FORM 2 AGRICULTURE NOTES
GENERAL AGRICULTURE
Land use
Population growth and land use
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Population is defined as the total number of people or organisms occupying an area at
any given time
Population growth refers to the increase in the number of people living in an area
Population growth is a result of births and migration of people into an area
As the total of settled people increases, more land is used to build homes, towns,
industries, recreational parks and many other human activities
Effects of population growth on land use
Pressure on resources
• Population growth results in increased need for resources such as roads, schools, clinics
and hospitals
• Demand for natural resources such as firewood also increase leading to high levels of
deforestation leaving the soil bare and prone to erosion causing land degradation
Increased demand for residential land
• As the total number of people living in an area increase, more land is needed to build
homes social facilities such as parks, sports facilities, industries and commercial business
areas
• This will take up potential land for agriculture and some farms leading to reduced
cropping and grazing land
Increased demand for agricultural land
• Population increase results in family land holdings being reduced to smaller units as a
result of subdivision of land to younger generations
• Each created family unit will have smaller subdivision units with less cropping land
• When family units have small land holdings, food production levels are reduced,
eventually leading to hunger and starvation
Degradation of the environment
• Destruction of natural surroundings will result from overuse of some natural resources to
levels that impact negatively on the environment
• Intensified agricultural activities are carried out while industrial activities increase to
meet the increasing demand in agricultural and industrial products
• This leads to high levels of erosion and pollution of the environment by agro-chemicals
and industrial wastes as well as domestic wastes
• Gas pollutants from vehicles and industries can result in the formation of acid rain which
is destructive to vegetation resulting in reduced soil cover and reduced evapotranspiration
leading to increased erosion and reduced rainfall respectively
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FORM 2 AGRICULTURE NOTES
Solutions to problems of population growth
Family planning awareness
• This involves making people aware of the need for family planning, its advantages and
details available birth control methods
• This can be done through public shows by relevant health authorities, community based
health workers and public media adverts on televisions, phones, newspapers and
billboards
Environmental awareness campaigns
• Government departments (EMA & AGRITEX), schools and authorities should educate
people on the effects of pollution and encourage safe disposal of waste materials
• Farmers should be encouraged to adopt better methods of farming by extension workers
from the ministry of agriculture
• Awareness campaigns will the citizens to use resources wisely in a way that promotes use
of the resources over generations thus minimizing pressure on resources is minimized
Technological advances
• This involves the use of electricity, production equipment, processes and agricultural
practices that have reduced or no environmental damage
• Use of alternative energy sources such as solar and gas energy reduce the number of trees
cut down for firewood thus reduce deforestation and its effects
• There is also need for advanced technology that treats industrial and vehicle fumes to
harmless wastes that have no effect on the environment
• Other advances in technology involves environmentally friendly technology that are
efficient and ensure sustainable use of natural resources e.g. energy saver lights
Establishment of social facilities
• The availability of schools, universities, social welfare funds and entertainment facilities
help slow down population growth as the sexually active generations will be occupied to
some extent in their studies and carrier specialization areas
Farming systems
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Farming systems are ways in which production s carried out on a farm as a unit e.g.
mixed farming, monoculture or crop rotation
Mixed farming
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Involves practicing both crop and livestock production on the same farm
The farm is partitioned into sections which are allocated to crop and livestock production.
The farm will have different livestock and crop enterprises e.g. broiler production, dairy
farming, wheat and tobacco farming on the same farm.
Advantages
• Crop residues can be used as supplementary animal feed
• Manure from animals can be used in crop lands as a source of nutrients
• There is additional income from animals or crops instead of relying on one enterprise
• Improved nutrition for people due to a variety of products on the farm
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FORM 2 AGRICULTURE NOTES
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Economics on space.
Allows spreading of risks or reducing the impact of unforeseen hazards that results in
production losses
Disadvantages
• Loss of specialization thus needs a lot of capital to purchase various equipment
• More labour is required
• Control of pests and diseases is difficult
• It is difficult to practice on a small piece of land
Monoculture
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Is a practice of growing the same crop year after year on the same piece of land
It is practiced where crop is in high and constant demand e.g. Maize in communal areas
or when perennial crops such as citrus fruits, apples, peach and banana are grown
Advantages
• Allows specialisation and use of machinery without difficulties
• Supplies crops on high and constant demand
• Works well under limited land use in small holder farmers
Disadvantages
• Leads to destruction of soil structure thus weakening the soil resulting in increased
erosion
• Results in continuous depletion of nutrients due to their extraction at the same depth
• Leads to high levels of disease and pest build up which may be difficult to control
• In the event of drought or pest outbreak, total crop failure and yield loss may occur
Intercropping
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This is a farming practice that involve the growing of more than one crop at the same
time on the same piece of land e.g. A farmer can grow field beans and maize at the same
time in the same field
Advantages
• If one crop fails a farmer can rely on the other crop
• Economics on space as more than one crop can be produced on the same piece of land
• There is one land preparation for two crops or more
• There is uniform utilization of nutrients at all depths of soil because different crops
have different rooting zones.
• Reduces disease build-up
• Reduces soil erosion through provision of ground cover when broadleaved crops are
included
Disadvantages
• Prevents the use of machinery e.g. One cannot use a cultivator to control weeds.
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FORM 2 AGRICULTURE NOTES
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Prevents the use of selective herbicides
Bushy crops may harbour pests that may affect other crops in the intercrop
Environmental factors influencing agriculture
Modification of adverse environmental factors
Excessive rainfall
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May result in flush floods which are very destructive to crops and livestock
Farmers should avoid settling and carrying out farming activities in low lying areas that
are prone to flooding
Dam construction helps to collect flood water and reduce flooding on other areas
Drought
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This is when very little rainfall is received during the rainy season resulting in crop
failure and reduced crop yield as well as death of livestock
Construction of dams and other water harvesting methods can help provide a constant
supply of water for irrigation and livestock
Tied ridging and pot holing help to reduce surface runoff and encourage infiltration of
water for storage in the soil thus increases the effectiveness of rainfall
Practicing mulching and conservation tillage methods which reduces evaporation and
conserve soil moisture
Hailstorm
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This refers to precipitation in the form of frozen water that fall at high velocity and shred
plant leaves or kill small livestock
Farmers in hailstorm prone areas should carry out practices that are not affected by
hailstorm such as small livestock production in protected housed environment
In such areas, farmers should avoid growing leaf crops and grow plants less affected by
hailstorm
Strong wind
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Strong winds destroy crops, cause flower drop, fruit drop and lodging in some crops
This may significantly reduce yields or result in no yields at all
Farmers can grow wind breaks (tree lines) to reduce wind speed to levels that are less
destructive to crops
Farmers can also carry out activities that are less affected by strong winds
Extreme high temperature
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Causes crops to wither and die
Methods of reducing the effects of extreme high temperature
o Supply adequate water through irrigation.
o Mulching to reduce evaporation.
o Transplanting under cool conditions such as late afternoon or cloudy conditions.
o Shading seedlings or transplanted seedlings to reduce heat from direct sunlight
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FORM 2 AGRICULTURE NOTES
o Use of greenhouses in which temperature can be modified to suite the crop’s
requirements
Extreme low temperature
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Causes frost damage on crops and death of animals
Methods of reducing the effects of extreme low temperature
o Sprinkling water on crops early morning or late in the evening
o Avoid having tea, coffee and tobacco seedbeds in areas prone to frost e.g. valleys.
o Choose planting dates which prevent frost hitting the crop at its susceptible growth
stage.
o Construct frost barriers e.g. thatch grass barriers.
o Building proper housing facilities that supply adequate warmth to livestock
o Use of greenhouses in which temperature can be modified to suite the crop’s
requirements
Forestry
Softwoods and hardwoods
Differences between softwoods and hardwoods
Softwoods
• Produce less durable timber
• Produced from coniferous tree species
• Easy to cut and work with
• Examples: Mexican pine, Slash pine
Hardwoods
• Produce very strong and durable timber
• Produced from pod bearing tree species
• Difficult to cut and work with
• Examples: Mukwa (bloodwood), Teak,
Mahogany, Saligna gum (Eucalyptus
grandis)
Tree nursery
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A tree nursery is a place set aside for raising of seedlings or young plants before they are
transplanted to their permanent planting positions
The seedlings in a tree nursery can be raised in float trays, plastic pockets filled with
planting media (soil mixtures) or prepared beds on the ground
Factors influencing the choice of a tree nursery site
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The suitable site should be free from termite and ant activity
Soils must be well drained
Areas that are prone to frost should be avoided
The site must be near a good and reliable water source
The slope must be gentle to allow free drainage
Establishment of a tree nursery
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Most forest trees are established from seeds in polythene bags or kaylite trays filled with
prepared soil mixtures or pine bark as planting media
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FORM 2 AGRICULTURE NOTES
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The seed is sown to correct depth guided by a wood tool while small seeds such as gum
tree seeds are picked using a nail head for sowing
The pockets sown with seeds are then watered and treated with Adrin to prevent termite
attack on the seedlings
The pockets are covered with grass and watered with a can fitted with a fine rose
The pockets are watered regularly and germination is checked every day after 7-10 days
from sowing
When the seeds germinate, watering continues steadily avoiding aver watering which may
encourage damping-off of the seedlings
Small seeded trees sown in trays are pricked or transplanted into polythene pockets until
for growth until they reach the ideal size for transplanting onto permanent stations
Constantly check for pests and diseases
Hardening off is done to condition the seedlings for field environment usually by
reducing watering frequency
Tree establishment
Site for planting
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A good site should have deep, fertile and well drained soils
The site should be cleared off all plant material by stumping and cutting grass
The land should be ploughed and levelled
Tree plantation layout
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Forest planting layouts include triangular, rectangular, hexagonal and quincox layout
Most forest trees are spaced 2.5 metres apart using any one of the four planting layouts
however, where thin straight logs are required, a smaller spacing of 75cm to 100cm
between rows and 25cm to 30cm between plants in rows is used
Seedling selection
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Healthy disease free seedlings should be used for establishing plantations
Seedlings should be transplanted when they are pencil thick and about 20cm to 30cm tall
Transplanting
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This is the removal of seedlings from the nursery for planting onto their permanent
planting stations
The seedlings should be watered at least an hour before they are pulled out
The polythene bag should be carefully removed with minimum damage to the roots,
making sure the soil on or around the roots remain intact
Place the seedlings gently in the planting hole and cover with soil
Firm the soil around the planted tree to exclude air pockets
Water the planted trees and shade if temperatures are too high
Tree plantation management
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Established tree plantations are managed by protecting the plants from animals, veld fires,
harsh weather, weeds, pests and diseases
Termites should be monitored and controlled
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FORM 2 AGRICULTURE NOTES
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Fire guards (grass free bands) should be made around plantations to protect the trees from
veld fires
It is also necessary to prune and train the trees to grow straight
Wildlife
Sustainable utilisation of wildlife resources
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This refers to the use of resources in a way that does not affect the natural balance, quality
and availability of the resources for future generations
Methods of sustainable wildlife utilisation
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Monitoring killing of wild animals and harvesting of forest products following set
government policies and laws
Practicing non-consumptive use of wildlife resources which have little harm to the
wildlife such as game viewing, biological and ecological studies, bird watching and
photography
Protecting wild animals in parks and sanctuaries
Controlling trade of wildlife resources and preventing trade on endangered species
Use of traditional customs that help in sustainable utilisation of wildlife where some
communities still respect them
Traditional customs that help in sustainable utilisation of wildlife
o Certain clans do not kill their totem animals
o Some forests, rivers or mountains are regarded as sacred thus they are not frequented
by humans and are left in their natural state
o Cutting of trees or harvesting of wild fruit trees is prohibited and monitored by
traditional leaders
o Some animals are regarded as sacred and cannot be killed or eaten by the public e.g.
python and pangolin
Endangered plant and animal species
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Endangered species are organisms which are near levels of disappearing completely
(extinction)
Endangered plants
o Flame lily
o Aloe
Endangered animals
o Pangolin
o Python
o Elephant
o Rhinoceros
o Cheetah
Dangerous and problem animals
Dangerous animals
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These are wild animals that cause harm to livestock and humans e.g. hyena, leopard, king
cobra snake, buffalo, rhino and hippopotamus
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FORM 2 AGRICULTURE NOTES
Ways of dealing with dangerous animals
• Putting the animals in protected enclosures to prevent them from encountering people in
the local community
• The department of wildlife should assist by controlling the animals through fencing to
keep the animals away from homesteads and through provision of game reserves or
protected areas
• Animals such as elephants and stray lions are killed or captured by wildlife authorities
Problem animals
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These are animals that destroy crops and disturb livestock e.g. quelea birds, baboons,
elephants, buffaloes, warthogs, spotted hyena, black backed jackal and wild dog
Ways of dealing with problem animals
• Problem animals can be harvested by killing as a ways of managing them
• Fencing can be done to keep the animals away from human settlements
• Scarecrows can be put to scare baboons and some birds
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FORM 2 AGRICULTURE NOTES
SOIL AND WATER
Soil profile
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This refers to the different soil layers found vertically form the soil surface to the parent
rock.
Horizon A: Topsoil
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This is where most plant roots grow in.
It is the soil that is cultivated and nourishes the crops.
Most biological activities take place here (decomposition)
It is dark in colour because it contains a lot of organic matter.
Its structure is influenced by farming activities.
A soil pan may form in this horizon if ploughing depth is not varied.
Horizon B: Subsoil
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It mainly consist of clay or sand particles
It is lighter in colour than the topsoil because it contains less organic matter.
There is less biological activity
Has fewer plant roots
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FORM 2 AGRICULTURE NOTES
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There is less disturbance of the soil through tillage
Nutrients in this layer can be utilized by deep rooted crops e.g. citrus
Horizon C: Partially weathered rock
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This layer contains partly weathered rocks.
It contains both soil (mostly clay) and rock.
No organic matter and a few plant roots (mainly of deep rooted trees) are found in this
layer.
Horizon D: Parent rock
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This is the un-weathered parent rock.
It is a layer of solid rock from which the soil above was formed.
No water can pass through this layer.
It may mark the water table.
Importance of soil profile
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Enables the assessment of nutrient and organic matter content in the soil
Studying the soil profile help to determine soil texture, structure and colour.
Helps to assess the depth of soil and water table.
Allow the farmer to determine soil drainage, water retention and aeration.
Evidence of toxic material can be assessed from the soil profile
Soil types
Composition and properties of soil types
Sandy soil
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Particles are loose and coarse over 50% sand and 20% clay and silt combined
It has poor water-holding capacity
It does not stick when wet
It is well drained and well aerated
It has low capillarity and high erodibility
It leaches nutrients readily especially nitrogen
It is easy to work and provides easy root penetration
Clay soil
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Consists of fine soil particles, over 30% clay and less than 50% sand
It is sticky when wet
It has high water holding capacity
It retains soil nutrients
Clay soils swell when wet and shrink when dry resulting in cracks
It is poorly drained and poorly aerated
It is hard to work with and provides poor root penetration
It has low erodibility
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FORM 2 AGRICULTURE NOTES
Loam soil
• Contains almost equal proportions of sand, silt and clay (30% clay and over 30% sand)
• It sticks to some extent and forms threads with difficulty
• It has moderate water holding capacity
• It is well drained and aerated
• It does not leach soil nutrients (has satisfactory levels of soil nutrients)
• It is easy to work with and provides easy root penetration
• It has moderate porosity
NB: loam soils are the most suitable for crop production.
Soil fertility
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This refers to the amount of plant nutrients in the soil
Soil fertility determines the capacity of a soil to produce crops
Major nutrient sources are classified as organic (containing carbon) and in-organic (manmade)
Organic fertilizers
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These are remains from decomposed plant and animal parts that release nutrients into the
soil
Types of organic fertilizers
Farmyard manure
• they contain a fairly high amount of organic matter
• also contains almost all plant nutrients
• bulk of phosphate is excreted in the dung while urine contains the bulk of nitrogen and
some phosphate
• nitrogen available to plants in farmyard manure is largely in ammonium form (NH+4) and
has to be converted into nitrates through the process of nitrification
• generally applied at 2-4kg/m2
• poultry and sheep manure are more concentrated and should be applied at a lower rate of
1kg/m2 otherwise they cause leaf burns.
Composition of various farmyard manure
Animal
N%
P2O5%
K2O%
Sheep
0.9
0.4
1.0
Horse
0.7
0.3
0.6
Cattle
0.5
0.2
0.5
Pig
0.5
0.4
0.4
Poultry
1.0
0.8
0.4
NB: The nutrient content of each manure depends on the quality of feed taken in by the
animal.
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FORM 2 AGRICULTURE NOTES
Compost manure
• A mixture of organic residues and soil that have been piled in layers, moistened and
allowed to decompose.
• When applied to the soil it adds both organic matter and plant nutrients.
• It is made from a heap either above or below the soil surface (pit method).
• The pit method is not widely practiced because it requires more labour for digging the
compost material takes longer to decompose because there is less aeration.
Green manure
• A crop (usually leguminous) is grown on a piece of land then ploughed in while it is still
green.
• The best time for ploughing in is just before planting because:
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The crop will have attained maximum vegetative growth and thus provides a lot of
material for decomposition.
ii. The crop will still be succulent and easily decomposed to release nitrogen and
other nutrients in the form in which they are available for plant uptake.
• Legumes are mostly used as green manures and the common ones are sun hemp, cowpeas
and jack beans.
Advantages and disadvantages of organic fertilizers
Advantages
• Improves nutrient status and water
holding capacity of the soil
• Improves soil structure therefore
drainage and aeration
• Improves soil temperature
• Buffers soil pH
• Improves resistance of the soil to
erosion
• Releases nutrients to the soil over a long
period of time
• Readily available
• Relatively cheap
Disadvantages
• Takes time to decompose
• May cause pest and disease carry over
• They are bulky and large quantities are
required to be effective
• A lot of labour is required to apply
organic fertilizers
Inorganic fertilizers
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These are man-made or synthetic nutrient formulations that do not contain carbon
They are also known as artificial fertilizers
Types of inorganic fertilizers
Straight fertilizers
• These are inorganic formulations that supply only one major nutrient; nitrogen,
phosphorus or potassium
• They are used as top-dressing or for addressing nutrient shortages
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FORM 2 AGRICULTURE NOTES
Various straight fertilizers
Type of straight fertilizer
Nitrogenous fertilizers
Phosphoric fertilizers
Potassic fertilizers
Examples
• Ammonium nitrate (34.5% N)
• Urea (46% nitrogen)
• Ammonium sulphate (21% N)
• Sodium nitrate (16% N)
• Single super phosphate (SSP)
• Double super phosphate (DSP)
• Muriate of potash (60% K4O
• Sulphate of potash (50% K2O)
Advantages and disadvantages of straight fertilizers
Advantages
Disadvantages
• Reduces costs by applying specific
• More labour is required if one nutrient is
required nutrient
needed
• Supply known quantities of nutrients
• More storage space is needed for storage
of different fertilizers
• Exact amount of nutrients recommended
are applied
Compound fertilizers
• These are inorganic formulations that supply more than one major nutrient
• Compound fertilizers are usually applied as basal dressing before planting or at planting
Various compound fertilizers
Compound
N%
P%
K%
S%
Micro elements %
A
2
17
15
10
0.1 Boron
B
4
17
15
9
0.1 Boron
C
6
17
15
7.5
0.1 Boron
D
8
14
7
6.5
--------------J
15
5
20
3.4
0.1 Boron
L
5
18
10
8
0.25 Boron
M
10
10
10
6.5
--------------P
10
18
0
6.5
--------------S
7
21
7
8
0.04 Boron
T
25
5
5
5
--------------V
4
17
15
8
0.1 Boron
X
20
10
5
3
--------------Z
8
14
7
6.5
0.8 Zinc
Advantages and disadvantages of compound fertilizers
Advantages
Disadvantages
• Required nutrients are applied at once
• Supply some nutrients not lacking in
the soil thus may lead to nutrient
• Supply known quantities of nutrients
toxicity (over-supply)
• Granular therefore are easy to apply
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FORM 2 AGRICULTURE NOTES
Irrigation
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This is the application of water to the soil for good crop growth.
Irrigation is practised because there will be inadequate or no rainfall for a farmer to grow
crops.
It is also the artificial application of water to the soil in areas where rainfall is insufficient.
Reasons for irrigation
1. To supply water when rainfall is inadequate for plant growth: in semi-arid areas rainfall is
totally inadequate for crop production e.g. the South-Eastern Lowveld (Triangle, Hippo
Valley and Mkwasine Estate) where the soil is suitable for crop growth but rainfall is
limited.
2. To supplement rainwater: in some areas may be adequate in quantity but badly distributed
that is there will be dry spells during the rainy season. For optimum growth of plants the
farmer must irrigate during those dry spells.
3. To extend the growing season: planting and irrigating the crops before the rains come or
irrigating the crop to reach maturity after the rains have stopped. Extension of the
growing season can be used for long season varieties of maize and groundnuts.
4. To grow crops during the dry season: farmers use irrigation to grow wheat and barley
during winter months. The farmer can therefore grow two crops per year, a practice called
double cropping.
NB: The supply of adequate moisture to a crop throughout the season ensures high yields
of good quality crops which fetch higher prices on the market.
Sources of irrigation water
Natural sources
• Rivers
• Streams
• Lakes
• Aquifers
Artificial sources
• Dams and Weirs
• Ponds
• Wells
• Boreholes
Suitability of water for irrigation
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Not all water is suitable for irrigating agricultural crops
Some water sources are polluted to the extent that the water cannot be used by crops or
causes damage to the crops
It is therefore important to manage wastes properly, minimise the use of persistent
chemicals and improved farming methods that do not contaminate or pollute water
sources
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FORM 2 AGRICULTURE NOTES
CROP HUSBANDRY
Classification of plants
Classification of plants into Monocots and dicots
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This classification groups plants according to the number of seed cotyledons and other
characteristics such as leaf an root structure
Monocotyledonous plants
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These are plants that produce seeds containing a single cotyledon
The plants have narrow shaped leaves which have parallel veins
They have a fibrous root system
Monocots are mostly grasses, cereal crops and palms e.g. maize, wheat, rice, onion and
banana
Dicotyledonous plants
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These are plants that produce seeds containing two cotyledons
The plants have broad shaped leaved which have net veins
They have a tap root system and perennial plants have woody stems
Dicots are broadleaves e.g. groundnuts, tomatoes, soya bean and sunflower
Botanical classification of plants
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This is a scientific classification of plants into families based on biological characteristics
Plants of the same family share common features and are related
Legumes
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This is a family of plants that are capable of fixing atmospheric nitrogen into the soil
The plants have root swellings called nodules where nitrogen fixing bacteria called rhizobia
inhabits
Bacteria in the nodules acquires nutrients from the plant and converts atmospheric nitrogen
into a form that can be used by plants
The legumes and rhizobia have a symbiotic relationship
Leguminous plants include crops such as groundnuts, peas, beans, round nuts and soya
bean
Graminae (cereals)
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This is a family of grass crops mostly grown for their carbohydrate rich grains e.g. maize,
wheat, barley, sorghum, millet and rapoko
Brassicas
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This is a family of plants made up of leafy vegetables that have produce edible leaves and
flowers e.g. cabbage, rape, cauliflower and broccoli
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FORM 2 AGRICULTURE NOTES
Cucurbits
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This is a family of herbaceous creeping plants which produce edible fruits e.g. pumpkin,
watermelons, squash and cucumbers.
Solanaceous
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This is a family of having typically tubular flowers with reflexed petals, producing anthers,
and often poisonous or narcotic properties e.g. potato, tobacco, tomato, pepper etc.
Structure of flowering plants
Structure of a flower
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A flower is the sexual organ for plant reproduction
Flowering structures differ with classes of plants, some have male and female parts in the
same flower e.g. bean, while others produce male and female on different parts of the plant
e.g. maize
The structure of a bean flower
Part
Peduncle
Receptacle
Sepals
Petals
Ovary
Ovules
Style
Stigma
Filament
Anther
Pollen grains
Functions
Supplies nutrients to the flower
Large end of the flower which bears parts of the flower
Protect the male and female parts of the flower while in bud
Brightly coloured to attract insects
A female part which produce female sex cells called ovules
Female sex cells which when fertilised develop into seeds
Holds the stigma in position and also connects the stigma to the ovary
A female organ which receives pollen grains
Hold the anther in position
A male organ which produce male sex cells called pollen grains
Male sex cells which fuse with ovules to form seeds
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FORM 2 AGRICULTURE NOTES
The structure of a maize flower
Part
Ear
Silk
Tassel
Functions
Female flower part that contains the ovary and ovules that produce grains
after fertilization
Elongated style and stigma which receives pollen grains
Male flower at the top of the plant which have anthers that produce
pollen grains
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FORM 2 AGRICULTURE NOTES
Plant reproduction
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This refers to the generation of new plants (plant propagation)
Plant propagation occurs through sexual reproduction or asexual (vegetative) reproduction
Sexual plant reproduction
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Sexual reproduction involves the fusion of a male and female gamete.
The male gamete is a pollen grain nucleus produced by anthers
The female gamete is a large egg cell in the ovule found in the ovary.
The main stages involved are pollination, fertilization and germination
Pollination
•
•
Pollination is the transfer of pollen grains from the anther to the stigma.
There are two forms of pollination:
i. Self-pollination – the transfer of pollen grains from the anther to the stigma of the
same flower or flowers on the same plant.
ii. Cross-pollination – the transfer of pollen grains from the anther of one flower to the
stigma of another flower on different plants of the same species.
• Pollen grains are transferred either by wind or insects
• Plant flowers have special adaptations to wind or insect pollination
Wind pollinated flowers e.g. maize
Do not produce nectar
Have no scent
Have small petals which are not brightly
coloured
Anthers hang out of the flower at maturity
exposing them to wind which carries pollen
Large amounts of small and light pollen
grains are produced to increase the chances
of landing on the stigma
The stigma is feathery to increase surface
area for pollen reception.
The stigma is outside the flower
Insect pollinated flowers e.g. beans
Produce nectar to attract insects
Produce a scent to attract insects
Have fleshy brightly coloured petals to
attract insects
Anthers are inside the petals
Small quantities of sticky or spiky pollen
are produced because there are increased
chances of pollen landing on the stigma.
The stigma is sticky
The stigma is enclosed within the flower
Fertilisation
•
•
•
•
•
•
Fertilization is the fusion of male and female nuclei or gametes to form a zygote.
A pollen grain lands on the stigma, absorbs nutrients secreted by the stigma and its
cytoplasm grows out into a pollen tube.
The pollen tube grows down through the style.
On reaching the ovary, the pollen tube enters into the ovule through a hole called
micropyle.
The male nucleus in the pollen tube fuses with the female nucleus in the ovule forming a
zygote.
After fertilization the floral parts (petals, stamens, style and stigma) wither, die and fall
off.
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FORM 2 AGRICULTURE NOTES
•
•
•
•
The zygote and ovary grow rapidly by cell division.
The zygote develops into a seed which has an embryo.
The embryo consists of a radicle, plumule and one or two cotyledons which act as food
reserves at germination.
Integuments form the seed coat or testa while the ovary develops into a fruit.
Advantages of sexual reproduction
•
•
•
•
•
Seed is easy to handle and store.
Provides a means of multiplication for some crops that cannot be grown asexually e.g.
maize.
It is easy to mechanize in many crops.
There is variation between individuals making them better adapted to the environment.
This method can be used to produce hybrid crops (crop improvement)
Disadvantages of sexual reproduction
•
•
•
•
It is expensive as seeds have to be purchased every production season
The method does not maintain some desirable characteristics over generations e.g. taste
Seed produced fruit trees take long to produce fruits
Seeds have smaller food reserves and developing seedlings may fail to emerge from the
soil
Asexual (vegetative) reproduction
•
•
•
Asexual reproduction is the production of offspring from one parent without the fusion of
male and female gametes.
It involves the use of already existing plant material to produce offspring
The production of offspring is due to a process of cell division called mitosis thus the
offsprings are genetically identical to each other and the parent.
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FORM 2 AGRICULTURE NOTES
Natural asexual reproduction methods
•
Naturally, new plants are produced from some plant parts that develop their own rooting
systems and become independent plants usually in the rainy season
Bulbs
• A bulb is a heavily condensed fleshy shoot with buds that can develop into new plants
• Crops that can reproduce with buds are onions, leak and garlic
Tubers
•
•
•
Tubers develop from stems and have auxillary buds commonly referred to as ‘eyes’.
Each eye can produce a new shoot using food stored in the bud
Plants that can reproduce by means of tubers are Irish potatoes
Corms and rhizomes
• These are modified underground stems, swollen with food reserves, that can develop into
new plants e.g. cocoa yams
Runners
• These are surface stems that run parallel to the ground
• The stems develop new roots on sections where they touch the ground
• Areas that develop roots become separate plants e.g. in strawberry plants
Suckers
• Suckers are side shoots that can develop roots and become independent plants
• Such plants include covo and banana
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FORM 2 AGRICULTURE NOTES
Artificial asexual reproduction methods
•
Farmers make use of natural processes and modify them to produce new plants for
commercial production of crops
Stem cuttings
•
•
•
•
•
A section of the stem with at least three buds, 30 – 40 cm long is used for propagation.
Cuttings should only be taken from vigorously growing plants free from diseases in order
to produce high yields of good quality.
It is used to propagate crops such as sweet potatoes and cassava
Planting is done during the rainy season on ridges with ½ of the cutting in the soil with
individual cuttings 30 cm apart along the ridge.
Roots will develop from stems in the ground and shoots develop from the nodes above
the ground.
Grafting
• This method is used to unit a shoot (scion) of desirable characteristics to a root stalk.
• The joined area should be disinfected, tied with a clean wrap plastic to prevent infections
and loss of water until the wound heals
• Grafted plants are kept under close monitoring in a nursery
• Grafting is used for the propagation of most fruit trees such as citrus, apple, apple,
avocado, peach and mango.
Budding
• This is the joining of buds from desired plant onto another plant of the same species
• It is done by making an incision on the stem then a bud is inserted into the incision
• Citrus trees and roses are multiplied through this method
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FORM 2 AGRICULTURE NOTES
Layering
Ground layering
• Branches are trained to the ground and pegged.
• An earth mound is made around the peg and water is applied.
• Roots develop at the part pegged into the ground.
• The branch or shoot with roots is carefully removed and planted onto the desired place.
Air layering
• Branch of a growing fruit tree is ring barked and the area is wrapped around with a root
medium.
• The root medium is kept moist until roots develop.
• After rooting has taken place the branch is cut and then planted either in pots or in the
field.
Advantages of asexual reproduction
•
•
•
•
•
Fruit trees grown asexually produce fruits in a shorter period than those grown from seeds
The offsprings are identical to their parents and can thrive in conditions favourable to
their parents.
It is the only way of multiplying sterile plants such as bananas.
It is the only way of preserving good characteristics of plants which deteriorate if grown
from seed due to genetic interaction.
Greater chances of survival due to availability of food from parent stalk.
Disadvantages of asexual reproduction
•
•
•
•
•
•
New crop varieties cannot be produced
The planting material is bulky and therefore difficult to transport.
It cannot be mechanised and is labour intensive.
Since the plants are generally similar if there is a disease outbreak the whole crop can be
wiped out.
Many plants cannot be produced quickly
Storage of vegetative parts is difficult and some may rot
Germination
•
•
•
•
Germination is the development of a seed into a new plant
The plumule of the seed develops into a shoot (stem and leaves) while the radicle develops
into a root system
The seed swells and breaks the testa making way for the for the shoot and root to break out
The process of germination is initiated when the right conditions are provided
Requirements for seed germination
Water
•
•
Absorption of water into the seed occur by imbibition through the micropyle
Water activates the seed and facilitates chemical reactions required for germination
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FORM 2 AGRICULTURE NOTES
•
It also makes the seed swell and break the testa making way for the for the shoot and root
to break out
Oxygen
•
•
•
Germinating seeds respire to produce energy for the development of shoot and roots
Oxygen is required for the process of respiration to occur
The soil should be well aerated to ensure the availability of air for the germination of seeds
Temperature
•
•
•
Seed germination requires suitable temperatures to enhance chemical reactions taking place
inside the seed
Low temperatures reduce or stop the germination process
Very high temperatures may even kill the seeds
Structure of maize seed
Seed part
Testa
Plumule
Radicle
Cotyledon (single)
Endosperm
Micropyle
Functions
A tough and strong outer coating that protects the embryo
Develops into the shoot (stem and leaves) upon germination
Develops into the rooting structure upon germination
Absorbs food from the endosperm to supply the actively growing tip
Stores food for the seed embryo
Is the point of entry for water that is required for water that is
required during the germination process
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FORM 2 AGRICULTURE NOTES
Structure of bean seed
Seed part
Testa
Plumule
Radicle
Cotyledons (two)
Micropyle
Functions
A tough and strong outer coating that protects the embryo
Develops into the shoot (stem and leaves) upon germination
Develops into the rooting structure upon germination
First leafing structures that store and supply food to the developing
seedling until proper leaves are formed and start to photosynthesise
Is the point of entry for water that is required for water that is required
during the germination process
Emergence
•
•
•
Emergence is the appearing of a germinated seedling onto the soil surface
It occurs after germination when the new shoot grows out of the soil
Seedling emergence is affected by planting depth and soil crusting
•
•
•
The cotyledons and testa are pushed out of the ground at emergence
It is common to most dicotyledonous plants e.g. bean and soya bean
Epigeal germination is largely affected by crusted soil
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FORM 2 AGRICULTURE NOTES
•
•
•
The cotyledons and testa remain underground as the shoot breaks out of the ground
It is common in monocotyledonous plants such as maize and sorghum
Such plants have less difficulties in breaking through soil crusts
Crop production
Orchard establishment
•
•
•
An orchard is an area of land set aside for fruit production
A variety of fruit trees can be planted in the same orchard
An orchard is different from a fruit plantation in which one type of fruit trees is planted in
the whole area
Factors which influence site selection of an orchard
Soil type
• Fruit trees need deep, fertile and well drained soils thus an orchard should be sited on such
suitable soils
Water
• Fruit trees require water and during dry seasons they may need irrigation
• An orchard should therefore be located near a reliable source of water
Orchard land preparation
•
•
•
Where a few trees are to be planted, a farmer only pegs planting stations and digs out
planting holes needed
When establishing an orchard where a good number of fruit trees are to be planted, the land
needs to be ploughed first
The land is levelled after ploughing
Marking out planting stations
The square pattern
• A base line is marked by pulling a rope along one side of the area, a metre from the fence
• A knotted 12-metre rope is used to make segments on 3-metre, 4-metre and 5-metre knots
on one end of the baseline until a right angle is marked by the 3-metre and 4-metre pieces
of ropes
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25
FORM 2 AGRICULTURE NOTES
•
•
•
Take a 2.5-metre stick and measure the length along the base line then dig holes using a
hoe at every 2.5 metre marks
This planting pattern maintains the distance between rows and within rows
The method allows free operational movements in different directions
The rectangular pattern
• This method is like the square pattern but the in-row spacing is made greater than the interrow space
• The same method for marking out the square pattern is used to get the rectangle planting
pattern but a 3-metre stick will be used in place of the 2.5-metre stick
The staggered pattern
• This method gives each tree more space and does not follow a regular pattern
Digging planting holes
• Deep planting holes are needed for fruit trees
• Square holes measuring 60cm long, 60cm wide and 60cm deep are dug
Stages when digging a planting hole
1. Dig the top 30cm of soil and put it on one side of the hole
2. Dig out the bottom 30cm of soil and put it on the other side of the hole
3. Loosen the soil at the bottom of the hole
4. Mix the topsoil with compost, half of the bottom soil and 500g of SSP fertilizer
5. Use the mixture to fill the hole and construct a basin around the of the hole using the
subsoil
6. Finally, add 300g of compound D fertilizer and water the hole
Planting
• A wooden board called a planting board is used to make sure trees are planted in the correct
place
• Usually the board is 150cm long and 15cm wide in size
• The planting board ensures that a straight line and correct depth of planting is maintained
Watering of fruit trees
•
•
•
Fruit trees require irrigation especially in winter and dry season when there is no rainfall
High temperature areas require frequent watering as evaporation losses are high
Soil type also determines frequency of watering e.g. sandy soils have poor water storage
capacity thus needs frequent irrigation
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FORM 2 AGRICULTURE NOTES
Crop protection
Pests
Life cycle of pests
Complete metamorphosis
• This is a life cycle which follows four
distinctive stages of development which
are egg stage, larva stage, pupa stage
and adult stage
• An insect goes through complete
change in body size and structure as it
develops from the egg stage to the adult
stage
• Such pests include butterflies, moths,
beetles and fruit flies
Incomplete metamorphosis
• This is a life cycle which does not
follow the four distinct stages but
follows three stages which are egg
stage, nymph stage and adult stage
• After hatching from the egg, the insect
does not go through significant changes
in body shape
• The insect only grows in size as it
develops into an adult e.g. locusts,
grasshoppers, aphids, termites, scales
and bugs
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FORM 2 AGRICULTURE NOTES
Plant diseases
Disease transmission
•
This refers to how plant diseases are spread from one plant to another
Methods of disease transmission
Vectors
• These are insect pests that carry disease causing pathogens especially viruses from infected
plants to other plants
• The pathogens are carried in saliva of sap sucking pests such as leaf hoppers and aphids
Wind
• Pathogens can be carried from one plant to another by wind e.g. fungal spores
Rainfall
• Rain splashing causes the spread of bacterial diseases that may be carried from infected
plants in splashing rain drops
Poor weed management
• Weeds can act as alternate hosts of diseases therefore if not controlled result in rapid spread
of the disease pathogens
Poor hygienic practices in nursery
• Plant diseases can be spread to seedlings through farmer’s hands or clothing therefore high
levels of hygiene should be maintained in the nursery
• Farmers should restrict entry into the nursery and put foot baths to disinfect shoes
Movement of agricultural products
• Some fruits, leafy vegetables, grains and seeds may carry diseases with them as they are
distributed in the market
• These products may introduce diseases to crops in some areas
General symptoms of plant diseases
Disease
Symptoms
Fungal diseases
•
•
Bacterial diseases
•
•
•
•
•
Viral diseases
Light coloured patches
White or greyish moulds on upper and lower leaf surfaces
respectively or fruits
Development of lesions and spots on leaves or fruits
Changes in leaf colour may occur
Plants may wilt as a result of bacterial wilt
Stunted growth of plants
Chlorosis, leaf curling and spots
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FORM 2 AGRICULTURE NOTES
Weeds
Classification of weeds based on morphology
•
This is the classification of weeds based on the type of leaves
Broadleaved weeds
• These are weeds which have very wide and broad shaped leaved
• Broadleaved weeds are also classified as dicotyledonous plants
• Their leaves are net veined e.g. black jack, wondering jew, pig weed and thorn apple
• They are controlled by selective herbicides known as broadleaved herbicides
Annual broadleaved weeds
o These are monocotyledonous weeds that produce seeds in one season e.g. black jack,
witch weed, Mexican marigold and thorn apple
Perennial broadleaved weeds
o These complete their life cycle after more than one season e.g. oxalis and lantana
Grass weeds (grasses)
• This class of weeds is made of monocotyledonous plants that have long, narrow and spiral
shaped leaves
• Grasses have a small and narrow leaves which have parallel veins e.g. rapoko grass, couch
grass, goose grass and Shamva grass
Annual grass weeds
o These weeds are in the grass family (monocotyledonous) and produce seeds in one
season e.g. finger grass, Shamva grass and goose grass
Perennial grass weeds
o These are weeds in the grass family that require more than one season to complete their
life cycle e.g. star grass, couch grass, rapoko grass, spike and kikuyu grass
o Perennial weeds can exist for several years in a field
Mode of spread of weeds
Wind dispersal
• Wind is an agent of dispersal for some weed seeds
• Weed seeds that are feathery, papery and winged in nature are blown away and spread to
other areas by wind e.g. e.g. thorn apple
Water dispersal
• Some weed seeds float in water and are spread to other areas through surface runoff
Animal dispersal
• Some weeds such as black jack and star burr produce seeds that have hooks which can
attach to furs, feathers of animals or clothes and are deposited a distance from the parent
plant
• Other weed seeds have a tough testa and when eaten, pass out undigested, away from the
parent plant e.g. pig weed seeds
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FORM 2 AGRICULTURE NOTES
ANIMAL HUSBANDRY
Types of livestock
Ruminants and non-ruminants
•
•
Ruminants are animals that have four stomach chambers e.g. cattle, sheep and goats
Non-ruminants are animals that have one stomach chamber e.g. poultry, rabbits, mules,
donkeys, horses and pigs
Characteristics of ruminants and non-ruminants
Ruminants
Have four chambered stomach (polygastric)
Have no ptyalin in the saliva
Chew the cud (regurgitate)
Most of the digestion and absorption takes
place in the four stomachs
Can digest food with high cellulose content
RODRECK WISEMAN NYAKABAWU
Non-ruminants
Have a single stomach (mono-gastric)
Contain ptyalin in their saliva
Do not chew the cud
Most of the digestion and absorption takes
place in the small intestines
Cannot digest food with high cellulose
content
30
FORM 2 AGRICULTURE NOTES
Anatomy and physiology
Reproduction in poultry
The reproductive system of a cock
Functions of reproductive parts of a cock
Part
Functions
Testicles
Manufacture and store sperms
Sperm duct
A tube which leads sperms from the testicles to the cloaca
(Ductus deferens)
This the opening through which sperms are passed out during mating
Cloaca
During mating, the cloaca of the male and the female are pressed
together and the sperms are transferred from the cock to the hen
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FORM 2 AGRICULTURE NOTES
The reproductive system of a hen
Functions of reproductive parts of a hen
Part
Functions
Ovary
Produces the ova/eggs
Ova/eggs
Sex cells which when fertilized develop to produce a zygote
Receive mature eggs from the ovary and lead them into the
Funnel/infundibulum
oviduct/egg tube
Oviduct/egg tube
This is where fertilization of an ovum/egg takes place
Secretes albumin and wraps it around the ovum
Magnum
Directs ovum to the isthmus
Adds shell membrane to the ovum
Isthmus
Leads the ovum to the shell gland
Produces the egg shell around the ovum
Shell gland/uterus
Moves the egg into the vagina
It is where the sperms are deposited during mating
Vagina
It is also a passage of a fully developed egg into the cloaca/vent
It is an opening through which eggs are passed out during egg
Cloaca/vent
laying
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FORM 2 AGRICULTURE NOTES
The process of egg formation
• A mature ovum is released from the ovary then passes through the funnel into the oviduct
• In the oviduct, it meets the sperm from the cock and is fertilized
• As the fertilized egg moves down the reproductive system, albumen is added in the
magnum, egg membrane is added in the isthmus and a shell is produced around the egg in
the shell gland
• A fully developed egg is laid through the cloaca
The egg
The structure of an egg
Functions of parts of an egg
Part
Functions
This is a hard protective coating which is porous
Egg shell
It allows air movement and gives shape to the egg
Albumen/egg
Serves as a food reserve and as a protective layer for the developing
white
embryo
Chalaza
This is a twisted white material which balance the egg yolk
Yolk
Develops into an embryo when fertilized
Air space
Contains air for the developing embryo
Shell membranes Protects the egg against disease causing organisms
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FORM 2 AGRICULTURE NOTES
Animal nutrition
Livestock nutrients
•
•
•
•
•
Animal diet should contain six main nutrients
The nutrients should be in the right proportions, which are well balanced
Each nutrient has specific functions it performs in the animal body
Under supply of one or more of the nutrients can result abnormal functioning of the
animal’s body known as deficiency disease
The six main nutrients required by livestock are:
o Carbohydrates
o Proteins
o Fats and oils
o Minerals
o Vitamins
o Water
Functions, source and deficiency symptoms of livestock nutrients
Nutrient
Functions
Supply energy for
body functions such
as digestion,
Carbohydrates
pumping blood and
maintenance of body
temperature.
Repair of worn out
tissues, growth of
tissues, form part of
enzymes, hormones,
haemoglobin, cell
Proteins
walls and all
structural tissues,
maintenance of body
pH and for milk, egg
and wool production
Provide energy,
stored under the skin
for use in times of
need.
Fats and oils
Insulates the body,
act as protective
tissue around organs
Carry fat soluble
vitamins
Minerals
RODRECK WISEMAN NYAKABAWU
Sources
Deficiency
Plant leaves (grass or
trees)
Cereals (maize,
sorghum, millet)
Hay
Molasses
Emaciation or muscle
wasting
Loss of weight
Starvation leading to
death.
Leads to marasmus
Milk, meat, bone meal Muscle wasting and
and fish meal
eventually death
Beans, groundnuts,
Slow growth
peas and other legume Reduced reproduction in
crops
meat, milk, wool and
eggs
Groundnut seed cake,
sunflower seed cake,
cotton seed cake
Respiratory disorders
Night blindness
Pneumonia
Blindness in newly born
calves
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FORM 2 AGRICULTURE NOTES
Calcium and
Phosphorus
Bone and teeth
formation
Mono- and Dicalcium phosphate
Magnesium
Soft tissue and bone
formation
Part of enzymes and
red blood cells
Epsom salt
Good eye sight,
improves resistance
to diseases
Green leafy material
Pneumonia, night
blindness, watery eyes,
low fertility
Help in protein
synthesis
Helps animals to
absorb and utilise
calcium
Most cereal grains
Poor growth, dermatitis
Synthesized by
animals when
exposed to the sun
Rickets
Vitamin E
Helps in
reproduction
Green leafy material
Vitamin K
Helps in blood
clotting
Most green plants,
fish meal
Muscular incoordination, poor
reproduction
Delayed blood clotting
Helps transport
nutrients to all body
parts.
Required in
digestion, enzyme
reactions and
excretion
Temperature
regulation
Drinking water, moist
food material
Iron
Vitamins
Vitamin A
Vitamin B
Vitamin D
Water
Green plants
Abnormal appetite,
rickets in young
animals, weak and
brittle bones in older
animals, thin shelled
eggs in poultry
Poor soft tissue and
bone formation
Anaemia in piglets
Poor digestion,
transportation of
nutrients and enzyme
activity
Animal health
•
•
•
•
Animal health deals with the well-being of livestock
An animal can be regarded as healthy or unhealthy
Healthy animals have normal body functioning whereas unhealthy animals suffer from
abnormal body functioning
Ill health in animals is as a result of diseases which are caused by several factors
Causes of livestock diseases
Heredity
•
Sometimes undesirable characteristics passed from parents to off-spring can cause cells of
the body to malfunction and degenerate
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FORM 2 AGRICULTURE NOTES
•
•
These are diseases passed from parents to offspring also called hereditary diseases
Hereditary diseases can only be controlled through strict selection of breeding animals
Nutrient deficiency
•
•
A poorly balanced diet may lead to lack of some nutrients which cause deficiency
diseases such as rickets, night blindness, osteomalacia and piglet anaemia
Deficiency diseases can be controlled by providing a balanced diet to the animals and
supplementing deficient nutrients
Poison
•
•
•
•
•
These are substance which can disrupt the normal functioning of the processes inside the
animal body
The poisons may cause cell degradation and animal death
Animals may eat poisonous plants e.g. Lantana camara or wilted sorghum
Poison may also be accidentally eaten by livestock from poorly disposed agro-chemicals
or chemical containers
Snake bites are also a source of poison to livestock
Injury
•
•
•
These can be bruises, cuts, lameness, twisted muscles or joints
Sometimes injury is serious and difficult to correct by treatment such as in the case of
broken limbs or broken ribs
Injury can also expose animal tissues to pathogens
Pathogens
•
•
•
These are disease-causing microorganisms e.g. bacteria, virus and protozoa
The pathogens can multiply and are picked by livestock in unhygienic conditions
They are spread from animal to animal by direct contact, vectors, or through
contaminated food, water and air
Transmission of livestock diseases
•
•
•
This refers to the spread of diseases from one animal to another
Only diseases caused by pathogens (pathogenic diseases) can be spread to other animals
They are spread by direct or indirect contact, vectors, contaminated food or water
Direct contact
•
•
•
Infected can rub against or get in contact with un-infected animals in a kraal or fowl run
resulting in the spread of pathogens
This method of spread is common in contagious diseases
Contagious diseases are diseases that are spread through animal body contact or body
fluids
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FORM 2 AGRICULTURE NOTES
Indirect contact
•
•
•
•
This is the spread of pathogens through contaminated air
Infected animals may cough or sneeze discharging the pathogens into the air
Other animals are infected after breathing in the contaminated air
This method of transmission is common with infectious diseases
Contaminated food or water
•
•
This is the spread of pathogens through shared food or water
Saliva containing pathogens from infected animals can drop into food or water containers
where they are picked by healthy animals through feeding resulting in disease
transmission
Vectors
•
•
•
•
Vectors are blood sucking insects that can transmit pathogens from one animal to another
e.g. tsetse fly
Pathogens such as protozoa survive in the saliva of the vectors
As the vectors move on and suck blood from animal to animal, they pass on the
pathogens in their saliva as they feed
Spread of pathogens with vectors in animals is common with diseases caused by protozoa
e.g. trypanosomiasis (nagana)
Methods of disease control
Providing a balanced diet
•
•
Well-nourished animals are better able to resist diseases
Livestock should be provided with the right amounts of feed to supply adequate nutrients
and prevent deficiency diseases
Separating young from old animals
•
Old animals may be carriers of some diseases and can pass on the infection to young
animals whose immunity will still be weak therefore it is important to separate old and
young animals
Isolation
•
This refers to keeping diseased animals away from healthy ones to prevent spread of
diseases through contact
Providing good housing
•
•
Good housing structures are well ventilated, have enough space and have good lighting,
are easy to clean and disinfect
This creates an environment that is not ideal for the occurrence and multiplication of
pathogens
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FORM 2 AGRICULTURE NOTES
Hygiene
•
•
•
•
•
This is the most important element in controlling pathogenic diseases of animals
Clean sanitation aims at keeping pathogens in livestock housing at minimum levels
Hygiene involves cleaning of the housing and feeding containers, disinfection of the
housing and feeding containers and ventilating the housing
Cleaning removes dirt which invites flies and other insects which spread diseases while
disinfection kill the pathogens
Ventilation aerates the housing, keeps the it dry and discourage breeding of pathogens.
RODRECK WISEMAN NYAKABAWU
38
FORM 2 AGRICULTURE NOTES
Small livestock production
Broiler management
•
•
•
•
Successful broiler production calls for proper management
Broiler managements involves meeting all the requirements of broilers from day old to
slaughtering
The requirement include housing and feeding requirements
Broilers must be given the right type of feeds in the right quantities to the right age of the
birds
Feeding of broilers
•
•
•
The feeds can be in the form of mashes or crumbs or pellets
Pellets and crumbs are economical as they reduce wastage during feeding
The feeding of broilers follows a three-phase regime
Phase 1 (0 – 2 weeks)
• Broiler chicks are fed with broiler starter feed from day old to two weeks of age
• Broiler starter feed has a high protein content of about 21% protein composition and
is mashed to accommodate the size of the chicks
Phase 2 (3 – 4 weeks)
• In this phase the broilers are fed with broiler grower feed from the third to the fourth
week
• The broiler grower feed is either in the form of mash or pellets which contain a
relatively high protein content of about 19%
Phase 3 (5 – 6 weeks)
• Broilers are fed with broiler finisher from five weeks to slaughtering
• This feed has a reduced protein content as is high in carbohydrates to trim and
produce birds with a good even cover of fat
Rearing of broilers
Preparation for the arrival of day old chicks
• Clean and disinfect the housing thoroughly at least 10 days before the arrival of dayold chicks
• Lay the brooders in place
• Pre-warm the brooder a day before the arrival of the chicks
Care on arrival of the chicks
• Collect the chicks in the morning before they are stressed
• Check temperature in the brooder and correct accordingly
• Physically check and count the chicks as they are placed into the brooder
• Give chicks water with a stress mix for about 30 minutes before feed is added
RODRECK WISEMAN NYAKABAWU
39
FORM 2 AGRICULTURE NOTES
Daily routines
• Daily livestock management practices ensure the well-being of livestock is
maintained
• Always attend to younger stock before older stock
• Always walk calmly among the birds and check for abnormalities
• Clean drinkers and fill them with fresh clean water before putting feeds
• Shake feeders or top up feed without overfilling them
• Cover wet patches with fresh dry litter to keep the birds warm and dry
• Periodically fork out the bedding for aeration and drying
• It is very important to practise good hygiene in broiler production to reduce chances
of disease attack
• Good poultry house management and strict vaccination programme can also help to
avoid diseases
Assessing growth rate of broilers
•
•
•
The broilers should be weighed weekly to monitor growth
A few randomly picked birds are weighed and the average weight for each bird calculated
The average weekly weights are plotted on a graph to show the growth rate of the broilers
Growth curve of broilers
Broiler average mass (g)
3000
2500
2000
1500
1000
500
0
1
2
3
4
Broiler age in weeks
5
6
Record keeping
•
It is very important for farmers to keep physical and financial records for a broiler
enterprise
Physical records
• These show the number of assets, broilers in stock, amount of feeds, medicines
administered, broiler mass and many other records of daily activities
RODRECK WISEMAN NYAKABAWU
40
FORM 2 AGRICULTURE NOTES
•
Daily records are important for tracing source of errors and efficient adjustment in
management
Daily record
Date
Broilers
in stock
Age in
weeks
Feeds
used
Average
mass
Medicine
Mortality
administered and cause
Financial records
• These are records of cash flow throughout the production cycle e.g. income and
expenditure record, and profit and loss account
Income and expenditure record
Date
Sales
(income)
Description
Costs
(expenditure)
TOTAL
Slaughtering of broilers
•
Broilers are slaughtered once they have reached the desired weight usually five to six
weeks
Before slaughtering
•
•
•
•
Make sure the birds are in a health state before they are slaughtered
The birds should have stayed the recommended time before slaughter after administration
of drugs to ensure that consumers will not take in residual drugs in the meat
Withdraw food 12-18 hours before the intended slaughter time to save the feeds and
minimize spoilage by gut contents during dressing
It is important to weight and work out the average weight of the birds before slaughtering
Stunning
•
•
Stunning should be done by knocking the sense out of the broiler before cutting the throat
This can be achieved by neck dislocation, knocking on the back of the head of the bird
using a heavy object or electric shocking
Cutting and bleeding
•
•
•
•
After stunning, the broilers are placed in slaughtering cones for neck cutting and bleeding
Cutting is done to open blood vessels to allow draining of blood from the bird
Bleeding should be allowed to take place for one or two minutes
Blood not drained out of the bird will:
o taint the meat giving it the taste of blood
o make the meat go bad easily
RODRECK WISEMAN NYAKABAWU
41
FORM 2 AGRICULTURE NOTES
o give the carcass a purplish discolouration
Scalding
•
•
•
•
•
•
This is the removal of feathers after bleeding
The birds are immersed inti hot water (50-54oC) for about one minute
Hang the bird by the legs over a clean table and start by plucking the tail and wing
feathers then the rest of the body
After plucking, pin feathers and some hairs can still be seen on the carcass
The pin feathers can be removed using a blunt knife and the hairs by passing the carcass
over a flame of fire
Cut the head off and the legs where the sheens join the thighs
Removing internal organs
•
•
•
•
•
Lay the carcass on a clean table and make sure your hands are clean
Open the skin on the back of the neck and cut the neck bone out
Loosen the internal organs through the hole created by removing the neck
Make a hole by cutting the skin across the abdomen in front of the vent and pull out the
internal organs that include the crop, intestines, lungs, heart, gizzard and liver
The crop and intestines (giblets) should be washed and packed separate from other organs
Dressing
•
•
•
•
The carcass should be cleaned thoroughly after removing the internal organs
The neck skin should be folded back to cover the hole left by neck removal
Fold the wings to press on the neck skin, hocks should be tucked into the abdomen and
out through the vent
The carcass should be given a final was then packed before freezing
Dressing/Killing out percentage
•
•
The average cold dressed weight of the carcass is calculated after dressing
Killing out percentage is calculated using average cold dressed carcass weight and
average live weight calculated before slaughtering
𝑎𝑣𝑒𝑟𝑎𝑔𝑒 𝑐𝑜𝑙𝑑 𝑑𝑟𝑒𝑠𝑠𝑒𝑑 𝑤𝑒𝑖𝑔ℎ𝑡
𝐴𝑣𝑒𝑟𝑎𝑔𝑒 𝑘𝑖𝑙𝑙𝑖𝑛𝑔 𝑜𝑢𝑡 𝑝𝑒𝑟𝑐𝑒𝑛𝑡𝑎𝑔𝑒 =
× 100
𝑎𝑣𝑒𝑟𝑎𝑔𝑒 𝑙𝑖𝑣𝑒 𝑤𝑒𝑖𝑔ℎ𝑡
Example
Average live weight = 2.0kg
Average cold dressed weight = 1.5kg
𝐴𝑣𝑒𝑟𝑎𝑔𝑒 𝑘𝑖𝑙𝑙𝑖𝑛𝑔 𝑜𝑢𝑡 𝑝𝑒𝑟𝑐𝑒𝑛𝑡𝑎𝑔𝑒 =
RODRECK WISEMAN NYAKABAWU
1.5𝑘𝑔
× 100 = 75%
2.0𝑘𝑔
42
FORM 2 AGRICULTURE NOTES
Marketing of broilers
•
•
Broilers can be marketed live or cold dressed depending on the market
Broiler meat can also be processed into chicken sausages and patties before marketing
Broiler markets
•
•
•
•
•
•
•
Large retail supermarkets
Butcheries
Restaurants
Boarding schools
Food vendors
Individual households
Meat processing industries
RODRECK WISEMAN NYAKABAWU
43
FORM 2 AGRICULTURE NOTES
FARM STRUCTURES AND MACHINERY
Farm implements
Adjustments of animal drawn implements
•
The animal drawn implements need to be adjusted to achieve desired ploughing depth and
plough width
Mouldboard plough
•
An animal-drawn mouldboard plough is used for primary tillage, it digs and turns over the
soil
Adjustment of plough depth on a mouldboard plough
• This is achieved by moving the depth control rod up or down on the hitch assembly
• For the plough to cut deeper into the soil, the clamp screw is undone and the control rod is
raised to the required level then the clamping screw is tightened
• For the plough to cut or dig shallower, the clamping screw is undone and the depth rod is
lowered the required level then the clamping screw is tightened
• Depth adjustment is done with the wheel removed and when the desired depth is achieved
it is replaced at such a height that it just touches the ground surface
• The trek chain can also be used to control depth of plough, it is lengthened for a deeper
plough depth and shortened for a shallower plough depth
Adjustment of plough width on a mouldboard plough
• This is done by moving the depth control rod to the left or right on the hitch assembly
• For the plough to make a wider cut, the depth rod is moved to the furrow side (right)
• For the plough to make a narrower cut, the depth rod is moved to the land side (left)
Animal-drawn cultivator
•
This implement is used to mechanically control weeds in row crops, loosen the soil between
rows of crops, and making planting furrows for some crops
Adjustment of depth of cut on an animal drawn cultivator
• This is done by lowering or raising the wheel (skid)
• The wheel is raised or lowered by inclining the wheel arms or setting them in an upright
position
• Raising the wheel makes the animal-drawn cultivator dig deeper and lowering the wheel is
done for a shallower cut
• The trek chain can be shortened for a shallower cut or lengthened for a deeper cut
• Adjustment of depth of cut is necessary to accommodate seeds of different sizes as they
require different sowing depths
Adjustment of width of cut on an animal drawn cultivator
• This is done by operating the lever forward or backward
RODRECK WISEMAN NYAKABAWU
44
FORM 2 AGRICULTURE NOTES
•
•
•
The lever is pushed backward to push out (spread) the two outermost frames which holds
the tines for a wider cut
The lever is pushed forward to draw the two outermost frames towards the central frame
for a narrower cut
Width adjustment makes it possible for the cultivator to be operated between crop rows of
different inter-row spacing
Animal-drawn spike toothed harrow
•
•
•
This is a secondary tillage implement used for covering seed sown in furrows, breaking soil
clods, levelling or gathering unburied weeds and trash
The animal-drawn spike toothed harrow must be pulled by fast moving animals for
breaking of soil clods and covering of sown seed to be effective
The spike toothed harrow has a fixed frame therefore width covered during operation is not
adjustable
Adjustment of depth of operation on a spike toothed harrow
• This is done by slightly altering the length of the trek chain until the desired depth is
achieved
• Weights can also be placed on top of the harrow to force it to go deeper
Fencing
Fencing materials and tools
Advantages and disadvantages of fencing materials
Material
Metal posts
Advantages
• Durable
• Fire and termite resistant
• Straight and neat
Treated wooden
poles
•
•
Concrete poles
•
•
•
•
•
Barbed wire
•
Diamond wire
mesh
•
Durable
Cannot be attacked by
termites since they are treated
Durable
Fire and termite resistant
Do not rust
Easy to pull with strainer
Animals cannot pass through
it.
Very durable
Disadvantages
• Very expensive
• Can be corroded by rust if not
painted or galvanised
• Can be stolen and used for
something (welders)
• Expensive
• Not readily available in rural
areas
• Very expensive
• Very heavy
•
•
•
Provides maximum protection, •
even small livestock like goats •
and sheep cannot pass through
RODRECK WISEMAN NYAKABAWU
Expensive
Can injure workers during
straining
Barbs makes it difficult to
handle
Very expensive
Difficult to set up
45
FORM 2 AGRICULTURE NOTES
Plain wire
•
•
Easy to strain
Does not cause injuries during
straining
•
•
Animals can interfere with it
since it has no bards
Not strong compared to barbed
wire
Fencing tools
Tool
Wire strainer
Pliers
Shovel
Claw hammer
Wheelbarrows
Axe/Machete
Mattock
Digging bar
Digging auger
Tape measure
Bow saw
Hacksaw
Use
• Pulling or straining wire
• Cutting and tying wire
• Mixing concrete which is put into holes where upright poles are
placed
• Remove soil for pits for anchoring straining posts
• Drive U-nails into wooden poles to hold strands of wire at
appropriate positions.
• Remove nails from the posts
• Carrying rolls of wire, cement, stones and other materials
• Cut trees, tree branches and shrubs along the line of fence
• Stumping trees and shrubs along the fence line
• Digging pits for putting large stones for anchoring straining posts
• Digging holes for erecting fencing poles/posts
• It resembles a screw and has a drilling effect and is used or digging
holes for erecting fencing posts in place of a digging bar
• Measuring distance between posts, standards, wire strands and
droppers
• Cutting trees along the path of the fence
• Cutting wooden posts, standards and droppers to required length
• Cutting metal posts, standards and droppers to required length
Farm roads
•
•
Farm roads link critical points on the farm
They allow the farm to be reachable easily by vehicles, tractors, delivery vehicles and
scotch carts
Siting of farm roads
•
Farm roads should be correctly sited to minimise erosion and effectively serve their purpose
Factors considered when siting a farm road
Topography
• farm roads should be constructed on a high ground (crest or watershed) to facilitate
drainage.
Soil type
• avoid areas with easily erodible soils.
Slope
• avoid steep gradient to prevent soil erosion caused by run-off water.
RODRECK WISEMAN NYAKABAWU
46
FORM 2 AGRICULTURE NOTES
Physical features
• avoid areas which cross streams or rivers to reduce number of bridges to be constructed
(bridges are expensive to construct).
Nature of the area
• farm roads should be constructed on the straightest possible path to reduce cost on
distance to be travelled.
Siting equipment of farm roads
Siting equipment
Dumpy level
Staff/levelling rod
Surveying chain
(Gunter’s chain)
Wooden pegs
Tape measure
Hammer
Axe
Bow saw
Description and uses
• It is an optical instrument used to establish or verify points at the
same level
• Used to measure height differences and determining the gradient
along the road
• It is a graduated aluminium or wooden rod used to determine
differences in height between two points
• A chain of known number of links used to measure distances for
land surveys
• to mark edges of the road
• measuring and determining distances
• driving in pegs to mark the road site
• clearing bushy shrubs
• cutting trees along the path
Characteristics of a well sited farm road
•
•
•
•
•
Cambered (sloping towards the edges) to drain water out of the road.
Wide enough to allow two vehicles or tractors to pass each other in opposite direction.
Firm so that tractors and vehicles do not get stuck during the rainy season.
Gently sloping to avoid soil erosion.
Straight to reduce distance and cost of fuel incurred when the road is meandered.
Harnessing
Collar and breast band harnesses
Collar harness
•
•
•
•
•
These are made up of a shaft and skeis of wood used to harness oxen
They have metal clamps on which trens and trek chain are attached
Strops made of hides, ropes or tree bark strings are used to secure the yoke onto the necks
of animals
A trek chain connects the yoke to the implements such as plough, planter and harrow is
made of metal
The neck collar harness can be single neck or double neck
RODRECK WISEMAN NYAKABAWU
47
FORM 2 AGRICULTURE NOTES
RODRECK WISEMAN NYAKABAWU
48
FORM 2 AGRICULTURE NOTES
Breast band harness
•
•
This type of harness is used on donkeys, mules or horses which use wither muscles
This harness is made of hides, canvas, or strong tent
RODRECK WISEMAN NYAKABAWU
49
FORM 2 AGRICULTURE NOTES
AGRI-BUSINESS
Farm records and accounts
Profit and loss account
•
•
•
•
This is a financial record of money that comes into the farm (income) and money that goes
out of the farm (expenditure)
Income on the farm may come sales of crops, livestock or livestock products
Expenditure arises from payment for inputs such as seed, fertilizers, feeds, chemicals and
labour
Wages and salaries, repairs of machinery, fuel and other paid for items are part of the farm
expenditure
Functions of the profit and loss account
•
•
A profit and loss account compares the income and expenditure to reveal profit or loss
made by farm enterprises or farm business
It helps the farmer to decide on which enterprise to drop or continue with depending on
their levels of profit or loss
Calculations to determine profit or loss
Profit
• Profit is made when income from sales is greater than the expenditure from purchases and
other paid for services directly linked to production
𝑃𝑟𝑜𝑓𝑖𝑡 = 𝐼𝑛𝑐𝑜𝑚𝑒 − 𝐸𝑥𝑝𝑒𝑛𝑑𝑖𝑡𝑢𝑟𝑒
Loss
• The farmer makes a loss when money spent on the farm enterprise is greater than money
earned from agro-sales
𝐿𝑜𝑠𝑠 = 𝐸𝑥𝑝𝑒𝑛𝑑𝑖𝑡𝑢𝑟𝑒 − 𝐼𝑛𝑐𝑜𝑚𝑒
Breakeven
• This is when the income and expenditure are equal
• The farmer has not made a profit and has not made a loss
𝐵𝑟𝑒𝑎𝑘𝑒𝑣𝑒𝑛 = 𝐼𝑛𝑐𝑜𝑚𝑒 = 𝐸𝑥𝑝𝑒𝑛𝑑𝑖𝑡𝑢𝑟𝑒
Example of a profit and loss account
Income
Amount Expenditure
Eggs sold
$4000 100 × point of lay pullets
Eggs home consumption
$380 Layers mash
Off-layers sold
$400 Drugs
Total income
$4780 Total expenditure
(𝐼𝑛𝑐𝑜𝑚𝑒 ($4780) − 𝐸𝑥𝑝𝑒𝑛𝑑𝑖𝑡𝑢𝑟𝑒($3400) = 𝑃𝑟𝑜𝑓𝑖𝑡($1380)
RODRECK WISEMAN NYAKABAWU
Amount
$1200
$2100
$100
$3400
50
FORM 2 AGRICULTURE NOTES
Agricultural marketing
•
•
•
•
This mainly involves the buying and selling of agricultural products
Marketing is a process in which several activities such as cleaning, grading, packing,
processing, storage, advertising and transportation take place
The marketing of agricultural products on demand of the produce, availability of storage
facilities and quality of the produce
The produce may be sold directly to the market or is stored before it is sold
Types of agricultural markets
Controlled markets
•
•
•
This is a set up where the marketing of agricultural products is controlled by the
government or a marketing board
The prices of the commodity are predetermined by the government or marketing board
Marketing boards control the marketing of certain products or commodities and are the sole
buyers of such agricultural commodities which they then sell the produce to manufacturers,
processors of final consumers
Marketing boards in Zimbabwe and commodities they handle
Marketing board
Commodity
Sold to
Grain Marketing Board
(G.M.B.)
•
•
•
•
Millers and public
Oil processors
Stock feeds processors
•
•
•
•
Oil processors
Farmers
Cotton spinners
Public butcheries
•
•
•
Processing industries
Shops
Public
Cotton Marketing Board
(C.M.B.)
•
•
Cereal grains (Maize,
Wheat, Rapoko, Millet
& Sorghum)
Legumes (Groundnuts,
Roundnuts, Soya beans,
Field beans)
Coffee
Oil seeds (Sunflower,
Soya beans etc.)
Cotton seed
Cotton lint
Cold Storage Commission
(C.S.C.)
Dairy Marketing Board
(D.M.B.)
•
Livestock for slaughter
•
Milk
•
•
•
Uncontrolled markets
•
•
A farmer sells the farm produce to a market of own choice e.g. wholesale or directly to
consumers
Prices are not predetermined but are controlled by market forces of supply and demand
Formal markets
•
These are regular, well established, well organized and officially recognised markets for
particular agricultural products
RODRECK WISEMAN NYAKABAWU
51
FORM 2 AGRICULTURE NOTES
Formal markets in Zimbabwe and products they buy
Formal market
Product(s)
Tobacco Marketing Board (T.M.B.)
Grain Marketing Board (G.M.B.)
Tobacco
Maize, Wheat, Rapoko, Millet, Sorghum,
Groundnuts, Roundnuts, Soya beans, Field
beans & Coffee
Cotton
Livestock
Milk
Pigs
Cotton Marketing Board (C.M.B.)
Cold Storage Commission (C.S.C.)
Dairy Marketing Board (D.M.B.)
Colcom Zimbabwe
Informal markets
•
•
These are markets where no fixed procedures are followed
The suppliers of commodities and buyers can meet in public or private to conduct business
e.g. on the farm, street on in a retail shop
Agricultural co-operatives
Benefits of agricultural co-operatives
•
•
•
•
•
•
•
Create room for sharing of skills
Members in a co-operative have a better chance of getting loans as a co-operative than as
individuals
Transport costs are reduced when the farmers transport their produce in bulk
Can afford better storage facilities
Farmers can get information easier and quicker than as individuals
Can employ well-trained people
Members share costs of production therefore earn higher net income.
Problems associated with agricultural co-operatives
•
•
•
•
•
There may be disharmony if a co-operative is made up of members from different
backgrounds
The co-operative fails if there is insufficient capital to support its goals
Leaders of the co-operative may misuse funds
There may be lack of essential skills among members
Members may lack commitment and fail to commit themselves fully to the demands of the
co-operative
RODRECK WISEMAN NYAKABAWU
52