Agroforestry - Agriculture Form 4 Notes

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  • In Kenya land use is changing from extensive methods of farming to more productive and sustainable intensive methods.
  • Agroforestry is a method of farming which has become increasingly important.


  • This is the practice of integrating a variety of land use
  • It combines tree growing, pasture and crop production practice on the same piece of land to improve the output of the land.

Forms of Agroforestry

  • Agroforestry;
    • It is a combination of trees/shrubs and crops in agricultural production.
  • Silvopastoral:
    • It is a combination of growing tree/shrubs, pastoral and keeping of livestock.
  • Agrosilvopastoral:
    • It is a combination of growing trees/shrubs, animals, pastures, and crops.



Importance of Agroforestry

  • Environmental protection.
  • Source of income.
  • Afforestation for timber production.
  • Maintenance of soil fertility.
  • Aesthetic value.
  • Labour saving in firewood collection.
  • Source of food and feed.
  • Source of fuel wood.

Important Trees and Shrubs for Particular Purposes

  • Eucalyptus Spp;
    • Timber,
    • Bee forage,
    • Fuel wood,
    • Medicinal,
    • Production of essential oils.
  • Acacia Spp;
    • Leaves and pods eaten by animals,
    • Provision of shade.
  • Cajanus cajan (pigeon peas);
    • Proteinous feed for human,
    • Used as fodder
  • Croton megalocarpus(croton);
    • Fuel wood timber for poles
    • Handles for hand tools.
  • Erythrina abyssinica (flame tree);
    • Wood carvings,
    • Bee forage,
    • Nitrogen fixation
  • Markhamia lutea (markhamia tree)­;
    • Timber for construction,
    • Shade,
    • Soil protection,
    • Bee forage.
  • Grevillea robusta (silky oak.)
    • Timber,
    • Fuel wood,
    • Fodder,
    • Bee forage,
    • Soil protection,
    • Wind breaker
  • Sesbania sesban (sesbania);
    • Fodder,
    • Nitrogen fixation,
    • Shade,
    • Fuel wood.

  • Calliandra calothyrsus (calliandra);
    • Fuel wood,
    • Fodder,
    • Nitrogen fixation,
    • Shade,
    • Bee forage.
  • Persea american (avocado) ;
    • Fodder,
    • Fruit production,
    • Shade,
    • Fuel wood.
  • Mangifera indica (mango);
    • Fruit production,
    • Shade trees,
    • Wind break,
    • Soil protection,
    • Fuel wood.

Characteristics of Agroforestry Tree Species:

  • Fast growth rate.
  • Deep rooted.
  • Nitrogen fixation ability.
  • By-product production ability.
  • Be multipurpose in nature.
  • Should not possess competitive ability with main crop ..
  • Have coppicing and lopping ability.
  • Have appropriate canopy - should not shade others.
  • Nutritious and palatable.

Trees and Shrubs to Avoid at Certain Sites and Reasons

  • Eucalyptus Spp.-should not be planted near water sources because it would absorb the water.
  • Eucalyptus Spp. -should not be planted on the arable land as the roots have allelophathic effects on other vegetation including crops.
  • Tall trees should not be planted near farm buildings because they may fall and damaging the buildings, their roots will break the building stones gradually.
  • Bushy trees or shrubs should not be near farm buildings as they may harbour predators.
  • Tall trees planted with main crop of a lower canopy intercept the rainfall, affecting the growth of the main crop.
  • Cypress trees have leaves which produce acidity in the soil preventing undergrowth beneath the tree.
  • These trees should not be planted within the farm but at the periphery.

Tree Nursery

  • Tree nurseries are structures used to raise tree seedlings until they are ready for transplanting.



Types of Nurseries

  • There are 2 main types:

Bare Root Nurseries:

These are also known as 'Swaziland' beds where the seedlings are raised directly into the soil.


  • Cheap and less time consuming.
  • Require less labour
  • Occupy a small space.
  • Many seedlings are raised in a small space.
  • Transportation of seedlings is easy.


  • Root damage when uprooting the seedlings.
  • Difficult to transport.
  • Lower survival rate after transplanting.

Containerized Nursery:

  • The seedlings in this type of nursery are raised in containers such as pots, polythene bags or tubes and tins.


  • Higher survival rate after transplanting.
  • No root damage.
  • Successful in arid areas.


  • Labour intensive.
  • Difficult to get containers.
  • Sometimes it may be difficult to get the right type of soil to use in the containers.

Seed Collection and Preparation

Seed Collection

- Seeds should be collected from;

  • Adaptable trees,
  • High yielding,
  • Healthy
  • Resistant to pests /diseases.
  • The mother plant should be identified first.

The following methods used to collect seeds.

  • Shaking the tree.
  • Gathering from under the tree.
  • Lopping of the tree.
  • Climbing on the trees.
  • Hooking method.

Seed Preparation

- This done when seeds are collected from a fresh fruit, they should be soaked in water, then washed and dried.

  • Cleaning and sorting: done to remove immature seeds, rotten seeds, broken or damaged seeds.
  • Drying: Done by sun-drying or oven drying.
  • Seed testing: this determines;
    • Seed quality for percentage purity,
    • Seed weight,
    • Moisture content,
    • Germination percentage.
  • Seeds should be stored in dry containers at room temperature.
  • Seed treatment: seeds are treated first to break the seed dormancy and ensure rapid germination;
    • Hot water treatment: used to soften the seed coat to make it more permeable to water. Examples of seeds which require this treatment are leucaenia, calliandra and
  • Mechanical breaking: done by nicking the seed coat with a knife for easy entrance of water for example seeds of croton
  • Light burning: applied to the wattle tree seeds.

Nursery Management

- The following are the practices carried out in the nursery when the seedlings are growing:

  • Mulching:
    • Aim is to reduce excessive evaporation,
    • Moderates the soil temperature,
    • When it decays it improves the soil structure,
    • Reduces the impact of the raindrops.
  • Weeding:
    • Done to reduce competition for growth factors by uprooting the weeds,
    • Use a sharp pointed stick.
  • Watering:
    • Done by use of a watering can
    • Done twice a day in the morning and in the evening.
  • Pricking out:
    • It is the removal of seedlings in an overcrowded area to another nursery bed,
    • This allows the seedlings to grow strong and healthy.
  • Root pruning:
    • It is the cutting of the roots longer than the pots.

    Root pruning is done for the following reasons;
    • Make lifting easier
    • Encourage fast establishment.
    • Reduce damage to the seedlings.
    • Encourage development of a short dense and strong rooting system.
  • Shading:
    • Done to reduce the intensity of sunlight .
    • Dark conditions should be avoided.
  • Pest and disease control:
    • Use of appropriate chemicals,
    • Sterilization of soil through heat treatment,
    • Fencing to protect seedlings against animal damage.
  • Hardening off:
    • It is the practice of preparing seedlings to adapt to the ecological conditions prevailing in the seedbed.
    • It involves gradual reduction of shade and watering 1-2weeks before transplanting.


  • The practice of transferring seedlings from the nursery bed to the main field where they grow to maturity.

Procedure of Transplanting

  • Holes are dug early before transplanting.
  • Topsoil is mixed with compost manure.
  • The seedlings are watered well a day before transplanting.
  • The seedlings are removed from the nurseries carefully with a ball of soil for the bare root seedlings and roots trimmed for the containerized seedlings.
  • The seedling is placed in the hole at the same height it was in the nursery.
  • The container is removed carefully. 
  • The soil is returned into the hole and firmed around the seedling.
  • The seedling is watered and mulched.

Care and Management of Trees

  • Protection:
    • From damage by animals such as goats and cattle by eating the leaves.
    • It is done by fencing the fields or using small poles around each seedling with or without wire nettings, can be done for individual trees or an entire field.
  • Pruning and trimming:
    • Pruning is the removal of extra or unwanted parts of a plant.
    • The unwanted part may be due to breakage, overcrowding, pests or disease attacks and over production.
    • Pruning initiates growth of shoots and trains the tree to have the required shape.
    • Regular cutting back of the trees is known as coppicing,
    • It is done at the beginning of each cropping season to reduce competition for water, minerals, nutrients and sunlight with crops.
    • The materials pruned or coppiced are used as fuel wood or for fodder crops.
  • Grafting old trees:
    • This is the practice of uniting two separate woody stems.
    • The part with the rooting system is known as root stock (base)
    • The part which is grafted onto the rootstock is called a scion which has buds that develop into the future plant.
    • The ability of the scion and the rootstock to form a successful union is known as compatibility.
    • Methods of grafting include whip or tongue grafting, side grafting and approach grafting.

Agroforestry Practices

Alley Cropping/Hedgerow Inter­cropping:

  • The growing of multipurpose trees and shrubs together with crops.


  • Improve soil fertility through nitrogen fixation and organic matter.
  • Provision of green manure.
  • Used as fence and mark boundaries.
  • Acts as windbreaks.
  • Suppress weeds.
  • Source of timber and fuel wood.

Multi-storey Cropping;

  • This is the growing together of trees of different heights.
  • The system is based on crops which can tolerate shading.
  • The trees and crops form different levels of canopy which look like storey.


  • Increases water conservation for pastures.
  • None of the crops or trees included will be shaded.
  • Act as windbreak for crops.
  • Creates suitable micro-climate in the area.
  • Trees are used for timber, fuel wood and forage.

Woodlots (Farm Forests)

  • These are plots of land set aside for trees only.
  • They are established in the hilly and less productive parts of the farm.
  • Fast growing tree species such as Eucalyptus spp. should be grown.

Sites for Agroforestry:

  • Farm boundaries - provide live fences.
  • River banks - protect water catchment areas.
  • Homesteads - provision of shade and windbreak
  • Terraces - for soil conservation.
  • Steep slopes - as contour hedges to encourage water seepage.

Tree Harvesting Methods


  • This is the extensive cutting back of the crown of the tree about 2-3 meters above the ground level to harvest all the side branches.
  • It stimulates the development of a new crown and branches.




  • Cutting the main stem of the tree completely at a height of 10 - 50 cm above the ground.
  • The tree should be cut in a slanting angle.

Lopping or Side Pruning

  • The removal of selected branches of the tree
  • Done to produce fuel wood and fodder.

Shaking of the Tree;

  • This is a method of harvesting pods and seeds from trees without cutting the tree.

Cutting Back;

  • The tree is cut from the base to allow new growth as done in coffee when changing the cycle.


  • The removal of some of the trees growing in lines to give the remaining trees enough space to grow.
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