Do Now (5 min.)Do Now (5 min.)

Directions: Answer in complete Directions: Answer in complete sentences in your research journals:sentences in your research journals:

Which solution has a higher buffering Which solution has a higher buffering capacity, filtered water or HRE water?capacity, filtered water or HRE water?

Back up your answer with an Back up your answer with an explanation.explanation.

What makes a solution have more What makes a solution have more Buffering Capacity?Buffering Capacity?

HWHW

Complete your Germination Lab Complete your Germination Lab report.report.

How does electrical How does electrical conductivity relate to conductivity relate to

plant nutrition?plant nutrition?

Mr. M. GonzalezMr. M. Gonzalez

ObjectivesObjectives

I can explain why organisms of the I can explain why organisms of the plant kingdom need nutrients.plant kingdom need nutrients.

I can describe the relationship I can describe the relationship between elements and nutrients.between elements and nutrients.

I can relate electrical conductivity to I can relate electrical conductivity to nutrients.nutrients.

Question?Question?

How can a plant perform photosynthesis?How can a plant perform photosynthesis?

http://www.eoearth.org/files/121601_121700/121668/Irrigation-photosynthesis.gif

Make a list Make a list of the of the

elements elements you see on you see on this figure this figure

in your in your notebooks.notebooks.

Use your table of Use your table of elements.elements.

Question?Question?

Why does a plant perform photosynthesis?Why does a plant perform photosynthesis?

Because it needs to make Because it needs to make ATP ATP - - plant body energy!plant body energy!

You may have noticed You may have noticed CHNOPS.CHNOPS.

C = C = CarbonCarbon H = H = HydrogenHydrogen N = N = NitrogenNitrogen O = O = OxygenOxygen P = P = PhosphorusPhosphorus S = S = SulfurSulfur

Mg = ?Mg = ? Na = SodiumNa = Sodium Cl = ChlorineCl = Chlorine K = PotassiumK = Potassium Ca = CalciumCa = Calcium Fe = IronFe = Iron Cu = CopperCu = Copper Zn = ZincZn = Zinc OthersOthers

What What element element is Mg.is Mg.

Notice it Notice it makes up makes up the heart the heart of this of this molecule.molecule.

Plants also need to make the 4 organic Plants also need to make the 4 organic compounds that make up their body. compounds that make up their body.

Which requires ATPWhich requires ATP

Carbohydrates

Proteins

Lipids Nucleic Acids

So, how does electrical So, how does electrical conductivity relate to this?conductivity relate to this?

Electrical Electrical Conductivity Conductivity is a is a measure of the measure of the raterate (how fast) at (how fast) at which a small which a small electric current electric current travels through a travels through a solutionsolution.. http://hothardware.com/newsimages/

Item15076/Electricity.jpg

Molecules & NutrientsMolecules & NutrientsMost plant Most plant nutrientsnutrients (plant food) are (plant food) are

made of charged molecules or made of charged molecules or saltssalts..The more The more nutrientsnutrients (salts) the (salts) the fasterfaster the the

electricity will travel through the solution.electricity will travel through the solution.

Element + Element = Element + Element = MoleculeMolecule

When When somesome elements come together elements come together they form they form chargedcharged molecules or salts. molecules or salts.

Nutrients and plants (Nutrients and plants (+ all living + all living thingsthings) are made of molecules!) are made of molecules!

So, in a sense, living So, in a sense, living molecules (life) needs molecules (life) needs non-living molecules non-living molecules (nutrients) to keep on (nutrients) to keep on

living.living.

QuestionQuestion

What will happen to the What will happen to the electrical electrical conductivityconductivity if there are a lot of if there are a lot of nutrientsnutrients (salts) in a solution? (salts) in a solution?

AnswerAnswer

If you send a small electrical current If you send a small electrical current through a solution with a lot of through a solution with a lot of nutrientsnutrients the electricity will travel the electricity will travel very fast.very fast.

This means you will get a big This means you will get a big measurement.measurement.

Measuring ECMeasuring EC

You can use the Hanna You can use the Hanna Combo Meter to Combo Meter to measure EC.measure EC.

The units that measure The units that measure EC are “EC are “µµS” and they S” and they appear at the top right-appear at the top right-hand portion of the hand portion of the screen.screen.

Press the set button Press the set button firmly and continuously firmly and continuously until it appears.until it appears.

µS

RememberRemember

ConductivityConductivity is a measure of the is a measure of the raterate at which a small electric current at which a small electric current flows through a solution.flows through a solution.

When the concentration of nutrients When the concentration of nutrients is high, the current will flow ________.is high, the current will flow ________.

When the concentration of nutrients When the concentration of nutrients is low then the current will flow is low then the current will flow ________.________.

QuestionQuestion

Why is measuring EC important?Why is measuring EC important?

Why is measuring EC Why is measuring EC important?important?

Measuring the EC of your Measuring the EC of your solutionsolution is is important because it will determine if it important because it will determine if it has enough has enough nutrientsnutrients to feed your plants. to feed your plants.

3 EC Facts3 EC Facts

An EC meter shows the reading in An EC meter shows the reading in microohms per centimeter cubed microohms per centimeter cubed ((µµMho/cmMho/cm33) or microsiemens per ) or microsiemens per centimeter cubed (centimeter cubed (µµS/cmS/cm33).).

1 1 µµMho/cmMho/cm33 = 1 = 1 µµS/cmS/cm33

High temperatures will affect the EC High temperatures will affect the EC measurement giving.measurement giving.

EC levels for most plantsEC levels for most plants

Fruiting Fruiting PlantsPlants

Leafy PlantsLeafy Plants

Initial growthInitial growth 1600-1800 1600-1800 µµS/cmS/cm33 1400-1600 1400-1600 µµS/cmS/cm33

Average ECAverage EC 2500 2500 µµS/cmS/cm33 1800 1800 µµS/cmS/cm33

FruitingFruiting 2400-2600 2400-2600 µµS/cmS/cm33

Winter (low light)Winter (low light) 2800-3000 2800-3000 µµS/cmS/cm33 2000 2000 µµS/cmS/cm33

Summer (high light)Summer (high light) 2200-2400 2200-2400 µµS/cmS/cm33 1600 1600 µµS/cmS/cm33

Problems With NutrientsProblems With Nutrients

When a plant uses a nutrient from a When a plant uses a nutrient from a chemical “salt” molecule in a chemical “salt” molecule in a nutrient solution, it is actually only nutrient solution, it is actually only using up a part of that molecule. The using up a part of that molecule. The remaining part of that molecule remaining part of that molecule generally stays in the solution and generally stays in the solution and can eventually reach dangerous can eventually reach dangerous levels of concentration. levels of concentration.

What needs to be done?What needs to be done?

Log entry (5 min.)Log entry (5 min.)

Explain why organisms of the plant Explain why organisms of the plant kingdom need nutrients.kingdom need nutrients.

Describe the relationship between Describe the relationship between elements and nutrients.elements and nutrients.

Explain how electrical conductivity Explain how electrical conductivity relates to nutrients.relates to nutrients.

HWHW

Complete your Germination Lab Complete your Germination Lab report.report.

BibliographyBibliography

Nelson/Pade Multimedia (1999). Nelson/Pade Multimedia (1999). Hydroponics Guide. 100+p.Hydroponics Guide. 100+p.