What's what

The LI-6800 Portable Photosynthesis System can be used to measure CO2 efflux from soils when outfitted with the soil CO2 flux chamber. Here we describe the components of the chamber.

Soil CO2 flux chamber

Part number: 6800-09

The chamber enables the LI-6800 to measure changes in CO2 concentration inside the chamber when it is closed over the soil. It has one connector for the Stevens HydraProbe. It uses the SDI-12 communication protocol. An air inlet and outlet connect to the custom chamber adapter block. The cable attaches directly to the LI-6800 head connector labeled LS. There is also a dock where you can place the soil probe when it is not in use.

Figure 11‑3. Components of the Soil CO2 chamber.

Head mounting bracket

Part number: 9968-285

The chamber has a removable mounting bracket that is used to attach the LI-6800 head to the chamber. Be careful not to lose the bracket. It is a surprisingly expensive custom-made part that must be purchased from LI-COR.

Stevens HydraProbe

Part number: 900-19016

The HydraProbe is equipped with a custom connector for the soil gas flux chamber. The probe measures soil moisture content and temperature, which are stored in the dataset. It uses the SDI-12 communications protocol. Older HydraProbes had part number 900-17114.

Custom chamber adapter block

Part number: 9968-182

The custom chamber adapter block is included with the soil gas flux chamber. The accessories kit has Swagelok fittings and plugs that are needed to plumb the adapter block to the chamber.

Soil collars

Part number: 6581-044

Three 20 cm soil collars are included with the chamber. Soil collars must be installed at the measurement site at least 6 hours prior to measurements (24 or more hours is better). Additional collars can be purchased from LI-COR or made in a shop if you have access to suitable materials.

Accessories kit

Part number: 9968-290

The soil gas flux chamber accessories kit includes additional parts and replacement parts.

The chamber package includes the following items:

Description Quantity Part Number
Chamber 1 9968-287
Head Mounting Bracket 1 9968-285
Stevens HydraProbe 1 900-19016
Custom Chamber Adapter Block 1 9968-182
Soil Collars 3 6581-044
Accessories and Spares Kit 1 9968-290
Disposable Air Filter 1 301-08119
O-ring; 6 ×1.5 mm 1 192-14314
O-ring; 15 ×1.5 mm 2 192-16274
Bev-a-line Tubing; 2 meters total 1 222-01824
Swagelok Ferrule Set' ¼"; Vinyl 2 300-05375
Swagelok Fittings; ¼"; 7/16 - 20 2 300-16268
Stainless Steel Plug with O-ring 4 300-16271
Elbow connector; 5/16 - 24 × 1/4 1 300-16515
Chamber gasket kit (see Accessories kit) 1 9981-198

Useful software

You may need to acquire some software to make use of the soil chamber. Software is available from www.licor.com/env/support. Select the LI-6800, and then select Software. The following apps are available free of charge for LI-COR customers:

Bluestem™ OS

Bluestem Operating System runs on the LI-6800. Both the LI-6800 console and head need to run software version 1.3 or newer in order to use the soil CO2 flux chamber.

SoilFluxPro™ Software

SoilFluxPro Software is a free PC- and Mac-compatible application for analyzing soil efflux data sets. SoilFluxPro makes it easy to recompute data sets with altered parameters, create graphs, and analyze results. Version 4.1 or newer is required to read the .json data files created by the LI-6800.