The term agriculture comes from two Latin words:

Ager: meaning land or field

Cultura: meaning cultivation

Agriculture means field cultivation. But agriculture has continued to grow and expand that it can now be broadly be defined as:

The art and science of crop and animal production

Agriculture as an art

Agriculture is referred to as an art because it involves the following:

  • Tilling of land
  • Construction of farm structures
  • Measuring of distances
  • Machine operations
  • Harvesting of crops
  • Feeding and handling of livestock
  • Marketing of agricultural produce

Agriculture as a science

Agriculture is referred to as a science because it involves the following:

  • Crop pathology: study of crop diseases
  • Entomology: study of insects and their control
  • Soil science:
  • Genetics: plant and breeding
  • Agricultural engineering

Branches of agriculture

  1. Crop production
  2. Livestock production
  3. Soil science
  4. Agricultural economics
  5. Agricultural engineering
  6. Crop production

This is the production of crop on cultivated land.

Crop production is divided into:

  1. a) Field crops

These are crops grown on fairly large area of land. May be annual or perennial crops.

  1. b) Horticultural crops

The growing of perishable crops. It involves the following:

  1. i) Floriculture: growing of flowers
  2. ii) Olericulture: growing of vegetables
  3. ii) Pomoculture: growing of fruits
  4. Livestock production

This is the rearing of all types of animals. It involves:

  1. a) Pastoralism (mammalian livestock farming)

Rearing of farm animals on pastures eg cattle, goats, sheep etc

  1. b) Aquaculture

Rearing of aquatic animals eg fish farming (pisciculture)

  1. c) Apiculture: keeping of bees
  2. d) Aviculture: keeping of poultry
  3. Soil science

This is a branch of agriculture that provides knowledge how soil is formed, how it works to sustain life and how it can be kept alive through many years

  1. Agricultural economics

This branch deals with the utilization of scarce resources in the production of agricultural products.

  1. Agricultural engineering

This branch deals with the use and maintenance of farm tools, machinery and structures.

Roles of agriculture in the economy

  • Provision of food
  • Source of employment
  • Provision of foreign exchange
  • Source of raw materials to the industries
  • Provision of market for industrial goods
  • Source of money or capital
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This is how the farm and all the enterprises in it are organized. There are two main farming systems namely:

  1. Extensive system
  2. Intensive system
  3. Extensive farming system

This is a farming system which involves the use of large tracts of land. Its characterized by:

  • Low capital investment
  • Low labour per unit area
  • Low yield per unit area
  1. Intensive farming system

This is a system of farming which requires high capital and labour investment. Its characterized by:

  • High yield per unit area
  • Use of modern technology
  • High labour per unit area
  • High capital investment

N/B: Extensive and intensive farming systems can be practiced under:

  1. a) Large scale farming
  2. b) Small scale farming
  3. a) Large scale farming

This involves the use of large tracts of land. Its features include:

  • Heavy capital investment
  • Use of skilled labour
  • High level of management
  • Products are for commercial purposes
  • Large tracts of land is used

Large scale farming can either be:

  1. i) Plantation farming: growing of one type of crop (monoculture)
  2. ii) Ranching: rearing of beef animals
  3. b) Small scale farming

This is a type of farming which is practiced on small piece of land. The products are either for subsistence or commercial purposes.


Methods of farming

  1. Pastoralism
  2. Arable farming
  3. Mixed farming
  4. Shifting cultivation
  5. Organic farming
  6. Agro forestry
  7. Pastoralism

This is the practice of rearing livestock on natural pasture can be:

  1. Settled livestock farming
  2. Nomadic Pastoralism
  3. a) Nomadic Pastoralism

This is the practice of rearing livestock and moving with them from place to place in search of water and green pasture. Nomadic Pastoralism can only be practiced where:

  • Land is not a limiting factor
  • Land is community owned


  1. Arable farming

This is the growing of crops on a cultivated land: can be,

  1. Mono cropping
  2. Mono culture
  3. Mixed cropping
  4. Inter cropping
  5. a) Mono cropping

This is the growing of one type of crop per season. Its disadvantages include:

  • Cause soil erosion
  • Diseases spread easily
  • If the crop fails, the farmer suffers total loss
  • Leads to nutrient depletion in the soil

N/B: Mono cropping can be practiced under mono culture where only one crop is grown throughout as in plantation farming eg in Tea, Coffee plantations.

  1. b) Mixed cropping

This is the practice of growing different crops on the same piece of land but on different plots or strips. Usually helps to control soil erosion.

  1. c) Intercropping

This is the practice of growing different crops on the same piece of land per season.

Advantages of intercropping

  • If one crop fails, the farmer has the other crop to support him, ie does not suffer total loss
  • Helps to control soil erosion
  • If legumes are included, they will enrich the soil with nutrient
  • Also interrupts the spread of diseases
  • There is high yield per unit area of land
  • There is also proper utilization of land

Disadvantages of intercropping

  • Requires a lot of labour
  • Routine crop management practices difficult to carry out
  • Requires high capital investment


  1. Mixed farming

This is the growing of crops and rearing of animals on the same piece of land.

Advantages of mixed farming

  • Animals benefit from crop residues /remains as food while crops benefit from animals wastes as manure
  • Gives farmers income throughout the year
  • Ensures proper utilization of labour and land throughout the year
  • In case one enterprise fails, the farmer will still depend on the enterprise

Disadvantages of mixed farming

  • Requires high initial capital investment
  • There is lack of specialization
  • Limited land area allowed for each enterprise
  • Requires a lot of labour
  1. Shifting cultivation

This involves farming on a piece of land continually until its exhausted after which the farmer moves to a new fertile land. Shifting cultivation can be practiced where:

  • Land is abundant
  • Population is sparse
  • Land is communally owned
  • Low number of livestock units per area

Advantages of shifting cultivation

  • Low capital investment
  • No pests and diseases build up
  • Soil structure is regained
  • No land disputes as the land is owned communally

Disadvantages of shifting cultivation

  • Yield per unit area is low
  • A lot of time is wasted when the farmer shifts to new area and builds structure
  • Farmers have no incentive to develop and conserve water and soil
  • Cannot be practiced in areas where there is high population density


  1. Organic farming

This is the growing of crops and rearing of animals without using agricultural chemicals. It can be practiced through:

  • Use of organic manures instead of artificial fertilizer
  • Use of medicinal plants instead of chemical
  • Mulching
  • Crop rotation, to control diseases

Importance of organic farming

  • Its environment friendly
  • Its cheap
  • Does not require special skills
  1. Agro forestry

This is the growing of trees, crops and keeping of animals on the same piece of land.

Advantages of agro forestry

  • Trees help to conserve water and soil
  • High output per unit area
  • Helps to reduce soil erosion
  • Provides trees for building and fuel



There are a number of factors which influence both crop and animal production, some of these factors include:

  1. Human factors
  2. Biotic factors
  3. Climatic factors
  4. Edaphic factors

These are factors which are due to the behavior of human beings or how they do things and how they influence agriculture. These human factors are:


  1. Level of education and technology
  2. Health of the people
  3. Economic conditions
  4. Government policy
  5. Transport and communications
  6. Cultural beliefs and religion
  7. Market forces
  8. a) Level of education and technology
  • High level of education leads to:
  • Accuracy in applying inputs and assessing results
  • Helps in proper decision making and organization
  • Better problem solution
  • Better utilization of livestock feeds and fertilizers
  • Understanding of technical language used in agriculture
  • Development of skills for operating machines and their maintenance
  • Increase in efficiency and minimizes costs
  1. b) Health of the people
  • Today the biggest threat to farming is the HIV/AIDS, ill health makes people do little or no work. The general effect of HIV/AIDS and ill health on agriculture includes:
  • Shortage of farm labour
  • Increase the cost of living through treatment, thereby lowering their purchasing power thus low demand for agricultural products
  • Low standards of living leads to lack of motivation to invest in agriculture, thus increasing poverty
  • Low food supply
  • A lot of funds used to control it, instead of being used to develop agriculture
  1. c) State of the economy

Economic conditions which have affected agriculture include:

  • Collapse of cooperative societies which affected the sale of farm produce such as milk, sugar, cotton etc
  • Liberalization of the economy, which has led to dumping of cheap products from other countries, this has caused the drop in price of agricultural products leading to low income to farmers


N/B: Kenya can benefit from liberalization by:

  • Producing goods of high quality and selling them competitively
  • Diversification
  1. d) Government policy

These are the laws which are put in place by the government that govern the production, marketing and distribution of agricultural products. The policies that the government can put in place which can encourage the agricultural production include:

  • Heavy taxation of imports to prevent dumping of cheap goods into the local market
  • Subsidizing the growing of local crops thus making them affordable to farmers
  • Enact policies to enforce the production of high quality products
  • Put in place, policies aimed at conservation of natural resources in order to sustain agriculture
  • Stepping up disease and pest control eg through quarantine, vaccination etc
  1. e) Transport and communication
  • Transport and communication plays an important role in conveying agricultural products
  • Railway lines are goods for transporting bulky goods to long distances
  • Airways are also efficient for air lifting horticultural products
  • Weather roads are necessary to transport farm produce to factories

N/B: proper transport and communication therefore will promote the development of agriculture, the electronic media eg radio, TV, internet, all need to be cheap and affordable to all farming areas.

  1. f) Cultural practices and religious beliefs
  • The society’s beliefs and culture may also effect agriculture eg Muslims do not eat pork and therefore may not see the need for rearing pigs even if pigs are very productive.
  • Pastoral communities also only keep animals and may find it difficult to diversify to livestock farming even if its profitable.

N/B: A combination of the above factors may retard agricultural development

  1. g) Market forces:

The local demand and supply of agricultural produce will also affect the level at which farmers produce, also the international demand eg of Kenyan coffee, Tea will affect how much the farmers produce.



These are influences (factors) caused by living organisms, living both in and on the soil surface. These organisms include:


  • Pests
  • Parasites
  • Predators
  • Decomposers
  • Pathogens
  • Pollinators
  • Nitrogen fixing bacteria



Effects of pests

  • They feed on plants lowering both the quality and quantity of produce
  • They transmit diseases
  • Injure the plants, thus exposing them to secondary infection
  • Increases the cost of production eg through buying chemicals to control them

N/B: other effects of living organisms on agriculture include:

  • They decompose the organic matter in the soil eg the decomposers
  • Encourage aeration through burrowing into the soil
  • Cause nitrogen fixation and denitrification
  • Cause soil borne diseases
  • Acts as soil borne pests to growing crops
  • Mans activities eg cutting trees, earth moving etc affect soil formation
  • Some living organisms eg ticks also acts as parasites to animals thereby transmitting diseases
  • Some insects and birds also act as pollinators to flowering plants thus enabling cross pollination

These are factors due to the changes in the climate. Climate is the weather condition of a place taken over a long period of time. These climatic factors include:

  1. Rainfall
  2. Temperature
  3. Wind
  4. Humidity
  5. Light



  1. a) Rainfall

Rainfall is very important in agriculture production as it ensures supply of water required by all life processes. Aspects of rainfall important in agriculture include:

  1. i) Rainfall reliability
  2. ii) Rainfall amount

iii) Rainfall distribution

  1. iv) Rainfall intensity
  2. v) Form of rainfall
  3. i) Rainfall reliability

This is the assurance that rain will fall come the expected time eg there are two rainy seasons in Kenya. Long rains begin around march 15 – 20 of every year and short rains occur in October – November.

Reliability of rainfall determines:

  • Time of land preparation
  • Time of planting

N/B: when rainfall fails to follow the expected patterns, there is usually heavy crop failure and loss of livestock.

  1. ii) Rainfall amount

Rainfall amount is the quantity of rainfall that falls in a given area within a year. Its measured in mm/year. Rainfall amount determines:

  • Type of crop to be grown
  • Type of animals reared

iii) Rainfall distribution

Rainfall distribution refers to how the rainfall was spread throughout the year. It determines the crop variety grown in an area




  1. iv) Rainfall intensity

Rainfall intensity is the amount of rain that falls in an area within a period of 1 hour. Its measured in mm/hr.

High rainfall intensity causes: damage to crops, and also soil erosion

  1. v) Form of rainfall

This is the form in which rainfall falls ie may be form of hailstones etc

  1. b) Temperature

This is the hotness or coldness of a place measured in degrees Celsius or centigrade

N/B: All crops thrive well under certain range of temperature known as cardinal range. These crops require narrower ranges of temperature within the cardinal range this is called optimum range.

Effects of low temperature on crop production

  • Slow growth rate of crops as process like photosynthesis etc will be slow
  • High incidences of diseases infection to crops eg Elgon die back, CBD, hot and cold diseases in coffee
  • Quality of crops eg tea, pyrethrum improves with the lowering of temperature

Effects of high temperature on crop production

  • Increase evaporation leading to wilting in crops
  • Increase rate of growth or hasten the maturity of crops
  • Improve the quality of crops such as pineapples
  • Causes incidences of diseases infection eg leaf rust in coffee and pest infestation eg aphids in vegetables
  1. c) Wind

Wind is air in motion. Wind influences agricultural production by:

  • Causing lodging in cereals and damage to crops
  • Blowing away and bringing in rain bearing clouds
  • Acting as an agent of seed dispersal
  • Acting as agent of pollination
  • Increasing the spraed of pest and diseases
  • Destroying farm structures by carrying away roof tops
  • Also causes a cooling effect
  1. d) Humidity
  • Humidity is the amount of water vapour in the air at a given temperature.
  • Relative humidity is the amount of water vapour held in the air at a given temperature compared to what it would hold when saturated
  • Evaporation is the loss of water from the soil surface in form of water vapour
  • Transpiration is the loss of water vapour through the leaf pores
  • Evapotranspiration is the loss of water vapour both from the soil and leaf pores

N/B: humidity influences:

  • Rate of evapotranspiration
  • Temperature of a given area
  1. e) Light

Light provides energy required for photosynthesis

Photosynthesis is the process by which carbon dioxide in the air and water in the soil are synthesized in the presence of light to form carbohydrates. The light is absorbed by green pigments called chlorophyll.

Carbon dioxide + water  =  glucose

3CO2     +     6H2O           =     C6H12O6

Aspects of light important in crop growth are:

  1. i) Light intensity
  2. ii) Light duration

iii) Light wavelength

  1. i) Light intensity

This is the strength in which light is harnessed by chlorophyll for the purposes of photosynthesis.

N/B: The rate of photosynthesis increases with increase in light intensity up to where other factors become limiting eg water.

  1. ii) Light duration

This refers to the period during which light is available to plants per day. The duration is usually 12 hours in a 24 hour day. Plant varieties are classified into:


Short day plants:  requires less than 12hrs eg soya beans, rice, tobacco

Long day plants:  requires more than 12hrs of day light eg some wheat varieties

Day neutral plants: requires 12hrs of light eg coffee, maize, beans etc

iii) Light wavelengths

Chlorophyll only absorb certain wavelengths of light which are not present in artificial light a part from ultra violet or infra red light

N/B: light influences:

  • Rate of photosynthesis in green plants
  • Flowering of plants
  • Performance of livestock eg growth rate and laying % in poultry

Soil is derived from latin word solum

Solum means floor

Soil is the natural, consolidated material that originates from weathered mineral rock and decomposing organic matter.

Importance of soil

  • It’s a natural medium on which seeds germinate and roots grow.
  • It supplies plants with the mineral nutrients necessary for crop growth
  • It provides water, air, and warmth for small animals, micro organisms and plant roots to sustain life
  • It provides anchorage to plants
  • It also shelters many micro organisms


  • Soil is formed through the process of weathering and decomposition of organic matter
  • Weathering is both chemical and physical transformation that take place in the rocks, converting the components minerals into soils
  • Decomposition is the decaying/rotting of organic matter.( remains of dead plants and animals) that break down to form soil



Types of weathering

  1. Physical weathering
  2. Biological weathering
  3. Chemical weathering
  4. a) Physical weathering

Agents of physical weathering include:

  1. i) Water
  2. ii) Moving ice

iii) wind

  1. iv) temperature
  2. i) Water
  • Running water wears away the rocks over which it flows by rolling stones and hand particles on them.
  • Rain water dissolves carbon dioxide and forms weak carbonic acid which falls into rocks and dissolve them
  • Moving ice also has a grinding effect
  • When it rains, the rain drops hit the ground with force
  • Rainfall erodes soil surfaces
  1. ii) Wind

Strong winds carry rock dust which hit hard on the surface of rocks which then break down to form soil.

iii) Temperature change

  • Due to temperature changes taking place within the rocks, they crack and crumble to form soil.
  • Also in cold places, the water in rocks freezes and expands which then produces pressure on rocks then they break to small particles




  1. b) Biological weathering
  • This is carried through plants, animals and mans activities
  • Large animals eg elephants, buffalloos, cattle etc when they move, cause pressure on the rocks causing them to break down
  • Mans activities like mining cultivation and construction of buildings, roads, reduce the size of rocks into smaller particles
  1. c) Chemical weathering

This is weathering which takes place due to chemical decomposition or change in the chemical structure of the rocks

Types of chemical weathering

  1. i) Carbonation
  2. ii) oxidation

iii) Hydration

  1. iv) Hydrolysis
  2. v) Dissolution
  3. i) Carbonation

When it rains, rain water combines with free carbon dioxide in the air to form a weak carbonic acid eg

Rainwater  +  carbon dioxide    =  carbonic acid

H2O  +  CO2    =  H2CO3

The weak carbonic acid reacts with limestone found in the rocks to form calcium bicarbonate eg

Weak carbonic acid + Limestone   =  calcium bicarbonate

H2CO+   CaCO3       =       Ca(HCO3)2

Calcium bicarbonate formed from this reaction is soluble in water and the process effectively dissolves the rock minerals

  1. ii) Oxidation

This is common in rocks having iron. Oxygen reacts with iron which is in ferrous state. This process forms unstable crystal which is easily decomposed and disintegrated

iii) Hydration

Minerals in rock combine with water to form hydrated compounds.  Hydrated compounds so formed are weaker than the original form and these are then acted upon by physical or mechanical agents of weathering

  1. iv) Hydrolysis


this is the reaction of minerals with water which then undergoes weathering process through other agents.

  1. v) Dissolution

The minerals in the rock dissolve in water leaving behind unstable rock, which can break easily.


  1. Parent material
  2. Climate
  3. Topography
  4. Time
  5. Living organisms
  6. Parent material

The texture of the parent material affects the rate of soil formation. Freely drained parent materials can develop soils faster than dense impermeable parent materials. Also minerals composition of the soil depends on the nature of the materials eg coarse grained soils are from granite which when fully disintegrated will separate into constituent minerals like feldspar, quartz and mica

  1. Climate

Climate factors like rainfall, temperature, light and relative humidity and wind are all important in soil formation. Due to continuous weathering, rainfall for example provides water which is an important reactant in all forms of weathering high temperature also spend up most chemical reactions

  1. Topography

Topography may either increase or delay the effects of climate on soil reaction eg factors like slope, degree of exposure or shelter may influences the degree of sol erosion which leads to shallow or deep soils.

Topography also affects the movement of products of weathering which consist of soluble and solid particles. It therefore affects the soil depth and type of vegetation

  1. Time

The length of time over which the soil forming processes have been in action affects the age of the soil. Where the soil forming processes have been taking place for a long time, deep mature soils can be found. This is possible if other factors such as topography, parent materials climate etc, favour the development of deep soils. Where soils erosion has been severe because of topography there is a tendency for the soils to remain shallow and youthful with poorly differentiated profile.

  1. Living organisms

Living organisms affect accumulation of organic matter and also profile mixing. The micro organisms eg rhizobium add nitrogen to the soil

Vegetation cover also reduces surface erosion and this in turn mineral removal is reduced. Therefore the nature and number of organisms growing on and in the soil play a big role in the kind of soil that develops



Soil profile is the vertical arrangement of soil layers. The layers are called horizons

There are four broad groups of horizons, namely: A,B, C, and D

Top soil ———– horizon A

Sub soil ———– horizon B

Substratum —— horizon C

Parent rock —— horizon D

Cross – section of soil profile

  1. Superficial layer

This is a layer consisting of dry and decayed organic matter covering the soil surface

  1. Top soil (horizon A)

This is the top layer of the soil. Its dark in colour because it contains humus in it. It has many living organisns and plant nutrients, this layer of the soil has goodcrumb structure and is quite permeable to air and water.

  1. Sub soil (horizon B)
  • Its below the top soil
  • Has no humus and usually orange brown in colour
  • It has few living organisms and deeper growing roots of plants
  • It may have an impermeable layer called the hardpan

Causes of hardpan

  • Working the soil when wet with heavy machinery
  • Cultivation at the same depth throughout

Disadvantages of hardpan

  • Hinders air circulation in the soil
  • Prevent crop root penetration
  1. Weathered rock (substratum)

This layer is found beneath the sub soil. Its made of partly weathered rolck with no humus. Its hard and therefore impermeable to water.

  1. Parent rock

This is the bedrock. The soil formed from this rock. Ponds of water are often formed on this rock. Roots of some plants in very dry areas reach these ponds to absorb water

Transitional zone

This is a zone between any two bordering soil layers, whereby one layer gradually merges into the next one in the series

Influence of profile on crop production

  • Most plant nutrients are found in the top soil
  • The deeper or thicker the profile, the better its for crop production
  • Loosely packed soil allows for easy root penetration
  • The nature of the bed rock also determines the nutrients availability in the soil.



Soil is made up of the following:

  1. Mineral matter
  2. Soil water
  3. Soil air
  4. Organic matter
  5. Living organisms
  6. Mineral matter

These are inorganic compounds formed from the weathering of rocks. They differ in size ranging from an clay to gravel. They include:

  • Clay
  • Silt
  • Sand
  • Gravel

Influence of mineral particles on crop production

They make the main frame work of the soil

They hold plant roots firmly together

How to determine the mechanical composition of the soil

Using various sieves of different  diameter

  1. Soil water

Soil has water which comes from rainfall and also from irrigation in dry lands

Forms of soil water

  • Superfluous water
  • Capillary water
  • Hygroscopic water

Superfluous water

  • This is water which is held by gravity. Its also called gravity water.
  • Its easily lost because its loosely held by soil particles
  • Its readily available to plants but not useful because too much of it limits aeration

Capillary water         

  • This is water occupying the micro pores. Its held by soil particles
  • It’s the water available to plants. Its also reffered to as available water

Hygroscopic water

This is water which forms a thin film around the particles. Its not available to plants



Functions of water to plants

  • Soil water maintains the life of plants
  • Its used as a raw material for protein for diffusion of mineral salts and oxygen into the root hairs and the mineral salts dissolved in water are conducted upwards to the leaves.
  • Its also acts as a solvent for the diffusion of other substances from one part ofplant to another
  • It makes protoplasm and cell sap of the growing plants
  • It keeps the cell turgid and thus supports plant
  • Also cools the leaves of the plant during transpiration

Experiment 1  to find the percentage of soil water content

Apparatus: – dish, stirring, weighing balance, soil sample and heater or oven

Procedure: –

  • Measure the mass of the dish
  • Pour soil in the dish and weigh
  • Half fill the dish with water
  • Heat upto a bout 105oc
  • Cool the sol with a dessicater then reweigh – repeat the process until you get a constant mass
  1. Soil air

The spaces between the soil particles are filled with air. These include

Oxygen —————– 20.6

Carbon dioxide ——- 0.6 – 0.6

Nitrogen  ————– 78.6

Other rare gases.

The amount of air available in the soil is inversely proportional to the amount of water in rhe soil pore spaces.

Oxygen present in the air is essential for the respiration of roots and other living organisms in the soil

Nitrogen in the soil  is converted into nitrates by the nitrogen fixing bacteria

Air is also needed by the micro organisms living in the soil

Excess carbon dioxide in the soil is poisonous to plants

Experiment 2: To find the percentage of air by volume in a soil


  • Small tin
  • Graduated cylinder
  • Knife and stirring rod


  • Turn the empty tin upside down and press firmly into the ground until the tin is completely filled with soil
  • Turn the tin upright and level the soil to the brim of the tin with a ruler
  • Pour 250cm3 of water into a cylinder and scrap off soil into the water until no bubbles comes out
  • Record the final volume of soil and cylinder
  1. Soil organic matter
  • Organic matter in the soil is the remains of the dead plants and animals plus their waste products
  • Humus is the decayed organic matter

Importance of organic matter

  • Decomposes to release nutrients to plants
  • Makes the soil lighter to cultivate
  • Also improves the soil structure

Experiment 3 To find the % of humus content in the soil

  • Apparatus
  • Dish
  • Garden soil
  • Tripod stand
  • Wire gauze
  • Bunsen burner


  • Weigh the empty dish
  • Put the garden in the dish and reweigh
  • Place in an oven at about 105oc
  • Cool in a dessicater and reweigh
  • Repeat the process several times until a constant weight is obtained
  • Note the difference weight
  1. Soil living organisms

There are two types of living organisms in the soil namely:

Macro organisms

Micro organisms

Macro organisms are large organisms found in the soil eg rodents, earthworms, ants, termites, plant roots etc

Micro organisms are tiny organisms which can only be seen with the help of a microscope they include bacteria, fungi, protozoa etc.

Importance of soil living organisms

  • They barrow in the soil and aerate the soil and improve drainage
  • They help in the decomposition of organic matter
  • Some also fix nitrogen in the soil eg the nitrogen fixing bacteria

Experiment 4: To show the presence of living organisms in a soil sample


  • 2 flasks
  • Rubber cork
  • Muslin bag
  • Heater
  • Lime water
  • Garden soil


  • Put a handful of garden soil in two muslin bags labeled A and B
  • Heat the soil in muslin bag B strongly to kill the micro organisms
  • Suspend the two bags in the flasks also labeled A and B, the flasks should contain lime water
  • Leave the apparatus for 4hrs


  • Lime water in flask A turns milky
  • Lime water in flask B remains clear


  • Lime water in flask A turns milky because of the presence of carbon dioxide produced during respiration. Carbon dioxide turns lime water milky
  • Lime water in flask B remained clear since the living organisms were killed during heating so no respiration took place


Physical properties of soil

These include:

  1. Soil structure
  2. Soil texture
  3. Soil colour


  1. Soil structure

This is the  way in which the individual soil particles are arranged

Types of soil structure

  • Single – grained structure
  • Crumby structure
  • Granular structure
  • Platy structure
  • Blocky structure

(a) Single – grained structure

In this structure, the particles are not cemented together. They exist as individual grain. They form no aggregates and are non porous.

They are mostly found in top soils of sandy soils and in arid climate and in alkaline soils

(b)  Crumby structure

This type consists of small, soft porous aggregates of irregular shapes. They are not closely fitted together


(c)  Granular structure

This is made of friable rounded aggregates of irregular shapes called granules. Its formed when particles co agulate and are cemented together to form rounded aggregates whose diameter is not more than 15cm

When wet it becomes porous since the spaces are not readily closed by swelling. The structure is found in top horizon in cultivated soils and in the sub- soil under grass. The structure is not porous and is usually affected by tillage.

(d)  Prismatic structure

This is where the structure aggregates are arranged vertically. The primary particles are vertically oriented forming distinct columns which vary in length depending on the type of soil.

The structure is found in sub soil of arid and semi arid soils

N/B: If the tops are rounded, they are called columnar. But if the tops have clear cut edges, the its called Prismatic

  • Platy soil structure


In this structure, the aggregates are arranged on top of one another on thin horizontal plates. The plates overlaps and impair permeability and hence drainage and root penetration. The structure is found in top soils of clay soil and forested area.



(f) Blocky structure

Here the aggregates are in form of rectangular blocks. The aggregates easily fit together a long vertical edges


Influence of soil structure on crop production

  • A loosely packed structure ensures good air circulation in the soil
  • Good structure also ensures proper water holding capacity
  • Good structure also gives proper root anchorage
  • Good structure also reduces then soils liability to erosion

Factors that influence the soil structure

Parent material

The physical and chemical properties of the parent rock will determine the type of structure being formed

Soil forming processes

Processes which lead to soil formation will determine the type of structure being formed


In areas where a lot of rainfall is followed by dry periods cracks tend to form giving rise to good structure which is well aerated

Organic matter

Presence of organic will stabilize the soil structure

Living organisms

Living organisms also help to decompose organic matter which turn improve structure


The nature of cultivation eg digging channels results in a better structure

Inorganic compounds

Presence of compounds like iron oxide have binding properties and help in the formation of granules

  1. Soil texture

This refers to the various mineral particles present in a soil sample.

Particles                                                      Diameter

  • Clay 002mm and below
  • Silt 002 —— 0.02
  • Fine sand 02 ——- 0.2
  • Coarse sand 2 ——– 2mm
  • Gravel                                         2 ———- 20mm
  • Stone 20mm and above


Determination of soil texture

Can be determined by:

  • Mechanical analysis
  • Chemical analysis

Mechanical determination of soil texture


  • Sieves of different diameter
  • Containers
  • Weighing balance


  • Put a known amount of soil sample in a container
  • Pass the soil through a sieve of the smallest diameter and shake
  • Weigh the soil that remains in the sieve
  • Repeat the process using sieves of different diameter until all the soil I passed through


After every sieving it will be observed that a certain amount of soil remains in the sieve


Soil is made up of different sized particles of different diameter

Experiment 6: to show that soil is made up of different sized particles


  • Measuring cylinder
  • Sodium carbonate
  • Garden soil


  • Put some soil sample in a measuring cylinder
  • Add about 4 times its volume of water with sodium carbonate to aid in dispersion of particles
  • Cover the mouth of the cylinder with the hand and shake vigorously for about 2min.
  • Place cylinder on the bench for about 1hr or more to allow the contents to settle down


  • At the end of the period, it will be seen that fractions have settled in layers
  • The heavy, coarse gravels settle first, then followed in succession by sand, silt and clay
  • The humus and organic matter remain floating in the water or on top of the clay


From the above observations, it can then be concluded that soil is a mixture of particles of different sizes.

Influence of soil texture on crop production

  • Coarse soils have poor water holding capacity
  • Very fine textured soils also have poor aeration

Soil colour

  • Soil colour depends mainly on the mineral composition of the soil
  • If the soil was made from a rock containing a lot of iron compounds, it tends to be brownish yellow, reddish or orange in colour
  • Humus content also gives dark brown colour
  • Soil colour influences temperature of the soil

Soil classification

Soil can be classified based on the following

  • Soil structure
  • Soil texture
  • Soil colour
  • Soil ph

According to structure, soils could be classified as granular, crumby, blocky, or platy soil structures

According to texture, a soil containing high proportion of sand particles is called sandy soils, if it contains  high amount of clay then its called clay soils

In terms of colour, soils could be either dark coloured soils or light coloured soils

Types of soils

  1. Sandy soils
  2. Silty soils
  3. Clay soils
  4. Clay loams
  5. Loamy soils

Sandy soils

  • They have bigger particles
  • Contains 50 – 80% sand, and 20 – 50% silt and clay
  • Organic matter content is 0.1 – 3%
  • Are well drained
  • Are more prone to soil erosion have low water holding capacity
  • They are slightly acidic
  • Easy to cultivate but less fertile

how to improve sandy sols

  • Add organic matter
  • Addition of fertilers

Silty loams

  • They contain 20 – 30% sand
  • Also contains 70 – 30% clay
  • Has 0.1 – 4% organic matter
  • They are fine textured, well drained and have a good water holding capacity
  • They have moderately acidic ph
  • Moderately fertile and aerated
  1. Clay loams
  • They contain 20 – 50% sand
  • Clay and silt is 20 – 60%
  • Has organic matter content of 0.1 – 6%
  • They are fine textured
  • Poorly drained and aerated
  • Has capillarity and water retention
  • They are rich in plant nutrients
  • Are suitable for flood irrigation for rice growing
  • This soil can be improved through drainage
  1. Clayey soils
  • Have clay content of more than 40%
  • Have high water holding capacity
  • Have crystalline and platy structure
  • Expand when wet
  • Crack when dry
  • Get water logged easily
  • Also suitable for flood irrigation
  • Have high capillarity
  1. Loamy soils
  • They contain 30 -50% sand, 50 -70% silt and clay and 0.4% organic matter
  • Are moderately textured and drained
  • Are slightly acidic
  • Have good water holding capacity
  • Can be improved by planting cover crops and adding organic manures




Experiment 7: To compare the porosity and water holding capacity of sand, loam and clay


  • Measuring cylinder
  • Funnels
  • Cotton wool
  • Dry sand, loam and clay



  • Place equal volumes of each soil in each funnel plugged with cotton wool
  • Tap all the funnels persistently until all visible air spaces are filled up
  • Stand each funnel in the open end of measuring cylinder and add 50cm3 of water into each funnel
  • Note the time taken for the first drop of water through into the cylinder


After some time, it will be seen that water level is high in sand than the rest


Sandy soil is more porous than the other 2

Clay soil has the highest water holding than the other 2

Experiment 8: To compare the capillarity of sand, loam and clay


  • 3 long cylinders
  • Dry sand, clay and loam
  • Water trough
  • Clock
  • Ruler


  • Close the lower end of each tube with a plug of cotton
  • Fill each tube with different soils
  • Tap the end of each tube gently in the bench to tightly pack the soils
  • Stand and clamp each tube with a clamp and put in an empty water trough
  • Poor water into the trough to a depth of 5cm
  • Measure the height of water in each tube after 3 – 5min
  • Take as many readings as much as possible
  • Record the readings


  • Water will be seen to be rising up the tubes
  • It rises very fast in sand and loam in the first 3 – 5min. but very slow in clay
  • After 2hrs water level will be higher in loam than in clay soil and least in sand
  • Water rise continues in clay soil but stops after some time in loam


  • Clay and loam have higher capillary action due to their fine pore spaces
  • Sand has poor capillary action due to their large pore spaces
  • Clay soil has the highest capillarity

Chemical properties of soil

  1. Soil ph
  2. Soil mineral content
  3. Soil pH
  • This is the acidity or alkalinity of soil solution
  • Acidity is determined by hydrogen ion concentration while alkalinity is determined by hydroxyl ion concentration

Influence of soil ph on crop production

  • Soil ph affects the availability of various nutrients eg low ph makes P, and molybdenum less available and high ph makes Mn, K, Fe and zinc less available
  • Very low ph affects the activities of micro organisms eg nitrogen fixing bacteria
  • Different crop species require different ph ranges

Ways of modifying pH

  • Apply lime to raise the pH
  • Apply basic fertilizers
  • Apply sulphur to raise the pH
  • Apply acidic fertilizers to lower the Ph



A tool is any instrument held in the hand and used to do work


This is something used for specific purpose

Why farmers use tools and equipment

  • To increase efficiency
  • To make farm operations easier
  • To minimize injuries
  • To enhance production

Precautions in handling tools and equipment

  • Proper maintenance
  • Proper use of tools
  • Proper storage
  • Use safety devices and clothing
  • Proper dressing
  • Skilful handling of tools

Categories of farm tools and equipment

  1. Garden tools and equipment
  2. Livestock production tools and equipment
  3. Workshop tools and equipment
  4. Plumbing tools and equipment
  5. Masonry tools and equipment

Factors determining the choice of tools to use

  • The task to be performed
  • The tools efficiency
  • The level of knowledge and skill of user
  • Availability of the tools

General Maintance practices of farm tools

  • Sharpen the cutting edge
  • Grease the moving parts
  • Repair or replace worn out parts
  • Proper and safe storage
  • Clean after use
  • Tighten loose nut and bolts
  • Oil and paint before long storage

Reasons for maintaining farm tools and equipment

  • To durability
  • To improve efficiency
  • To avoid injury
  • Reduce production cost





Land preparation involves all those activities that make land suitable for planting eg ploughing, harrowing, ridging and rolling

Seed bed: this is apiece of land prepared ready for planting. To achieve good germination of seeds the following must be achieved:

  • Suitable size of clods
  • Good depth
  • Looseness of soil
  • Absence of weeds

Reasons for land preparation

  • To kill weeds
  • To incorporate manure and other organic matter in the soil
  • To destroy different stages of crop pest such as eggs, larva or adult stages by burying them and exposing them to the heat
  • To encourage the penetration of roots in the soil
  • To make subsequent operation easy
  • To encourage water penetration in the soil

Operations in land preparation

  1. Land clearing
  2. Primary cultivation
  3. Secondary cultivation
  4. Tertiary operations
  5. Land clearing

This is the removal of vegetation cover from the surface before land is cultivated. Its done to prepare land for  cultivation as well as a method of land reclaimation

Conditions that necessitate land clearing

  • When opening up virgin land
  • Where a stalk growing crop was previously planted
  • Where the interval between primary and secondary cultivation is long such that land is reverted back to its original virgin state
  • Where land was left fallow for a long time

Methods of land clearing

  1. Tree felling
  2. Burning
  3. Slashing
  4. Use of chemicals
  5. a) Tree felling

This involves cutting down trees. Axes, pangas, are used and small power saws where the trees are few. Bulldozers and root rakers are used where trees are on large scale. After cutting down the trees, destumping or removal of stumps and disposal of trash is done.

  1. b) Burning

here fire is set on the vegetation cover. Should be done when the speed of wind is low to avoid spread of fire to other fields. Burning should be discouraged because:

  • it destroys organic matter
  • kills soil micro organisms
  • also destroys plants nutrients
  1. c) Slashing

Small bushes or grasses can be cleared by slashing. Slashers or pangas are used in a small area, while a tractor drawn mower can be used in large areas

  1. d) Use of chemicals

Chemicals used to kill weeds are called herbicides. They kill weeds faster and more easily.

  1. Primary cultivation

This is the initial opening of land either after land clearing or following a previous crop. Primary cultivation should be done well before the onset of rains to give time for all operations to be done in good time.

Importance of primary cultivation

  • To remove weeds
  • To burry organic matter for easy decomposition
  • To facilitate water infiltration and aeration
  • To destroy soil borne pests by exposing them to predators and sun
  • To make planting easy

Ways of carrying out primary cultivation

  1. Hand digging
  2. Mechanical cultivation
  3. Use of ox plough
  4. a) Hand digging

This is mainly the use of simple hand tools such as jembes, mattocks and fork jembes to cut and turn the soil slices.

  1. b) Mechanical cultivation

Where large pieces of land is involved, farmers use tractor mounted implements which include mould board, disc ploughs. Also there is use of sub soilers to break the hard pan.

  1. c) Use of an ox plough

This is use of ploughs drawn (pulled) by animals such as donkeys, camels, oxen etc. common in areas where such animals are available and the terrain is flat.

Aspects to be considered when carrying out primary cultivation

  1. i) Time of cultivation
  2. ii) Depth of cultivation

iii) Choice of implements

  1. i) Time of cultivation

land preparation should be done early enough before the onset of rains.



Reasons for early cultivation

  • To give weeds and other vegetation enough time to dry up and decompose into organic matter
  • To allow carbon dioxide and other gases to diffuse out of the soil while being replaced by oxygen required in seed germination and growth of soil organisms
  • Also gives time for subsequent operations to be done giving way for early planting
  1. ii) Depth of cultivation

factors that determine the depth of ploughing are:

  • The type of crop to be planted: Deep rooted crops require a soil which has been cultivated deeply, because it will facilitate easy root penetration. Shallow rooted crops may not need deep cultivation
  • The implements available: There are some implements which canot cut the soil beyond a certain depth. Such implements can be sharpened or weight be added
  • Type of soil: heavy soils are hard particularly when they are dry. Simple implements such as jembes tend to dig shallowly on such hard soils

iii) Choice of implements

Choice of implements used in primary cultivation is determined by:

  • The condition of the land: If the land has a lot of stones and stumps, it would be advisable for one to choose a disc plough which would not break easily when working on such land. A jembe cannot be used efficiently on land which has a lot of couch grass because it cannot pull all the rhizomes.
  • The type of tilth required: very fine tilth requires the use of different types of implements
  • The depth of cultivation needed: heavy implements are necessary when deep cultivation is needed and light implements are required when shallow cultivation is necessary
  1. Secondary cultivation

These are operations which follow the primary cultivation and means seedbed refinement practices before planting, also called harrowing



Importance of secondary cultivation

  • To remove any weeds that might have germinated after primary cultivation
  • To break the soil clods into small pieces for easy planting
  • To level the field on order to achieve a uniform depth of planting
  • To incorporate organic matter into the soil in order to encourage decomposition before planting

Factors that determine the number of times of secondary cultivation

  • Size of planting materials: Big seeds such as those of groundnuts, maize etc require a fairly rough seedbed, and small seeds such as those of finger millets require fine seedbed
  • Slope of the land: When the land is very steep, less cultivation should be done to discourage soil erosion
  • The moisture content of the soil: In dry soils less cultivation are preferred so as to conserve the available moisture
  • Condition of the soil after primary tillage: where there is plenty of trash, more harrowing operations should be carried out to incorporate most of the trash into the soil

N/B: Implements used for secondary cultivation are: pangas, jembes, fork jembes, and garden rakes. Tractor drawn harrows eg discs, spike toothed and spring tine harrows

  1. Tertiary operations

These are operations carried out to suit production of certain crops. They are carried out after land clearing primary cultivation and secondary tillage. They include:

  1. Leveling
  2. Rolling
  3. Ridging
  4. a) Leveling

This is the practice of making the soil surface flat and uniform so as to promote easy germination of small seeded crops such as wheat, grasses, and barley. It facilitates uniform germination of seeds.



  1. b) Rolling

This is done to compact soil which is loose or fine tilth. Its done to prevent small seeds from being carried away by wind and to prevent soil erosion. Also increases seed soil contact. Implements used are: simple hand tools and heavy rollers

  1. c) Ridging

This is the process of digging soil in a continuous line and heaping it on one side to form a bund ( ridge) and a furrow. The ridges are important for planting root crops like Irish potatoes, cassava etc. ridging helps in: tuber expansion and easy harvesting of root crops.

N/B: Other tillage operations include:

  1. Sub soiling
  2. Minimum tillage
  3. Sub soiling

This is the process of cultivating the soil for the purpose of breaking up the hard pans which might have formed as a result of continuous use of heavy machinery in land preparation. Implements used in sub soiling are:

  • Sub soiler
  • Chisel ploughs
  • Cultivators

Importance of sub soiling

  • Helps to break up hard pans
  • Helps to facilitate gaseous exchange in the soil
  • Also brings to the surface, minerals which might have leached to the deeper layers

N/B: hard pan is an impervious layer of soil found within the sub soil.

  1. Minimum tillage

This is the application of a combination of farming practices aimed at least disturbance to the soil.

Reasons for carrying out minimum tillage

  • To reduce the cost of cultivation or ploughing by reducing the number of operations
  • To control soil erosion, mulching and cover cropping greatly reduce chances of soil erosion
  • To maintain soil structure, continuous cultivation destroys soil structure hence its avoided
  • To conserve moisture, continuous cultivation exposes the soil to the heat of the sun thus enhance evaporation of available moisture
  • To prevent disturbance of roots and underground structures for example tubers and bulbs
  • To prevent exposure of humus to adverse conditions such as the suns heat that cause volatilization of nitrogen

Ways of carrying out minimum tillage

  • Application of herbicides in controlling weeds
  • Use of mulch on the soil surface. Mulch prevents weeds from growing by smothering them
  • Timing cultivation, late weeding of cotton crop, for example often produces a clean seedbed for finger millet to be sown without further cultivation
  • Restricting cultivation to the area where seeds are to be planted. Weeds in the rest of the field are controlled by slashing
  • Establishment of cover crop on the field
  • Uprooting or slashing weeds on perennial crops



Sources of water

  1. Surface water
  2. Ground water
  3. Rain water
  4. Surface water

Sources of surface water are:

  1. Rivers
  2. Streams
  3. Lakes



  1. Ground water

Sources of ground water are:

  1. Springs
  2. Wells
  3. Boreholes
  4. a) Springs
  • Here water comes out of the ground as a result of an impervous layer meeting the ground surface.
  • Low wall can be constructed around the spring to increase the water volume for easier pumping
  • Also on higher ground, water can be conveyed to lower grounds by gravitational flaw

Diagram of a spring


  1. b) Wells
  • Wells are holes dug in the ground until water table is reached. Can go up to 15m deep.
  • It’s advisable to dig the well during dry season to ensure that even during dry season water will be available
  • Fence around the well to avoid contamination
  • Construct a reinforced slab with a lockable lid to prevent contaminations and wearing of the top sides of the well. Water is lifted using buckets


Diagram of a well


  1. c) Boreholes

These are deep holes drilled or sunk into the ground by use of drilling machines. The holes are usually sunk into the Parent rock to ensure continuous supply of water. The hole is of small diameter and usually lined with metal casing perforated at the bottom end to allow the water to rise up. Special pumps operated by either electricity or engines are used to lift water out of the hole.

Diagram of borehole







  1. Rain water

Collected from roofs then stored in tanks. Ponds also constructed to store the run off. This is done during the rainy season.

Water collection and storage

Methods of water collection and storage include:

  1. Dams
  2. Weirs
  3. Water tanks
  4. Dams

This is a barrier constructed across a river or dry valley to hold water and raise its level to form a reservoir or lake. It has a spillway to allow excess water flow away. The accumulated water is then pumped to farms.

  1. Weirs

A weir is a barrier constructed across the river to raise the water level, but still allow water to flow over it

  1. Water tanks

Rain water, ground water and run off can be stored in tanks. The water storage structures (tanks) include:

  1. Concrete tanks (overhead or underground)
  2. Corrugated iron sheets
  3. Steel tanks
  4. Plastic tanks

Parts of a water tank


  • Funnel lid
  • Overflow pipe
  • Drainage pipe
  • Roof
  • Gutter
  • Outlet
  • Base

Diagram of water tank


Pumps and pumping of water

  1. Water pumps

Types of water pumps include:

  1. Centrifugal/Rotar dynamic pumps
  2. Piston/Reciprocating pumps
  3. Semi rotary pumps
  4. Hydram pumps
  5. a) Centrifugal pumps: These are made of metal discs with blades that rotate at high speed. They are powerful and can pump water for irrigation. Electric motors, diseal or petrol engines are used to operate them.
  6. b) Piston pumps: Consist of pistons that move back and forth thereby pushing water through the pipes. Do not pump a lot of water thus suitable only for domestic and livestock use.




Diagram of a piston pump

  1. c) Semi rotary pumps

These are operated by hand, and mostly used to pump water from wells for domestic and livestock use

  1. d) Hydram pumps

these are operated by the force of flowing water. The higher the speed of water, the greater the pressure created in the pump. Cannot pump stationary water and only suitable for slopy areas, where water flows at high speed.

N/B: Pumping of water is the lifting of water from one point to another by use of mechanical force.

Conveyance of water

This is the process of moving water from one point mostly from storage to where its used or stored

Ways of conveying water

  1. Piping
  2. Use of containers
  3. Use of canals
  4. a) Piping

This is where water is moved through pipes

Types of water pipes

  1. i) Metal pipes
  2. ii) Plastic pipes

iii) Hose pipes

  1. i) Metal pipes

These are two types: Galvanized iron and Aluminum pipes

Galvanized iron pipes are heavy and suitable for permanent installation of water system. Alumimium pipes are light and used for irrigation systems,

N/B: metal pipes are expensive but durable

  1. ii) Plastic pipes

These are made of synthetic materials. There advantages include:

  • They are cheap
  • Easy to install
  • Durable when installed properly

Disadvantages include:

  • Become brittle when exposed to sun
  • Can burst under high pressure
  • Can be eaten by rodents

iii) Hose pipes

There are two types: rubber hose pipes and plastic hose pipes

Rubber hose pipes are more expensive but durable, hose pipes are used to convey water from taps to various areas eg irrigation areas or washing places

  1. b) Use of containers

Water is drawn and put in containers such as drums, jerry cans, pots, tanks and buckets which are carried by animals, bicycles, human beings and vehicles

  1. c) Use of canals

Water is conveyed from a high point to a lower appoint along a gradual slope to avoid soil erosion. Water conveyed in canals is mostly used for irrigation and livestock drinks


Water treatment is the process of making raw water from source safe for use in the farm.

Importance of treating water

  • To kill disease causing micro organisms such as cholera and typhoid bacteria which thrive in dirty water
  • To remove chemical impurities such as excess fluoride this may be harmful to humans
  • To remove smell and bad taste
  • To remove sediments of solid particles

The process of water treatment

  1. Filtration at water intake
  2. Softening of water
  3. Coagulation and sedimentation
  4. Filtration
  5. Chlorination
  6. Storage

Stage 1: Filtration at water intake

At the pint of water intake, water is made to pass through sieves before entering the intake pipe. This is to trap large impurities. Several sieves of different sizes are made.

Stage 2: Softening of water

The water in the pipe flows into the mixing chamber. This is a small tank where water circulates and is mixed with soda ash ( sodium bicarbonate) and alum ( aluminium sulphate) these chemicals are added into water in equal proportions. Soda ash softens the water, while alum helps to coagulate solid particles which finally settle down to the bottom

Stage 3: Coagulation and sedimentation

The softened water moves to the coagulation tank which is a circular and large solid particles such as silt and sand coagulate and settle down. The tanks is also open to allow in fresh air into the water. Water should stay in this tank for at least 30 hrs to kill bilharzias which cannot survive in water stored that long

Stage 4: Filtration

Water with very few impurities passes into a filtration tank where all the remaining solid particles such as silt are removed. The filtration tank has layers of different sizes of gravel and a top layer of sand. At its bottom is a layer of large pieces of gravel, this is followed by another layer of gravel but of fine texture. A layer of fine sand is placed on top of this fine gravel. These layers allow water to seep through very slowly leaving all the solid particles behind. When water leaves this tank, its clean.

Stage 5: Chlorination

The filtered water enters the chlorination tank. In this tank, small amount of chlorine solution is controlled by a doser and the amount added will depend on the volume of water to be treated and the outbreak of water borne diseases. Chlorine kills pathogens

Stage 6: storage

Water is then stored in large tanks, before distribution to consumers.




General uses of water in the farm

  • For domestic purposes eg washing, cooking etc
  • For watering livestock eg washing pigs
  • For diluting chemicals
  • For processing farm produce eg coffee etc
  • For construction of buildings
  • For irrigation



Irrigation is the artificial application of water to soil for the purpose of supplying sufficient moisture to crops.

Conditions that make it necessary for irrigation

  • In dry areas
  • During dry periods
  • In the growing of paddy rice
  • Soften the soil during transplanting
  • To effect the application of fertilizers and other chemicals

Types of irrigation

  1. Surface irrigation
  2. Sub surface irrigation
  3. Overhead irrigation
  4. Drip/Trickle irrigation

Factors that determine the type of irrigation to use

  • Capital availability
  • Topography of the land
  • Water availability
  • Type of soil
  • Type of crop to be irrigated
  1. Surface irrigation

Here water is applied to the field by allowing it to flow on top of the ground surface.

Methods of surface irrigation

  1. Flood irrigation
  2. Furrow irrigation
  3. Basin irrigation
  4. Boarder irrigation
  5. a) Flood irrigation

In flood irrigation, water is allowed to cover the whole field a few centimeters in depth. Its suitable for growing paddy rice fields.

Advantages of flood irrigation

  • Its cheap to establish and maintain
  • Does not require skills

Disadvantages of flood irrigation

  • There is uneven distribution of water in the field
  • A lot of water is wasted
  1. b) Furrow irrigation

Here water is supplied by use of open ditches or furrows. Its suitable for all crops and application to most soils



Maintenance of furrows

  • Repair furrows when worn out or eroded
  • Remove weeds and silts

Advantages of furrow irrigation

  • Reduces chances of fungal diseases
  • Cheap to establish
  • Require little skills

Disadvantages of furrow irrigation

  • A lot of water is lost through evaporation and seepage
  • Erosion can occur if the furrows are not maintained
  • If water has high content of salt, it may have damaging effect on the plant roots
  1. c) Basin irrigation

Basin irrigation involves the application od water into basins that have been checked by construction of banks or ridges. The basins may be rectangular ring shaped or have contour checks

This system is suitable in:

  • Relatively flat areas
  • Soils of low infiltration
  • For crops requiring large quantities of water
  • Soils that require leaching

Advantages of basin irrigation

  • Helps to control soil erosion
  • Retains rain water in the basins

Disadvantages of basin irrigation

  • Much land is occupied by water covering channels and ridges
  • There is no surface drainage
  • Requires precise land grading
  • Requires a lot of labour
  • Cannot be used in crops that require free draining soils
  • May result in accumulation of salts

Areas where basin irrigation is being practiced in kenya: mwea tebere, ahero, bunyala, west kano etc

  1. d) Boarder irrigation

This is where parallel ridges guide a sheet of water that spread cover a relatively flat, but slanting piece of land. The ridges form long boarders. This method is applied where:

  • Soils have low to relatively high infiltration capacity
  • Crops are closely spaced, such as wheat, barley fodder crops as well as legumes

Advantages of boarder irrigation

  • Its easy and simple to operate
  • Requires less labour as compared to basin irrigation
  • Boarder ridges can be constructed economically with simple farm implements eg ox drawn ridgers
  • Large irrigation streams can be efficiently used
  1. Sub surface irrigation

This is a system of irrigation where water is supplied to crops using underground perforated pipelines or any other porous medium that make water available from below the soil surface. Pipes sometimes referred to as conduits

The system is suitable in soils of high capillarity and water holding capacity

Advantages of sub surface irrigation

  • Little labour requirements
  • No need to construct dykes or soil grading
  • Can be practiced on both sloppy and flat land
  • Water does not cause soil erosion
  • Does not encourage fungal diseases
  • Economizes use of water
  • Minimizes theft of pipes

Disadvantages of sub surface irrigation

  • Its expensive method ie to buy pipes and to lay them
  • Pipes can be broken during weeding
  • Nozzles can get blocked
  1. Overhead irrigation

This is the application of water above the crops by means of sprinklers or watering cans. Wind breaks should be constructed to avoid misdirecting the water.

Advantages of overhead irrigation

  • Water is evenly distributed over the required area
  • There is less water wastage than in furrow irrigation
  • It can be practiced on slopy grounds
  • Foliar fertilizers can be applied together with irrigation water thus reducing labour costs
  • Sprinkler systems can be easily be moved from one place to another

Disadvantages of overhead irrigation

  • Its expensive to install
  • Encourages fungal diseases eg blight, CBD
  • Causes soil erosion
  • Requires establishment of wind breaks

Sprinklers used are: oscillatory sprinklers, spring loaded sprinklers

Sprinklers can also be classified into: rotating head, perforated pipe system

Maintenance of sprinklers and pipes

  • Lubricate the rotating parts
  • Repair broken parts
  • Cleaning and unblock the nozzles
  1. Drip/Trickle irrigation

Here pipes with tiny perforations are used. As water passes through the plastic pipes, water comes out through the holes in small amounts and drips to the ground.

Advantages of drip irrigation

  • Requires little amount of water
  • Can also use water of low pressure
  • Discourages fungal diseases eg blight, CBD
  • Does not encourage the growth of weeds
  • Can be used in sloppy topography

Disadvantages of drip irrigation

  • Pipes are expensive to buy and install
  • Require clean water, since dirty water will block the perforations

Factors to consider when choosing irrigation equipment

  • Capital availability
  • Topography
  • Availability of repair and maintenance
  • Type and source of power
  • Source


This is the method of removing excess water from water logged land. It’s a method of land reclaimation.

Land reclaimation is the process of bringing back waste land to agricultural production

Importance of drainage

  • Improves soil aeration: removal of excess water around the root zone allows for enough air for proper growth
  • Increases soil volume: increases the amount of soil around the roots
  • To raise the soil temperature: improves the rate at which soil worms up for better plant growth
  • Increases microbial activities: micro organisms in the soil increase in number due to proper aeration, they help to improve soil structure and make plant food more readily available
  • Reduce soil erosion: well drained soils have higher water holding capacity which helps to reduce water run off and increase infiltration
  • Remove toxic substances: due to water logging, soluble salts such as those of sodium increases in concentration to levels that are toxic to plants or may retard growth

Methods of drainage

Use of open ditches:

  • ditches are dug for the water to flow in by gravity to a water way thereby lowering the water table. May be U shaped or V shaped or trapezoidal

Underground drain pipes:

perforated pipes are laid underground. Water then seeps from the surrounding area into the pipes and flows to a water away. Such drains do not interfere with field operations. The pipes may be made of steel, clay or plastic materials


French drains:

  • ditches are dug, filled with stones and gravel, then covered with soil. Water from the surrounding area seeps into these drains and is carried into a water way

Cambered beds:

raised beds are constructed on the poorly drained soils

Pumping: where other methods of drainage are not possible, water is pumped out.

Areas where drainage has been carried out in kenya are: yala and bunyala to control flooding, ahero to control flooding of river nyando, loriaan region



This is the contamination of water by either chemical, industrial wastes, farm residues etc, making it unsafe for human beings and animals.

Agricultural practices that pollute water

  • Fertilizer and pesticides: chemicals compound found in the fertilizers and other pesticides do not decompose easily, hence they find their way into water sources through drainage, irrigation channels, erosion, seepage and leaching
  • Improper disposal of used farm chemicals: when containers contaminated with chemicals are disposed of into water sources, the result is water pollution
  • Damping of farm wastes: farm wastes such as slurry, manure used polythene, dead animals etc when improperly disposed of cause water pollution.
  • When land is cultivated or the soil is left bare erosion will easily occur leading to contamination through unwanted soil
  • Blockage of irrigation channels and water ways prevents free flow of water leading to stagnation of contaminated water
  • When pit latrines and sewage sites are located near water sources, they cause pollution
  • Other sources of pollution include industrial wastes and generalized contamination in the atmosphere and the environment

Methods of preventing water pollution

  • Practice organic farming
  • Safe disposal of used farm chemicals and industrial wastes
  • Proper location of pit latrines, sewage sites and waste dumps
  • Control of irrigation and establishment of grassed water ways to purify the water
  • Controlled use of fertilizers, manures and farm chemicals
  • Ensuring that the water source is free from contamination from the farm
  • Treating and piping water for farm use




This is the ability of the soil to produce and maintain high yields of crops for an indefinite period.

Characteristics of fertile soil

  • Should have good depth
  • Be well drained not water logged
  • Well aerated
  • Good water holding capacity
  • Supply nutrients needed by plants in correct amount and form available to plants
  • Correct soil pH for different crops
  • Free from crop pests and diseases

How soil loses fertility

  • Continuous growing of arable crops: continuous cultivation makes the soil loose and liable to erosion, this leads to lose of fertility.
  • Mono cropping: growing of crops every season leads to depletion of soil nutrients
  • Soil erosion: This leads to lose of top fertile soil
  • Leaching: leads to lose of soil nutrients into the lower horizons of the profile
  • Poor soil aeration: if soil is poorly aerated, the denitrifying bacteria increase in number and they make the infertile by converting nitrates into free nitrogen.
  • Poor drainage of the soil: If the soil poorly drained, the soil becomes flooded, forms acid soils which are useless for cultivation
  • Dry soils: If the soils are dry, the nutrients cannot be dissolved to be used by crops
  • Change of pH: soil pH influences the availability of certain nutrients eg low pH decreases solubility of phosphorus and high pH also decreases the availability of K, Mn etc
  • Accumulation of salts: certain salts usually become toxi if present in excess eg Mn, boron, fluorine etc
  • Burning of land: burning of land kills certain micro organisms and destroys certain nutrients

Ways of maintaining soil fertility

  • Control of soil erosion: control of erosion prevents loss of top fertile soil
  • Crop rotation : this ensures maximum utilization of crop nutrients. Also helps to control pest and diseases, will also add nutrients if legumes are included in the rotation
  • Maintaining soil pH: when soil pH is maintained at given ranges, particular nutrients will be available in the soils
  • Proper drainage: soil should be well drained to eliminate flooding
  • Weed control: control of weeds ensures no competition for nutrients, adequate space for crops and destroys alternate hosts for crop pests and diseases.
  • Minimum tillage: this helps to maintain soil structure and prevent erosion
  • Use of manures: manures supply a wide range of plant nutrients to the soil
  • Use of inorganic fertilizers: inorganic fertilizers supply specific plant nutrients

Organic matter, humus, and manures

Organic matter: this is the remains of dead plants and animals and their waste products

Humus: humus is the decayed organic matter ie the remains of plants and animals which have decomposed

Manure: manures are organic substances that are added to the soil to provide one or more plants nutrients. They have high matter content

Roles of organic matter in the soil

  • Increases water holding capacity and also water infiltration due to its colloidal nature
  • Releases a wide range of nutrients into the soil thus improves fertility
  • Provides food and shelter to micro organisms such as ants and rodents
  • Improves soil structure by binding soil particles
  • Buffers soil pH by avoiding rapid chemical changes due to the addition of lime and fertilizers
  • Reduces toxicity of plants poisons that have built up on the soil as a result of continous use of pesticides and fungicides

Classification of manures

Manures are classified according to: method of preparation and nutrients from which they are prepared.

There are 3 types of manures:

  1. Farmyard manure
  2. Compost manure
  3. Green manure


  1. Farmyard manure

Farmyard manure is a mixture of animal waste (urine and dung) and crop residues used as animal beddings.

Importance of farmyard manure

  • Increases yield of the crop
  • Adds organic matter into the soil and improves the texture and water holding capacity of thee soil
  • Adds useful bacteria to the soil

Factors influencing the quality of FYM

  • Type of animals: dung from fattening animals is richer in nutrients than farm growing animals which extract a lot of phosphorus from food eaten
  • Type of food eaten: the richer the food in terms of minerals the richer will be the manure
  • Type of litter used: wood shavings and saw dust are slow to decompose and contain no nutrients and absorb 1.5 times as much urine as their weight, while nappier grass provide both N and P, but has low absorptive capacity.
  • Method of storage: farmyard manure must be stored well in a place with a cemented floor and covered roof. The N and P are soluble and therefore can get leached by heavy rains
  • Age of FYM: well rotten manure is richer in nutrients and easier to handle and mix with the soil

Preparation of farmyard manure

  • A bedding of grass, wood shavings or saw dust is provided in the house of farm animals eg cattle, sheep
  • The animals deposit their droppings and urine on the bedding materials
  • After some time, ie daily, months or more as in poultry, the beddings are replaced with new ones
  • The discarded beddings are deposited in a specially prepared shaded place
  • New layers of used beddings are continuous added until a heap is formed
  • N/B: decomposition and mineralization of the materials take place through activities of certain bacteria resulting in a rich manure


  1. Green manure

This is  a type of manure prepared from green plants. The plants are grown for the purpose of incorporating into the soil when its green at the flowering stage for the purpose of improving soil fertility.

Characteristics of plants used for green manure

  • They should be highly vegetative or leafy
  • They should have faster growth rate
  • They should have high nitrogen content, thus preferably legumes
  • The plants must be capable of rotting quickly
  • The plants should be hardy ie can establish in poor conditions

Reasons why green manure is not commonly used

  • Most of the crops grown are food crops and its hard for people to use them as green manure
  • Green manure crops might use most of the soil moisture and leave very little for next main crop
  • Most of the nutrients are used up by micro organisms in the process of decomposing the green manure plant. These will only be released by micro organisms when they die.
  • It takes time for green manure crop to decompose and therefore planting is delayed

Preparation of green manure

  • The plant to be used is planted in the field
  • The plant is allowed to grow up to flowering stage
  • Its then incorporated into the soil by ploughing
  • Left for 2hrs to decompose after which the field is prepared for planting the main crop
  1. Compost manure

Compost manure is the accumulation of plants residue, mixed with animal waste, piled together in a heap where conditions are conducive for decomposition, sometimes contain refuse and kitchen left over foods





Preparation of compost manure

There are two methods namely:

  1. Indore method
  2. Four heap system (stalk method)
  3. Indore method

This was devised in a place called Indore in India


  • A pit is prepared which is 1 – 2 m deep. The material to be made into compost is placed is placed.
  • The first layer 0.5m deep consist of fresh material to be made into compost eg grass, maize stalk refuse etc
  • The layer is followed by dung, old compost to provide micro organisms to decompose the fresh material
  • Artificial fertilizers eg SSP and Muriate of potash are added to increase the nutrient level of the compost

N/B: Nitrogenous fertilizers are not added because they are easily leached

  • The 2nd layer is followed by a layer of top soil with micro organisms to decompose plant and animal remains
  • The same is repeated until the pit is full. Its also kept moist by applying water during dry season
      Pit        Pit          Pit         Pit        Pit
        1          2            3           4         5


Pit 1, 2, 3, and 4 are simultaneously filled and after 3 – 4 wks, the materials in pit 4 is taken to pit 5

This process is repeated until the material that was prepared 1st is well rotten and taken to the field as composed.



  1. The Four heap system





















  • In this method, 4 – 7 heaps are used.
  • Materials used are crop residue, animal waste old manure FYM or onorganic fertilizers and top soil.
  • The materials is placed in heap X, then transferred to heap Y after  3 – 4 wks. After another 3 – 4 wks, the compost is taken to heap Z  where it stays for another 3 – 4 wks then taken to the field

N/B: The manure heaps must be turned occasionally at least every 3 months to facilitate circulation within the heap, manure should be ready after 6 months.

Cross section through a compost heap

  • N/B: too much water runs the compost
  • Too little water stop the bacterial action
  • Always keep the compost under cover of grass and soil
  • Posts are fixed at a distance of 1.2 m a part to form the 4 corners of the heap, the post should be 2m high

Factors to consider when selecting a site for compost manure

  • Drainage of the site
  • Direction of prevailing wind
  • Size of the farm ie centrally placed
  • Accessibility

Problems associated with organic manures

  • Bulkiness
  • Laborious in application and transport
  • They spread diseases, pests and weeds
  • Loose nutrients when poorly stored eg through leaching
  • If not fully decomposed, crops will not benefit since it releases nutrients which can scotch the crops



Economics: this is the study of how man and society choose with or without money to employ scarce resources to produce goods and services over a period of time and eventually distribute them for consumption now and in the future.

Agricultural economics: this is an applied science that aims at maximizing out put while minimizing costs by combining the limited factors of production to produce goods and services for use by the society over a period of time.

Factors of production

  • Land
  • Capital
  • Labour
  • Management/entrepreneurship

Basic concepts of economics

These concepts include:

  1. Scarcity
  2. Preference and choice
  3. Opportunity cost
  4. Scarcity

Scarcity means limited in supply

The factors of production named above are scarce and the production needs are many therefore the need for choice

  1. Preference and choice

Since the factors of production are limited, the farmer needs to make a choice on what to produce. This choice has to be guided by the needs of the society and the preference of the farmer on what he needs to produce.

  1. Opportunity cost

When the farmer makes a choice on what to produce, he is forced to leave others due to scarcity of resources eg a piece of land is suitable for growing both rice and maize and he choose to grow maize, the value that could have been derived from rice becomes the opportunity cost.

Opportunity cost is the value of the best foregone alternative



Farm records can be defined as the systemic entries and storage of information of various farm business activities and transactions in appropriate books and sheets.

Uses of farm records

  • Helps to compare the performance of different enterprises within a farm
  • Show the history of the farm
  • Guides a farmer in planning and budgeting of farm operations
  • Help to detect loses or theft on the farm
  • Help in the assessment of income tax to avoid over or under taxation
  • Helps to determine the value of the farm or to determine the assets and liabilities of the farm
  • Make it easy to share the profits and loses in partnership
  • Helps in settling dispute among heirs to the estate when a farmer dies without leaving a will
  • Help to show whether a farm business is making profits or loses
  • Helps in supporting insurance claims on death, theft etc
  • Provide labour information like terminal benefits eg NSSF

Types of farm records

  1. Production records
  2. Inventory records
  3. Field operation records
  4. Breeding records
  5. Feeding records
  6. Marketing records
  7. Labour records
  8. Inventory records

This is the physical count of everything that the farm owns and all that it owes others. There are two types of inventory records namely:

  1. Consumable goods inventory
  2. Permanent goods inventory
  3. a) Consumable goods inventory

This is inventory showing a list of goods which normally are used up during a production process, therefore needs constant replacement. Such goods include:

  • Fertilizers
  • Livestock feeds
  • Planting materials eg seeds
  • Chemicals eg insecticides, herbicides
  • Sisal ropes and strings etc

Example of consumable goods inventory



  1. b) Permanent goods inventory

    This is inventory showing a list of goods which are permanent in nature ie the type of goods which will not get used up in the production process such goods include:

  • Farm machinery and implements
  • Farm equipment and buildings
  • Livestock such as breeding stock
  • Annual crops
  • Hand tools
  • Land (arable)

Example of permanent goods inventory



  1. Production records

This is a record which show the total yield from each enterprise and also the yield per unit of the enterprise.

Example of production records (dairy milk production record)


Name or no. of cow   Days of the month
1 2 3 4              31st day TOTAL


Example of production record ( crop)

Plot/field No. 15



  1. Field operation records

This record contains all the activities carried out in the production from land preparation, planting to harvesting. It contains the following information:

  • Date of land preparation
  • The size of field
  • Crop variety planted
  • Type and amount of fertilizer applied
  • Seed rate

Example of field operation record

SEASON……………………………………………………………….FIELD NO………………………………………………………

Crop grown………………………………………………………….Variety……………………………………………………………

Ploughing date……………………………………………………..Planting time…………………………………………………


Seed rate kg/ha…………………………………………………………………………………………………………………………….

Fertilizer at planting………………………………………………Amount………………………………………………………..

Top dressing………………………………………………………….Amount……………………………………………………….

Other treatment………………………………………………………………………………………………………………………….

Pests ……………………………………………………………………..Control………………………………………………………..

Diseases ………………………………………………………………..Control……………………………………………………….

Weeds ……………………………………………………………………Control………………………………………………………

Other treatment…………………………………………………………………………………………………………………………..


Harvesting date…………………………………………………………..Method used…………………………………………

Yield /hac…………………………………………………………………….



























  1. Breeding records

These are records showing the breeding activities and programmes for different animals in the farm.

Importance of breeding records

  • Help the farmer to plan his breeding programmes
  • Help in selection of animals within a herd

Example of cattle breeding record

Name/No. of cow Name of bull/sire Date of service Date of pregnancy diognosis Expected date of calving Actual date of calving Sex of calf Wt. of calf rmks

N/B: students to draw sheep, pig, and sow breeding records

  1. Feeding records

This is a record showing the type and amount of feeds used in the farm.

Example of feeding records



Type of feed……………………………….


Date No. of animals Amount received (kg) Amount used (kg) Balance in stock (kg) remarks


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