Video transcript
Hi I'm Julie-Anne from the Field of Mars Environmental Education Centre. In this video we're going to look at the methods we use to record three terrestrial abiotic factors to do with the soil.
But before we get started let's consider what soil is and what it's actually not. Soil is rock and mineral particles mixed with organic matter. It is not the leaf litter and it's not the bedrock underneath. Remember you will have to dig through the leaf litter to get your soil sample and make sure it's well off the track.
Here's the equipment you're going to be using in the field to test for soil pH, soil texture and soil temperature.
Okay let's test soil pH. We're going to use the saturated paste method which comes in a kit. Get a teaspoon sized sample of soil, place the indicator solution on top and mix it in to make a saturated paste. The barium sulphate goes on top and within 60 seconds the colour will develop. We then match this color to the pH chart and a result is taken. Please take the soil sample, put it into the waste jar, clean it down and it's ready to go again.
Now let's determine a soil texture. Put simply soil texture tells us the relative proportions of sand, silt and clay in a soil. A sandy soil looks like this. And a clay soil looks like this. In our study sites we're going to be most interested in the proportions of sand and clay in the soil.
The soil texture test is a manual test and knowing how to do it is a bit of an art. Basically we take a handful of soil, remove the rocks roots and bits of leaves. We're going to wet the soil down and we're going to work it into our hand until we have a nice wet ball of soil. Feel for the texture. Are there grains? What colours on our hand? We're then going to make a ribbon using our thumb and index finger. The length of the ribbon will determine what type of soil we have.
Okay let's wash off with a squirt bottle and then we can go and test the soil temperature. To test soil temperature we use a thermometer, like this. We take it out of its case and then we're going to place it into the soil five centimeters deep away from the leaf litter. We take our result and now all our soil testing is done.
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