Humic and Fulvic Acids in Agriculture: Applying the 4 Rs.
Humic and Fulvic Acids: Start With the Right Agronomic Question
Black Earth’s Clay Williams joins RealAgriculture to explain why effective humic use begins with source, type, rate and timing – not a one-size-fits-all product promise.
Humic and fulvic products are receiving greater attention across agriculture, but the most useful question is not simply whether they work. It is what a grower is trying to accomplish, which fraction and formulation fit that objective, and how the product will integrate into the existing crop program.
That practical distinction shaped a recent episode of RealAgriculture’s The Agronomists. Host Lyndsey Smith was joined by Clay Williams, Head of Research and Development at Black Earth, and Mohammad Rahbari, EVP of Innovation and Sustainability at CanGrow/Bioline, for an in-depth discussion about humic substances, biological products and their place in modern crop production.
Watch the full episode on YouTube
Not all humic products are designed to do the same job
Humic substances are naturally occurring organic complexes formed through humification and are part of the stable organic matter found in productive soils. Within that broad category, however, different fractions and formulations behave differently.
As Clay explains in the episode, heavier humic components may be selected for objectives such as nutrient holding, soil structure and long-term soil-building programs. Lighter humic fractions and fulvic products may be used differently, including in formulations intended to support plant response. The right choice depends on the agronomic objective, soil conditions, cropping system and application method.
This is why treating every humic product as interchangeable creates inconsistent expectations. A product designed to accompany an in-season application is addressing a different need than a granular material selected for a longer-term soil program.
A familiar framework: the 4 Rs of humic use
Clay organizes the decision around four practical questions: Is it the right source, the right type, the right rate and the right time? The framework borrows familiar nutrient-stewardship language and applies it to a category in which product origin, composition and intended function can vary considerably.
1. Right source
Source reflects both how the material was formed and what it contains. Humic materials originate through long biological and geological processes, and those differences affect their composition and performance characteristics.
Black Earth mines HUMALITE from its reserve in east-central Alberta and manages the material from source through processing and formulation. That source control supports consistency, traceability and the ability to develop products for specific agricultural uses.
2. Right type
The desired outcome should determine the product type. Is the priority longer-term soil improvement, nutrient management, root establishment, an in-season plant response or compatibility with a particular fertilizer program? Granular, liquid, heavier-humic and fulvic-based products each have different roles.
Formulation matters operationally as well as agronomically. Products can behave differently depending on pH, fertilizer chemistry, moisture and storage conditions. Compatibility information and a jar test should be part of planning whenever a liquid product will be added to a tank mix.
3. Right rate
Rate must match function. A low-rate in-season biostimulant application is not intended to add meaningful quantities of stable organic matter to the soil. Conversely, a soil-building or remediation objective requires substantially more material than a plant-response application.
Using a single rate across different objectives can create disappointment even when the product itself is sound. The target outcome needs to be defined first; the appropriate rate follows from that decision.
4. Right time
Timing should align with both crop need and farm logistics. Pre-seed and post-harvest windows may suit granular applications or broader soil programs. At seeding, the focus may shift toward establishment and nutrient placement. In season, compatible liquid or fulvic formulations may accompany another planned pass.
That last point matters economically. As Clay notes, logistics can overwhelm good agronomy if a product is difficult to handle or requires an additional trip across the field. The strongest program is one that can be applied correctly, consistently and at a cost that protects return on investment.
Evidence matters – and local context matters too
The episode also addresses one of the most important questions surrounding biological products: consistency. Results from one soil, crop or geography should not automatically be generalized to another.
Replicated field trials across multiple locations help clarify where a product performs, what problem it addresses and how repeatable the response may be. Standardized analytical methods are also important. Clay highlights the difference between ISO testing and other measures of humic content, reinforcing the need to compare products using equivalent methods rather than relying on a single headline number.
For growers evaluating a humic program, the practical starting point is to identify the agronomic constraint, select a product designed for that purpose and preserve an untreated comparison where possible. A challenging field can be informative because its limitations are visible, but the problem still needs to be one the selected product can reasonably address.
Build a program, not a product expectation
Humic and fulvic products are not a replacement for sound fertility, water management or agronomy, and they are not a universal fix. Their value comes from matching the material to a clearly defined need and integrating it into a larger crop and soil strategy.
For long-term soil goals, consistency matters. One application may address a specific seasonal challenge, while a sustained program can support broader objectives over time. As Clay summarizes in the conversation, it is about building a system and building soil for the long term.
Watch the full conversation
The full episode explores humification, plant and soil responses, product handling, local trial data, standardized testing, application timing and return on investment. It offers a grounded discussion for growers, agronomists and agricultural partners who want to understand where humic and fulvic products fit – and where they do not.
Interested in identifying the right humic product for your soil, crop or fertilizer program?