The document discusses rates of decomposition and composting. It explains that decomposition rates can be reduced by removing warmth, moisture or oxygen from the environment. The document also discusses the composting process, noting that compost heaps break down plant materials through decomposition, releasing nutrients into a form plants can absorb. Composting requires oxygen, warmth, and a mixture of wet and dry materials.

1. Rates of
decomposition
LO: how we reduce the rate of decomposition of
food and produce compost

2. Learning outcomes
5 explain the process of decay and condition needed
8 calculate the rate of decay

3. Apply now task
1 Why do farmers spread fertilisers
on their crops?
2 Which term means growing
different crops in the same field in
different years?
3 Which type of nitrogen
compound can plants absorb?
4 Which part of the
environment do plants absorb
minerals from?
5 Which organisms break
down complex nitrogen
compounds such as proteins
to simple nitrogen
compounds?
6 Why are the bacteria found
in root nodules of legume
plants useful to the plant?
7 Why do we put fresh food in the
fridge?
8 A gardener piles dead plant
material into a heap in a corner of the
garden. What does the dead plant
material form after a few months?

4. Apply now task (starter)
1 Why do farmers spread fertilisers
on their crops?
adds plant nutrients/minerals/so plants
grow well
2 Which term means growing
different crops in the same field in
different years?
crop rotation
3 Which type of nitrogen
compound can plants absorb?
nitrates
4 Which part of the
environment do plants absorb
minerals from?
soil/soil water
5 Which organisms break
down complex nitrogen
compounds such as proteins
to simple nitrogen
compounds?
decomposers
6 Why are the bacteria found
in root nodules of legume
plants useful to the plant?
They fix nitrogen
gas into nitrates.
7 Why do we put fresh food in the
fridge?
anything similar to: keep
it fresh for longer
8 A gardener piles dead plant
material into a heap in a corner of the
garden. What does the dead plant
material form after a few months?
compost

5. keywords
Preservation
Dehydration
Pickling
Freeze drying

6. knowledge
Usually the soft parts of organisms decay
soon after death by decomposers.
These microorganisms grow best in warm
and wet conditions with plenty of oxygen.
Food can be preserved by removing any
one of these conditions. Other methods
change the pH.

12. Food preservation
Coffee
Strawberries
Salami
Peas
Crisps
Beetroot
Peaches
Canned in syrup
Irradiation
Freeze drying
Salting
Freezing
Pickling in vinegar
Vacuum packed
Packed in nitrogen gas
How it works

13. Making compost
Gardeners often collect waste garden material
into a heap and leave it until it decays.
The compost contains many nutrients that
were in the plant tissues, but in a form that
are easier for plants to absorb.
Compost needs to get oxygen in order to
break down.It also needs to be kept warm. (
You can use a garden fork and an old bit of
carpet) a mixture of wet and dry material also
needs to be used.

14. Application task