IT’S A IT’S A GREEN WORLD GREEN WORLD Plants need Plants need minerals too minerals too
Feb 10, 2016
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