IT’S A GREEN WORLD

IT’S A IT’S A GREEN WORLDGREEN WORLD

Plants need Plants need minerals toominerals too

What is ‘slash and What is ‘slash and burn’ agriculture?burn’ agriculture?

What problems can arise from using What problems can arise from using this method?this method?

Starter

Plants need minerals tooPlants need minerals too

Learning objectivesLearning objectives

Understand that:Understand that:

The production of The production of many important many important compounds by plants compounds by plants requires elements that requires elements that are obtained from soil are obtained from soil mineralsminerals

Fertilisers contain Fertilisers contain mineralsminerals

Success criteriaSuccess criteria

Complete a table stating Complete a table stating what how various what how various minerals are used by minerals are used by plantsplants

Completion of Completion of worksheets on worksheets on fertiliser usagefertiliser usage

What do plants need for a balanced diet?

Plants need carbon dioxide and water for photosynthesis.Do they need any other nutrients to keep healthy?

Just like humans, plants need a balanced diet that includes small amounts of mineral elements.

What mineral elements do they need?

What minerals do plants need? Plants need mineral elements for healthy growth.

Some of the most important minerals needed by plants are:

The mineral elements are found in salts dissolved in water.Plants obtain minerals when they absorb water from the soil.

How do plants obtain these minerals?

nitrogen

potassium ions

phosphorus

potassium

magnesium magnesium ions

phosphates

nitrates

What type of salt are each of these elements found in?

What are minerals needed for? Use p67 of the textbook to complete the table below

MineralsHow mineral is used in plants

What happens to these minerals

Nitrates

Phosphates

Potassium compounds

Magnesium compounds

Used to make proteins (for growth)

Used in respiration and growth esp in roots

Used in respiration and photosynthesis

Used in photosynthesis

Nitrogen is used to make amino acids which are then joined together to make different proteins

Phosphorus is used to make cell membranes and DNA ( which carries genetic information)

Used to make some enzymes needed in respiration and photosynthesis

Used to make chlorophyll molecules

Where do minerals come from?

Rocks: The minerals in rocks are slowly dissolved by slightly acidic rainwater. These minerals are washed into the soil.

Natural fertilizers: Animal faeces and the decay of dead plants and animals return minerals to the soil.

Artificial fertilizers: These contain a ready-made mixture of the minerals needed by plants.

What are the sources of minerals in the soil?

Task - FertilisersTask - Fertilisers

Complete worksheet B4d3 – Complete worksheet B4d3 – Rothamsted experimentRothamsted experiment

Extension – complete worksheet B4d2 -Extension – complete worksheet B4d2 -Nitrogen fertilisersNitrogen fertilisers

B4d3 – Rothamsted B4d3 – Rothamsted experimentexperiment

As a control/comparisonAs a control/comparison Potatoes do not need much nitrogen but wheat Potatoes do not need much nitrogen but wheat

doesdoes Field 4; a fertiliser containing nitrogen, Field 4; a fertiliser containing nitrogen,

phosphorous and potassium would be phosphorous and potassium would be expensive – the increase in crop yield may not expensive – the increase in crop yield may not justify the expensejustify the expense

Soil type (clay, sand, chalk), drainage, Soil type (clay, sand, chalk), drainage, aeration, climate conditions, pests, diseaseaeration, climate conditions, pests, disease

B4d2 – Nitrogen B4d2 – Nitrogen fertilisersfertilisers

0.7 tonnes/hectare0.7 tonnes/hectare This uses ‘the law of diminishing returns’ – by doubling This uses ‘the law of diminishing returns’ – by doubling

the amount of fertiliser from 0 to 50, the crop increases the amount of fertiliser from 0 to 50, the crop increases from 2.5 to 7 tonnes/hectare, almost three times the sizefrom 2.5 to 7 tonnes/hectare, almost three times the sizeIf the amount of fertiliser is again doubled from 50 to 100 If the amount of fertiliser is again doubled from 50 to 100 tonnes/hectare, the crop only increases from 7 to 8.4 tonnes/hectare, the crop only increases from 7 to 8.4 tonnes/hectaretonnes/hectare

It is tempting to state the highest amount of fertiliser, as It is tempting to state the highest amount of fertiliser, as this would give the largest crop, however by spending this would give the largest crop, however by spending more and more money, the farmer’s increase in yield more and more money, the farmer’s increase in yield becomes less and less; the correct amount of fertiliser becomes less and less; the correct amount of fertiliser depends partly on its costdepends partly on its costMost farmers would choose 50 kg of fertiliser/hectareMost farmers would choose 50 kg of fertiliser/hectare

PlenaryPlenary

Organic farmers do not use artificial Organic farmers do not use artificial fertilisers.fertilisers.

Who would pay more for organic Who would pay more for organic food and why?food and why?

Plants need minerals tooPlants need minerals too

Learning objectivesLearning objectives

Understand that:Understand that:

The production of The production of many important many important compounds by plants compounds by plants requires elements that requires elements that are obtained from soil are obtained from soil mineralsminerals

Fertilisers contain Fertilisers contain mineralsminerals

Success criteriaSuccess criteria

Complete a table stating Complete a table stating what how various what how various minerals are used by minerals are used by plantsplants

Completion of Completion of worksheets on worksheets on fertiliser usagefertiliser usage