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Non-Conventional Feeds

Value Chain
Climatic Zone
Water Source
Decision Making
Farming Characteristics
Mechanisation
Labour Intensity
Initial Investment
Maintenance Costs
Access to Finance/Credit
Extension Support Required
Access to Inputs
Access to Markets
Gender/Youth Smart
Description

Non-Conventional Feeds (NCF) are either traditional or commercial animal feed-types that are not traditionally utilised as animal feed. These feeds are generally in one of two categories: by-products of agroecological industrial processes, or plants/plant materials from other processes. Examples of industrial by-products include groundnut cake, molasses and cotton seed meal, which are outputs from other processes and are found in proximity of manufacturing points, but often have a short shelf-life. Plant materials can be vegetable peels or locally available crop residues such as maize stalks and other remaining parts of harvested plants not consumed by humans. NCF decrease the demand of land to grow fodder, act as an alternative source for animal feed, resulting in the decrease of food competition between animals and humans ensuring food security. Furthermore, the use of bi-products optimises the use of raw materials and can increase profitability for the producer and the farmer.

Technical Application

To effectively implement NCF practices:

  • Step 1: Determine potential sources of NCFs in the local area and consider if the potential products are suitable (provide enough energy, are digestible, palatable to livestock animals, etc) and require additional investment to access or use.
  • Step 2: Collect for free/negotiate lower rates with producers of agroecological industrial process biproducts or plant materials to gain access to their ‘waste’ materials.
  • Step 3: Determine how sustainable and consistent the supply will be from the providers. If possible, identify a range of suppliers to mitigate potential losses of stockpiled NCFs.
  • Step 4: Before being used as feed, NCF’s from agroecological processes must be appropriately processed - (grinding (8 mm) and pelleting) and mixed into a uniform blend. Hence, labour requirements may increase. This could be mechanised.
  • Step 5: Livestock should be monitored when these feeds are introduced to ensure digestibility of the product for the animals.
  • Step 6: Based on advice from the suppliers of agroecological industrial process biproducts, ensure appropriate storage of materials to avoid loss of nutrition, pests and waste.
Return on Investment Realisation Period
Crop Production
Fodder Production
Farm Income
Household Workload
Food Security
Soil Quality/Cover
Biological Diversity
Flooding
Crop/Livestock Water Availability
Wind Protection
Erosion Control
Increase Production
Can supplement conventional feed to enhance productivity.
Increase Resilience
Reduces pressure on land to produce fodder.
Mitigate Greenhouse Gas Emissions
As these are by-products of industrial processes, no additional inputs to produce fodder are required.
Additional Information
PDF File
/sites/secondsite/files/tb/CCARDESATechnicalBrief_40_NonConventionalFeeds_2019-10-17_0.pdf
Benefits and Drawbacks

Benefits

  • The use of NCFs could be a cheap and good source of nutrients for livestock.
  • NCF act as an alternative source for animal feed, resulting in a decrease of food competition between animals and humans.

Drawbacks

  • NCF’s need to be handled properly to avoid formation of moulds that are not good for animal health.
  • Farmers need to acquire skills on how best to conserve these residues for animal consumption, like drying before storing to avoid the loss of nutritional value.

Physical Storage Options

Value Chain
Climatic Zone
Decision Making
Farming Characteristics
Mechanisation
Labour Intensity
Initial Investment
Maintenance Costs
Access to Finance/Credit
Extension Support Required
Access to Inputs
Access to Markets
Gender/Youth Smart
Description

Grains are stored to reduce the opportunities for loss, damage or infestation by pests. On the farm grain storage can be short-term (>3 months) before it is moved to the supply chain, long term (3-12 months) while farmers store it for home consumption, to sell when prices are more favourable or for planting in the next season. During this phase of post-harvest processing, grains can be stored in bags, silos or other bulk storage containers. Bag storage utilises permeable sacks that will allow air movement in and out of the bag. Structures can be built to store grains and solid-wall bins or silos should be used in areas where grains can be dried properly. Other options include airtight underground pits, steel bins, while concrete silos and warehouses can also be used as storage options. While storing grains to ensure favourable storage, facilities should be kept clean, covered, and never exposed to the elements.  However, pest control measures need to be established, such as adhering to acceptable grain moisture content levels at storage to deter insect infestation, as pests (rodents, insects, etc.) can devastate grains in storage. Physical storage options are built to meet the demand and supply of grains season-to-season and to make seeds available for the next planting season.

Technical Application

To effectively implement Physical Storage Options:

  • Step 1: When making a choice of which storage option to choose, farmers must consider the type of crop to be stored, storage requirements of the crop and the form in which the crop must be stored (for 0-6months/3-12months).
  • Step 2: Grains must be stored in a dry place with a constant temperature.
  • Step 3: Crops should be dried and have low moisture content prior to storage.
  • Step 4: Airtight containers should be used to avoid insect infestation.
  • Step 5: Based on farmer resources and time of storage, there are a number of containers that can be utilised to store harvested crops including metal silos, polythene sacks (that can be layered), mud silos, plastic bags.
  • Step 6: As a last measure, insecticides in the form of a powder can be applied to harvested crops. The powder comes in pre-measured packets and are low dosage so generally safe to handle. Information is provided on each packet and should be read before integrating it into the crop. Grain needs to be cleaned before consumption.
Return on Investment Realisation Period
Crop Production
Fodder Production
Farm Income
Household Workload
Food Security
Soil Quality/Cover
Biological Diversity
Flooding
Crop/Livestock Water Availability
Wind Protection
Erosion Control
Increase Production
Reduces losses during storage.
Increase Resilience
Storage that is protected from flooding, extreme rain and heat will protect grain. Potential to store until prices are higher and increase income.
Mitigate Greenhouse Gas Emissions
More efficient use of resources.
Additional Information
PDF File
/sites/secondsite/files/tb/CCARDESATechnicalBrief_39_PhyscialStorageOptions_0.3_2019-07-18_0.pdf
Benefits and Drawbacks

Benefits

  • Storage options can support food security and assist farmers respond to supply and demand, leveraging favourable market prices and conditions.
  • Suitable for short- and long-term storage.

Drawbacks

  • Uncontrolled grain moisture may lead to insect infestation and loss in grain.
  • Insect fumigation may contaminate grains.

Drying Techniques

Value Chain
Annual Average Rainfall
Climatic Zone
Decision Making
Farming Characteristics
Mechanisation
Labour Intensity
Initial Investment
Maintenance Costs
Access to Finance/Credit
Extension Support Required
Access to Inputs
Access to Markets
Gender/Youth Smart
Description

Drying techniques are agricultural practices applied to assist with the balance of moisture in grains post-harvest, determined by a combination of ambient temperature and relative humidity. Spoiling due to insufficiently dried grain is one of the main causes of grain deterioration, loss in grain quality, and thus market value. Grains have the capability to absorb or evaporate moisture, and a balance of moisture content in the air and grains should be sought to achieve an Equilibrium Moisture Content (EMC). EMC prevents the formation of moulds that may affect the quality of grains, spread of pests and germination of grain seeds. After harvest, transportation and threshing, grain needs to be further dried to be preserved. Natural drying techniques are based on ambient air circulation to reduce the moisture content of the grain before storage. Artificial drying techniques apply fans and/or heating elements to move air and maintain constant temperatures .Natural drying (sun drying) is the preferred, commonly used agricultural technique in southern Africa and does not require use of machinery. Drying techniques preserve the contents of seeds thus assuring sustainable agricultural productivity and the practice as climate smart.

Technical Application

To effectively implement Drying Technique practices:

  • Step 1: Harvest crops.
  • Step 2: Consider the number of different crops that need to be dried.
  • Step 3: Dry the crops naturally using air temperature or direct sunlight or artificial drying through using fans or other mechanical means.
  • Step 4: Never place crops directly on the soil but rather on a cement area, woven mats or a layer of sacks.
  • Step 4: Livestock should be kept away from drying grains to prevent contamination and loss.
  • Step 5: Farmers should consult storage life charts that will help determine dry crop characteristics and approximate times for drying.
  • Step 6: Cover all drying grain at night to prevent loss or damage.
  • Step 7: Sorghum should be left on the seed, maize should be de-husked and left on the cob, grain and pulses are normally left in their pods.
  • Step 8: Monitor the stored grain by checking at least every two weeks.
Return on Investment Realisation Period
Crop Production
Fodder Production
Farm Income
Household Workload
Food Security
Soil Quality/Cover
Biological Diversity
Flooding
Crop/Livestock Water Availability
Wind Protection
Erosion Control
Increase Production
Reduces potential losses of ripened grain.
Increase Resilience
More grain of a higher quality to consume and sell.
Additional Information
PDF File
/sites/secondsite/files/tb/CCARDESATechnicalBrief_38_DryingTechniques_2019-10-17_0.pdf
Benefits and Drawbacks

Benefits

  • Prevents loss in grain quality.
  • Outside on a flat surface, drying system costs less.
  • The drying crib system can be used for many years.
  • Forced air/hot air dryer systems are not weather dependent.

Drawbacks

  • Imbalanced EMC leads to low quality seed, possible mould/decay and possible germination of grain seeds.
  • The natural drying technique is not suitable for humid climates as EMC is difficult to achieve without artificial drying.

Changing Harvest Time

Value Chain
Climatic Zone
Decision Making
Farming Characteristics
Mechanisation
Labour Intensity
Initial Investment
Maintenance Costs
Access to Finance/Credit
Extension Support Required
Access to Inputs
Access to Markets
Gender/Youth Smart
Description

Changing harvest time refers to adjusting harvest time to focus on optimal moisture conditions, thereby avoiding losses from mould, decay and possible disease, while also considering optimal maturity of the crop. This approach encourages the reduction in potential losses of ripened grain and increases potential higher quality grain for consumption or market. Harvesting of crops when physiologically mature can minimise losses during transportation to the homestead. Physiological harvesting refers to the time when a grain (fruit, etc.) can be separated from its parent plant and continues to ripen over time. Farmers should consider planting earlier or later or consider planting faster or slower maturing varieties to avoid issues of post-harvest loss. This is a climate smart practice because it reduces potential losses of ripened grain, increase the quality of grain harvested, and is overall a more efficient use of resources, all while mitigating the spread of diseases and reducing GHG emissions.

Technical Application

To effectively implement Changing Harvest Time practices:

  • Step 1: Consider researching recent rainfall records and consult national meteorological services to as accurately predict start of rainy season as possible.
  • Step 2: Farmers should consult data provided by the African Post Harvest Loss Information System (APHLIS), which provides information on harvest loss and additional resources to consult.
  • Step 3: Consult with national agricultural extension and research to determine growing periods of chosen crops. Request information about quicker or slower maturing seeds.
  • Step 4: Plant crops at the right time so as to avoid harvesting during rainy season.
  • Step 5: Harvest as soon as crops are physiologically mature.
  • Step 6: Wait 24 hours after a rain period to harvest if rain is unavoidable. This may take several days, however, harvesting crops after one rain is better than leaving it for an entire rainy season.
  • Step 7: Crops should be transported to the storage for immediate drying.
Return on Investment Realisation Period
Crop Production
Fodder Production
Farm Income
Household Workload
Food Security
Soil Quality/Cover
Biological Diversity
Flooding
Crop/Livestock Water Availability
Wind Protection
Erosion Control
Increase Production
Reduces potential losses of ripened grain.
Increase Resilience
More grain of a higher quality to consume and sell.
Mitigate Greenhouse Gas Emissions
More efficient use of resources.
Additional Information
PDF File
/sites/secondsite/files/tb/CCARDESATechnicalBrief_37_ChangingHarvestTime_2019-10-17_0.pdf
Benefits and Drawbacks

Benefits

  • Reduces the potential loss of ripened grain and increases potential higher quality grain for consumption or market.
  • It improves crop production, food security and farm income.

Drawbacks

  • Moisture from rainfall at harvest time can risk crop degradation post-harvest, due to mould, decay and disease.
  • Different crops have different growing seasons, and this should be known and monitored constantly, specifically as climate change has been shown to alter growing seasons, which will in turn impact harvesting times.

Best Practice Harvesting Techniques

Value Chain
Climatic Zone
Decision Making
Farming Characteristics
Mechanisation
Labour Intensity
Initial Investment
Maintenance Costs
Access to Finance/Credit
Extension Support Required
Access to Inputs
Access to Markets
Gender/Youth Smart
Description

Best Practice Harvesting Techniques are formalised harvesting practices intended to reduce breakage and bruising of crops during collection and storage. These techniques minimise harvest losses and maintain the quality of the produce. To maximise this approach, factors such as moisture content, cleanness of the grain, colour, odour and potential pest infestation need to be considered during harvest periods. Considering each of these factors will increase grain value as quality standards are directly related to grain price. Harvesting can be performed manually or mechanically, with obvious cost implication of employing the latter.

Technical Application

To effectively implement Best Practice Harvesting Techniques:

  • Step 1: Obtain equipment and supplies needed for the harvest and post-harvest activities, e.g. clean sacks, drying mats, etc.
  • Step 2: Allocate drying and threshing areas, ensuring the areas are swept, dry, and there is no/limited access for livestock or rodents. If in a dry climate or season, drying outside is optimal. If necessary, construct drying cribs elevated from the ground with rodent guards on legs can reduce access for rodents.
  • Step 3: Allocate sufficient storage space for the harvested crop.
  • Step 4: Clear weeds from the farm to prevent weed seeds from contaminating the harvest.
  • Step 5: Place the harvested crop directly onto clean mats and bags to avoid contact with the soil, which may lead to moisture uptake and also prevent contamination with tiny Striga.
Return on Investment Realisation Period
Crop Production
Fodder Production
Farm Income
Household Workload
Food Security
Soil Quality/Cover
Biological Diversity
Flooding
Crop/Livestock Water Availability
Wind Protection
Erosion Control
Increase Production
Reduces potential losses of ripened grain.
Increase Resilience
More grain of a higher quality to consume and sell.
Mitigate Greenhouse Gas Emissions
More efficient use of resources.
Additional Information
PDF File
/sites/secondsite/files/tb/CCARDESATechnicalBrief_36_BestPracticeHarvestingTech_2019-10-17_0.pdf
Benefits and Drawbacks

Benefits

  • Best practice harvesting techniques improve grain quality and minimise post-harvest loses.

Drawbacks

  • Lodging can cause significant losses as well as contamination.

Boundary Planting

Climatic Zone
Decision Making
Farming Characteristics
Mechanisation
Labour Intensity
Initial Investment
Maintenance Costs
Access to Finance/Credit
Extension Support Required
Access to Inputs
Access to Markets
Gender/Youth Smart
Description

Boundary planting, also known as live fence planting, is a technique used to protect crops from the interference of people and animals that can disturb plant growth. Trees/shrubs are a good example of this approach as they can form a shield when planted along the boundaries of the garden or surrounding a planted field. The trees/shrubs act as wind break to shield plants against strong winds causing physical damage to plants themselves, or the removal of soil (erosion). Additional benefits include the use of branches for firewood or building materials, and the other parts of trees can be used as fodder, fruit or leave harvested for consumption, or for medicinal use. Tree/shrub spacing is critical, as trees that have dense canopies can conversely cause destructive down-drafts, negating the intended benefits. Boundary planting helps limit global warming by mitigating GHG emissions through reducing harmful gases such as, carbon dioxide, from the atmosphere and releasing oxygen.

Technical Application

To effectively implement Boundary Planting practices:

  • Step 1: Plant long lines of two fast growing trees, Caesalpinia velutina trees, between a Bombacopsis quinate and a Swietenia humilis to be replaced over time.
  • Step 2: Consider planting the boundary trees 1.5 metres apart along pre-existing fences.
  • Step 3: Attach metal fencing to the trees to support the large trees without endangering their growth. Harvest fodder when the tree is overgrown.
  • Step 4: Prune lower brunches to encourage upward growth of trees and reduce shed on the plants.
Return on Investment Realisation Period
Crop Production
Fodder Production
Farm Income
Household Workload
Food Security
Soil Quality/Cover
Biological Diversity
Flooding
Crop/Livestock Water Availability
Wind Protection
Erosion Control
Increase Production
Increases availability of tree shrub products (nuts, fruits, timber etc.) and biomass, which improves soil fertility, and thus production.
Increase Resilience
Reduces erosion of soil and evaporation. Increases water retention and infiltration. Diversifies income sources. Improves yield stability.
Mitigate Greenhouse Gas Emissions
Locks more carbon in plants and in the soil.
Additional Information
PDF File
/sites/secondsite/files/tb/CCARDESATechnicalBrief_33_BoundaryPlanting_2019-10-17_0.pdf
Benefits and Drawbacks

Benefits

  • Live fence planting is cost effective, conserves soil moisture, acts a windbreak and reduces soil erosion. These trees have various benefits such as medicinal use, mulch, livestock feeds, fruits, bee forage, timber and firewood.
  • Maintenance of boundary trees is low with short, medium and long ecological and economic benefits.

Drawbacks

  • Boundary planting occupies more land than a single row.

System of Rice Intensification (SRI)

Value Chain
Annual Average Rainfall
Soils
Climatic Zone
Water Source
Altitudinal Zone
Decision Making
Farming Characteristics
Mechanisation
Labour Intensity
Initial Investment
Maintenance Costs
Access to Finance/Credit
Extension Support Required
Access to Inputs
Access to Markets
Gender/Youth Smart
Description

System of Rice Intensification (SRI) is an agro-ecological practice for increasing the productivity of irrigated rice cultivation by changing the management of water, plants, soil and nutrients. SRI promotes the growth of root systems, increases the abundance and diversity of soil organisms by keeping the soil moist but not flooded, and provides frequent aeration and conditioning of soil with organic matter. This agro-ecological practice stimulates plant growth by transplanting young seedlings, avoiding disturbance to roots and providing crops with wider spacing to encourage greater root and canopy growth. The agricultural methodology is based on well-founded agro-ecological principles which have been successfully adapted to upland rice and have shown increased productivity over current conventional planting practices.

Technical Application

To effectively implement SRI practices:

  • Step 1: Consider separation of high-quality seeds from low-quality seeds through soaking them in plain or salt water and the unviable seeds will float on the surface of the water.
  • Step 2: Plant the seeds on an unflooded, raised bed with adequate drainage and fertile soil.
  • Step 3: After 8-12 days, transplant single young seedlings into a grind pattern with wide spacing between hills (25 cm x 25 cm).
  • Step 4: During crop growth period, control the flooding and research and follow alternate wetting and drying irrigation practices.
  • Step 5: Consider application of compost and mineral fertiliser for nutrient enhancement.
  • Step 6: Use a mechanical weeder for the control of weeds and maximisation of soil aeration.
Return on Investment Realisation Period
Crop Production
Fodder Production
Farm Income
Household Workload
Food Security
Soil Quality/Cover
Biological Diversity
Flooding
Crop/Livestock Water Availability
Wind Protection
Erosion Control
Increase Production
Reduced inputs for greater yield.
Increase Resilience
Predictable yields. Higher production equals increased food security/income and resilience..
Mitigate Greenhouse Gas Emissions
May reduce GHG emissions from irrigation pumps.
Additional Information
PDF File
/sites/secondsite/files/tb/CCARDESATechnicalBrief_32_SRI_2019-10-17_0.pdf
Benefits and Drawbacks

Benefits

  • Increased and diversified crop yield resulting in increased farm income.
  • Improved food security.
  • SRI reduces GHG emissions.
  • Existing water availability patterns to accommodate the irrigation schedule.

Drawbacks

  • SRI is a labour-intensive agricultural practice.
  • Occurrence of methane emissions from rice fields caused by flooding.

Alternate Wetting and Drying

Value Chain
Annual Average Rainfall
Soils
Climatic Zone
Water Source
Altitudinal Zone
Decision Making
Farming Characteristics
Mechanisation
Labour Intensity
Initial Investment
Maintenance Costs
Access to Finance/Credit
Extension Support Required
Access to Inputs
Access to Markets
Gender/Youth Smart
Description

Alternate wetting and drying also called intermittent flooding is a technique developed by the International Rice Research Institute (IRRI) to control water consumption in rice fields (CGIAR 2014). This technology saves water throughout the year in areas of variable rainfall. It is designed as a pick-up water system in cases when water consumption is cut. Water levels are monitored and controlled by the removal of excess water, leaving enough water to sustain crops. Alternate wetting and drying reduces greenhouse gas emissions especially methane, which is emitted from flooded rice fields (FAO 2016). The drying phase helps to sustain and develop plant roots. Moreover, costs on fuel used for irrigation are reduced.

Technical Application

To effectively implement Alternate Wetting and Drying practices:

  • Step 1: Alternate wetting and drying should be considered by the farmer after two weeks of rice transplant.
  • Step 2: The farmer should consider digging half of 30 cm tube into soil to monitor water level.
  • Step 3: When the water level is 15 cm below the soil surface the field should be irrigated again with a depth of 3 to 5 cm before water drains.
  • Step 4: This cycle should be repeated until flowering stage to avoid disturbing reproduction because at this stage the crops are sensitive to water stress.
Return on Investment Realisation Period
Crop Production
Fodder Production
Farm Income
Household Workload
Food Security
Soil Quality/Cover
Biological Diversity
Flooding
Crop/Livestock Water Availability
Wind Protection
Erosion Control
Increase Production
Cost of production reduced through less use of water.
Increase Resilience
Maintain production with reduced inputs. Predictable yields.
Mitigate Greenhouse Gas Emissions
May reduce GHG emissions from irrigation pumps.
Additional Information
PDF File
/sites/secondsite/files/tb/CCARDESATechnicalBrief_31_AlternateWettingandDrying_2019-10-17_0.pdf
Benefits and Drawbacks

Benefits

  • Alternate wetting and drying maintains rice yields in areas with variable rainfall/irrigation water supply.
  • Reduces greenhouse gas emission such as methane.
  • The technology can be carried out in regions prone to heavy rainfall.

Drawbacks

  • Water levels need to be monitored carefully to avoid water stress which might decrease yield.
  • Not recommended in areas with potential salinity stress as reduced water inputs might aggravate salinity levels and cause yield decline.

Rainwater Harvesting

Annual Average Rainfall
Climatic Zone
Decision Making
Farming Characteristics
Mechanisation
Labour Intensity
Initial Investment
Maintenance Costs
Access to Finance/Credit
Extension Support Required
Access to Inputs
Access to Markets
Gender/Youth Smart
Description

Rainwater harvesting is an agricultural technique of collecting and storing rainwater or runoff in tanks or natural reservoirs. This practice is mostly practiced in arid or semi-arid areas with temporal and spatial variability of rainfall mostly lost as surface runoff or evaporation. Runoff is harvested and utilised as a preventative measure for soil erosion, as well as a water management strategy for irrigating crops and for livestock water. This technique enables farmers to capture and store rainwater during times of plenty for use during times of scarcity. Rainwater harvesting is a technology that maximises the use of existing freshwater resources and is a useful technology for water resource planners and managers in both governmental and non-governmental organisations, institutions and communities.

Technical Application

To effectively implement Rainwater Harvesting practices:

  • Step 1: Create a water collection zone connected to a gutter system.
  • Step 2: Install filters to the water collection zone.
  • Step 3: Connect a hose pipe for easy distribution of irrigation water.
  • Step 4: If a farmer intends to use water for human consumption other than flushing toilets, etc, water quality must be frequently tested using reliable and low-cost/low-tech solutions.
  • Step 5: Use of filters can be considered to reduce particulate and other pollutants but should be thoroughly investigated – as a separate subject – by the extension officer and the farmer, otherwise it could lead to illness. It is recommended that farms utilise harvested rainwater for irrigation and other farming activities only.
Return on Investment Realisation Period
Crop Production
Fodder Production
Farm Income
Household Workload
Food Security
Soil Quality/Cover
Biological Diversity
Flooding
Crop/Livestock Water Availability
Wind Protection
Erosion Control
Increase Production
More water available to plants when it is needed.
Increase Resilience
Mitigate dry spells.
Additional Information
PDF File
/sites/secondsite/files/tb/CCARDESATechnicalBrief_30_RainwaterHarvesting_2019-10-17_0.pdf
Benefits and Drawbacks

Benefits

  • Rainwater harvesting acts as a source of water at a point where it is needed, usually stored in a tank.
  • Works as an alternative water source in cases of drought or irrigation system breakdown.
  • Rooftop rainwater catchment construction is simple.
  • Success in rainwater harvesting depends on frequency and amount of rainfall.

Drawbacks

  • Asphalt, tar and wood roofs may contaminate the water making it unsafe for direct human consumption.
  • For potable water collection, lead containing gutters should not be used.
  • Harvested water may be contaminated by animal waste.

Permeable Rock Dams

Value Chain
Annual Average Rainfall
Soils
Climatic Zone
Water Source
Decision Making
Farming Characteristics
Mechanisation
Labour Intensity
Initial Investment
Maintenance Costs
Access to Finance/Credit
Extension Support Required
Access to Inputs
Access to Markets
Gender/Youth Smart
Description

A permeable rock dam is a water harvesting technique where flooding rain water is collected in valley bases or other depressions to irrigate crops later/elsewhere, filling in gullies, controlling water flows, increasing crop production and reducing soil erosion.. Permeable rock dams are long and relatively shallow to reduce erosion while accumulating silt and distributing water. They comprise of long low rock walls with smooth crests so that water can spread to avoid overflow from the dam. However, this technology is site specific; it cannot be practiced in areas where there are no rocks/stones and means of transporting these building materials. The impoundment of silt prior to runoff entering a watercourse can be beneficiary to downstream users and can contribute to improved water quality in the catchment

Technical Application

To effectively implement Permeable Rock Dam practices, the following steps should be carried out:

  • Step 1: Consider constructing a permeable rock dam across relatively wide and shallow valleys.
  • Step 2: Permeable rock dams should consist of long, low rock walls with level crest along full length although farmers should consider central spillways where water course has cracks.
  • Step 3: The dam should be between 50-300m in length and 1m in height within a gully.
  • Step 4: Consider making the dam wall flatter on the downslope side than on the upslope side.
  • Step 5: A foundation of small stones should be set in the trench.
  • Step 6: An apron of large rocks is essential to split the erosive force of the overflow.
  • Step 7: Downstream banks of the water stream should be shielded by stone pitching to prohibit the increase of the gully.
Return on Investment Realisation Period
Crop Production
Fodder Production
Farm Income
Household Workload
Food Security
Soil Quality/Cover
Biological Diversity
Flooding
Crop/Livestock Water Availability
Erosion Control
Increase Production
Supports agricultural productivity as soil structure is retained and provides access to more sustainable water supplies.
Increase Resilience
Supports adaptation strategies in climate changes scenarios with improved access to water for irrigation and reducing soil erosion.
Additional Information
PDF File
/sites/secondsite/files/tb/CCARDESATechnicalBrief_29_PermeableRockDams_2019-10-17_0.pdf
Benefits and Drawbacks

Benefits

  • Permeable rock dams increase crop production.
  • Reduce soil erosion.
  • The system increases groundwater recharge.

Drawbacks

  • The technology is site specific; should be on a site where rocks and stones are present.
  • Need for large quantities of stone.
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Beneficiaries Reached

97000

Farmers Trained

3720

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41300

Lead Farmers Supported