Soil Carbon Challenge: procedures, deliverables
The Soil Carbon Challenge soil carbon monitoring procedure is aimed at detecting change over time. Remonitoring can happen after 3-10 years depending.
- Decide on number and locations for permanent plots or monitoring locations with the people involved, and on depths to sample. Considerations of experimental design, differences in past, present, or future management, vegetation, soil types, and slope all play a role. Try to be representative and strategic with plot locations: not at foot of eroding slope, not right next to a water trough.
- Each plot is located on a transect. Set up transect with GPS as well as reference locations or lines of sight with tape and compass. Mark the transect with permanent stakes or markers, depending on the situation. If one or more markers disappear, or if GPS satellites become space junk, the plot can still be relocated.
- At each plot, do a surface assessment of ecological processes, including photography of the surface cover. For rangelands, we like the Land EKG method.
- The carbon plot is 4 m x 4 m, larger in forested areas. During monitoring, try to keep surface disturbance to a minimum. Take bulk density samples from a small soil pit at a plot corner for each depth sampled (e.g. 0-10 cm, 10-25 cm, 25-40 cm, which in inches is approximately 0-4, 4-10, 10-16 inches).
- Take water infiltration measurements with single infiltration rings.
- Take 8 core samples for each depth sampled. In general, we bulk samples from each layer. For specifics of the sampling method, see the latest version of Measuring Soil Carbon Change (2 Mb pdf).
- Surface monitoring report, including photographs.
- Lab data for each sample tested. Minimum here is total carbon and nitrogen percent, using an elemental analyzer. If carbonates are detected by acid test or soils report, separate tests for organic and inorganic carbon can be done, but we usually don't do this as the total carbon test is the most accurate and practical for detecting change in soil organic matter. Density for bulk density samples.
- Summary data report for each plot, including calculated values of carbon tonnage for each layer sampled, and map of transect with sampling points indicated.
- Placement of project location on http://soilcarboncoalition.org/changemap.htm, with link to summary report(s). This is normally public.
- Repeatability. The procedures are well documented, each site is marked and mapped, and any competent monitor with basic soil sampling tools and ecological monitoring experience will be able to repeat monitor the site.
- For each subsequent sampling, repeat above steps, and summarize change on map links.
This basic plot and sampling method can also be a platform or occasion for other soil tests. The focus is on establishing representative, strategic permanent plot locations by which to gauge change over time, so as not to be overwhelmed by the spatial variability of soil properties or ecosystem function. Each plot, both surface and underground, can also be an excellent platform and occasion for community learning and participatory discussion of carbon cycling, ecosystem functions, and the influences of management, and we like to facilitate these.