MakingFood

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7

Plants need mineral salts from the soil for healthy growth. In nature, plants die, decompose and mineral salts return to the ground.

When crops are harvested, the plants are removed, there is no decomposition, and the quality of the soil decreases as less nutrients become available.

Slide 51

Slide 52

Manufactured fertilisers are added to the soil to replace those that are lost. This enables healthy crops to grow quickly, but at a cost to the farmer.

Questions

Why do farmers want to harvest crops quickly?

What do fertilisers contain to help plants grow?

Slide 53

Signs of Nutrient deficiency in plants

Lack of Nitrogen causes

Yellowing of leaves.

leaves on lower parts of the plant may die

Weak stem meaning the plant cannot grow tall.

Slide 54

Lack of Potassium causes ….

1. Yellowing of leaves

2. Poor fruit growth.

Slide 55

Lack of Magnesium causes leaves to turn yellow from the bottom of the plant upwards

Leaf from the bottom of a plant

Leaf from the top of a plant

Slide 56

Lack of Phosphorus causes ….

1. Purpling of leaves

2. Poor root growth

3. Small plant size

Copy out the diagrams from p63 Co-ordinated Biology (second Edition) showing nutrient deficiency in plants