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Soil Carbon Baseline Sample Plan
Demo Farm / Demo Project Developer
🎉 Stratification and sample plan design is done!
Explore your project’s sample plan results
Sample plan design details
Stratified by expected soil carbon stock (via POLARIS)
Predetermined sample sites to avoid bias
25 foot setback from all field boundaries to avoid head rows
“Backup” points if primary points are inaccessible
Optimized number of strata, balancing size and accuracy
Explore your fields and sample sites
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Sample plan ZIP contains fields and strata boundaries, sites, and strata report
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Plan summary
Plan precision target
90%
Confidence
93
Sample sites
Total acres 603
Total samples 93
Avg sampling density 6.5 acres / sample
Minimum sample sites/stratum 3
About your plan
Field-level plan details
Field name Sample Sites Acres
Northeast Field 23 146.9
Southwest Field 25 153.4
Northwest Field 24 155.9
Southeast Field 21 146.5
Total 93 602.7
Sample plan design techniques

Soil carbon stocks are estimated from measurements taken at sample sites. Determining how many samples to take is a balancing act. Too many and the project becomes expensive. Too few samples and the results have an unacceptable level of uncertainty.

Yard Stick solves this challenge with a process known as "stratified random sampling." Using published, peer-reviewed soil data from the United States Geological Survey, we estimate expected soil carbon values and then use data science to divide fields into areas of similar types of soil. These are known as "strata" (singular: “stratum”). Next, we calculate required number of samples based on your project’s budget and/or required precision. Lastly, we randomly place the required number of samples within each stratum. By taking random samples within a stratum, we can consider the samples as being representative of the stratum as a whole, and therefore a smaller number of samples are needed to achieve a target level of precision.

For more technical detail on our stratification techniques, click here, or select “Stratification methods doc” from the dropdown above.

Next steps to a baseline
Develop a sampling team strategy
Option 1 - Hire a sampling team
Many field services and agronomy consultants offer soil sampling services in most agricultural areas. By hiring an outside team, you can reduce the labor and equipment burden on your team, but the organization you hire is not likely experienced with sampling for soil carbon specifically.
Option 2 - Hire Yard Stick
Yard Stick focuses exclusively on sampling best practices for soil carbon. It’s literally all we think about all day long! We’d be glad to sample your soils affordably and accurately.
Option 3 - Do it yourself
It can be hard to do right, and physically taxing, but if you’re experienced in this domain, it’s possible to DIY. Let us know if you’d like recommendations on equipment or process.
Choose a soil lab for core analysis
Make sure your lab is experienced with soil carbon. Analytical techniques for soil carbon vary widely from lab to lab, but only a limited set of techniques are reliable. Pay attention to the following:
  • Require dry combustion (sometimes also called “total combustion”) for carbon analysis. Loss on ignition (“LOI”) is cheaper but not as accurate, and will not be accepted by the highest-quality soil carbon markets.
  • Ensure samples will be treated to remove inorganic carbon (IC) before analysis for organic carbon (OC). Organic carbon is also sometimes called “Total Carbon,” but just be sure IC is removed first.
  • Limit your search to labs with either NAPT or ALP accreditation.
  • Confirm your lab will do bulk density analysis before soil carbon analysis.
Yard Stick has vetted many labs working in soil carbon; let us know if you’d like a recommendation.
Calculate your carbon stocks
Once you get lab results back, calculate the carbon stocks of your fields via your preferred method. Simple means by strata are acceptable (depth-weighted if you’ve sampled to multiple depths), while inverse distance weighting may be more accurate. To do this work, consider three options.
Option 1 - Hire an agronomist
Some trained agronomists are likely able to research the process for calculating stocks, but we’d recommend you work with one specifically experienced in soil carbon.
Option 2 - Hire Yard Stick
Our software calculates stocks automatically. If Yard Stick is doing your sampling, we’ll prepare a custom dashboard showing the results from your farms and fields.
Option 3 - Do it yourself
If you’re comfortable with the statistics of soil carbon stock calculation, you can DIY.
Sampling costs
Labs typically charge $20-25 total per sample for both soil organic carbon (SOC) via combustion and bulk density analysis. Labor costs vary depending on sample density and geography, but a good estimate is $40-60 per sample site.
Yard Stick's services
Yard Stick can provide turn-key sampling services for all aspects of stock quantification described above. We handle everything: Team hiring and training, equipment, lab coordination and QC, data management, and stock quantification. Let your Yard Stick contact know if this would be of interest.