Environmental Management (0680) | Increasing agricultural yields

IGCSE Environmental Management (0680): Increasing Agricultural Yields

Hello future Environmental Managers! This chapter is all about one of the most important challenges facing humanity: how do we grow enough food to feed a growing population without destroying the planet?

We will explore the key techniques farmers use to boost their harvests, known as increasing agricultural yields (getting more food from the same amount of land). This is crucial for keeping up with global food demand.

3.4 Techniques Used to Increase Agricultural Yields

To get higher yields, farmers use a combination of methods. These methods can be grouped into four main areas: managing the soil, protecting the crop, improving the stock (plants/animals), and controlling the environment.

1. Techniques Focused on Soil and Nutrient Management

Healthy plants need a healthy foundation. These techniques ensure the soil has the structure and nutrients required for maximum growth.

A. Crop Rotation

This involves growing different types of crops sequentially on the same land over a period of time.

• Mechanism: Instead of planting the same crop (like wheat) every year, you might plant a nutrient-demanding crop one year, and then a nitrogen-fixing crop (like legumes/beans) the next.
• Benefit: It prevents the exhaustion (running out) of specific mineral ions from the soil and helps break the cycles of pests and diseases that rely on one type of crop host.
• Think of it like giving your stomach a rest by eating different foods, so you don't use up all of one vitamin!

B. Fertilisers

Fertilisers add essential mineral ions back into the soil that plants need for growth.

• Essential Nutrients (NPK): Plants primarily need Nitrogen (N, usually as nitrate ions (NO₃^-) for leaf growth), Phosphorus (P, as phosphate ions (PO₄^3-) for root growth), and Potassium (K, as potassium ions (K⁺) for flower/fruit quality).
• Inorganic (Chemical) Fertilisers: These are manufactured chemicals. They are highly concentrated, fast-acting, and precise, allowing farmers to deliver exactly the right balance of NPK.
• Organic Fertilisers: These include manure (animal waste) and compost (rotted plant material). They improve soil structure and release nutrients slowly over time. (They are also a strategy used in sustainable agriculture).

Quick Review: The NPK Trick
N - Nitrogen (N = Needs leaves)
P - Phosphorus (P = Primary roots)
K - Potassium (K = Knobs and flowers)

C. Irrigation

Irrigation is simply the artificial supply of water to the land to help crops grow. It allows farming in arid areas or during droughts.

• Methods: Can range from large-scale techniques (like flooding fields or using sprinklers) to more efficient methods (like trickle drip irrigation, which reduces water waste).
• Warning! Mismanagement of irrigation can lead to major environmental problems (as discussed in syllabus 3.5), such as salinisation (salt buildup) and waterlogging (too much water, suffocating roots).

Key Takeaway for Section 1:

Managing the soil involves cycling crops (rotation), topping up essential nutrients (fertilisers), and ensuring adequate moisture (irrigation) to maximise the growing potential of the land.

2. Techniques Focused on Protecting the Crop (Control)

Pests (like insects), weeds (competing plants), and fungi can severely reduce a crop yield. Control methods aim to eliminate or reduce these threats.

A. Chemical Control

This uses manufactured chemicals to kill unwanted organisms.

• Insecticides: Kill insect pests (e.g., chemicals to kill aphids).
• Herbicides: Kill unwanted weeds (e.g., chemicals to kill grasses competing with the main crop).
• Fungicides: Kill fungi, which cause plant diseases (e.g., chemicals to prevent potato blight).
• Benefit: Fast, effective, and allows for large-scale crop protection, leading to very high yields.

B. Biological Control

This is an environmentally friendly method that uses natural predators or diseases to manage pests.

• Mechanism: Introducing a natural enemy of the pest into the crop area.
• Example: Ladybugs (the predator) are introduced to eat aphids (the pest).
• Benefit: Reduces the need for harmful chemical pesticides, which prevents pollution and avoids the pests developing chemical resistance.

Did you know?
Chemical control gives quick results but can harm beneficial insects (like bees) and cause pollution. Biological control is slower but is a great strategy for sustainable agriculture because it works with nature.

Key Takeaway for Section 2:

Farmers protect their yields by managing pests, weeds, and fungi, either through fast-acting chemical sprays or slower, more sustainable biological methods.

3. Techniques Focused on Improving the Stock

These methods improve the crops and livestock themselves, making them naturally higher-yielding or more resilient.

A. Mechanisation

This involves using machinery (like tractors, combine harvesters, and milking machines) rather than human or animal labour.

• Benefit: Dramatically increases the scale and speed of agricultural operations (ploughing, planting, harvesting).
• Result: Allows a small number of people to manage huge areas of land efficiently, leading to mass production and high yields.

B. Selective Breeding

Also called artificial selection, this is the process of choosing organisms (plants or animals) with desirable traits and breeding them together.

• Goal: To develop new varieties of crops that are higher yielding, more resistant to local diseases, or have better nutritional value.
• Example: A farmer might only breed the cows that produce the most milk, or only use seeds from the wheat plants that grew tallest.

C. Genetically Modified Organisms (GMOs)

This is a modern technology where the genetic material (DNA) of a plant or animal is intentionally altered in a laboratory to introduce a desired characteristic.

• Key Difference: Selective breeding takes generations; GMOs can be created in a single step by transferring a gene from one species to another.
• Benefits for Yield: Creating crops resistant to insects (so less insecticide is needed) or crops resistant to certain herbicides (allowing farmers to spray weeds without killing the crop). They can also be bred for drought resistance.

Key Takeaway for Section 3:

Technology (mechanisation) and genetic manipulation (selective breeding and GMOs) allow us to increase the efficiency of farming and create "super crops" that are more productive and hardy.

4. Controlled Environments

These techniques remove environmental uncertainty (like weather) and allow farmers to provide optimum conditions for growth all year round.

A. Greenhouses

A greenhouse is a structure made of glass or plastic that allows sunlight in and traps heat, maintaining a warm temperature (like a small-scale greenhouse effect).

• Control: Allows for precise control over temperature, light, water supply, and humidity.
• Benefit: Enables crops to grow out of season and protects them from wind, frost, and outside pests, resulting in reliable, high yields.

B. Hydroponics

This is a method of growing plants without soil. The roots are suspended in mineral-rich water solutions.

• Control: Every mineral ion (N, P, K, etc.) can be delivered directly to the plant in the exact required concentration.
• Benefits: Requires far less water and space than traditional farming, zero risk of soil exhaustion, and very high yields in small, controlled environments.
• Analogy: If traditional farming is eating a regular meal, hydroponics is giving the plant a highly efficient IV nutrient drip.

Final Quick Review Box: Increasing Yields Checklist

What are the main ways to increase crop yield?

1. Rotation (using different crops yearly)
2. Fertilisers (adding NPK nutrients)
3. Irrigation (adding water)
4. Pest Control (chemical or biological)
5. Mechanisation (using machines)
6. Selective Breeding/GMOs (improving the plant itself)
7. Controlled Environments (greenhouses/hydroponics)