Soil Incubations!

I started my independent project this week - everything is going smoothly thus far and the bulk of the work is underway. As quick refresher, my project is to study the respiration rates of soil microbes at different levels of plant productivity around Myvatn.  Higher productivity levels should correlate with higher levels of respiration, since that means the microbes are more active and are decomposing more things to provide nutrients to the plants.  The first step was to collect soils from the different plots - a lava field, a grassland, and two types of heathland - and to measure plant productivity with LAI.  That stands for leaf area index and measures the amount of vegetation covering the ground.

The lava field plots

 We took two types of soil samples.  The hammercore sample was bigger and was used to measure the amount of mineral soil vs duff (plant material on top of the soil) and to measure the amount of water contained in the soil.  The smaller cores were used in our actual soil incubations.  Before I could run incubations on those, I had to sift all of the roots and rocks out.

Sifting

Picking out the smaller roots

 After that I was ready to run my incubations.  We are measuring the rate of CO2 production as an indicator of decomposition and microbial activity.  I put a standard amount of soil from each plot in a small beaker and put each into a larger container with a rubber septum.  At times 0 min, 15 min, and 30 min, I pulled gas out of the chamber and placed it in a vial.  We'll have to bring the vials back to Madison for analysis, and we'll use the three vials at different time points to get a rate of CO2 production.  These soils will be sampled periodically over a month, so we'll be able to see how the rate changes over time. 

The easiest way to do this is to sample an incubation chamber every minute.  It was hectic at first but it didn't take long for me to get the hang of it!  The sad part is that I won't be able to get any data until we get back to Madison.