Agroforestry - Agriculture Form 4
Suggested Topic Activities
- Find an example in your community where trees are inter-planted with crops. Name the type of crop and type of trees.
- Name the common agroforestry trees around your community and write its importance .
- Collect seeds from the school compound and carry out the appropriate method of seed treatment
- In pairs discuss some of the practices carried out in terms of :[a]Liming [b]digging appropriate holes [c]planting [d]protection.
- Which tree harvesting technique would you advice in each of the following situation [a]when harvesting tree for timber [b]when you want to provide fodder for livestock. [c]when you want to harvest leaves without killing the tree
In form one, you learnt Agroforestry as a method of farming. In this chapter you will learn its importance and various forms of Agroforestry.
There are three forms of agroforestry:
Intensive hedgerow or Intercropping.
Wide row planting.
Aesthetic: The beauty of something, usually the natural environment.
Agroforestry: Form of land use where trees or shrubs are grown with crops or livestock pastures.
Conservation: The protection of natural resources such as forests to prevent them from being destroyed for the benefit of future generations.
Grafting: A process where a piece is cut from one plant and tied to or put inside a cut in another plant so that it grows there.
Pruning: The process of cutting some of the branches of a tree or bush to make it grow better.
Seedling: A young plant grown from a seed.
Shrub: A small bush with several woody stems.
Thinning :To make more room for plants to grow by removing the weak ones
By the end of the topic, you should be able to:
- define agroforestry.
- state the importance of agroforestry.
- describe various forms of agroforestry.
- explain the importance of trees for different uses.
- select appropriate trees for different uses.
- describe the nursery management and transplanting.
- explain routine tree management.
- select appropriate site for trees in the farm and other areas.
- describe various methods of tree harvesting.
Agroforestry is defined as the practice of growing food crops and Agroforestry trees and shrubs, keeping livestock on the same piece of land at the same time.
Forms of agroforestry
- Rows of shrubs/trees are inter-planted between the rows of crops.
- Spacing depends on the trees/shrubs and crops involved.
- Legumes are best inter-cropped with grasses e.g Leucaena in a maize field.
- Rows of shrubs should assume an East to West direction to facilitate sunning.
Choice of shrub species
For maximum production certain management practices must be observed.
- Establishment using seedlings for faster growth.
- First cutting when 3-4meters tall.
- Cutting back/coppicing at the beginning of each cropping season to avoid shading effect and reduce competition for water, mineral nutrients and sunlight.
- Removing shoots during the growing season, when weeding.
Wide row planting.
- wide row planting involves planting trees at wide spacing of 4m by [8-12]m
- Trees are planted in East to West direction.
- Tree growth is allowed unchecked. wide row planting involves planting trees at wide spacing of 4m by [8-12]m
- Trees are planted in East to West direction.
- Tree growth is allowed unchecked.
- This involves planting of trees, shrubs or hedges on the borders of the farm.
- They can be used as a fence, mark boundary, windbreaks, provide wood and timber.
- The trees should not interfere with public amenities such as electricity and telephone lines, water supply and roads.
Importance of Agroforestry
Agroforestry practices contribute a wide range of benefits for the rural farmer as well as the environment. These include:
- Soil and water conservation
- Balancing of atmospheric gases.
Fruit Trees products provide food. Examples are fruits trees such as coconut trees grown along the edge of the field.
Coconut tree producing fruits.
Trees provide timber and rafters for construction as well as shade for resting. Trees providing timber and rafters for construction of sheds to livestock or people
Energy and fodder
Energy- Agroforestry provide sustainable source of firewood. Income-Products from timber such as fruits, poles can be sold for cash or used on the farm to save cash. Fodder- Some tree species acts as a good source of highly nutritious feeds for livestock examples are Leucaena and Calliandra photo of livestock feeding on Leucaena cuttings
Trees decrease the amount of water lost to the atmosphere, prevent erosion, restore degraded soil and increase the yield of useful products.
Various trees species make the environment look more beautiful example, Bauhinia variegata and Bottle brush
Balancing of atmospheric gases
Trees use atmospheric carbon dioxide as a raw material for photosynthesis and give out oxygen which is used by animals in an area
illustration of carbon cycle and oxyges cycles as they circulate on a tree .
Importance of agroforestry trees
The common agroforestry trees and shrubs with positive importance to man include the following: Eucalyptus spp -Used for timber, woodfuel, bee forage and eucalyptus oil.
Used for timber, woodfuel, bee forage and eucalyptus oil.
The most important uses include; wood fuel, edible gum, animal forage, soil conservation & Nitrogen fixation.
This agroforestry tree produces wood fuel, timber, poles, shade, bee forage and charcoal.
This can be used as; Timber, poles, shade, windbreak, soil conservation, bee forage, aesthetic
This can be used as; Timber, wood fuel, fodder, soil conservation, windbreak, shade, aesthetic, bee forage.
This can be used as; wood fuel, fodder, nitrogen fixing, shade, mulch, soil conservation
This can be used as; timber, poles, wood fuel, fodder, mulch, bee forage, soil conservation
Cajanus cajan [pigeon peas]
This can be used as; human food, fodder, soil conservation,wood fuel.
Trees and shrubs with negative effects
They have been grouped as follows: Eucalyptus spp should not be planted near water sources because of excessive absorption of water.Cypress tree leaves acidify soils hence should not be inter-planted with crops.
Trees with negative effects
Tall trees e.g Eucalyptus should not be planted near buildings as they can fall and damage them or their extensive roots damage building foundations e.g fucus trees.
Shrubs with negative effects
Trees with wide canopy for example Cassia Siamea should not be interplanted with crops as their canopy intercepts rainfall. Some trees such as mathenge produce poisonous pods and should not be fed to livestock for example goats. Some tree species have harmful effects both to animals and to the environment.
In this chapter you shall learn about tree nurseries, their establishment and management., Previously you learnt about nurseries in crop production. Some of the practices to be captured include watering , weeding, planting, filling soil in
Types of tree nurseries
Tree nurseries are categorised as follows; Box nursery bed. Raised nursery bed. Sunken nursery bed. Polythene sleeves nurseries. Tree nurseries are categorised as follows; Box nursery bed. Raised nursery bed. Sunken nursery bed. Polythene sleeves nurseries. photography of raised, box, sunken and polythene sleeves nurseries with tree seedlings growing with them arranged side by side
Factors considered when selecting nursery site
The following factors should be considered when selecting the nursery site: Nearness to the water source for easy watering. Type of soil should be well drained, deep & fertile preferably sandy loam. Topography should be gentle to prevent flooding and erosion through run-off. Security- should be well protected from theft and destruction by animals. Well sheltered place. Windbreaks are necessary to prevent strong wind uprooting seedlings and causing excessive evapotranspiration
Tree seeds are prepared by extraction using three main methods before treatment. Example of these methods include:
Drying in the sun -Seeds are placed in the sun to dry until they are open for example croton seeds
Tree seeds are prepared by extraction using three main methods before treatment. These methods include Drying in the sun Seeds are placed in the sun to dry until they are open e.g croton seeds Tree seeds are prepared by extraction using three main methods before treatment. These methods include Drying in the sun Seeds are placed in the sun to dry until they are open e.g croton seeds
Seed treatment is done to break seed dormancy and ensure rapid germination. Also to improve vegetative growth associated with Nitrogen fixation. This is called seed innoculation. Other treatment methods used for seed treatment include: Hot water treatment-it helps to soften the seed coat and make it more permeable to water. The seed is soak in hot water [about 80oc ] for 3-5min then the hot water is replaced with cold water and allowed to soak for 24hrs. Examples of seeds treated in hot water include Leucaena, calliandra and acacia.
Management practices of trees in the fieldThese are practices carried out on trees after they have been transplanted in the field.
Sites for tree planting
Trees for agroforesry are categoriesed as follows
- Steep slopes
Boundaries with trees growing
The riverbanks with trees growing
Homestead with trees growing
Steep slopes with trees growing
Management of trees
These are practices carried out on trees when growing in the field.
Weeding a tree in the field.
Care and management of trees
These are practices carried out on trees after they have been transplanted in the field
Trees are protected against livestock trespassing and browsing especially in early growth stages. They include
This is done as in vegetable nursery to reduce competition for nutrients and moisture to enhance growthWeeding a nursery bed.
Pruning and training
Pruning and training -Any part of the seedling unwanted due to breakage , overcrowding, pest or disease attack and productivity is removed through pruning. Pruning may also be done to train the plant to required shape e.g Cordia abyssinia and acacia spp can be trained through pruning.
Grafting and budding
It can be done using back grafting and cleft grafting This usully done to improve the quality of trees
Various practices carried out in agroforestry include:
- Alley cropping
- Mult-storey cropping
- Farm forest
This is where crops are grown between lines of trees or shrubs that are spaced and managed at regular intervals in the crop land. Species commonly used include Leucaenia leucocephalla and Calliandra Caloithyrsus. A good alley cropping should have the following characteristics:
- Deep root system.
- Good leaf letter.
- Fast in growth after pruning, coppicing or pollarding.
- Light open growth, e.g poles, fodder, food etc.
- Shallow lateral roots.
- Nitrogen fixing.
- Resistant to drought and foods.
A system that maintains forest cover in a farming system.
What should be done in an area where trees are harvested
Pollarding is intensive cutting back the crown of the tree about 2-3 meters above the ground level.
Coppicing is cutting the main stem of the tree completely at a height of 10-50 cm above the ground.
Looping is removal of selected branches of the tree to produce fuel wood and fodder.
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