Hi,

To calculate a flux, you need to have consecutive measurements of the gas concentration (CO2, CH4 and N2O) over time. The time frame here will depend on your soil, and the type of process you are studying. You may want to get samples within minutes, hours or days, depending or the gas release dynamics of your soil (you will need to determine this in a preliminary incubation). Once you have your gas concentrations over time, you will need to do a regression (you can use excel) between the concentrations and the time. The slope of the regression is the flux; that is, the rate of change in flux with time. Concentration of the gas in ppm has to be transformed into mass (ug, mg, g or kg) by using the 'ideal gas law'. Flux will be expressed as the mass of gas per time unit (seconds, minutes, hours or days) and per mass of soil. I hope this helps!

Best regards

Cristina 

Dear Khan, I think that you don't need a formula to calculate the gas flux from soil incubation. I'm not a specialist in the field but, I think that you can measure the gas production by analyzing the initial gas concentration right at the time you close your incubation bottle. After that, you can measure the concentration every 6, 12 or 24 hours till the stabilization of the CO2 level that refers to the total consumption of the O2 by microorganisms. The difference between initial values and the other measurements ( n samplings) can indicate you the gas production. This is just a though, maybe other colleagues can help better than I did. Good luck

http://www.licor.com/env/products/soil_flux/

hello

These documents that relates theme

http://www.sciencedirect.com/science/article/pii/S0038071700001255

http://www.sciencedirect.com/science/article/pii/S0038071705001975

There are several equations you can use, these require that you know several parameters of your experiment. Check three different papers by Oelbermann and Schiff, and one paper by Oelbermann, English and Schiff. You should be able to find each of these papers on my ResearchGate home page. If not, then I can gladly send them to you. These papers focus on CO2 and CH4 but you can easily substitute the correct values for N2O into the equation. This assumes that you measured the GHG emissions in a specific time interval, using a known quantity of soil, volume of headspace and have access to a gas chromatograph with ECD, TCD and FID detectors.

To measure gas sample we need some details. Did u keep the soil in a plastic cup and the length and height of the cup. Then I  can give the formula.since your calculation depends on area 

Titration method can be used.  Alternatively, direct measurement uses gas analyzer.

you can read these papers

you can read these papers

Good evening, at first you have to say wich instrument you will use

2)If you will use an IRGA you have to say if is a dynamic or static system.

3) For CO2 you can use alkali traps

In few words when answered me the instrument I can help you.

Final units for this porpouses you can use mg CO2 g-1 soil day -1

micro moles CO2 g-1 soil day -1

Ciao

Good evening, at first you have to say wich instrument you will use

2)If you will use an IRGA you have to say if is a dynamic or static system.

3) For CO2 you can use alkali traps

In few words when answered me the instrument I can help you.

Final units for this porpouses you can use mg CO2 g-1 soil day -1

micro moles CO2 g-1 soil day -1

Ciao

Hi,

To calculate a flux, you need to have consecutive measurements of the gas concentration (CO2, CH4 and N2O) over time. The time frame here will depend on your soil, and the type of process you are studying. You may want to get samples within minutes, hours or days, depending or the gas release dynamics of your soil (you will need to determine this in a preliminary incubation). Once you have your gas concentrations over time, you will need to do a regression (you can use excel) between the concentrations and the time. The slope of the regression is the flux; that is, the rate of change in flux with time. Concentration of the gas in ppm has to be transformed into mass (ug, mg, g or kg) by using the 'ideal gas law'. Flux will be expressed as the mass of gas per time unit (seconds, minutes, hours or days) and per mass of soil. I hope this helps!

Best regards

Cristina 

Article Soil heterotrophic respiration assessment using minimally di...

This paper explains the method for doing the conversions and the equations you should use to calculate fluxes from ppm meansurements.