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Water Spreading Bunds

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

Water spreading bunds are barriers used on gradual slopes to slow down surface water and slow filter runoff, increasing the chance of infiltration, capturing runoff sediment, and decreasing soil erosion. Bunds can be built of different materials including packed earth or stones. Bunds can be spread across fields or used in micro-settings around individual trees or plants and should be applied in semi-arid or arid conditions. Bunds efficiently spread rainwater across the system and prevent streams from developing. Implementing bunds in areas with adequate rainfall or irrigation, may cause waterlogging and adversely affect crop growth.

Different types of bunds include:

  • Contour bunds: ridges of soil that follow slope contours and can be implemented at a large scale. Crops are cultivated between bunds.
  • Semi-circle bunds: ridges of varying size build in a half-moon or semi-circle. They are generally applied to rehabilitate rangelands and/or in the production of fodder.
  • Contour stone bunds: lines of stones laid in a shallow dug out areas that slow down the flow of runoff
Technical Application

To effectively Water Spreading Bunds the following should be carried out:

  • Step 1: Farmers should consider making earth bunds by hand, animal ploughs or mechanised ploughs.
  • Step 2: Contour bunds:
    • Contour lines must be plotted and marked prior to developing the bund.
    • A 40 cm deep infiltration pit is dug directly above where the bund will be plotted.
    • Bunds should be spread 5 m to 10 m apart.
    • Material from the infiltration pit will be piled and compacted to form a 25 cm to 30 cm in height with a base of 75 cm.
    • Soil is piled to form a ridge along the contour. The more significant the slope, the closer the bunds must be plotted.
  • Step 3: Semi-circle bunds:
    • Contour lines must be plotted and marked prior to developing the bund.
    • A centre point is chosen as diameter for the bund is selected (this could be 3 m or 30 m depending on the available space). From the centre point a string is used to stake out an even semi-circle.
    • Excavate a small trench before the bund and pile the excavated material. Pile and compact a bund wall, wetting it often to form the wall.
  • Step 4: Contour stone bunds:
    • Developed on less steep slopes.
    • Must have access to local stones.
    • Dig out a shallow ditch, 10 cm to 15 cm in depth.
    • Lay largest stones at the bottom of the ditch and pile smaller stone upward.
    • Step 5: Regular monitoring of bunds should take place, especially after rain events or after significant periods of time. Repairs should be done if any damage is found.
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 soil erosion and enables farmers to maintain agricultural productivity.
Increase Resilience
Reduces soil erosion in higher rainfall environments, especially relevant as climates change.
Additional Information
  • The Food and Agriculture Organisation (FAO), 1991. Water Harvesting. Rome, Italy.
PDF File
/sites/secondsite/files/tb/CCARDESATechnicalBrief_28_waterSpreading_2019-10-17_0.pdf
Benefits and Drawbacks

Benefits

  • Water spreading bunds are implemented on slopes of varying degrees to slow the flow of surface water, increasing infiltration and nutrient capture.
  • Bunds capture water and spread it across an area more evenly, preventing streams, erosion channels and gullies from forming at depression points.

Drawbacks

  • Developing bunds can be laborious.
  • Bunds in areas with adequate rainfall or irrigation may cause waterlogging and affect crop growth.

Half Moon Pits

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

Half-moon Pits are water harvesting techniques that assists crop growth in harsh climatic conditions, improving water and nutrient availability, promoting biodiversity and restoring the fertility of the degraded soil. The technique is similar to Zai pits in terms of its purpose. Half-moons are semi-circular wide-open basins used to collect runoff water. The mouth of the half-moons must face a slope where rainwater will flow during precipitation events. Water will be trapped in the pit to irrigate crops. Stones are used to support the half-moon curve to avoid being washed away during rain. The amount of fertilisers required in farming systems decreases when this technique is adopted by farmers. Areas with lots of rainfall are not suitable for this technique as it may lead to water logging effect.

Technical Application

To effectively implement Half-moon techniques, the following steps should be carried out:

  • Step 1: Farmers should consider the diameter of the half-moon  between 2 m – 3 m, with a total surface area of approximately 1.5 sqm and 3.5 sqm.
  • Step 2: Pits should be dug to a depth of between 15 cm to 30 cm.
  • Step 3: Excavated material can be piled around the curved section of the half-moon.
  • Step 4: The curved section of the half-moon can be reinforced by stones to prevent washouts of the half-moon.
  • Step 5: 35 kg of organic fertilisers/compost should be evenly distributed in the half-moon.
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
Half moon pits support water and nutrient availability, in turn promoting agricultural productivity, especially in harsh climates.
Increase Resilience
Retaining soil water and nutrients supports agricultural productivity.
Additional Information
PDF File
/sites/secondsite/files/tb/CCARDESATechnicalBrief_27_HalfMoons_2019-10-17_0.pdf
Benefits and Drawbacks

Benefits

  • Pits are left to sit while fertiliser/compost material converts to productive soil material.
  • Half-moons allow for nutrient concentration and water infiltration that provides improved conditions for crops to grow.
  • Land that was previously degraded can become productive through the implementation of half-moons.

Drawbacks

Implementing half-moons is very laborious and takes significant people power to implement.

Zai Pits

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

Zai pits are based on a traditional technology approach originating from West Africa that assists farmers working on marginal and degraded land. This approach involves the concentration and conservation of nutrients and water at the crop root systems through the digging of small pits (Zai pits) and filling them with compost, with the aim of increasing soil fertility and water infiltration. Zai pits are dug between planting season and filled with organic fertilisers/composts, which attract worms, termites and other insects, creating mix of material that can be used to fertilise crops. Farmers plant crops directly in these pits, prior to rains and water will infiltrate the pits more easily than the surrounding soil. Applying this technology is laborious to implement, but it  has been found to assist farmers in times of drought or in arid conditions to produce successful crops by maximising the resources available. Zai pits allow for mitigation of desertification in degraded land and an economic use of resources in conditions of scarcity, especially in resource constrained environments

Technical Application

To effectively implement Zai Pits the following should be carried out:

  • Step 1: Zai pits should be dug with a diameter of 30 cm to 40 cm and 10 cm to 15 cm deep. 
  • Step 2: Pits should be spaced 70 cm to 80 cm apart resulting in approximately 10,000 pits per hectare.
  • Step 3: The farmer should place 2 – 3 handfuls (200 g to 600 g) of organic fertilisers or compost in each pit.
  • Step 4: Holes that are dug between planting seasons will trap wind eroded soils, which are fertile and form good soils for plating crops.
  • Step 5: It is recommended that 3 tonnes of fertiliser/compost per hectare be available.
  • Step 6: Farmers should consider planting crops in these pits prior to periods of rain.
  • Step 7: Repeated application of Zai pit technology on an annual basis will increase productivity of degraded land in the long term.
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
Increased soil fertility from zai pit implementation improves agricultural productivity.
Increase Resilience
This approach to fertilising crops and enhancing nutrient content can aid adaptation, especially in arid and semi-arid climates.
Additional Information
PDF File
/sites/secondsite/files/tb/CCARDESATechnicalBrief_26_ZaiPits_2019-10-17_0.pdf
Benefits and Drawbacks

Benefits

  • Earth that is excavated from the hole dug can be used to form a ridge around each pit to help capture and retain water.
  • Zai pit technology can be applied to marginal or degraded land or in semi-arid to arid conditions to allow farmers to rehabilitate soil/land and productively grow crops.
  • Zai pits allow for nutrient concentration and water infiltration that provides improved conditions for crops to grow.
  • Land that was previously degraded can become productive through the use of zai pits.

Drawbacks

  • Implementing zai pits is laborious and takes significant people power to implement – but may be the only option in marginal environments.

In Field Water Harvesting

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

In-field water harvesting is the practice of increasing water infiltration and moisture retention in the soil. The agricultural technique involves the collection of rainwater runoff from fields that is collected and stored for future needs. This water can be stored in infiltration pits and later used to water the same crops, other crops through an irrigation system (usually high value crops, including fruit trees), or used for domestic purposes. Factors like soil, water, and plant type influence the effectiveness and productivity of rainwater harvesting. This type of water harvesting is generally implemented in areas of very low rain (semi-arid) conditions. In-field water harvesting entails establishing micro-catchments at the farm scale, where sloped areas have been cleared or cropped to direct rainwater to the water storage area (a pit that has been dug to store/hold water). Utilising strip cropping to growing crops while providing a method for directing rain is sometime practiced. The soil type has a limiting factor in collecting in-field water due the infiltration rates. In-field water harvesting saves rainfall water that can be used over a longer period than during and immediately after a rainfall event, reduces the risks of crop failure due to no or limited rainfall, and increases rain water productivity.

Technical Application

To effectively In Field Water Harvesting techniques, the following steps should be carried out:

  • Step 1: Land is cleared, berms are developed, and crops are planted in order to direct water to the infiltration point.
  • Step 2: The catchment areas should be sloped no more than 5 % and the area should be cleared to promote catchment as much as possible.
  • Step 3: The infiltration pit (where water is stored) should be dug at the lowest point of the catchment areas and line infiltration pits with plastic or concrete roofing to limit water loss, and can be used as a source of irrigation for fruit trees and other high value crops.
  • Step 4: Paths can be built of soil to guide water to the infiltration pit.
  • Step 5: Alley cropping, or strop cropping can be used, with areas between trees and crops dug deeper like a trough to direct water to the infiltration pit.
  • Step 6: To access water from infiltration pits, farmers can introduce a pumping system and water can be distributed around the farm as necessary
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
Water is available to plants when it is needed. Reduced nutrient leaching.
Increase Resilience
Mitigate dry spells.
Mitigate Greenhouse Gas Emissions
Can lock more carbon in the soil. More efficient use of fertilisers.
Additional Information
PDF File
/sites/secondsite/files/tb/CCARDESATechnicalBrief_25_InFieldWaterHarvesting_2019-10-17_0.pdf
Benefits and Drawbacks

Benefits

  • Harvested water used in irrigation systems.
  • In-field water harvesting saves rainfall water that can be used over a longer.
  • Reduces the risks of crop failure due to no or limited rainfall.
  • Increases rainwater productivity.

Drawbacks

  • Major issues with a dug-out infiltration pit is evaporation and seepage. Evaporation can be combated by the addition of mulch to water and seepage can be prevented by including some kind of liner (plastic sheet, concrete, etc.). In addition, large plastic, steel or concrete container can be built or sunk below surface to prevent major seepage. Roofs can be built over infiltration pounds or built containers to limit the loss of water to evaporation.

Drip Irrigation

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

Drip irrigation is a method of slow delivery of water to crops, through highly-controlled flow management, applied along the soil or at the sub-surface level directly to crop root systems. Drip irrigation is an effective system for conserving water while ensuring that it is used optimally without losing it to evaporation through high efficiency water delivery. Drip irrigation involves establishing a network of tubes, values and pipes connected to water source by a pump, along crop rows. A water source is required which is a drawback as many dryland areas lack these water sources. Drip irrigation is a climate smart option as it increases farmer resilience to the effects of climate change.

Technical Application

To effectively implement drip irrigation:

  • Step 1: A reliable water source must be available - natural (natural or through rain-water harvesting).
  • Step 2: Acquire a pump system (approximately $US 100) that maintains enough pressure to deliver water through the system or an elevated tank.
  • Step 3: Connect lines or hoses and laterals that run from the pump system across the planted fields.
  • Step 4: Run lines or hoses with emitters (drippers) or small punctures at the surface level along planted crops or just below the surface providing water to the roots system of the plants.
  • Step 5: Once the system is operable, the pump can be turned on and water dispersed as required by the nature of the crop and can also be implemented with supplemental irrigation strategies (Technical Brief 23).
  • Step 6: Monitor the irrigation system regularly to ensure there are no malfunctions and the system is maintained. Crops that receive regular water can develop shallow root systems and any prolonged disruptions in service could have   significant impacts.
  • Step 7: If applying drip irrigation in sloped conditions, follow the contours of the slope as outlined in Technical Brief 16.

Once a drip irrigation system is up and running, farmers can explore fertigation, the addition of soluble fertilisers into the irrigation system water for distribution directly to 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
Energy saving.
Increase Resilience
Increase crop yield.
Mitigate Greenhouse Gas Emissions
Continued production in changing environments.
Additional Information
PDF File
/sites/secondsite/files/tb/CCARDESATechnicalBrief_24_DripIrrigation_2019-10-17_0.pdf
Benefits and Drawbacks

Benefits

  • Maximises efficiency in crop irrigation in dryland or variable climate conditions.
  • Minimizes the loss of water to evaporation.

Drawbacks

  • Requires consistent water source.
  • Costs of establishing the system, pump and lines/hoses can be significant depending on configuration, etc.
  • Requires continual monitoring and may need regular maintenance.

Supplemental Irrigation

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

Supplemental irrigation (SI) , also referred to as  Deficit Irrigation, is the application of water below full crop-water requirements, generally in drylands to assist crop growth in areas that experience low rainfall (300-500 mm/year). Supplemental irrigation involves adding limited amounts of water to rainfed crops to improve and stabilise yields when rainfall is insufficient for plant growth. Supplemental irrigation is a valuable and sustainable production strategy in dry regions or when experiencing irregular climatic conditions. This practice requires understanding of the yield response to water and the economic impact of loss in harvest. The aim of this technique is to ensure that the minimum amount of water is available during critical stages of crop growth.

Technical Application

To effectively undertake deficit irrigation:

  • Step 1: Determine critical growth cycle of desired crops.
  • Step 2: Experiment with SI strategies to determine critical watering times prior to upscaling.
  • Step 3: Strict management is required to determine the level of transpiration deficiency allowable without significant reduction in crop yields.
  • Step 4: Farmers capable of implementing deficit irrigation must have access to the minimum required water to implement deficit irrigation.
  • Step 5: Farmers must have access to a reliable water source, irrigation systems, including water distribution system, sprinklers and/or drip irrigation system.
Return on Investment Realisation Period
Crop Production
Fodder Production
Farm Income
Food Security
Soil Quality/Cover
Biological Diversity
Flooding
Crop/Livestock Water Availability
Wind Protection
Erosion Control
Increase Production
Stabilises yield.
Increase Resilience
Adapts to real time rainfall conditions.
Additional Information
PDF File
/sites/secondsite/files/tb/CCARDESATechnicalBrief_23_SupplementalIrrigation_2019-10-17_0.pdf
Benefits and Drawbacks

Benefits

  • Increase crop production in dry areas or those experiencing drought.
  • Assist farmers manage crops at optimal times (low rainfall).

Drawbacks

  • Farmers must have access to enough water to meet minimum water requirements.
  • Require water distribution system that is functional.
  • Close management of crops to ensure that SI is implemented at critical crop production moments.

Saving Seeds

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

The process of saving one’s own seed involves the collection of seeds from the best performing (most yield, largest size, early maturing or other desired traits, etc.) plants from one season to plant them in the next cropping season. The aim of this practice is to select seed from parent plants in the hope that desired characteristics are replicated in the next generation of plants. Seeds that have been selected will likely be adapted to local farming conditions including soil types and rainfall amounts. The seed most likely to carry intergenerational traits (size, colour, water use efficiency, and other biophysical traits) are open-pollinated (those plants pollinated by birds, insects, wind, etc.) seed varieties as they are cross-pollinated by the same type of crop. Different crops have different reproduction cycles with some species flowering or producing seeds annually, biennially or on a perennial basis. Thus, understanding seeding time is important for farmers aiming to save their own seeds. Almost as important as selecting the correct seeds is seed storage, which must be done correctly to avoid spoiling and losses. Seed saving is a cost-effective measure for farmers to employ and helps them avoid having to buy seeds at market on an annual basis. Seed trading or community seed banks provide a climate resilience strategy as they secure farmers access and availability of diverse, locally adapted crops and varieties while enhancing indigenous knowledge. Often crops from hybrid seeds or improved varieties do not generate viable seeds ensuring that seeds cannot be saved and must be purchased on an annual basis.

Technical Application

To effectively undertake seed saving:

  • Step 1: Communicate with national agricultural extension and local farmers regarding seed harvesting timing and practices for local crop species.
  • Step 2: Clear field and sow desired crop using climate smart agriculture practices.
  • Step 3: Monitor plant life cycle and ensure that seeds are extracted correctly and are not spoiled in the process. Employ local expertise to ensure seed harvesting is carried out correctly.
  • Step 4: Post-harvest, seeds should be adequately dried and then transferred to proper storage facilities.
  • Step 5: store seeds in dry, cool, and dark locations. This will prevent them from spoil. Different strategies for seed storage are implemented around the region so local expertise should be sought.
  • Step 6: Ensure that pests are excluded from storage areas to prevent loss or spoil (Technical Brief 61-65).
  • Step 7: Community seed banks or seed trading should be established to allow farmers to integrate different varieties into their farming system that are resilient to local climatic conditions
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 reduce losses from pests and diseases.
Increase Resilience
More predictable yields.
Additional Information
PDF File
/sites/secondsite/files/tb/CCARDESATechnicalBrief_21_SavingSeeds_2019-10-17_0_0.pdf
Benefits and Drawbacks

Benefits

  • Climate resilient method for crop diversification.
  • Many farmers have been using this technique for generations and this should be encouraged.
  • Cost effective method for sustainable crop growth.

Drawbacks

  • Attention must be closely paid to plant lifecycle and seeds should be collected at appropriate time.
  • Storage methods should be employed to manage pests and rot.

Crop Variety Selection

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

Selecting crop varieties is a key resilience strategy for farmers facing changing climatic conditions. There are two types of seed varieties: traditional varieties and improved varieties. Traditional varieties have been selected by farmers for their special characteristics and due to many years of selecting the strongest seeds over generations, they are generally adapted to local natural conditions. In some respects, these seeds increase the chance of getting a return on investment in stable environments, but are less likely to mitigate GHG emissions. Traditional crop varieties are usually selected by small scale farmers due to their relatively low cost and availability and can be saved and replanted for further growing seasons. Improved varieties are seeds that have been altered by scientific processes to incorporate desired characteristics using techniques such as following pure line breeding, classical breeding, hybridisation and molecular breeding. Desirable characteristics include higher yields, shorter growing seasons, drought resistance, salt tolerance, etc. Improved varieties are selected when facing adverse conditions such as higher temperatures and/or less predictable rainfall and normally result in the efficient use of water reducing use of energy for irrigation systems. While these seeds offer improvements they are usually commercial products and as a result can be expensive. Furthermore, as they are sold by seed companies availability is driven by demand. Most seed companies protect enhancements using  intellectual property rights that legally limit seed saving and replanting of seeds. In fact, many of these seed varieties have been designed to prevent plants to be reseeded. Thus, seed varieties afford farmers the opportunity to incorporate crops that can be planted to exploit their unique characteristics – traditional or improved, assisting farmers to grow crops that are resilient to changing climates to produce crops that are market-appropriate.

Technical Application

To effectively undertake leverage traditional seed characteristics, or improved crop varieties  the following should be carried out:

  • Step 1: Prior to selecting seed varieties, perform a Cost Benefit Analysis (CBA) to identify how crops will perform and their benefits compared to the costs of the seed, considering the following:
    • Local  farming system(s): land availability per household, crops traditionally grown, access to inputs such as fertilisers,
    • Local environmental conditions: soil conditions, disease, pests, climatic conditions, occurrence of flooding/droughts and other natural disasters.
    • How climate change has impacted or will impact the farming system and how crop variety selection can be a climate- smart practice.
    • Local access to seeds – is seed collected at the householder level, do neighbours exchange seeds, do farmers have access to commercially produced seeds?  Are the costs for accessing commercial, improved seeds manageable or prohibitive? The CBA should weigh the benefits of a new seed against perceived actual or transactional costs for selecting a new seed.
  • Step 2: Obtain information and guidance from local experts, lead farmers, and government regarding best varieties to grow.
  • Step 3: Evaluate results of the CBA and select appropriate seeds that match the farm system/requirements, and available financial resources/access to credit.
  • Step 4: Plant test plots of selected seeds to understand if benefits are realised and demonstrate outcomes with farmers, showing possible alternatives and discuss implementation.
  • Step 5: Following full demonstration and discussion with farmers, implement at farm level – planting the first crop in accordance with guidance provided by seed provider, or traditional knowledge.

Consider in-country seed sources to access different varieties through local extension or research services. When buying seeds ensure that the seeds are adequately dry and look for seed that is certified by a national seed laboratory to ensure that the variety is the highest quality possible. Seeds should be properly stored to avoid high temperatures and humid air to reduce chances of early germination.

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
Selecting improved seed varieties allows the farmer to maintain agricultural productivity as the climate changes.
Increase Resilience
Selection of improved varieties may assist farmers adapt agricultural production to assist adaptation to climate change.
Additional Information
PDF File
/sites/secondsite/files/tb/CCARDESATechnicalBrief_20_CropVarietySelection_2019-10-17_0.pdf
Benefits and Drawbacks

Benefits

  • Exploring crop variety is a key way for farmers to grow more resilient crops within the context of changing climatic conditions. Drought resistant or faster maturing varieties, for example, allow you to respond to reduced rainfall conditions.
  • Improved crop varieties have been altered by scientific processes to incorporate desired characteristics.
  • Understanding local context is important when researching the best crop variety for the area.

Drawbacks

  • Improved crop varieties are commercially sold and can be expensive as they often require additional inputs (inorganic fertilisers etc.)
  • Traditional crops have generally adapted to local climatic and landscape conditions, are widely available and are cost effective for local populations; however, these varieties may not be resilient to climatic changes, and are less likely to mitigate GHG emissions.

Weed Control

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

Weeds are any unwanted plant species that compete with crops for sunlight, water, nutrients, air and space, hindering crop growth and in some cases are even toxic to crop plants. Weed control measures can be applied in an integrated manner to help prevent the growth and spread of weeds in agricultural systems. An integrated weed management approach aims to restrict weed growth until a crop is well established and can outcompete weeds. This integrated approach includes biological, chemical, cultural and/or physical tactics to combat weed spread and growth and these practices can be more cost effective than herbicide applications. Integrated weed management is climate smart as it combines multiple climate smart practices that increase farmers resilience, limits GHG releases and increases productivity. Options for weed control include crop rotation, intercropping, cover crops (which can be used as green manure or mulch), mulching, seed-bed preparation, livestock grazing, seed/variety selection, mowing, and hand-weeding.

The application of integrated weed control is climate smart as it reduces herbicide application and reduction in machinery usage (i.e. through no-tillage practices).

Technical Application

To effectively undertake weed control measures:

  • Step 1: Review weed control measures - crop rotation, intercropping, cover crops, mulching, seed-bed preparation, livestock grazing, seed/variety selection, mowing, hand-weeding and adjustments to tillage practices - and determine which methods are available and appropriate for the farming system and farmer. Two or more of these techniques can be applied to assist in ensuring farmers have more chance of success. Understand possible negative impacts of each weed control method.
  • Step 2: Improve weed identification knowledge in specific areas.
  • Step 3: Prevent weeds from spreading – clean clothes, animals, machinery, vehicles to limit weed transport; use only well stored/rotted manure (4-5 months) (Knowledge Product 16), include fencing, irrigation and other farm ‘breaks’ where possible
  • Step 4: Apply a combination of weed control methods including – cover crops (Technical Brief 15), mulching, intercropping (Technical Brief 07), crop rotation (Technical Brief 09), livestock grazing, seed selection (Technical Brief 20), mowing, hand-weeding. Try to avoid the application of herbicides, tillage and burning.
  • Step 5: monitor and document most effective weed management strategies for each farmer, and use lessons learned from the area with other farmers where applicable.
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
Weed control supports agricultural productivity by removing competition while reducing the need for herbicides.
Additional Information
PDF File
/sites/secondsite/files/tb/CCARDESATechnicalBrief_19_WeedControl_2019-10-17_0.pdf
Benefits and Drawbacks

Benefits

  • Integrated weed management involves employing two or more climate smart practices.
  • Reduced consumption of chemicals
  • Cost effective methods that do not require additional inputs.

Drawbacks

  • More time consuming than applying herbicides or other more destructive methods.
  • Strategy requires careful planning.
  • May not be 100% effective.

Agroforestry: Alley Cropping

Annual Average Rainfall
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

Agroforestry is a land management practice that combines the planting and management of trees and shrubs with crops and pasture, providing benefits of soil health, crop yields, resilience to climate change, biodiversity and economic opportunities. Agroforestry encompasses numerous practices, including silvo-pasture, agro-silvo cultural, and agro-silvo-pastural. One successful agro-silvo-cultural practice is alley cropping, where the farmer plants rows of trees, shrubs or hedges between crop rows. Usually hedges comprise leguminous plants intended to fix nitrogen in the soil and provide leaf litter and prunable biomass. The hedges are pruned with the pruned material spread on the ground, to reduce shading and competition with the primary crop. Timing of pruning is important to ensure that the pruned biomass releases nutrients to the soil at a time when the primary crop needs them for maximum crop productivity; e.g. when alley-cropping maize, the pruned biomass needs to breakdown with and release beneficial nutrients into soil from two and eight weeks after planting the maize crop. This approach has proven to be highly successful, with examples in Malawi where gliricidia was alley-cropped with maize where the prunings created a three-fold increase in maize production, which was increased a further 29 % when fertilisers were added. This fertilisation could be achieved with green manure, and other climate smart soil amendment approaches. The space and number of hedge rows to primary crop is dependent upon the field size and the regular growth height of the shrub/hedge. The hedge must not be planted so close that it shades the primary crop. In larger fields, larger deep-rooted timber trees can be planted between groups of rows of primary crop, providing soil benefits, reducing wind-speeds/erosion, and providing timber products.

This approach is considered climate smart as it increases productivity, provides a mechanism for more climate resilient farming, whilst increasing soil carbon levels.

Technical Application

While agroforestry practices are deemed highly beneficial and climate smart, it is important to ensure that proposed practices are appropriate for the specific context – the benefits of the agroforestry practice match the needs of the farmer - and are fit for purpose. Obtain advice from an agroforestry expert before embarking on secondary crop/hedge species selection.

To effectively implement alley-cropping the following should be carried out:

  • Step 1: Clearly understand the objectives of the intervention and identify an appropriate species for intercropping. For maize and sorghum in a smaller subsistence farm setting, selection and growth of hedge rows of a legumes such as cowpea or Gliricidia can provide sustainable benefits in terms of soil quality and secondary fodder/food products. In larger fields, timber trees can be planted every five to ten crop rows, depending on the height of the mature tree, and the shade-tolerance of the crop.
  • Step 2: Identify and understand key conditions, such as prevailing wind direction, and sunlight to ensure that the field is planted in an appropriate configuration, with primary crop and secondary (hedge/shrub/tree) crops planted in such a way as to benefit the primary crop and not compete with it. East to west row orientation should maxmise sunlight, topography permitting.
  • Step 3: For beneficial hedgerow growth with legume species such as Leucaena, cliricidia, and Sesbania sesban, the trees should be planted in rows between two and four metres apart, with individual trees planted as close as possible - between 10 to 15 cm apart. If planted closely, the trees will favour leaves over step growth, creating more mulch to prune for cover. Note that if rows are planted too closely, the secondary crop can dominate the available crop land reducing productivity. Furthermore, the closer the hedges, the more shade will present, which can depress crop growth, and also start to compete for soil water and nutrients, which is not beneficial.
  • Step 4: Once reaching sufficient maturity, after approximately six months (one-metre tall for legumes)– hedges should be pruned to generate mulch for working into the soil. Then the primary crop (maize) can be planted. Pruning once per month thereafter provides cover and ensures that light penetration is maintained. Planting legumes approximately six months before planting the primary crop can ensure that sufficient pruned material is available to incorporate into the soil to enhance growth.
  • Step 5: After harvesting the primary crop, hedgerows can be left to grow taller so that shade reduces weed grown, and to develop material to prune and incorporate into the soil again during the following crop cycle. However, hedges should not be allow to grow too high or dense as their roots will dominate the soil and out-compete primary crops for water and nutrients.

Before implementing any of these technologies, further research may be required beyond the guidance provided here. The World Agroforestry Centre (ICRAF) has many resources, toolkits and success stories that can support such research.

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
Alley cropping and pruning of leguminous hedges increases productivity of primary crops such as maize.
Increase Resilience
Helps farmers to be more resilient to climate change, by sustaining productivity and controlling soil health, especially when faced with changing climates.
Mitigate Greenhouse Gas Emissions
The planting of alley hedge rows of legumes and the introduction of pruned material contributes more carbon to the soil.
Additional Information
PDF File
/sites/secondsite/files/tb/CCARDESATechnicalBrief_17_AgroForestry_2019-10-17_0.pdf
Benefits and Drawbacks

Benefits

  • Trees, shrubs, and hedges are incorporated into farming systems and have many different biophysical and socio-economic benefits.
  • Use of leguminous hedges no only provides pruned materials to provide cover, but they also help fix nitrogen in the soil.
  • Hedges planted in alleys can also provide other benefits such as edible seed pods for human or animal consumption.
  • Hedges and trees can reduce soil erosion from run-off or wind erosion.
  • Alley cropping can provide opportunities for diversified income – selling secondary crops and/or timber.
  • Alley cropped timber trees can provide building materials fire wood.

Drawbacks

  • Initial labour requirements will likely be significant; however, this will be primarily at the earlier stages of the intervention.
  • Ongoing maintenance such as pruning and maintenance of hedges will be needed, although relatively minimal.
  • There may be some costs involved in obtaining hedge seedlings.
  • Use of trees rather than hedges and shrubs introduces more labour, but yields more benefits.
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