4.3 Plant minerals
Summary: Farmers and gardeners regularly check their plants for signs of poor health. If your plants start to wilt drop down, they need water. What does it mean if the leaves turn yellow? Tags: science oxford-science student-book-7 biology Created: 2026-05-19 Last Updated: 2026-05-19
After this topic, you will be able to:
- describe how a plant uses minerals for healthy growth
- describe the symptoms (signs) of plant mineral deficiencies
- explain why farmers use fertilizers.
Think back
- How does water get into a plant?
- Why do leaves have stomata?
- Give three adaptations of a leaf.
Key idea Plants need nitrates, phosphates, and magnesium to grow into a healthy plant. Fertilizers add minerals to the soil.
Key words nitrate, phosphate, magnesium, chlorophyll, deficiency, fertilizer
Farmers and gardeners regularly check their plants for signs of poor health. If your plants start to wilt (drop down), they need water. What does it mean if the leaves turn yellow?
What minerals do plants need?
For healthy growth, plants need a range of minerals:
- nitrates (contain nitrogen) – for healthy growth
- phosphates (contain phosphorus) – for healthy roots
- magnesium – for making chlorophyll.
A Name three minerals that plants need for healthy growth.
Where do plants get minerals from?
Plants get the minerals they need from the soil. The minerals are dissolved (mixed) in soil water. They are absorbed into the root hair Cells, and then travel through the plant with the water in the water vessels.
B Describe how minerals enter plants.
Mineral deficiency
If a plant does not get enough minerals, it will not grow well. This is called a mineral deficiency. Different mineral deficiencies have different symptoms (signs of a problem):
- Nitrate deficiency – plant has poor growth, and older leaves become yellow (see Figure 1). Figure 1A nitrate deficiency results in poor growth.
- Phosphorus deficiency – plant has poor root growth, and younger leaves look purple (see Figure 2). Figure 2Purple leaves are a symptom (sign) of a phosphorus deficiency.
- Magnesium deficiency – plant leaves turn yellow (see Figure 3). Figure 3Magnesium deficiency results in yellow leaves.
C Identify the mineral missing from a plant with poor roots.
The chlorophyll molecule, which makes plants green, contains magnesium. If a plant does not get enough magnesium, it cannot make as much chlorophyll as it needs. This results in yellow leaves.
Nitrates are involved in making amino Acids. The amino acids join together to form proteins. These proteins are needed for cell growth, to grow leaves and shoots.
Why do farmers use fertilizers?
When plants grow, they remove minerals from the soil. These would normally be replaced when the plant dies, or when leaves drop off. However, when crops are cut and gathered, this cannot happen. To prevent future crops suffering from a mineral deficiency, farmers add chemicals to the soil to replace missing minerals – these chemicals are called fertilizers. Figure 4 shows a farmer adding fertilizers to crops.
Figure 4Farmers use fertilizers to add minerals to their
Around the world, many farmers do not use chemical (artificial) fertilizers. Instead they add minerals to the soil by spreading manure on their fields. Manure is dung (waste products) from farm animals or from people.
D List two ways farmers add minerals to the soil.
Literacy skills Produce an information leaflet for farmers. The leaflet should help them decide which mineral their plant is missing. Include an image of an unhealthy plant that farmers can compare with their own.
Summary questions
- Copy and complete the sentences. To stay healthy, plants need to absorb minerals/vitamins from the soil. These include phosphates, oxides/nitrates, and magnesium. They are absorbed through the root hair cells/stomata and then travel through the plant in the water stoma/vessels.
- Explain why farmers use fertilizers.
- Explain the role of nitrates in healthy plant growth.