Summer on a Shoestring


Gavin MacKellar, thoughts, dreams, and soil cores
July 21, 2010, 12:53 pm
Filed under: Soil Power Coring, Soil Respiration, Trenching

Taking soil cores with a power corer and a power house!  by Gavin MacKellar

At the start of last week, 7/12, April arrived from Cornell with the
power corer to start taking soil samples from sites HB Mid, HB Old, JB
Mid, JB Old, C3, C5 and C7.  Within each of these sites April, with
extensive help from the field crew, will take five soil cores from
each plot.  One core will be in the very center of the plot and the
remaining four will be placed in the buffer (for minimal disturbance)
at each plot corner.  Each soil core is 50cm into the mineral layer
and including the Organic layers above it. The organic layers are
sampled as Oi & Oe and the second sample as the Oa.

After this the mineral layer is exposed and the increments measured for samples are 0-10cm, 10-20cm, 20-30cm, 30-50cm soil and roots.  These depth measurements are marked on the corer in marker.

At each depth increment the sample is removed and placed in its appropriate and labeled bag, with the core half way done.

After each sample is taken the corer is reinserted into the core hole and drilled to the appropriate depth then removed, repeating the process.  After each core the hole is measured to double check the depth and April scoops out any loose soil from the bottom of the core, which by the end can be really deep to reach.  For the 30-50cm core the sample is divided into two, the extra being for root sampling.  Once the samples have been taken there is a total of eight bags of samples from each power core.  Taking eight (big) samples from each core and taking five cores per plot, the amount of soil samples adds up very quickly and is quite a heavy load to carry out of the plot.

Once all the soil samples are removed a smooth core into the soil is left behind.  The power corer has the ability to cut through small rocks and sometimes, with persistence, big rocks.  Additionally with a bit of misfortune a rock may get stuck in the core, but can be removed. The soil samples that are being taken by the power corer are going to be measured for bulk density and nitrogen/carbon ratio.  Since the corer cuts through rocks, which releases minerals, minerals such as calcium and phosphorus cannot be measured.  For the deep samples, 30-50cm there is a root sample that is being taken which will go to Tim Fahey for fine and coarse root measurements.

Other Shoestring thoughts:
The soil respiration in the trenches has been measured three times
since the trenching, leaving one more measurement this Friday then
monthly until next July.

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2 Comments so far
Leave a comment

Everybody should subscribe by email to this site! You’ll get the latest additions in your inbox (and in the email, the pictures weren’t overlapping like I see them on the blog–what happened?)

Hey, Gavin, post an updated figure of what’s happened to respiration in the trenches!

Comment by Ruth Yanai

I’ve asked Gavin to update his trench data figure… it’s up and coming. Hopefully by the end of Friday or this weekend…

Comment by Bartletteers




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