Agricultural Science Keypoints 1

SECTION A – AGRIC CONCEPTS

WHAT IS AGRICULTURE? Agriculture can be defined as the art and science of
cultivating the soil, producing livestock, preparing livestock feeds, processing crops and
livestock products for man; and the process of selling excess crops and livestock.

OR

Agriculture may also mean the product of crops, rearing of animals and the
general management of soil.

IMPORTANCE OF AGRICULTURE

i. Provision of good
ii. Provision of employment
iii. Provision of income
iv. Provision of raw materials for industries
v. Provision of foreign exchange
vi. Provision of shelter and clothing
vii. Rural development
viii. Provision of market for industrial goods
ix. Afforestation
x. Provision of means of transportation
1.2 PROBLEMS OF AGRICULTURAL DEVELOPMENT

  1. PROBLEM OF LAND TENURE: Land tenure is the way land is owned in a
    society which often discourages agricultural land utilization leading to fragmentation of
    land. Also increase in population and soil erosion affect the use of land.
    SOLUTIONS: (i) Adoption of crop rotation (ii) The strict adherence to the land
    use decree of 1978 (iii) The use of fertilizer must be encouraged.
  2. PROBLEM OF BASIC AMENITIES: Basic amenities like electricity, cinema,
    standard schools, good and functioning health centres, recreational parks for relaxation,
    good roads, telephone, television viewing centres etc. are lacking in the rural areas.
    SOLUTION: (i) Provision of good roads, hospitals, electricity, good pipe borne
    water, cinema houses etc. will discourage rural-urban migration (ii) community
    development must be encouraged among the farmers.
  3. PROBLEM OF FINANCE OR POOR FINANCING: Most agricultural activities in
    the developing countries are subsistent in nature, hence the farmers are very poor and
    cannot secure the necessary collateral for loans.
    SOLUTIONS: (i) Farmers should form cooperative societies to grant loan and
    subsidies to members (ii) Banks should be more liberal in some of the terms for granting
    of loans. (iii) Loans should be monitored by banks so as to prevent diversion into
    unproductive sectors (iv) Government should also assist the farmers by providing loans.
  4. POOR TRANSPORTATION: Most farmers in rural areas are linked by bad
    roads, inadequate vehicle and spare parts.
    SOLUTIONS: (i) Construction of good roads by government (ii) Provision of
    vehicles, and spare parts (iii) Construction of water links to rural areas (iv) Construction
    of railways to link rural areas (v) Regular supply of fuel (vi) Construction of bridges and
    culverts.
  5. POOR COMMUNICATION: This includes lack of good radio, television, telex, fax
    etc. for quick message to farmers on latest discoveries in agriculture.
    SOLUTION: (i) The establishment of good and functioning communication
    network.
  6. PROBLEM OF GOOD STORAGE AND PROCESSING FACILITIES: Storage
    facilities like silo, rhombus, cribs, barn etc. are inadequate.
    SOLUTIONS: (i) Excess products should be purchased by government. (ii)
    Government should provide storage facilities to farmers at subsidized rate (iii) Farmers
    should form cooperative societies to build storage and processing facilities (iv)
    Education on usage (v) Provision of loans to farmers.
  7. LACK OF GOOD AGRICULTURAL EDUCATION: Most of the farmers in the
    developing countries are illiterate and cannot adopt new innovation in agriculture.
    SOLUTIONS: (i) Employment of more extension agents (ii) Government must
    embark on anti-illiteracy campaign (iii) Non-governmental organizations should be
    involved in educating the farmers.
  8. POOR EXTENSION ACTIVITIES: Extension workers are well-equipped for the
    dissemination of recent information in agriculture. Also there is language barrier, and
    inadequate vehicles.
    SOLUTION: (i) Provision of more vehicles to extension workers to ease
    transportation problem (ii) Employment of more extension workers (iii) Farmers should
    be trained by the extension agents on recent agricultural technology.
  9. POOR TOOLS AND FARM MACHINES: Farmers still rely on crude tools like
    cutlass, hoe, rake etc. which are time wasting, and bring low income and yield to
    farmers.
    SOLUTIONS: (i) Government should purchase farm machines like tractor,
    plough, harrow for the farmers to hire to subsidized rate (ii) Cooperative societies
    should procure machines for their members (iii) Local fabrication of farm machinery and
    equipment should be encourage (iv) Establishment of tractor hiring units (v) Training of
    skilled manpower for maintenance (vi) Provision of loan to formers.
  10. UNSTABLE POLICIES AND PROGRAMMES OF GOVERNMENT: Government
    comes with different policies and programmes which often tell on the farmers.
    SOLUTION: (i) There should be continuity of government programmes.
  11. POOR MARKETING SYSTEM: Due to lack of good roads, storage facilities, poor
    marketing channels and non-functional food commodity boards, farmers find it very
    difficult to control the price of their farm produce.
    SOLUTIONS: (i) Establishment of good and functioning marketing channels to
    discourage activities of middlemen. (ii) Government should create enabling marketing
    environment for the farms (iii) Farmers should form unions so as to control price (iv)
    Government should form functional food commodity boards (v) Government should buy
    excess produce from farmers.
  12. PROBLEM OF PESTS AND DISEASES: Diseases and pests reduce the quality
    and quantity of farm produce, and farmers income. This discourages farmers from
    further production.

SOLUTIONS: (i) Government should establish pests and diseases control units
(ii) Government should supply chemicals and insecticides to farmers at subsidized
rates.

  1. UNPREDICTABLE CLIMATE: This includes drought, excessive rainfall and
    sunshine which often reduce farm activities, and lead to low yield or crop failure.
    SOLUTION: (i) Good irrigation and drainage systems should be practices.
  2. INADEQUATE AGRICULTURAL INPUTS: They include chemicals, improved
    seeds, seedlings, animal materials and fertilizers that are scarce and expensive.
    SOLUTION: (i) Availability of fertilizers (ii) Provision of day-old chicks and other
    starting stock (iii) Government should supply farm inputs at subsidized rates. (iv)
    Cooperative societies should procure inputs, and supply to farmers at subsidized rate.
    (v) Provision of feeds. (vi) Provision of drugs and vaccines to livestock (vii) Provision of
    pesticide at subsidized rate.
  3. SOCIOLOGICAL AND PSYCHOLOGICAL ATTITUDE TOWARDS FARMING:
    Farming is being regarded as a profession for the dropouts or never do well in the
    society.
    SOLUTION: (i) Government should make agriculture more attractive to young
    people by giving them necessary inputs like land and materials for farming (ii) Mass
    literacy should be adopted.
  4. SMUGGLING: This is illegal importation and exportation of food commodities
    which often place money in the hands of few individuals.
    SOLUTION: (i) Government should encourage production of some commodities
    like rice, maize etc. (ii) Government should ban the importation of certain food
    commodities.
  5. ENVIRONMENTAL DEGRADATION: This includes environmental pollution, soil
    erosion, flooding and deforestation which often affect crop and animal production.
    SOLUTIONS: (i) Erosion control should be embarked upon by the government
    (ii) Farmers must be trained on environmental management.

1.3 HISTORY OF AGRICULTURAL DEVELOPMENT
Four stages are very pronounced. They are:

  1. Hunting and Gathering
  2. Subsistence Farming
  3. Cash Crop Production
  4. Commercial Farming
    HUNTING AND GATHERING: The early man lived by hunting wild animals and
    gathering wild fruits which was characterized by the use of primitive tools like stones,
    bows and arrows, traps, clubs and ploughs.
    SUBSISTENCE FARMING: This is a system of farming whereby a farmer cultivates
    crops and rears animals in order to produce food for use by himself and his family only.

CHARACTERISTICS OF SUBSISTENCE FARMING

  1. Labour is provided by the farmer and his family
  2. Small area is used
  3. Crude implements like cutlass, hoe etc. are used
  4. The produce from the farm are not for sale
  5. Little capital is required
  6. The yield is also very low
    CASH CROP PRODUCTION: This is advanced stage of agricultural production in which
    the farmer cultivates cash crops like cocoa, kolanut, rubber etc. for export.
    COMMERCIAL AGRICULTURE: This is a production of cash crops and animals in
    large quantity.

CHARACTERISTICS OF COMMERCIAL AGRICULTURE

  1. It is very expensive to practice
  2. Large area of farmland is required
  3. Requires the use of farm machines like cultivators, tractors etc.
  4. Labour is both manual and mechanical
  5. Yield or output is very high
  6. Marketing of products is specialized
  7. It involves a lot of research into the different aspects of production.
  8. It requires good record keeping.
    DIFFERENCES BETWEEN COMMERCIAL AND SUBSISTENCE AGRICULTURE
    Commercial Agriculture Subsistence Agriculture
  9. Large scale farming is adopted
  10. Mechanization is the major practice
  11. Ideal for monocropping, intensive
    animal production and fish farming.
  12. Highly capital intensive which can be
    got from the bank.
  13. Labour is highly specialized and
    expensive.
  14. Marketing of products is specialized
  15. Research into all aspect of agriculture
    is required.
  16. Highly scientific with no superstitious
    beliefs.
  17. Yields and other returns are high,
    meant for everybody.
  18. Processing of final products is
    common.
  19. It requires good record keeping so as
    to make good decisions.

Small scale farming is adopted
Mechanization is not practiced.
Ideal for mixed cropping, mixed farming,
bush fallowing and shifting cultivation.
Low capital requirements which can be
provided by friends, money lenders and
family members.
Labour is from friends, family members
and cheap
No special marketing skills are required.
No research activity is required.

Highly traditional and superstitious in
nature.
Yields are low, meant for family
members.

No processing of any form is practiced.

No record keeping is done and so no
improvement is expected.
2.0 ROLE OF SCIENCE AND TECHNOLOGY IN AGRICULTURE
Government from time to time has been playing an important role in order to
supply food to her citizens. The roles include:
(i) Provision of loans and credits to farmers

(ii) Provision of subsidies to farmers which are given by Government, cooperative
societies, multinational organisations and foreign agencies like Food and
Agricultural Organisation (FAO), Agricultural Development Bank (ADB) etc.
(iii) Establishment of Agricultural Programmes like:
(a) Farm settlement scheme
(b) Operation Feed The Nation
(c) Green Revolution
(d) School to Land Programme
(e) National Directorate of Food, Road and Rural Infrastructure
(f) River Basin Development Authorities
(g) Agricultural Development Project
(h) National Agricultural Insurance Scheme
(i) National Agricultural Land Development Agency (NALDA).
(j) National Accelerated Food Production
(k) Agricultural Sector Rehabilitation Project
(l) National Accelerated Industrial Crop Production Programme. (NAICPP)
(iv) Provision of storage and processing facilities
(v) Provision of social amenities like water, electricity etc.
(vi) Provision of good road
(vii) Provision of quarantine services
(viii) Provision of agricultural education and extension services
(ix) Provision of agro service centres
(x) Creation of pest and disease control unit
(xi) Establishment of research institutes
2.1 ROLES OF NON-GOVERNMENTAL ORGANISATIONS
The non-governmental organisations perform several roles in agricultural
development. They enjoy government support and assist in producing crops, high
quality planting materials and good animal breeds, provide funds agricultural extension
projects, improves farmers awareness, funding research etc. Some of these research
centres are:

  1. Cocoa Research Institute of Nigeria (CRIN), Ibadan.
  2. Rubber Research Institute of Nigeria (RRIN), Benin City
  3. National Cereal Research Institute (NCRI), Badegi.
  4. Nigerian Institute for Oil Palm Research (NIFOR), Benin city.
  5. National Institute for Horticultural Research (NIHORT), Ibadan
  6. Forestry Research institute of Nigeria (FRIN), Ibadan.
  7. National Institute for Oceanography and Marine Research (NIOMAR), Lagos.
  8. National Institute for Fisheries and Fresh Water Research (NIFFR), Kainji.
  9. National Root Crops Research Institute (NRCRI), Umudike Umuahia.
  10. Nigerian Stored Products Research Institute (NSPRI), Ibadan.
  11. National Veterinary Research Institute (NVRI), Ibadan.
  12. National Institute for Trypanosomiasis Research (NITR), Kaduna.
  13. International Institute of Tropical Agriculture (IITA), Ibadan.
  14. Leather Research Institute of Nigeria (LRIN), Zaria.
  15. Lake Chad Research Institute (LCRI), Maiduguri.
  16. Institute of Agricultural Research (IAR), Zaria.
  17. Institute of Agricultural Research and Training (IART), Ibadan.
    Other research Institutes around Africa are:
  18. West Africa Rice Development Agency (WARDA), Sierra Leone.
  19. Catholic Relief Services in Gambia.
  20. International Livestock Centre for Africa (ILCA)
  21. International Crop Research Institute for Semi-Arid Tropical (ICRISAT)
  22. Adventist Relief Agency in Gambia & Ghana.
  23. Food and Agricultural Organisation (FAO)
  24. Hinger Project, and
  25. World Vision International in Ghana.
    3.0 AGRICULTURAL LAWS AND REFORMS
    This area is concerned with the laws guiding the acquisition and utilization of
    agricultural lands.
    3.1 LAND TENURE SYSTEMS IN WEST AFRICA
    Land tenure can be defined as the economic, legal, political arrangement regarding the
    ownership and management of land and its resources. It can be broadly classified into:

(i) Communal/primitive ownership
(ii) Inheritance
(iii) Individual
(iv) Leasehold Rent
(v) Gas
(vi) Freehold
(vii) Tenant at government will.
COMMUNAL LAND TENURE: This is a system where land belongs to a community
and the head decides the basis or sharing out land to every adult member.

Advantages
(1) Every adult member has right to use the land.
(2) It is cheap
(3) It is ideal for commercial farming
(4) Cooperative farming can be practised.

Disadvantages

(1) Non-indigenes cannot acquire land
(2) Sale of land not allowed
(3) It cannot be used obtain loan
(4) Unmarried women me
(5) Alloted land can be revoke by a new leader
(6) It leads to the fragmentation of land into small and scattered units.
INDIVIDUAL LAND TENURE: This is a system of ownership where the land can be
acquired by an individual either male or female.
Advantages

(1) Male and female can acquire any size of the land based on the financial resources
available (2) Permanent crops can be cultivated (3) Land can be used as a collateral for
loan (4) There is no discrimination in securing land (5) The owner has authority as to
how the land is used.

Disadvantages
(1) Only the rich may acquire land at certain areas
(2) Land may be diverted to non-agricultural use

(3) Land may be acquired in fragments.
INHERITANCE TENURE SYSTEM: This is a system where a piece of land is
transferred from one generation to another generation.
Advantages

(1) This is open to agricultural use (2) Permanent crops can be cultivated (3) Land can
be used as collateral for loans (4) Children yet unborn are provided for (5) The land can
be maintained by using fertilizer.

Disadvantages

(1) It leads to land fragmentation (2) The size of land alloted may not be good for
commercial farming (3) Sharing of land is a delicate issue that brings enmity among
family members (4) Sale of land is not accepted in some families (5) Women are not
often listed as beneficiaries during land allocation.
LEASEHOLD TENURE SYSTEM: This is a contract existing between a person called
the LEASOR and another called LEASEE for the lease of the land for a specified period
of years which may be 25 years, 50 years or 99 years.
Advantages

(1) It enables the farmer to have maximum use of land (2) It is available for permanent
crop cultivation (3) An agreed sum of money is paid for the period of lease.

Disadvantages

(1) The farmer cannot develop the land beyond the lease agricultural terms (2) Land on
lease cannot serve as collateral security for loan (3) A lease agreement of less than 50
years is not ideal for permanent crops.
GIFT TENURE SYSTEM: This is a system in which a piece of land is given out by a
person voluntarily to another for the good work done by that person.

Advantages

(1) Land on gift is irredeemable (2) Permanent crops and record keeping are accepted
(3) Land can be used as collateral security for loan (4) It ensures the maximum use of
the land for increased production.

Disadvantages

(1) The ownership of the land can be challenged at any time if given unwisely (2) If the
land given by Government is not backed by proper documentation, it can be retrieved
(3) There may be disagreement over such gift among family members
RENT TENURE SYSTEM: This is a system whereby a period of using the land tenant
pays some amount for the period of using the land to a stated landlord and is usually a
short period of compared to leasehold system.
Advantages

(1) Ideal for food production (2) The farmer makes maximum use of the land during
rentage period.

Disadvantages

(1) It affects long term planning (2) Development on the land is very slow (3) The land
cannot be used as security for loan.
PURCHASE OR FREEHOLD TENURE SYSTEM: This is a system whereby a person
pays a certain sum of money for land acquisition.
Advantages

(1) It can be used for agricultural purpose (2) Perennial crops can be grown (3) There is
a maximum use of land to increase production (4) It is open to both male and female to
acquire land (5) The land can be used to source for loan.
Disadvantages

(1) Land may be expensive (2) Size of fertile land may be too small (3) Prospective
farmers may not have access to the agricultural land (4) Farmers may fall into the hand
of fraudsters when negotiating for the land.
TENANTS AT GOVERNMENT WILL: This system where a piece of land is given out to
farmers by government by paying a stipulated amount of money.

Advantages

(1) Poor and rich farmers have access to the land (2) The land is widely used for
production purposes (3) The land is cheap to acquire.
Disadvantages

(1) Permanent crops cannot be grown (2) It cannot be used as collateral to secure loans
(3) There are usually lots of bureaucracy in the allocation, regulation and control over
such land (4) The land can be revoked if the farmer fails to meet the term of agreement.

LAND USE DECREE: The land use decree was enacted by Gen. Olusegun Obasanjo
(Rtd) on 28th March, 1978 but was reversed under Land Use Act 1990. The Land Use
Decree of 1978 vested land ownership in the country on the Federal Government of
Nigeria. The State Governments were empowered to allocate land to individuals on
behalf of the Federal Government. For a person to claim ownership of land, such a
person must obtain certificate of occupancy which will guarantee the true ownership of
such land. Adult Nigerians of 21 years and above have a right to acquire land.

AIMS OF THE LAND USE DECREE

(i) To encourage efficient use of the land
(ii) To create and re-allocate land opportunities for farmers
(iii) To reduce the controversies over the use of land
(iv) To manage all the land resources within the nation
(v) To bring about proper planning of land uses

Advantages Of Land Use Decree

(1) It has made land acquisition relatively easier for new entrants into agriculture (2) It
has reduced the number and frequency of court cases over land ownership (3) It has
facilitated borrowing of capital for further investment in agriculture (4) Availability of and
provision for large land holdings encourages large scale agriculture (5) It prevents
fragmentation of land since land acquired under the decree cannot be shared into bits
(6) Reduction in boundary disputes since survey of acquired land is mandatory for
occupying rights to be granted.

Disadvantages Of Land Use Decree

  1. Cost of land survey has escalated (2) Land acquisition process has become
    bureaucratic and often met with bottlenecks (3) It has encouraged dishonesty through
    illegal sale and back-dating of ownership/title deeds after 1978 (4) Land is not
    necessarily allocated to every potential agricultural developer (5) Land may be acquired
    by influential people for non-agricultural purposes (6) The state governor can abuse his
    power by revoking the certificate of occupancy prematurely (7) It may delay the
    execution of projects as the governor might not sign the certificate of occupancy on
    time.
    REASONS FOR GOVERNMENT TO ENFORCE THE LAND USE LEGISLATION
  2. Security of tenure: To safeguard farmers against unreasonable eviction.
  3. Ensuring proper land use: Action can be taken to ensure that agricultural land is
    not unnecessarily diverted for non-agricultural purpose.
  4. Government projects: Large tracts of land for government sponsored development
    of large-scale farms or resettlement schemes.
  5. Land improvement: There is the need to carry out large scale improvement such as
    irrigation, drainage, soil water conservation in order to ensure a reasonable standard
    of efficient production for a long time, and such a requirement should be obligatory
    irrespective of land tenure system.
  6. Influence on size of holdings: The need to prevent land fragmentation and
    encourage consolidation of small holdings into large units
  7. Freedom of enterprise: To encourage freedom of farming in cases where there are
    regulations or traditional views that militate against such freedom.
  8. Control of production: Government can insist on production of certain produce and
    curtail the production of others through the control of land use
  9. Land litigation: Government intervention reduces the number of land litigation
    amongst the citizens.

SECTION B: AGRICULTURAL ECOLOGY

4.0 LAND
Land is defined as the solid part of the earth crust in which agricultural activities can be
practised.

CHARACTERISTICS OF LAND

(1) It is a free gift of nature (2) It is limited in supply (3) It is immobile (4) It can
appreciate and depreciate in value. (5) It is subject to the law of diminishing return (6)
The reward for land is rent.
4.1 USES OF LAND
Land has two major uses:
(1) Agricultural land (2) Non-agricultural land

Agricultural Uses Of Land

  1. For production of food crops 2. For forestry 3. For wildlife and games reserve 4. For
    fishery 5. For livestock grazing

Non-Agricultural Land Use

(i) For construction of roads, bridges, railway lines, airport etc (ii) For social/recreational
centres such as cinema houses, amusement parks, churches, mosques, schools,
hospitals, cemeteries, markets, stadia, etc. (iii) For building offices, residential houses,
banks etc. (iv) For industrial building (v) For mining.
4.2 FACTORS AFFECTING LAND AVAILABILITY
(1) Land tenure system (2) Population size (3) The size of useful land in a country (4)
Climatic factors (5) Religious beliefs (6) Soil factors (7) Topography (8) Cultivation
practices (9) Infrastructural demands on land (10) Government policy.
4.3 AGRO-ALLIED INDUSTRIES
Agricultural Raw Materials Industries

  1. Cotton Textile and pharmaceutical
  2. Cotton seed Vegetable oil, livestock feed mill
  3. Coffee seed Beverage and pharmaceutical
  4. Groundnut seed Soap, livestock feed mill, vegetable oil
  5. Palm kernel Vegetable oil, soap, livestock feed oil
  6. Maize seed, rice, wheat & sorghum Beverage, bakery/flour mill, livestock, feed mill
  7. Tomatoes and pepper Food processing/canning
  8. Citrus and Banana Beverage
  9. Rubber latex Plastic, tyre, shoe manufacturing
  10. Coconut Beverage, soap
  11. Cocoa Beverage, food processing, pomade/body

cream

  1. Kolanut Beverage, pharmaceutical
  2. Timber Furniture, matches, stationery
  3. Jute Textile and rope
  4. Sugarcane Food processing
  5. Cattle & its products Shoe, food processing, dairy, livestock feed
    mill
  6. Fowls Fertilizer, food processing
  7. Sheep Textile, shoe, food processing
  8. Goat Shoe, livestock feed mill, dairy
    4.4 RELATIONSHIP BETWEEN AGRICULTURE AND INDUSTRY
  9. Agriculture provides food for industrial workers.
  10. Industries produce machinery and equipment for agricultural use.
  11. Agriculture can provide market for industrial products,
  12. Agriculture and industry compete for labour
  13. Rise in agriculture bring about good development in agricultural sector.
  14. Agriculture provides raw materials for industries.
  15. Industries provide a large range of products for the farmer to buy
  16. Industries produce agro-chemical for agricultural use.
  17. Industries provide storage facilities for agricultural produce.
  18. Agriculture allows a shift of factors of production to industries.
    5.0 ENVIRONMENTAL FACTORS AFFECTING AGRICULTURAL PRODUCTION
    Environmental factors affecting agricultural production are: (a) Climatic factors (b) Biotic
    factors (c) Edaphic factors. Climatic Factors: The following are climatic factors that
    affect agricultural production.
    (1) Temperature (ii) Sunlight (iii) Wind (iv) Rainfall (v) Relative humidity (vi) Cloud cover.
    Biotic Factors: These are living things and include (i) Parasites (ii) Soil micro-
    organisms (iii) Weeds (iv) Pests and diseases (v) Competition (vi) Predation (vii)
    Symbiosis.
    Edaphic Factors: These are soil factors and the major factors are: (i) Soil pH (ii) Soil
    texture (iii) Soil structure (iv) Topography (v) Soil fertility/organic matter (vi) Soil type.
    6.0 ROCK FORMATION
    A rock is a hard-compact mass made up of clusters of minerals. Rock minerals are
    classified into two:
    (i) Primary Rock Minerals – Quartz, Feldspar (orthoclase and plagioclase), Mica
    (Muscovite, Biotite), Olivine, Haematite, Limonite, Hornblende, Pyroxene etc. (ii)
    Secondary Rock Minerals – Oxides of metals (sodium oxide), Mortmorilonite.
    6.1 TYPES OF ROCK
    Igneous Rock: They are formed from the cooling of molten magma which cools and
    solidifies within or outside the earth surface. The two major types of igneous rock are

plutonic or intrusive igneous rocks (e.g granite, diorite, gabbro, syenite) and volcanic or
extrusive igneous rocks (eg basalt).
Sedimentary Rock: They are formed from pre-existing sedimentary, igneous or
metamorphic rocks, acted upon by agents of geological denudation such as rain, wind,
ice, flood, stream etc. and then deposited in a new place.
There are three major types:
(a) Mechanically Formed/Classic Sedimentary Rocks: Sedimentary rocks formed
from deposits of weathered rocks particles carried by wind, water and ice e.g pebbles
breccia, conglomerate, sandstone grit,clay, mudstone and shale.
(b) Chemically Formed/Non-Classic Sedimentary Rocks: Sedimentary rocks formed
from series of reactions between ocks and water e.g. Gypsum, Dolomite, livestock or
chalk, potash, iron (iii)oxide, common salt etc.
(c) Organically/Biologically formed Sedimentary Rocks: These are rocks formed
from dead decaying remains of plants and animals e.g. coal, peat, lignite etc.
7.0 FORMATION, COMPOSITION AND PROPERTIES OF SOIL
Soil can be defined as the loose weathered material covering the surface of the earth
which supports life.
7.1 FACTORS THAT DETERMINE SOIL FORMATION
There are five major factors that determine or influence soil formation. These are;
(1) Climate (2) Living organisms (3) Relief or topography (4) Parent material (5) Time
7.2 PROCESSES OF SOIL FORMATION
This refers to all the activities that will lead to the weathering of rocks.
Weathering Of Rocks: This is defined as the disintegration of rocks into tiny particles
to form soil. The processes of soil formation include the following: 1. Physical processes

  1. Chemical processes 3. Biological processes
    Physical Processes: This is the breaking down of rocks due to expansion and
    contraction caused by heating and cooling which results in cracks and disintegration of
    rocks by ice, water/rainfall, temperature, wind and pressure.
    Chemical Processes: This is simply the reaction of rock minerals with water. The
    processes include hydrolysis, hydration, solution, carbonation, oxidation and reduction.

Biological Processes: This involves the activities of plants and animals in the breaking
down of rocks to form soil.
7.3 COMPOSITION OF SOIL
The soil consists of the following components and their volumes.
Components Volume
(i) Inorganic/mineral water 45%
(ii) Organic matter 5%
(iii) Scil air 25%
(iv) Soil water 25%
(v) Microorganism Insignificant
7.4 TYPES OF SOIL AND PROPERTIES
There are three major types of soil particles: sand, clay and loam.
Sandy Soil: This is a type of soil in which sand particles are much more than the other
soil particles. The range in diameter is 2.00mm and 0.02mm.
Properties: (1) It is coarse grained (2) It is gritty (3) Leaching is high (4) Low capillary
action (5) It is not sticky when wet and therefore cannot be moulded (6) High percolation
(7) It easily gets hot and cold (8) It is usually white in colour (9) It can easily be worked
with.
Clayey Soil: This is a soil type which contains more than 40% clay with a mixture of
fine sand and silt. The relative range in diameter is 0.002mm.
Properties: (1) It is fine grained (2) It is plastic in nature (3) High water holding (4)
Poorly drained and aerated (5) Percolation is low (6) When dry, it is hard and cracks but
when wet, it is highly sticky and can be moulded. The colour is usually light brown (8)
Capillarity is high 19) It is difficult to work with (10) The particles are tightly bound
together with little pore spaces.
Loamy Soil: This is a combination of sand, clay and silt soil on a fair balance.
Properties: (1) Rich in plant nutrients (2) High water ng capacity (3) They are friable (4)
Well aerated (5) Low on rate (6) High capillarity (7) Withstand moderate holding
capacity percolation rate (6) periods of drought (8) Erosion and waterlogging not
possible (9) Its colour is brown/dark brown/black (10) It is classified as heavy, light or
medium.

Special Categories Of Soil

These are formed by the combination of one, two or all of the above soil particles e.g.
(a) Silt Soil: This is mid-way between sand and clay, it is smooth and powdery, has a
large surface and increases the water holding capacity.
(b) Silt Loam: This is the soil particle in which the quantity of silt is more than other soil
particles. It is moderately plastic, sticky to touch and has a smooth soap feel.
(c) Clayey Loam: It has more clay, distinctly sticky and plastic.
(d) Sandy Loam: The quantity of sand is higher than other soil particles. It is well
drained, highly workable and cannot be moulded.
(e) Silt Clay: This has a smooth slimy feel from the silt content and is also sticky from
the clay content
7.5 PHYSICAL PROPERTIES OF SOIL
This includes soil structure, soil temperature, soil porosity, soil pH and soil organism.
(a) Soil Structure: This is the arrangement of soil particles into various aggregate sizes
and shapes.
Importance: (1) Prevents soil erosion and waterlogging (2) Determines soil porosity (3)
Determines the rate of percolation in the soil. (4) It improves seed germination (5)
Determines level of fertility in a soil (6) Determines the availability of soil micro-
organisms.
METHODS OF PRESERVING SOIL STRUCTURE:
(1) Planting cover crops (2) Mulching (3) Application of manure (4) Avoiding overgrazing
(5) Application of lime fertilizer (6) Preventing & controlling erosion (7) Avoiding clean
clearing and bush clearing (8) Reducing activities of machines.
Types Of Soil Structure

(i) Single grained structure (ii) Crumb form (ii) Granular form (iv) Prismatic form (v)
Plate-like form (vi) Block form (v) Coherent form.
(b) Soil Texture: This refers to the relative proportion of various sizes and groups of
individual soil grains in a mass of soil OR is the relative proportion of different sizes of
mineral particles in the soil.

Importance of Soil Texture:

  1. Determine the type of crops to be cultivated in a farmland.
  2. Determines the degree of coarseness or fineness of a soil sample.
  3. Determines the nutrients availability in the soil
  4. Determines the rate of percolation and leaching in the soil.
  5. Determines the type of tillages to be used by the farmer.
  6. Determines the proportion of air and water in the soil.
  7. Determines the level of erosion in the farmland
  8. Can reveal different types of soil particles.
    METHODS OF DETERMINING SOIL STRUCTURE
    (a) Field method – (i) Feel method and (ii) Moulding method.
    (b) Laboratory method includes
    (i) Sieve method (ii) Sedimentation method

Size Or Fractions Of Various Soil Types

Fractions Size (in mm)
Stone Greater than 200mm
Gravel 200 – 20mm
Fine gravel 20 – 2mm
Coarse sand 2 – 0.2mm
Fine sand 0.2 – 0.02mm
Silt 0.02 -0.002mm
Clay Less than 0.002mm
(c) Soil Temperature: This is a measure of energy level in the soil.
Effects Of Temperature On Living Things

  1. Determines the rate of seed germination and root development
  2. Low temperature reduces metabolic activities and enzymatic reaction.
  3. High temperature affects the activities of microorganisms
  4. Affects the decomposition of soil organic matter
  5. Affects formation of soil organic matter.
  6. Affects population of soil microbes.
    (d) Soil Porosity: This helps to determine the rate of water infiltration and the amount
    of water and air in the soil

(e) Soil pH: This is a measure of hydrogen and hydroxyl Ion concentration in the soil or
is the degree of acidity or alkalinity in the soil.

Effects Of Soil Acidity On Soil And Plant:

  1. Causes disintegration of clay from the soil.
  2. Accumulation of aluminium and manganese in the soil.
  3. Influences nutrient availability for plant growth
  4. Dictates crops grown on the soil.
  5. Hinders the growth of micro-organisms and activity
    Causes Of Soil Acidity

(1) Leaching (2) Presence of sulphur (3) Crop removal (4) Application of excess
fertilizers e.g. Ammonium tetraoxo-sulphate vi (5) Acid rain, especially in petroleum
exploring areas.

Control Of Soil Acidity

(1) Application of lime, like limestone (CaCO 3 ), slaked lime (Ca(OH) 2 ). Quicklime (CaO),
calcium hydrogen trioxocarbonate (IV) (CaHCO 3 ) dolomite, gypsum and basic slag (2)
application of woodash (3) Application of manures like compost, green and farmyard
manures.

Determining Soil pH

(1) Use of litmus paper (2) Use of BDH universal soil indicator (3) Using printed colour
standards (4) Using universal indicator paper (5) Soil pH colourimetrically (6) Use of
electrometric method.
pH Scale: This is graduated from 0 to 14.

The pH scale can be analysed below
pH 2 = strongly acidic
pH 6 = slightly or weakly acidic
pH 7 = neutral
pH 8 = slightly alkaline or weakly alkaline
pH13 = strongly alkaline

pH 5 – 5 – pH 7.5 = best pH for plant and soil organisms.
(f) Soil Organisms: These are smaller microscopic organisms and other higher
organisms living in the soil, they include plants and animals. It may be beneficial or
harmful to crops and animals. Examples are Macro-organisms (earthworms, snails,
insects, centipedes, millipedes, rodents etc) and Micro-organisms (e.g fungi, bacteria,
viruses and nematodes).

Effects/Importance of Soil Organisms

  1. They are vectors of diseases.
  2. And the decomposition of dead organic matter in the soil.
  3. Improves soil structure.
  4. Add nutrient to the soil.
  5. Essential in breaking down of rocks
  6. Helps in burrowing thereby leads to good soil aeration and water movement
  7. Effects chemical changes in the carbon and nitrogen cycles.
    7.6 SOIL PROFILE
    This is the vertical section of the soil from the surface into the underlying

IMPORTANCE OF SOIL PROFILE

  1. It helps to determine the best soil suitable for agriculture.
  2. It determines the level of soil fertility.
  3. It determines the level in which water can be available in the soil.
  4. It determines the types of mineral salt available to plants.
  5. A loosely packed sub soil reduces erosion and soil run off.
  6. It determines easy penetration of roots of crops.
    7.7 SOIL WATER

This is the total amount of water present in the soil and available to crops.
FORMS OF WATER EXISTING IN THE SOIL

  1. Hygroscopic Water: Water held tightly in-between soil particles due to lack of
    sufficient water in the soil. It is got from atmospheric water vapour.
  2. Capillary Water: Water that rises above the water table in the soil.
  3. Field Capacity: Water left in the soil after evaporation and drainage have occurred.
    The soil will be slightly wet.
  4. Gravitational Water: Water that drains through the soil under the influence of the
    force of gravity.

IMPORTANCE OF SOIL WATER

(1) Needed for plant growth
(2) Helps in cooling soil
(3) Absorption of mineral salts
(4) Helps in transportation ci nutrients to other parts of plant
(5) Serves as raw material for photosynthesis
(6) Promotes activities of soil microbes
(7) Neutralises the effects of high temperature
(8) Helps to maintain plant tugor.

Processes By Which Soil/Plants Lose Water

(1) Evaporation from soil surface (2) Run-off from soil surface (3) Drainage (4) Erosion
(5) Transpiration from the openings in the leaves, stems and fruits.
Sources Of Water In The Soil

(1) Through irrigation (2) Rainfall (3) High humidity
7.8 SOIL AIR
This is the amount of air present in the soil pore spaces The components of air are
oxygen, carbon (IV) oxide, and water vapour. Air can be found only if the soil is no
waterlogged.

Importance of Soil Air

(1) Essential for respiration in plants (2) Hasten the germination of seeds (3). Essential
constituent of photosynthesis (4) Helps in the absorption of plant nutrients (5) Needed

by micro-organisms for respiration (6) Determines the relative proportion of water in the
soil (7) Essential for root development.
8.0 PLANT NUTRIENTS
Plant nutrients are the nutrients or elements required by the plants for growth,
maintenance and development. Plant nutrients are divided into two groups: (a) Macro
Nutrients or Major Nutrients (b) Micro Nutrients or Minor or Trace Nutrients.
Macro Nutrients: These are the mineral salts required in large amount and their
deficiency can easily manifest on the plants e.g. nitrogen, phosphorus, potassium,
calcium, magnesium and sulphur.
Micro Nutrients: These are mineral salts required in small quantity, and their deficiency
does not easily manifest but can manifest on the animals feeding on such plants e.g.
carbon, iron, manganese, molybdenum, boror. zinc, cobalt, copper and chlorine.
NOTE: Iron is a trace element in plants but a major element in animals.
FUNCTIONS AND DEFICIENCY SYMPTOMS OF PLANT NUTRIENTS
Elements Sources Excess
causes

Functions Deficiency

Nitrogen
(N)

  1. Fertilizer
    like
    (NH4NO3)2
  2. Action of
    thunder &
    lightning
  3. Organic
    manures like
    compose
    green manure
    etc.
  4. Excessive
    vegetative
  5. Growth
  6. Fruiting &
    ripening of
    fruits will be
    delayed.
  7. Maturity can
    also be
    enjoyed
  8. For growth &
    development of
    plant.
  9. For protein
    formation in
    plants.
  10. Promotes
    vegetative
    growth
  11. Encourages
    photosynthesis
  12. Necessary for
    reproduction
    Loss of nitrogen
    results in
  13. Stunted
    growth
  14. Older leaves
    turn yellow or
    chlorosis
  15. The leaves
    land to drop

erosion,
leaching, crop
removal, burning,
denitrification of
soil nitrates, &
through nitrite

Phosphoru
s (P)

  1. Fertilizer
    like NPK
  2. Woodash
  3. Organic
    manures
  4. Single
    sulphate
    fertilizer

Leads to iron.
Iron deficiency

  1. Essential for
    growth &
    development
  2. Necessary for
    crop
    maturation
  3. Essential for
    seed & fruit
    formation
  4. Essential for
    flowering &
    root
    development
  5. Increases
    crop
    resistance to
    diseases &
    prevent
    lodging in
    cereal
  6. Retarded &
    stunted
    growth
  7. Dull greyish
    green &
    purple of
    leaves.
  8. Lodging
    results due to
    poor root
    development
  9. Inhibition of
    flowering
    fruits & seed
    formation.

Potassium
(K)

  1. Wood ash
  2. Organic
    manure
  3. Oil palm
    bunch
  4. Helps in
    carbohydrate
    formation
  5. Preventing
    lodging by
  6. Weak &
    slender stem
  7. Premature
    leaf fall
  8. Stunted
  9. Rock
    minerals
    like mica,
    feldspar &
    albite

strengthening
the straw &
stalk quality

  1. Helps in the
    opening of
    stomata
  2. Activates
    various plant
    enzymes.
  3. Necessary for
    starch
    translocation.

growth

  1. Lodging in
    plants
  2. Brown leaf
    margin

Calcium
(Ca)

  1. Rock
    minerals
    e.g.
    feldspar
    calcite,
    dolomite.
  2. Wood ash
  3. Bone meal
  4. Basic slag
  5. Rock
    phosphate
  6. Leads to
    alkalinity
  7. Reduces
    boron
    utilization
    by plants
    3.

Phosphoru
s
unavailable
to plants

  1. Controls
    toxicity of
    aluminium,
    calcium and
    sodium
  2. Strengthens
    plant cell
    walls
  3. Necessary for
    the normal
    growth of root
    tips
  4. Improves the
    soil pH
  5. Helps in high
    flocculation
  6. Causes
    acidity
  7. Weak slender
    plants
  8. Pale yellow
    colour of the
    leaves
  9. Stunting of
    the root
    system

Magnessiu
m (Mg)

  1. Rock
    minerals
    e.g. mica,
  2. Necessary for
    photosynthesis
  3. Helps in
  4. Chlorosis
  5. Stunted
    growth.

dolomite
etc.
2.

Magnessiu
m salts

  1. Lime
    fertilizers

transportation
of phosphate
ions hence its
importance in
oil crop.

Sulphur (S) 1. Rock
minerals
like pyrite,
gypsum
MgSO4.

  1. Manures

Leads to
acidity in the
soil & in plants

  1. Essential for
    chlorophyll
    formation.
  2. For
    carbohydrate
    metabolism &
    nitrogen
    fixation by
    legumes
  3. Chlorosis
  4. Stunted
    growth
  5. Disturbed
    photosynthesis

Fertilizer
containing
iron, applied in
form of spray
to the leaves

Reduces
availability of
certain alkaline
mineral salts

  1. Necessary for
    chlorophyll
    formation.
  2. Essential for
    the synthesis
    of protein
    contained in
    the
    chloroplast.
  3. Important in
    enzyme
    systems for
    oxidation-
    reduction

Chlorotic
condition in
leaves which
become pale
green

reactions.
Cobalt (Co) Fertilizers Essential for the
symbiotic fixation
of nitrogen in
legumes

Lack of nitrogen
fixation in
legumes.

Manganese
(Mn)

Fertilizers Disturbs iron
availability to
plants

  1. Essential for
    certain
    nitrogen
    transformatio
    n in plants &
    microorganis
    m.

Pale greenish
discolouration
between veins of
young leaves

Copper
(Cu)

  1. Fertilizers
  2. Manures
  3. Iron
    unavailable
    2.

Molybdenu
m will be
deficient

  1. Necessary for
    photosynthesis
  2. Constituent of
    certain
    enzymes
  3. Involved in
    respiration,
    and utilization
    of iron
  4. Pale green
    colour of
    leaves
  5. Young leaves
    tips die-back
  6. The tip of
    older leaves
    dry of and die

Zinc (Zn) 1. Fertilizers

  1. Manures
  2. Iron
    unavailable
    to plants
  3. Essential for
    formation of
    some growth
    hormones.
  4. Aids in
    reproduction
    process of
    certain plants.
  5. Necessary for
    the action of
  6. Production of
    mottled
    leaves
  7. Small leaves
    are
    produced.

certain
enzymes.

Boron (B) 1. Fertilizers

  1. Manures
  2. Promotes the
    growth of root
    tip
  3. Promotes the
    growth of
    shoot tip
  4. Flower bud
    may fail to
    develop
  5. Death of roof
    & shoot tip.
  6. The rate of
    water is
    reduced.

Molybdenu
m (Mo)

  1. Fertilizers
  2. Manures
  3. Essential
    for nitrogen
    fixation in
    legumes
  4. Increase
    the pH
    level in the
    soil
  5. Promotes
    nitrate
    metabolism
    into amino
    acids and
    proteins
  6. Retarded
    growth in
    legumes
  7. Necrosis of
    leaf tissue.

8.1 FACTORS AFFECTING NUTRIENT AVAILABILITY IN THE SOIL
Nutrient availability is influenced by several factors and these include:
(1) Soil pH (2) The presence of other nutrients (3) Leaching (4) Crop removal (5)
Oxidation and reduction (6) Burning (7) Erosion.
8.2 METHODS OF REPLENISHING LOST NUTRIENTS

Several methods have been adopted by the present-day farmer to maintain the fertility
of the soil either by conserving them or replacing lost nutrients. The methods include the
following:
(1) Bush fallowing (2) Cover cropping and shade trees (3) Liming (4) Fertilizers (5) Corp
rotation (6) Manuring
8.3 WAYS IN WHICH SOIL NUTRIENTS ARE LOST
(1) Erosion (2) Leaching (3) Crop removal (4) Burning (5) Oxidation and reduction
reactions.
8.4 NUTRIENT CYCLES
Nutrient cycle is the circulation of nutrients between atmosphere and the earth.
A. NITROGEN CYCLE

EXPLANATION OF NITROGEN CYCLE

  1. Nitrogen Fixing: During thunderstorm and lightning, the atmospheric nitrogen gas is
    released and converted into soil nitrate. Also the atmospheric nitrogen is captured by
    root module bacteria and converted into soil nitrate.
  2. Putrefaction: The plants and animals that take nitrogen die and decay to form some
    organic acids
  3. Ammonification: Decomposition and conversion of organic materials to ammonium
    compounds.
  4. Nitrification: Involves two stages (1) Ammonium compounds are converted into
    nitrite by nitrosomonas bacteria (2) Conversion of nitrite into nitrate by nitrobacter.
  5. Oxidation: The addition of oxygen to nitrite to form nitrate by nitrobacter. It is the
    second stage of nitrification.
  6. Denitrification: The unabsorbed soil nitrate is converted into atmospheric nitrogen
    by nitrogen fixing bacteria (AZOTOBACTER).

IMPORTANCE OF NITROGEN CYCLE

  1. It adds nitrogen to the soil for the plant use
  2. It improves the soil fertility through the decomposition of plants and animals into
    humus.
  3. The bacteria decomposes plant residues to release nitrogen to the soil.

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