Agroforestry - Agriculture Form 4 Notes

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Agricultural Economics V (Agricultural Marketing and Organizations) - Agriculture Form 4 Notes

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Introduction
- Definition
- Forms of Agroforestry
Importance of Agroforestry
Important Trees and Shrubs for Particular Purposes
- Characteristics of Agroforestry Tree Species
- Trees and Shrubs to Avoid at Certain Sites and Reasons
Tree Nursery
Care and Management of Trees
Agroforestry Practices
Sites for Agroforestry
Tree Harvesting Methods

Introduction

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.

Definition

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.

Advantages

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.

Disadvantages

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.

Advantages

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

Disadvantages

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.

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.

Benefits

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.

Benefits

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

Pollarding;

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.