Environmental Factors Affecting Agricultural Productivity and Distribution – SS2 Agricultural Science Lesson Note (First Term)

Environmental factors are the conditions around crops and animals that decide how well they grow and where they can be raised.

What are the groups of environmental factors?

There are three groups of environmental factors: climatic, biotic and edaphic.

• Climatic factors: rainfall, drought, temperature, wind, sunlight and humidity.
• Biotic factors: living things such as soil organisms, pests and parasites.
• Edaphic factors: soil and land features such as pH, texture, structure, topography and fertility.

Behavioural objectives

By the end of the lesson, students should be able to:

1. name the three groups of environmental factors that affect agricultural production;
2. explain how rainfall, drought, temperature, wind, sunlight and humidity affect crops and animals;
3. state the effects of soil organisms, pests and parasites on agricultural production;
4. explain how soil pH, texture, structure, topography and fertility affect agricultural production;
5. compare sandy, clay and loamy soils.

What are climatic factors affecting agricultural production?

Climatic factors are the elements of climate, the average weather of a place over a long period, that affect crops and animals.

The main climatic factors are rainfall, drought, temperature, wind, sunlight and humidity.

How does rainfall affect agriculture?

Rainfall is water that falls from clouds to the earth after water vapour in the air condenses.

• Distribution: it decides which crops and animals can be raised in an area.
• Germination: seeds need moisture to germinate.
• Nutrient supply: it dissolves nutrients so that plants can take them up.
• Leaching: excessive rain washes nutrients down beyond the reach of roots.
• Vegetation: it determines the type of vegetation in an area.
• Seasons: it decides the wet and dry seasons in Nigeria.
• Shortage: insufficient rainfall causes crop failure and poor yield.

How does drought affect agriculture?

Drought is a period of lack of rainfall, or insufficient rainfall, in an area.

• Flowering: it delays flowering and causes flower abortion.
• Establishment: it causes poor crop establishment.
• Leaf area: it reduces leaf area.
• Dehydration: protoplasm dries out and body processes slow down.
• Photosynthesis: it is reduced, so less green matter is produced.
• Wilting: plants lose water and droop.
• Death: severe drought kills plants and causes crop failure.

How does temperature affect agriculture?

Temperature is the degree of hotness or coldness of a place.

• Germination: seeds need suitable warmth to germinate.
• Distribution: it affects where crops and animals can be raised.
• Growth: very hot or very cold conditions do not favour plant and animal growth.
• Dormancy: unfavourable temperature may make seeds and plants go dormant.
• Ripening: it affects the ripening and maturity of crops.
• Water loss: high temperature increases evapotranspiration and wilting of field crops.
• Soil microbes: it affects microbial activity in mineralisation.
• Nutrient loss: high temperature causes loss of some soil nutrients by volatilisation.
• Livestock: high temperature reduces performance and can cause abortion in farm animals.
• Poultry: heat stress causes egg drop in laying birds.

How does wind affect agriculture?

Wind is air in motion.

• Erosion: high wind speed causes wind erosion.
• Dispersal: it carries seeds and fruits to new places.
• Pollination: it helps the pollination of some crops, such as maize.
• Diseases: it spreads spores and other disease agents.
• Rainfall and seasons: it helps to distribute rainfall and bring changes in season.
• Crop damage: strong wind damages crops, for example by lodging (crops falling over).
• Water loss: it increases evapotranspiration.

How do sunlight and sunshine affect agriculture?

Sunshine is the amount of heat and the length of time the sun’s rays reach a place.

• Photosynthesis: plants need sunlight to make food.
• Photoperiodism: the length of day affects flowering and productivity of crops.
• Evapotranspiration: sunlight increases water loss from soil and plants.
• Animal behaviour: light affects the rising and roosting of animals.
• Poultry: day length affects the rate of egg production.
• Drying: solar radiation dries crops such as grain, cassava chips and cocoa beans.
• Farm power: solar radiation is a source of energy on the farm.
• Heat stress: high intensity of sunshine causes heat stress in animals.

How does humidity affect agriculture?

Relative humidity is the amount of water vapour in the air compared with the most the air can hold at that temperature, shown as a percentage.

• Rain formation: moisture in the air leads to the formation of rain.
• Crop choice: it determines the type of crops grown in an area.
• Performance: it affects the performance of plants and animals.
• Mouldiness: high humidity makes feed and poultry litter mouldy.
• Pathogens: high humidity favours the growth of disease-causing organisms.
• Heat stress: high humidity makes it hard for cattle, poultry and pigs to cool down.
• Intake: it affects feed and water intake in animals.
• Aridity: low humidity causes dryness of the air and land.

What are biotic factors affecting agricultural production?

Biotic factors are the living organisms that affect crops and animals, and they include soil organisms, pests and parasites.

How do soil organisms affect agriculture?

Soil organisms are the living things in the soil, such as bacteria, fungi, earthworms, rodents and termites.

• Diseases: some bacteria and fungi cause diseases of crops and animals.
• Soil structure: earthworms and termites aid aeration and percolation of the soil.
• Nitrogen fixation: bacteria in root nodules of legumes fix nitrogen for the plant and the soil.
• Humus: they decompose plant materials to form humus, which improves fertility.

How do pests affect agriculture?

Pests are organisms that attack and damage crops, animals or stored produce, such as insects, rodents, birds and some mammals.

• Yield: they reduce the yield of crops and animals.
• Quality: they reduce the quality of crops and animals.
• Vectors: some carry and spread diseases.
• Income: they reduce the income of farmers.
• Cost: they increase the cost of production because of control measures.

How do parasites affect agriculture?

Parasites are organisms that live on or in another living organism (the host) and feed on it.

• Examples in animals: ticks, liver flukes and tapeworms.
• Examples in plants: dodder and mistletoe.
• Diseases: some transmit diseases.
• Yield and quality: they reduce the quantity and quality of produce.
• Capacity: they reduce the production capacity of livestock and crops.
• Death: they can cause the death of plants and animals.
• Cost and income: control raises the cost of production and lowers farmers’ income.

What are edaphic factors affecting agricultural production?

Edaphic factors are the soil and land features that affect crops and animals.

How does soil pH affect agriculture?

Soil pH is a measure of how acidic or alkaline the soil is.

• Growth: it affects the growth of plants.
• Nutrient availability: it affects how easily plants take up soil nutrients.
• Microorganisms: it affects the kinds of microorganisms living in the soil.
• Toxicity: very acidic or alkaline soil can be toxic to plants and soil organisms.

How does soil texture affect agriculture?

Soil texture is the feel of the soil, which depends on the proportions of sand, silt and clay in it.

• Soil type: it determines whether the soil is sandy, clayey or loamy.
• Fertility: it influences the level of soil fertility.
• Crop choice: it determines the type of crop to be grown.
• Leaching and erosion: it affects how much leaching and erosion occur.

How does soil structure affect agriculture?

Soil structure is the way soil particles are arranged into crumbs or lumps.

• Fertility: it influences the fertility of the soil.
• Water-holding capacity: it determines how much water the soil can hold.
• Soil organisms: it affects the number of organisms living in the soil.
• Air and drainage: it determines aeration and percolation.

How does topography affect agriculture?

Topography is the shape of the land surface, including its slope and height.

• Steep slopes: they give rise to soil erosion.
• Flat land: soil and water accumulate on it.
• Farming sites: flat land is a better site for intensive farms.

How does soil fertility affect agriculture?

Soil fertility is the ability of the soil to supply plant nutrients in the right amounts for good crop growth.

• Crops: fertile soils give good yields of food and cash crops.
• Forage: they produce better forage crops for livestock.
• Fertiliser: they reduce the need for fertiliser.
• Soil organisms: they support the multiplication of beneficial organisms.
• Cost: they lower the cost of production.

What are the types of soil?

There are three types of soil: sandy soil, clay soil and loamy soil.

• Sandy soil: coarse soil with large particles, which drains fast and holds little water.
• Clay soil: fine, sticky soil with very small particles, which holds water and drains slowly.
• Loamy soil: a mixture of sand, silt, clay and humus, which is the best soil for agriculture.

How do sandy, clay and loamy soils compare?

Evaluation

1. Name the three groups of environmental factors that affect agricultural production.
2. State four effects of drought on crops.
3. List three ways in which high temperature affects crops and animals.
4. State three effects of pests on farmers.
5. Why is loamy soil the best for agriculture?

Assignment

1. Draw a table with three columns headed climatic, biotic and edaphic. List all the factors under each group, then write one effect of each factor on agricultural production.