Factors Affecting Availability for Agricultural Purposes – SS1 Agricultural Science Lesson Note (First Term)

Land availability for agricultural production is the amount of land that can actually be used for farming.

Behavioural objectives

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

1. list the factors that affect land availability for agricultural production;
2. explain how topography and soil type affect the use of land for farming;
3. describe how rainfall affects the distribution of crops and animals;
4. explain how cultural practices and socio-economic uses reduce the land available for agriculture;
5. suggest ways of making more land available for farming.

What are the factors that affect land availability for agriculture?

There are nine main factors: population pressure, land tenure, topography, soil type, government laws, pollution and oil spillage, climate, cultural practices and socio-economic uses.

How does population pressure affect land availability?

Population pressure is the strain on land caused by a rising number of people.

• Less land per person: as the population grows, the area available for each person falls.
• More demand for land: people need land for houses, schools, hospitals, roads and markets.
• Smaller farms: farmers are left with small plots that give low output.

How does the land tenure system affect land availability?

Land tenure is the way land is owned, held and passed on in a community.

• Fragmentation: land is shared among many heirs, so each person gets small, scattered plots.
• Small plots: such plots rarely give enough land for an effective agricultural venture.
• Communal tenure: land owned by the community is often used carelessly, which leads to land deterioration.

How does topography affect land availability?

Topography is the shape and slope of the land surface.

• Mountains and hills with rocks: these are not suitable for farming and make machines hard to use.
• Steep slopes: water runs off fast, which causes erosion and washes away topsoil.
• Depressed (low-lying) areas: these are easily waterlogged, so many crops cannot grow well.
• Gentle, flat land: this is easiest to farm and to mechanise.

How does soil type affect land availability?

Soil type decides how well land holds water and nutrients, so it limits what the land can be used for.

How do government laws affect land availability?

Government laws control who can hold land and how it is used, and in Nigeria the main law is the Land Use Act.

• Land Use Decree of 1978: the law, now called the Land Use Act, that controls land ownership in Nigeria.
• Ownership: it places land in each state under government control, held in trust for the people.
• Individuals: a person cannot own land outright but may hold a right of occupancy.
• Government acquisition: government can take land for public projects, which reduces farmland.

How do pollution and oil spillage affect land availability?

Pollution makes land unfit for farming by contaminating the soil with harmful substances.

• Oil spillage: crude oil spilt on land, common in the Niger Delta, which kills crops and soil organisms.
• Industrial waste: chemicals and refuse dumped on land make it unfit for cultivation.
• Effect: polluted land is unsuitable for agriculture until it is cleaned and restored.

How does climate affect land availability?

Climate is the average weather of a place over many years, and it decides which crops and animals a place can support.

• Rainfall: the major determinant of crop and animal distribution.
• Other elements: temperature, sunshine and humidity also limit what can be grown.

How do cultural practices affect land availability?

Cultural practices are traditional ways of living and farming that can damage land or take it out of use.

• Bush burning: fire destroys organic matter and soil organisms and exposes the soil.
• Shifting cultivation: farmers move on after a few years, so a large area is needed for a small output.
• Deforestation: removing trees exposes soil to erosion and loss of fertility.
• Sacred places: some land is kept for shrines or burial grounds and so cannot be farmed.

How do socio-economic factors affect land availability?

Socio-economic factors are the social and economic needs of people that compete with farming for land.

• Residential buildings: houses spread into farmland, especially around towns.
• Markets and schools: these need large areas of land.
• Roads: roads and railways cut through and take up farmland.
• Industries: factories and similar buildings use land that could grow crops.

How can more land be made available for farming?

Land can be made more available by using it carefully and by repairing damaged land.

• Crop rotation and manuring: these keep the soil fertile so land can be used for longer.
• Terracing and contour ridging: these reduce erosion on sloping land.
• Drainage: draining low-lying land stops waterlogging.
• Afforestation: planting trees protects bare land from erosion.
• Cleaning polluted land: removing contaminants restores land for farming.
• Land use planning: setting aside areas for farming stops towns from taking all farmland.

Evaluation

1. State four factors that affect land availability for agricultural production.
2. How does the steepness of a slope affect the use of land for farming?
3. Why is land with mainly sandy or mainly clay soil a problem for farmers?
4. Which type of crops is favoured by heavy rainfall, and which by moderate rainfall?
5. Give three examples of cultural practices that make land unsuitable for agriculture.

Assignment

Explain how population pressure and the land tenure system reduce the land available for agriculture.