Whose Farm Is More Sustainable? Calculating Farm Sustainability.

As discussions around sustainably grown grain become more prominent, it raises the question, “What qualifies it as sustainably grown?” It’s a question that has multiple answers since the current sustainable grain market is segmented, with multiple programs initiating their own certification requirements.

As the demand for sustainable grain expands, it’s expected that a more structured and uniform marketplace will be established. It’s likely that within this centralized market, carbon emissions and sequestration will be part of the formula used to determine whether grain was sustainably grown.

Is a farm’s carbon footprint small or large?

Measuring a farm’s carbon footprint is not as simple as saying, “Cover crops were used, so that grain’s sustainably grown.” Different agricultural practices emit or sequester different amounts of carbon, so multiple farming practices must be considered when determining a farm’s environmental impact.

Different agricultural practices emit or sequester different amounts of carbon, so multiple farming practices must be considered when determining a farm’s environmental impact.

Consider this scenario. Two neighbors, Farmer A and Farmer B: both farm 1,000 acres and use the same crop rotation schedule. Farmer A tills 30% of their fields, uses cover crops on 20%, and applies anhydrous ammonia. Farmer B tills 50% of their fields, uses cover crops on 40%, and uses stable nitrogen sources. Which farmer has the lower carbon footprint? They’re both using sustainable farming practices on some of their fields, so how do we calculate how much those practices are contributing to their carbon footprint? Can we use their data to know how other farms in the area are performing? And, perhaps most importantly, how do we know those results are accurate and reliable?

Calculating farm sustainability is complex

Calculating a farm’s carbon footprint starts by identifying the carbon emission sources (e.g., fertilizer application, irrigation, machinery use, pesticide application) and the sources of carbon sequestration (e.g., reduced tillage, cover crops, treed acres). This is done by employing remote sensing, data input and proofing, modeling, and verification. To help explain the complex calculations behind measuring a farm or field’s carbon footprint, we’ve summarized some of these tools and processes below.

Leverage remote sensing to assess environmental impacts

About one-third of the data needed to assess a field’s environmental impact can be provided by remote sensing. Satellite images can track the development of each field throughout the growing season or year. Trackable events include plowing, minimum-till cultivation, crop rotation, crop type, cover crop presence, irrigation events, harvest date, and crop residue presence.

About one-third of the data needed to assess a field’s environmental impact can be provided by remote sensing.

Data collection and projection to compare sustainable farm practices

To help estimate values for other variables, including the use of carbon products, panels of farmers are interviewed. A stratified quota sample (size and geography strata with a minimum farm size cut-off) and deliberate over-sampling of commercially important farms is taken. The over-sampling is to reflect the importance of large farms but is then corrected during weighting and projecting. Data from Farm Management Information Systems (FMIS) are also collected, where available, with any missing questions answered in person. All data are collected consistently with identical questionnaires deployed, irrespective of county, commodity, year, and farm type.

The data are weighted and projected using factors from the latest census or Earth Observation (EO). Small-area estimation uses EO to distribute projected data to grid squares, ZIP codes, and fields. Essentially, these estimations answer how similar a sampled farm is to other farms and how likely those other farms are to use the same practices. In doing this, input values obtained from the sample are applied to other fields not sampled.

Confirmation and proofing farm sustainability

To ensure that critical behaviors beyond the reach of EO are covered, another panel of farmers — each with more than 250 acres — is used to confirm or proof a small number of discriminating and impactful variables. The farmers’ responses are used to confirm or improve algorithms, enhance small-area estimates, replace estimates with actuals, and enrich farmer database information with additional data from each farm.

Examples of the variables proofed include:

• Number of fertilizer applications
• Proportion of nitrogen from ammonium nitrate or anhydrous ammonium
• Proportion of the crop treated with animal manure
• Use of slow-release technology
• Proportion of crop residue left in the field
• Use of gravity irrigation
• Frequency of machinery use
• Proportion of crop dried on the farm

Algorithms and verification

All of the inputs are applied to the latest and most powerful models to determine the environmental impact of each field and farm: how much carbon was created (or sequestered) based on input practices, crop yield, and acres. A third party verifies all these processes to ensure reporting meets GHG Protocol, SEC, SBTi, the Gold Standard, and Verra requirements and that the data can be trusted and relied upon.

The final result: carbon dioxide equivalent

The result for each farming practice and the overall field or farm, is a calculation called the carbon dioxide equivalent (CO₂e kg/acre). The CO₂e is used to standardize emissions from all types of greenhouse gases (e.g., carbon dioxide, methane, nitrous oxide, fluorinated gases). The EPA’s definition of CO₂e explains another way to look at it: “The number of metric tons of CO₂e with the same global warming potential as one metric ton of another greenhouse gas.” This value can then be used to compare the carbon footprint of multiple fields or farms.

There’s potential for CO₂e to be used in a scoring system so growers know where their sustainability efforts rank and where improvements could be made to be more competitive in the sustainable grain market. Ag retailers could also use this scoring system to their advantage, as it would allow them to target growers who could benefit from their sustainability-related products and services to improve their sustainability score.

Ag retailers could also use this scoring system to their advantage, as it would allow them to target growers who could benefit from their sustainability-related products and services to improve their sustainability score.

Calculating farm sustainability is complex but not impossible

The calculations behind farm sustainability are complex for a reason. Using primary data, EO, and representative large-scale sampling of farmers makes the assessment more accurate and reliable compared to data that is incomplete or dependent on EO alone.

Reliability and accuracy of sustainability reporting will be essential in the future as more and more companies source sustainable grain to meet their ESG goals and upcoming Scope 3 reporting requirements. So, it’s worth understanding these best practices now to be better prepared for a carbon-calculating future.

Learn more about how farm sustainability is calculated.