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Integrated Soil Fertility Management (ISFM)

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

Integrated Soil Fertility Management (ISFM) refers to a set of agricultural practices that can be applied simultaneously to improve agricultural productivity through increasing soil nutrients and improving crop water use. ISFM includes a broad range of agricultural practices that have all been adapted to local conditions to improve soil nutrients and include the combined application of the following approaches:

  1. Utilisation of organic fertilisers such as green manure, compost and crop residues.
  2. Application of locally available soil amendment methods, such as lime and biochar.
  3. Implementation of techniques like germplasm, agroforestry, crop rotation, intercropping etc.
  4. Limited use of inorganic or mineral fertilisers – seen as the last option in ISFM, when other interventions are not achieving optimal results.

ISFM can be successful for most arable farmers and has been known to double productivity and increase farm-level incomes by 20 to 50 percent if implemented correctly. It focuses on a series of practical approaches to sustainable farm productivity through locally available and affordable options for maintaining soil fertility and productivity, and is seen as a viable approach to reduce over-reliance on inorganic fertiliser. ISFM permits short- and long-term increases in productivity of cash crops and food security, and is considered climate smart as the combined ISFM approach maximises fertiliser uptake and sequestration of carbon in soil, allowing sustainable agricultural intensification driven by improved soil structure and fertility.

Technical Application

In addition to agricultural inputs and the following technical implementation steps, ISFM requires the farmer to consider farm size (land area), and property rights (land tenure) to ensure that investments are efficient and sustainable.

To implement ISFM approaches, the following should be considered:

  • Step 1: Prepare a needs assessment based on understanding of farm challenges – low or declining productivity, soil fertility, low organic content, etc
  • Step 2: Measure fields that require attention to understand volumes of inputs required.
  • Step 3: Develop (or update) an agricultural calendar to use as a platform for discussion between farmer(s) extension officer(s).
  • Step 4: Develop plan and schedule/programme of locally appropriate ISFM interventions between farmer(s) and extension officer(s), obtaining guidance from agricultural suppliers where necessary (lime application, etc). As ISFM is a blended approach, the plan should consider short and medium to long term interventions and outcomes.
  • Step 5: Examine cost implications of the plan, revising where necessary based upon available resources, and if necessary/available apply for credit to fund investments.
  • Step 6: Assess labour requirements within the ISFM plan to ensure that they can be fulfilled, and considerations of gender and youth have been accommodated – women are not expected to do the majority of work, and children are not missing school.
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
Improves soil structure. Increases soil fertility.
Increase Resilience
Aims at sustainable intensification, increasing resilience through more predictable production.
Mitigate Greenhouse Gas Emissions
ISFM has the potential to reduce greenhouse gas emissions owing to greater uptake of Nitrogen-based fertilisers by crops and soil carbon sequestration.
PDF File
/sites/secondsite/files/tb/CCARDESATechnicalBrief_06_ISFM_2019-10-17_0.pdf
Benefits and Drawbacks

Benefits

  • Applying an ISFM approach can be a sustainable way to improve/rehabilitate soil fertility.
  • ISFM is intended to optimise a combination of CSA strategies to achieve maximum outcomes.
  • The focus should be on leveraging locally available materials and resources to improve productivity.
  • ISFM should be seen as a scalable approach, involving a range of interventions that match available inputs and financial and human resources.

Drawbacks

  • Lack of knowledge of applying the different strategies individually or in combination.
  • Potentially high transaction costs as the process involves multiple interventions.
  • Lack of credit facilities.
  • Availability of labour.

Green Manure

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

Green manure (otherwise known as cover crops), is a climate smart fertiliser process that involves growing plants (mainly legumes) and distributing uprooted or sown crop-parts to wither and cover soil. It provides soil coverage to enhance biological, physical and chemical properties of soil while mitigating soil erosion, supressing weed growth, adding biomass to soils, improving soil structures, promoting biological soil preparation, and reducing pests, diseases and weed growth. These functions can increase economic return, reduce the need for herbicides and pesticides, while increasing productivity and potentially the quality of crops. It can also increase soil nitrogen, improve soil fertility, conserve soil humidity and reduce fertiliser costs. Green manure also has low management costs, presents good conservation characteristics, and improves biodiversity. Green manure is a feasible and sustainable option for farmers to improve soil quality and productivity, depending on local context and availability of different leguminous plants that best fit for farmers’ cropping systems. Examples of leguminous plants that can be used in southern Africa include: Mucuna (Mucuna pruriens); Sunhemp (Crotalaria juncea), Lab-lab (Lablab purpureus); Pigeon pea (Cajanus cajan); Cowpea (Vigna unguiculata) and Butterfly pea (Clitoria ternatea). Green manure has climate smart benefits as contributes to sustainable maintenance of agricultural production without the use of chemical fertilisers and depending upon the cover crop can contribute to adaptation of agricultural practices to climate change. Furthermore, coverage of soil with additional plant material can assist with carbon sequestration in soil. Not only does growing a secondary green manure crop provide a soil amendment benefit, but the crop can also be used as fodder for livestock. As the most common green manure plants are legumes, the pods and seeds can be fed to livestock while leaving the crop residue to perform the cover crop function in in the fields.

Technical Application

To effectively apply a green manure approach, the following should be considered:

  • Step 1: Select legumes that grow well under local conditions and in local soils. Green manure crops should be resilient and require few crop management practices. A thorough investigation should be made to ensure that green manure crops are appropriate for the local conditions in terms of rainfall, climate, soil pH and texture, and salt tolerance.
  • Step 2: Identify the appropriate time for planting the green manure crop to ensure growth, but not impacting the primary crop. Especially if the secondary crop is a climber/creeper. Main crop may need to be mature before planting the manure crop, as if a creeper, it may outcompete or constraint growth of maize or sorghum plants.
  • Step 3: If seeking to enrich soil properties, the farmer must allow crop residue to remain in the soil longer. This is particularly relevant with multiple uses – e.g. soil amendments and livestock fodder. In these cases, pods can be harvested for fodder, and the remaining plant residue left in the field to cover the soil.
  • Step 4: Crop planting should be alley cropped between the primary crop rows, allowing management of the primary and secondary crops, also reducing the competition between the primary and the secondary crop. If the secondary crop also has pest management properties, it may be beneficial to consider boundary planting.
  • Step 5: When harvesting the secondary crop, the farmer should consider leaving the residue in the ground. If it is uprooted, it should left on the soil surface. A common mistake is to remove it from the field and accumulate it in one location, missing the benefits of cover-crops, and exposing the residue to decay.

Unless local examples are available, small test plots should be used to test different cover crops to determine which is the most appropriate, and if necessary, demonstrate value to farmers and communities. As the secondary (green manure) crop is not a direct cash-crop, you may need to ensure expectations are measured. It may take several years to develop enough green manure crop to contribute to crop production; hence, crop production has to fit around existing cash/subsistence crops. Furthermore, benefits may not be realised within a single planting season., e.g. Nitrogen may only be available in the soil in the subsequent season.

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
Green manure can maintain or increase agricultural productivity through improved soils.
Increase Resilience
Adjustment of practices to include cover crops allows farmers to diversify crop types, and produce their own fertilisers.
Mitigate Greenhouse Gas Emissions
Reduction in carbon released from soil.
Additional Information
PDF File
/sites/secondsite/files/tb/CCARDESATechnicalBrief_02_GreenManure_2019-10-17_0.pdf
Benefits and Drawbacks

Benefits

  • Green Manure is a non-tillage method that promotes soil fertility through enhancement of soil organic content. In doing so, it mitigates erosion, maintains soil humidity, and promotes biological activity.
  • Many green manure plants can be used to feed livestock if there is an excess
  • Green manure cover crops also make organic matter to apply – compost requires work and time to develop, whereas this approach sees it added immediately.
  • Cover crops can reduce weed competition by shading soil.
  • If using legumes, they can thrive in poor quality soils.
  • Cover crops such as Cow pea can also be used for animal and human consumption.

Drawbacks

  • Require access to seedbanks for legumes and other viable cover crops.
  • May require the testing of crops in test plots prior to implementation.
  • If so, community action may be required to test varieties and make decisions.
  • Farmers may require more land to plant the same amount of the main crop, as they need to be intercropped with the cover crop. This can be unattractive to some farmers.

Compost

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

Compost is a biological process where micro-organisms recycle decaying or decomposing organic matter to produce a soil conditioner that can be applied as an additive to improve soil conditions. Composting takes place in the presence of oxygen (aerobic conditions), and with adequate temperature and moisture, transforming organic matter into plant-available nutrients. Compost can comprise organic plant and/or animal matter, and/or residues including leaves, dead roots, manure, urine, bones, and nematodes, amongst other organic materials. As it is generally rich in nutrients, the application of compost can naturally fortify soils, acting as a fertiliser, with soil humus or natural pesticide increasing the resistance of plants to diseases, foreign species and insects. The amount of organic matter in different soils depends on the soil type, vegetation species, and other environmental conditions, such as moisture and temperature. Thus, the application of compost may add important nutrients to soils that can benefit vegetation growth. Rainfall, temperature changes and other biophysical factors may result in a diminishing return of compost benefits to soil health. Therefore, the application of compost to soils should be a continuous practice, in order to increase physical, chemical and biological benefits. There are two main composting systems: Open Systems (compost piles or pits) or Contained Composting – see technical application below. This is a climate smart approach as it recycles readily available organic materials from a farm for use within the farming system, plus it avoids the use of chemical fertilisers. Composting is a climate smart approach as it reduces the need for chemical fertilisers, contributes to soil amendments that support adaptation to climate change, and helps retain soil fertility, which in turn aids agricultural productivity.

Technical Application

To effectively undertake composting:

  • Step 1: gather compostable materials - rests of harvests, animal manure and dung, organic kitchen waste (fruit and vegetable waste), other food waste, edible oils and fats, wood shavings, paper products (not printed), hair cut waste. Avoid non-compostable materials such as chemical residues, glass, metals, plastics, carcasses, cooked leftovers or meat.
  • Step 2: Chop/cut materials to achieve optimum particle size is between 5 – 20 cm – this will assist decomposition. Wire mesh can be used to sift smaller non-organic particles.
  • Step 3: Add water regularly using a watering-can to assist decomposition, ensuring that the materials do not become water logged.
  • Step 4: Using a pitchfork or shovel, turn-over or rotate compost materials regularly as oxygen is a key component to the decomposition process.
  • Step 5: If available, add earthworms (known as vermiculture) to compostable material, which enriches soil, enhances plant growth (hence yields) and suppresses disease.
  • Step 6: Once compost material has been decomposed (three months to two years, depending on climate and composting material) it will be a fine, dark material. Screen the material to remove large particles and mix with soils in gardens or fields prior planting and around plants throughout growing period.
  • Step 7: If compost does not include animal manure/waste it can be applied to crops as an organic fertiliser at any point up to harvest. If it does include animal waste, it can be incorporated into soil not less than 120 days prior to harvest, especially where edible portion of crops has been in contact with the soil surface.

Additional notes:

  • For Open Composting System (Piles): select a level area or dig a pit with a level bottom away from developed areas, chop collected materials into piles, turn over or rotate and add water to material regularly (weekly or bi-monthly). Cover pile if there is heavy rain to prevent materials from washing away and becoming water-logged.
  • For Contained Composting Systems: construct a container unit from mesh, wooden panels, bricks and other suitable building materials, fill the container with chopped material, turn over or rotate, and add water to material regularly (weekly or bi-monthly). Keep compostable material covered.
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
Retaining or improving soil fertility to ensure increased or sustained agricultural productivity.
Increase Resilience
As climate change places increased pressure on land management, compost can contribute to soil amendments to aid adaptation.
Mitigate Greenhouse Gas Emissions
Use of compost to amend soil avoids the use of chemical fertilisers and reduces greenhouse gas emissions.
Additional Information
PDF File
/sites/secondsite/files/tb/CCARDESATechnicalBrief_01_Compost_2019-10-17_0.pdf
Benefits and Drawbacks

Benefits

  • Composting is an effective and low-cost option to recycle organic matter that can improve soil nutrient health.
  • Composting in scalable, based on need and available organic materials.
  • Moisture and oxygen are very important. Ensure that compost materials are moist and regularly rotated to optimise decomposition conditions.
  • Cover during extreme weather events (heavy rain, extreme heat, high wind etc.).
  • Add earthworms to the material to increase decomposition and speed up process.
  • Compost should be regularly added to soils to increase soil organic nutrients.

Drawbacks

  • Developing productive compost material, with beneficial nutrient is not a quick process, and can take up to two years for productivity to reach optimal outputs.
  • Faster methods require more energy and inputs as significant amounts of organic material is needed, material must be shredded/chipped, and compost piles need to be turned every three days.
  • While composting is scalable, the amount of available organic material may be a limiting factor.
  • Composting plant material must include removal of any diseased plant material and weed seeds should be avoided.
  • Earthworms will need to be sourced to improve the productivity of composting operations.

Earthworms can be sourced from a worm farm – if worm farms are not available, you can create your own by purchasing worms from an agricultural supplier. Worm farms can also be purchased as kits.

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