Match a method to the production problem
Name the production problem, the method and how it could increase usable food.
Continue where you stopped
The core idea
Sources of Food · Lesson 2 of 4 · about 25–35 min
What you need to understand
Name the production problem, the method and how it could increase usable food.
Definitions
- fertiliser
- material added to supply mineral nutrients to plantsFor example: Excess fertiliser can wash into waterways.
- pesticide
- a substance used to control organisms that damage cropsFor example: A pesticide may also harm non-target organisms.
Explanation
A growing population needs more food, but suitable farmland is limited and also competes with housing and industry. Farmers therefore try to grow more usable food from the land available. Start with the problem: what is restricting growth or destroying part of the crop?
If mineral nutrients are in short supply, fertiliser can replace them and improve growth. If insects damage leaves or fruit, an appropriate pesticide can reduce that loss. Weeds compete with the crop for light, water and mineral nutrients; herbicides control weeds and reduce that competition. These methods act in different ways, so extra fertiliser cannot substitute for controlling a pest.
Slash-and-burn means cutting vegetation and burning it. Clearing opens land for planting, and ash can temporarily add mineral nutrients. This explains the intended short-term production benefit; it does not make the practice environmentally acceptable. The next lesson follows the smoke, runoff and exposed soil to examine the costs.
Pause and say it: Name the production problem, the method and how it could increase usable food.
Common mistake
Tempting wrong idea: World population can rise without increasing pressure on food production.
Why it fails: More people need more food, while suitable land is limited and is also needed for homes and industry. Population growth therefore increases pressure to produce more food from the available land.
Use this instead: More people increase food demand, while limited growing space strengthens the need to improve production.
Worked examples
Modelled example 1
A field crowded with weeds
Problem
Tall weeds shade young crop plants. Tests show enough mineral nutrients in the soil. A farmer proposes adding more fertiliser. Does that address the stated problem?
View complete solution
Find what restricts growth
Method
Identify the competition for light before choosing a treatment.Reason
A method helps only if its action addresses the problem.Working
The weeds shade the crop. Extra fertiliser supplies nutrients, which are already sufficient; it does not remove the shade. Controlling the weeds reduces their competition with the crop. A herbicide is one way to control weeds, although its environmental effects must also be considered.
Try it. Caterpillars eat a crop’s leaves. A student writes, “Fertiliser kills the caterpillars, so more leaves survive.” Identify the first error and replace it with a method → intended effect explanation.
Check the mechanism
Fertiliser supplies mineral nutrients; it does not kill caterpillars. An appropriate pesticide can reduce the pest population, so fewer leaves are eaten and more usable crop may survive. This describes the intended benefit; it does not establish that pesticide use has no other effects.
Guided practice
Try it with support
A field has enough nutrients, but weeds shade the young crop. Explain why a herbicide could increase crop growth while extra fertiliser may not solve this problem.
- Identify what the weeds compete for.
Check the guided answer
Answer: A herbicide controls the weeds, reducing competition for light, water and minerals. Extra fertiliser does not remove the weeds or the shading, and nutrients are already sufficient.
Check: The intended benefit must follow from the method's actual action.
Practise and continue
Practise this
A farmer says, ‘Pesticide feeds my crops and fertiliser kills the insects.’ Identify the first error and correct both roles.
Need a hint?
- Separate supplying nutrients from reducing damage.
Check your answer
Answer: Pesticide does not supply crop nutrients: it controls pests. Fertiliser supplies mineral nutrients and is not an insect killer.
Check: Correct the mechanism before predicting a benefit.
Think like a scientist
Why might a farmer clear and burn vegetation when farmland is scarce? State the intended benefit without claiming the method is harmless.
Check the reasoning
Clearing makes land available for planting, and ash can temporarily supply mineral nutrients. Those short-term benefits do not remove the environmental costs.
Remember: Explaining an intended benefit is different from recommending the method.
One-minute check
- Hide the page and explain match a method to the production problem in your own words.
- Give a new example that is different from the worked example.
- Correct this common mistake: “World population can rise without increasing pressure on food production.”