accumulation of fertile sediments. Maintenance-wise, stone lines need to be repaired annually, in particular after heavy precipitation events.

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Terracing

Terracing is a method of farming and soil conservation on hills and sloped lands. It was traditionally used by the Incas and is widely practised around the world today. It involves the building of platforms and forming step-like structures along a slope. The main goal of bench terraces is to periodically interrupt the slope of the terrain with flat sections; this helps to decrease the speed of water runoff,  significantly reducing soil erosion and surface runoff. By slowing down water speed, this intervention stops the washing away of topsoil containing important nutrients and promotes better water infiltration and soil moisture. The flat benches of the terraces create more effective and productive areas to farm on steep terrain.

There are two main types of terracing techniques: graded terracing and level terracing. With graded terracing, the slope can vary along the length of the terrace to direct water in the desired direction; this is especially useful for less permeable land. With level terracing, the terraces follow a contour line and do not vary in slope along this line, this ensures that water is more evenly distributed along the terrace. Stone or wooden walls are often used to hold terraces in place, although a simple earth wall without supporting material can be used with slopes and terraces on the smaller side. This intervention is similar to Fanya Juu and Fanya Chini which are specific types of terraces.

Terracing offers several ecological and socioeconomic benefits. Ecologically, it prevents soil erosion by slowing water flow, allowing it to infiltrate the soil and retain valuable topsoil, which is essential for agriculture. Terracing also manages water more effectively by evenly distributing it across levels, conserving water, reducing irrigation needs, and promoting nutrient cycling. It creates diverse habitats for various plant and animal species, enhancing biodiversity. Additionally, terracing stabilises slopes, reducing the risk of landslides by minimizing soil pressure and movement, especially in regions with wet seasons. Socioeconomically, terracing increases land productivity on slopes, allowing for larger crop beds and easier use of machinery, thus boosting agricultural efficiency.

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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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Exclosures & Enclosures

Enclosures are fencing structures that restrict animal and human access to land with the goal of supporting the regeneration or protection of said land. Enclosures also refer to the practice of fencing-off an area in order to protect it from human use and animal intrusion. The main goal of Enclosures through fencing is to allow natural regeneration and rehabilitation of degraded lands within the enclosed space. This intervention fosters natural regeneration and helps to restore organic matter and a healthy soil structure. Enclosures can also be used to change the cover of the land to allow time for new land coverage (vegetation) to be established. Enclosures can be applied in a variety of different landscapes and environmental conditions. This technique is a relatively cheap intervention if the materials are available on site but can be somewhat more expensive where materials need to be acquired or where more sophisticated Enclosures are built. Fencing could be done for a permanent or temporary use, and this is defined by the goal of the project. 

Some of the major features of Exclosures and Enclosures are the economic benefits linked to the environmental benefits coming as a result of their implementation. Firstly, the increased vegetation that comes as a result of fencing increases vegetation which in return enhances water-retention capacity of soil. This helps to both replenish the nutrients in the soil and to restore the ability of the soil to retain water.  Furthermore, the enhanced water retention capacity of the soil reduces the exposure to flood damage. When it comes to agriculture, Enclosures and Exclosures improve long-term returns from crop production and pastureland, as the long-term productivity of the land is improved by improved and regenerated soils. This helps to increase crop yields quality. Exclosures and Enclosures can increase security of land tenure and make property rights clearer due to clear demarcations of the boundaries of your land. This can, in turn result in a higher willingness to invest in the land. Finally, Enclosures and Exclosures provide an opportunity for complimentary economic activities to be realised, such as harvesting grass (‘cut and carry’), extraction of wood, or growing of fruits and vegetables. Growing additional crops can also increase and diversify income streams and contribute to enhanced food security.

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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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Tilling

Similair names: ploughing

Tilling is one of the most important and widely used agricultural techniques in the world. It dates back to ancient times. Tilling involves physically manipulating the soil to achieve optimal conditions for seed sowing and crop planting. Different tools and techniques for tilling agricultural land exist. Put simply, tilling consists of breaking, cutting, or turning over the first layer of soil (usually between 15 and 25 cm) before planting crops. This helps to achieve a range of potential benefits such as increased aeration of the soil, increased water infiltration capacity, improved nutrient availability, burying of leftovers of previous crops, and weed control. These effects provide good conditions for plant growth and root establishment. Although tilling aims to improve soil structure for planting crops, excessive tilling can have the opposite effect and create a detrimental impact on the soil by leading to a depletion of soil microorganisms and fertility. By loosening the soil, tilling also increases the vulnerability of land and soil to erosion.

Tilling offers several ecological and socioeconomic benefits. Ecologically, it improves soil aeration and drainage by breaking up compacted soil, facilitating better root growth and nutrient uptake, and aids in weed control by disrupting weed roots, reducing competition for resources. Socioeconomically, tilling enhances soil structure, creating a favourable seedbed for planting, which can boost crop yields and contribute to food security. It also accelerates nutrient cycling by decomposing organic matter and releasing nutrients back into the soil, reducing the need for chemical fertilizers. However, excessive tilling can lead to soil degradation and nutrient loss.

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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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Multi-storey Cropping

Multi-storey cropping, or multi-tier cropping, is a production system characterized by an extremely efficient utilization of space by focusing on both vertical space and ground arrangement. Crops of different heights, stages of maturation, sunlight requirements, and root systems are grown in tandem. By selecting crops of different heights, canopy patterns, and root systems, multiple layers of canopy (2 to 5 layers) can be grown on a farm. This farming system seeks to maximize farm productivity and income and usually involves cultivating entirely cash crops. It is best suited to smallholder farms in tropical zones that receive high levels of sunlight. 

Multi-storey cropping can be implemented in an intercrop or mixed-crop arrangement. Crops may also be planted in a more random arrangement where practitioners/farmers have specific knowledge of the local environmental and ecological system and which crops may be optimal for their context. Multi-storey cropping enables the diversification of crops produced and often brings higher yields per unit area than mono-crop settings. This type of crop-growing system leverages the synergies between plants to enhance productivity (foliage size, shade formed, nutrients used, etc.). Multi-storey cropping systems also place a strong emphasis on nutrient recycling;  these systems allow organic matter to re-enter the soil, thus improving the structure and fertility of soils (this can be aided further by actively implementing Mulching). Finally, a multi-storey cropping system reduces soil erosion by increasing the soil cover and water retention of an area.

Some of the main advantages of multi-storey cropping are the increased long-term productivity of farms due to improved soil health and the survival of different crop varieties thanks to the provision of shade by taller plants. The provision of shade and multiple crop types can increase soil fertility and restore the nutrient content of the soil. As a result, this can lead to long-term productivity of the soil which can contribute to long-term food security and quality due to improved soil health. Furthermore, what is also observed is a reduced exposure of farmers/implementors to market volatility due to diversified sources of income from planting multiple crops. This on its own can result in a potential increase in farm income (once the system is complete) due to diversification of income screams through the planting of multiple crops, and reduction in crop vulnerability (for crops which prefer shade). Finally, when the intervention is applied is can result in a decreased flood risk/flood damage due to the increased soil cover and dense vegetation preventing excessive water runoff downstream.