Experiments - LC Agricultural Science

To investigate the chemical properties of soil to show flocculation - hypothesis and prediction

Hypothesis: Lime caused flocculation

Prediction: If lime is added to a soil sample, particles will clump together at the bottom of the test tube to form aggregates

To investigate the chemical properties of soil to show flocculation - method

1. Gather soil sample
2. Collect two test tubes, label A and B
3. Add 5g soil to each
4. Add 1g lime to test tube A
5. Add 20ml of deionised water to each test tube
6. Stopper each test tube and shake
7. Stand for 1 minute

To investigate the texture of a soil by sedimentation - hypothesis and prediction

Hypothesis: Large soil particles will sink to the bottom of a soil/ water solution

Prediction: If a soil is sandy, then it will have a large % of particles at the bottom of the shaken solution

To investigate the texture of a soil by sedimentation - method

1. Gather soil sample
2. Mix soil sample and water in a beaker
3. Add mix to graduated cylinder
4. Stopper the cylinder and shake
5. Settle for 24 hours
6. Record volume of each layer (bottom = sand, middle = silt, top = clay)
7. Calculate as % of total soil and use soil triangle to determine texture

To compare the infiltration rate of compacted and uncompacted soil - hypothesis and prediction

Hypothesis: More compacted soil means lower infiltration rate

Prediction: If the soil is compacted, then the time taken for water to filter through will be longer than uncompacted soil

To compare the infiltration rate of compacted and uncompacted soil

1. Gather soil sample
2. Add a sample of soil to two funnels
3. Compress soil in one funnel to make compacted sample
4. Clamp funnels above beakers
5. Add the same amount of water to each of the funnels
6. Wait 30 seconds, record beaker with more water

To investigate the texture of a soil by hand testing - hypothesis and prediction

Hypothesis: The material of a soil is composed of will affect its feel and plasticity

Prediction: If a soil is sandy, it will not mould as well as clay soil

To investigate the texture of a soil by hand testing- method

1. Gather soil sample
2. Rub soil between fingers
3. Add water a little at a time
4. Attempt to roll soil into ball
5. Attempt to roll ball into long string
6. Record observations

Independent variable

What changes to compare results

Dependant variable

What changes as a result of the independent variable

Control variable

What stays the same

To investigate the texture of a soil using a soil sieve - hypothesis and prediction

Hypothesis: The size of the material in a soil will vary depending on soil type

Prediction: If a soil is sandy, then it will have a large percentage of large particles

To investigate the texture of a soil using a soil sieve - method

1. Gather soil sample
2. Dry out soil - place in oven for 24 hours
3. Find mass of full sample using electronic balance
4. Put sample in the top of the sieve and shake
5. Find the mass of each individual sieve
6. Calculate percentage of each particle
7. Use soil triangle to determine texture

To investigate the texture of a soil using a soil sieve - particle sizes

* Sand = 2mm - 0.5mm
* Silt = 0.05mm - 0.002m
* Clay = less than 0.002mm

To investigate the chemical properties of soil by demonstrating cation exchange capacity - hypothesis and prediction

Hypothesis: Calcium ions can be exchanged for potassium ions in a soil

Prediction: If potassium chloride is added to a soil, then the calcium ions will be displaced and washed away

To investigate the chemical properties of soil by demonstrating cation exchange capacity - method

1. Gather soil sample
2. Add sample to a funnel
3. Clamp funnel over a beaker
4. Add potassium chloride drop by drop
5. Collect filtrate and test using ammonium oxalate
6. White precipitate forms if calcium is present
7. Continue test until negative result is seen, implying exchange has taken place

To investigate the chemical properties of soil to determine pH - hypothesis and prediction

Hypothesis: pH will vary depending on the soil type

Prediction: If pH is measured in different soil samples, then different values will be recorded for each one

To investigate the chemical properties of soil to determine pH -method

1. Gather 5 samples of soil from different areas
2. Add one sample to a beaker
3. Add distilled water to same beaker to form a solution
4. Filter solution into test tube
5. Test using pH probe
6. Repeat for each sample, record results

To compare the capillarity rate of a compacted and uncompacted soil - hypothesis and prediction

Hypothesis: The more compacted a soil is, the less capillarity it will have

Prediction: If a soil is compacted, then the cress seeds will struggle to germinate as the water will fail to reach them

To compare the capillarity rate of a compacted and uncompacted soil - method

1. Gather soil sample
2. Plug the end of two open ended tubes using cotton wool
3. Compress soil in one tube
4. Add 20 cress seeds to the top of each tube
5. Stand tubes in water until the seeds begin to germinate
6. Record how many seeds germinate as a percentage as those planted