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Dawn chorus and investigating soils - Helen's journal and online home
Dawn chorus and investigating soils
I think I've mentioned before that G signed up for an Open University ecology course as being the cheapest way to gain access to an academic library. Also, new course!
Anyway, it involves practical work and we've already visited sand dunes, done the experiment where we had to take the temperature of the soil under oak trees and the next thing was an experiment to determine soil composition and record temperatures at the surface and two different depths.

Fortunately we were able to do this at the bottom of our own garden, so we dug a narrow hole, set up the digital thermometers with their probes in the soil at the prescribed depths and with the gadget itself sheltered from any possible rain by a bucket lying on its side. Then the temperature readings had to be taken at regular intervals for the next 24 hours. Because G is not good at mornings, I volunteered to do the early ones, though I drew the line at 6.00 a.m. and compromised on 6.45 a.m., which is only a little earlier than my normal getting up time.

So that's how I came to be standing at the bottom of our garden at the height of the dawn chorus...

This is a still photo of the trees on what we call "The Swamp" with the sound file of the bird song. (Length just over a minute)

Dawn chorus

There are a lot of trees beyond our garden. Though it was an open field when we moved in, because the land floods and can't really be used for anything, it's just been left to go wild. As a result, there are a lot of birds. This is only the start of the dawn chorus, it will get louder and more intense as the weeks pass and we go through the breeding season until we get to around May, then it dwindles away again. I may try to do another similar recording when the bird song is at its peak.

Anyway, back to the soils. G had to calculate water content, air content and also to see how much sand, silt and clay was in each sample. For this you simply shake up a sample of the soil in water to which a generous squirt of washing up liquid has been added. You then leave the jar to settle for 2 days. This was the result...

Comparing soil samples

The sample on the left is from higher up the garden. The one on the right is from the lowest part that floods several times a year. The layers (from the bottom upwards) are: sand, silt, clay.

I was surprised at how sandy our soil is in the main part of the garden. I'd thought it was a clay soil. It's also interesting how the left sample has a clear division between sand and silt, with just a thin layer of clay on the top whilst the sample on the right has sand at the bottom and silt on top, but the dividing line between the two is difficult to determine.

So that was what I learned yesterday. Today I learned how to import a sound file made on my phone into Audacity (it needed an extra file I had to download from the web) and also how to make a simple video from a still photo and a sound file. One has to keep the brain active as one gets older. :)
4 comments or Leave a comment
asakiyume From: asakiyume Date: February 21st, 2017 09:09 pm (UTC) (Link)
That dawn chorus is **lovely**.

And there's something very appealing about your soil samples, too--they remind me of those mixes in a jar that people sometimes make, where they layer all the dry goods you need to make some kind of baked good in a jar (flour, brown sugar, cinnamon, etc.)
heleninwales From: heleninwales Date: February 22nd, 2017 03:16 pm (UTC) (Link)
I'm glad you liked the birdsong. I'll see if I can do it again when spring is more advanced, though that will mean getting up even earlier!
eve_prime From: eve_prime Date: February 22nd, 2017 07:26 am (UTC) (Link)
Now I want to do a soil sample in a jar like that. Our soil here is mostly clay; it gets all gummy in the winter rains. They say we got our wonderfully fertile soil from massive prehistoric floods in Montana, hundreds of miles to the northeast, that covered the valley floors from there to the Pacific ocean.
heleninwales From: heleninwales Date: February 22nd, 2017 03:15 pm (UTC) (Link)
That soil separation was very easy to do. Just put a sample of the soil into a cylindrical jar. Around 1/3rd full is about right. Fill the jar with water and add a generous squirt of detergent. Washing up liquid is fine. Shake for a couple of minutes, then leave to settle. The sand should drop to the bottom after about 1 minute, but to get the fine clay to settle, you need to leave it for 48 hours. By measuring the thickness of the layers, you can work out the percentages of each component. It was interesting so see the difference between the two samples which were taken only a matter of a couple of metres (say 7-8 feet) apart horizontally. But there is a drop from one level to another of about 1.5 metres (say 4 or 5 feet). So the one with more clay gets flooded several times a year while the other part of the garden is above the flood level.

The other experiments involved working out moisture and air content.

4 comments or Leave a comment