Back to Resources Vol. 02 · Spring 2026
A magnifying glass is positioned over the soil
Sustainability May 2026

Biological Soil Amendments: The Living Data Powering Your CI Score

Learn how these living amendments drive plant vigor, reduce synthetic fertilizer needs, and ultimately lower your Carbon Intensity (CI) score.

Gradable Resources

Biological soil amendments are currently a major topic in the agricultural community. Numerous products have hit the market with big promises: lowering fertilizer needs, improving soil health, and increasing yields. But what exactly are these products? How do they work? Most importantly, how do they impact your Carbon Intensity (CI) score and your bottom line?

What are "Biologicals"?

Agricultural biologicals, or biological soil amendments, generally fall into three distinct categories:

1. Organic Animal-Based Amendments

Derived from animal origins—such as manure, bone meal, blood meal, and fish emulsion—these are often strictly regulated due to food safety concerns. While we know these materials are teeming with bacteria and microbes, they are not typically identified by specific Colony Forming Units (CFUs). The biological makeup is inherent to the material, but the specific organisms can vary significantly from batch to batch.

2. Plant-Based Biologicals

These result from "green manures" or recycled plant vegetation. This includes cover crops, crop residues from no-till production, or the addition of composted green waste. These amendments are applied with the understanding that microbes are present to break down and decompose the organic matter. However, like animal-based sources, the specific microbial species and the exact secondary benefits they provide aren't always lab-proven or quantifiable.

3. Microbial Inoculants

Inoculants are the "precision" branch of biologicals. These are lab-grown organisms, hand-selected and concentrated for specific agricultural roles. Because they are manufactured, they feature quantifiable numbers of CFUs and identifiable species. These are often "specialists" chosen for specific tasks: nitrogen fixation, metabolizing phosphorus, or acting as parasitic deterrents to pests. The specific role of the organism in the inoculant directly dictates the productivity of the crop.

From Soil Health to the CI Score

It is important to contextualize how these amendments impact your production practices and your overall Carbon Intensity score.

In short, biologicals are proven to improve soil and plant health. While the degree of impact varies by product, the overarching benefits are consistent:

  • Increased Soil Organic Matter (SOM)
  • Improved moisture retention
  • Better gas exchange in soil pores
  • Increased Cation Exchange Capacity (CEC)
  • Potential to decreased synthetic fertilizer applications

Because soil health dictates plant health, the downstream effects are clear: reduced crop stress, increased vigor, and better natural resistance to disease.

The Formula: Why Biology Lowers the Score

A great crop is its own reward, but in today’s market, the way you grew that crop has its own value. CI scores are formulated based on the full scale of your production: tillage, cover cropping, nutrient additions, chemical passes, and fuel usage.

While a biological product doesn’t "magically" lower a footprint on its own, the displacements it creates are powerful:

  • The Cover Crop Example: A cover crop may fix nitrogen, stabilize soil, and increase macro-pores. The microbes added through this "green manure" increase moisture retention. Because the soil is now more efficient at holding nutrients due to the increased cation exchange capacity being increased, there might be the potential to reduce synthetic fertilizer needs. This saves you the economic cost of the fertilizer and has the potential to reduce your CI score by reducing fertilizer application needs.
  • The Inoculant Perspective: The impact here is more surgical. An inoculant itself won't lower your score inherently, but its effect will. If a specific microbial strain improves fertilizer facilitation to the plant, you may find you can achieve the same yield with less fertilizer additions. If a microbe improves plant vigor to the point where you skip an extra fungicide or insecticide pass, you’ve just reduced your fuel and chemical "spend" on your CI sheet.

The Bottom Line

While there are many variables to consider, the foundation remains simple: Improving soil health leads to improved plant health. This synergy creates opportunities to optimize your inputs, which is the most direct path to a lower carbon intensity score and a more resilient, profitable operation.

G End of article · Gradable Resources · Vol. 02 · Spring 2026
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About the byline

Gabrielle Henrichs

Sustainability Program Lead

This piece was reported and written by the Gradable team — the program leads, agronomists, and policy analysts who run our partner programs day to day. We don't use outside agencies or ghostwriters.

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