Agricultural Soils

Author: Dr. M. Scott Demyan, Chair, C-MASC Agricultural Soils Working Group

The Agricultural Soils Group secured a CFAES equipment grant for the purchase of a Gasmet GT5000 Terra Portable FTIR Multiple Component Gas analyzer. The GT5000 quantifies CO2, CO, CH4, N2O, NH4, and H2O concentrations and when paired with a chamber, can be used to calculate fluxes of those gases. Along with the GT5000 gas analyzer we will also be acquiring two Eosense chambers, which are dynamic chambers that close for the flux measurement and then reopen, and a 12-port multiplexer. With this suite of components, we envision the following three uses: 

1) Survey type flux measurements where the GT5000 analyzer is taken from point to point for treatment or landcover comparisons. PVC collars can be pre-installed at the measurement points and then one of the Eosense chambers placed on the collar for a measurement. Depending on flux intensity and gases of interest, measurement time varies from 4-11 minutes. 

2) Longer-term continuous measurements. The GT5000 gas analyzer along with the multiplexer can connect up to 12 chambers. In this initial purchase, we will have two of the dynamic Eosense chambers, but in the future as funds become available, further chambers can be purchased or made. This continuous measurement mode would be useful to monitor highly dynamic short temporal events, e.g. freeze-thaw, manure application, tillage, flooding, rainfall, etc. The chambers can be placed up to 30 meters from the multiplexer location. The limitations of continuous measurement mode would be that the instrument typically needs to be zeroed every second day and power would need to be provided. 

3) Lab incubation experiments. With the GT5000 and multiplexer, tubing can be attached to sample the headspace of multiple mesocosms or incubation vessels. Based on other researchers’ experiences and guidance from the company, they recommend ca. 700-900 ml of headspace to sample, which is about the size of a quart Mason jar. 

Once the gas analyzer and components arrive (hopefully late winter), we plan on organizing as a group a process whereby we can optimally, and equitability allocate equipment time across different experiments and investigators of existing ongoing experiments where these types of flux measurements would be useful and for new project proposals.