🌿 The Haney test, how a Texan makes the soil speak
Rick Haney was not always a soil researcher in a white lab coat. Before he joined the USDA, he worked on a ranch, was a farmer himself, and earned a PhD in Soil Microbiology. After his time at the USDA, he now works independently as a consultant and speaker for regenerative agriculture, including collaborations with organisations such as Soil Regen and Regen Ag Lab. This connection to the soil led him to develop an analytical tool that is grounded in real life. Today, he is no longer with the USDA but works independently, advising farmers directly and regularly speaking at conferences about regenerative agriculture. The Haney test he developed goes far beyond traditional soil analyses. Instead of limiting itself to chemical values, it makes soil life measurable – and shows how active, hungry, and productive your field really is.
🤔 What exactly is the Haney test?
Traditional soil analyses often focus solely on chemical components, neglecting the living ecosystem in the soil. Dr. Haney wanted more. He developed a test that combines chemical, physical, and biological properties of the soil, thus creating a holistic picture of soil health.
🧪 What does the Haney test measure exactly?
Before we look at the measurement parameters, a brief comparison of the extraction methods used is important. This is where one of the key differences to conventional soil analyses lies.
🔍 H3A vs. Mehlich III – the extraction question
The Haney test uses the so-called H3A extract, consisting of three weak organic acids: citric acid, lactic acid, and acetic acid. These acids mimic plant root exudates and release those nutrients from the soil that are actually available to microbes and plants – that is, biologically relevant.
In contrast, the widely used Mehlich III extract employs aggressive substances such as ammonium fluoride, EDTA, and hydrochloric acid to chemically extract as many nutrients as possible – regardless of whether they would be available to plants under natural conditions.
Conclusion: The Haney test provides an ecologically realistic picture of actual nutrient availability – rather than just a chemical potential as with Mehlich III.
The Haney test combines biological, chemical, and ecological parameters to create a realistic picture of life and nutrient dynamics in the soil. It uses only water and weak organic acids (H3A extract) to extract those nutrients that are actually available to plants and microbes – no aggressive laboratory chemicals, but a practical approach that is more aligned with field reality.
Here are the key metrics at a glance – and what they mean:
- Soil Respiration: Shows how much CO₂ soil microbes release within 24 hours after wetting – indicating how alive and active your soil is.
- WEOC (water-soluble organic carbon): "Quickly available food" for microorganisms. The higher, the better – as long as it is in balance with nitrogen.
- WEON (water-soluble organic nitrogen): Indicates how much organic nitrogen is available to microbes – the "protein supply" of soil life.
- %MAC (microbial active carbon): Indicates how much of the WEOC is actually utilised. Between 50–75% is optimal.
- C:N ratio (WEOC to WEON): The balance of energy to nutrients. Optimal is 10:1 to 12:1. Too much C? Little decomposition. Too much N? No energy for the process.
- Ratio of organic to inorganic N: Reflects whether your soil is committed to biology in the long term – or whether you are giving (too) much mineral fertiliser. Target: >5.
- Organic N release: This value indicates how much nitrogen your soil can make available on its own – completely without fertiliser.
- Organic N-reserve: The remainder of the WEON after the N-credit – the larger, the more resilient your soil.
📈 The Haney Soil Health Score explained
The "Soil Health Score" is a composite value derived from soil respiration, WEOC, and WEON. It ranges from 0 to 50. Most soils do not exceed 30. A score above 7 is considered good – but what "good" means depends on the location and management:
- <7: Weak soil life, low microbial activity
- 7–14: Good biological activity, improvements possible
- 14: Very good biological function, often in humus-rich or permanently greened soil
Important: A value of 10 in a dry climate like New Mexico can mean more than a value of 14 in Central Europe. Always consider the context of the location!
🌱 Why was the Haney test developed?
Dr. Haney recognised early on that healthy soil is the key to sustainable agriculture. Conventional tests were not sufficient to capture the complex biology of the soil. His aim was to develop a tool that not only saves fertiliser but also enables farmers to improve their soil in the long term while farming more sustainably and profitably.
🧠 Practical benefits for farmers
The Haney test is not only a diagnostic tool but also a decision-making tool for daily operations management. It provides the foundation for smarter, more efficient, and more regenerative decisions. An overview of the specific applications:
- Detailed nitrogen management through consideration of organically bound nitrogen. Unlike classical tests, the Haney test provides realistic N credits from biological activity – this saves fertiliser and reduces environmental impact.
- More efficient fertilisation strategies thanks to the combination of available and potentially releaseable nutrients. This means: You not only know what is currently in the soil – but also what your soil will soon provide.
- Management recommendations for cover crops and crop rotations, tailored to biological activity and C:N ratio. This way, you can specifically promote microbial processes – for example, with legumes for nitrogen supply or grasses for carbon stabilization.
- Clear rankings and action guidelines: By categorising into levels (e.g. regarding soil respiration, C:N ratio, MAC%), you receive clear frameworks for assessing and developing your areas.
- Resilience assessment and progress measurement: You can see over the years how your soil changes through management practices. Especially in stressful climatic years, it quickly becomes apparent which areas have become more resilient.
- Business comparisons and benchmarking: Because the score is regionally comparable, you can relate your fields to those of neighbouring businesses – this creates transparency and motivation for improvement.
🔥 Soil biology is like a campfire
Haney likes to compare soil to a campfire: those who build it need the right ratio of kindling (C), fuel (C/N), and oxygen (microbial activity). Too much straw (C) without protein (N) – and nothing happens. Too much nitrogen, but no carbon – and the grill stays cold. The perfect balance ignites a hot, efficient fire: your fertile soil.
😂 A little humour to finish
Originally, Dr. Haney had considered naming the test "Soil Health Integration Tool" – abbreviated as "SHIT". Presumably, this name would have generated a lot of interest, but it might not have quite matched the serious tone that a USDA scientist envisions.
💡 Conclusion
The Haney test brings us closer to agriculture that works with nature rather than against it. It not only allows for savings on fertilisers but also promotes healthier soils, better yields, and more sustainable production methods in the long term.
Meanwhile, the Haney test has become an indispensable tool for any farmer who is serious about the health of their soil.