"A comparison of soils (e.g. garden/ school / park / woodland) linked to controlling environmental factors".

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Kirby Kruger

I.B Higher Biology

Group lab test

“A comparison of soils (e.g. garden/ school / park / woodland) linked to controlling environmental factors”.

Planning (a)

Introduction and background information

Soil is an abiotic factor when considered as a natural surrounding. Different soil types affects individual species of plants and animals.

A good example of how soil type affects plant life is to compare two different ecosystems with different soil compositions. The desert plains in central Australia consist of mostly sandy soil. The sand does not retain water well and is very dry and arid, but the plants have adapted so that their life cycles are completed in the 30 days that follow a good rainfall. Only some succulent plants which retain water very well manage to survive throughout the whole year.

A comparison may be a peat bog; cold, waterlogged and deficient in nutrients, mosses and plants which obtain minerals through “alternative” methods (carnivorism) thrive here.

Soil supports the basis of the Earth’s ecosystems, and the agriculture and economy of the world. The three main types of soil include:

  • Sandy soils, which are light, heat up quickly and retain water poorly. Particles are relatively large with relatively big airspaces. A sample with more than 90% sand particles is just called “sand”.
  • Clay soils and silty soils, which tend to be cold, dense, and are often waterlogged. They contain small particles with very small air spaces. A sample with more than 40% clay particles is true clay soil.
  • Loam, which is an “intermediate” type of soil. It is dark and has a sort of “crumb” structure; it has a mixture of particles of different sizes and usually a fairly high humus content, which consists of nutrient-rich organic matter, good for plants.  

The aim of the investigation is to test soils for various different properties, in terms of nutrient content, water content, organic content (living organisms), and find correlations between the results and observations of the individual samples.

Planning (b)

Soil samples

1 cup of each sample is to be collected from each area:

  • From homes – Alabang, Magallanes, Merville, Bel-air.
  • From school – Area behind basketball hardcover
  • Nature Garden
  • Football field
  • Area next to D-Block

Tests to be carried out:

  1. Organism test
  2. Geographical tests (observations)
  3. Water content
  4. Organic matter
  5. pH test
  6. Nutrient tests – nitrate
  • potassium
  • phosphorous
  1. Sedimentation method soil analysis
  2. Classify soil types as either clay, loam or sand. (sedimentation of soil analysis)

Apparatus:

  • Soil sieves
  • Air-tight containers
  • Measuring scales
  • Measuring cups
  • Nutrient soil testing kit
  • Bunsen burner
  • Tripod stand
  • Test tubes
  • Wire gauze
  • Crucible pot
  • Tongs (test-tube holder)
  • Forceps
  • Ethanol
  • Lamps
  • Graduated cylinder
  • Retort stands
  • Timer
  • Gloves
  • Beaker
  • Fireproof slate

Method

  1. Organism Test
  1. Set up retort stands and lamp, with sand filter and beaker of ethanol in place. Filter out half a cup of soil, of each sample, separately, and record necessary observations.

Independent variables: Amount of time exposed to lamp; amount of soil tested

Dependant variables: Soil type

Hypothesis – There did not seem to be many organisms in our collective samples at all. Most of the soil also seemed to be rather clay-like, and this type of soil tends to support less life.

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  1. Geographical Test
  1. For each soil sample, provide a detailed description of the area from which the soil was taken, including details such as plant volume, natural life, shade, sun, average humidity, etc.

Independent variables: Natural condition

Dependant variables: Area chosen for soil excavation

  1. Water Content
  1. This test aims to find the water content of soil. Set up Bunsen burner, tripod stand, wire gauze and crucible.
  2. Record the mass of the crucible
  3. Measure out about 10 g of soil and place it in the crucible. Record the mass of the soil ...

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