Soil testing is a vital step for improving crop performance and guiding farm inputs. Among the many tests available, the Haney Soil Test offers a unique perspective by simulating natural soil and plant processes. In this blog, we’ll break down why soil tests matter, explore the components of the Haney test, and show you how to read the results effectively.
But first, watch this video from our YouTube Channel Agriculture Explained (and make sure to subscribe!)
Why Use Soil Tests?
Soil tests help you answer one critical question: what is available to your crop?
This allows you to:
Tailor fertiliser applications
Track soil health trends over time
Determine if inputs like cover crops or biologicals are needed
Traditional soil tests often use harsh chemical extractants that don’t represent how plants naturally access nutrients. For example, the widely used mehlich 3 extractant uses acetic acid, ammonium nitrate, ammonium fluoride, nitric acid, and EDTA, much of which has never been seen by the soil naturally. An extractants can be limited in two ways: 1) some only work in a specific range of soil pH and 2) the accurancy of the mineral extraction.
The Haney test, however, mimics natural processes by using organic acids similar to those exuded by plant roots such as Malic Acid, Citric Acid and Oxalic acid. This gives a more biologically-relevant measure of nutrient availability, especially important in regenerative systems where biology plays a bigger role in nutrient cycling.
Components of a Haney Soil Test
The Haney test includes three major areas: Respiration, Water Extraction Nutrients, and H3A Extraction. Here’s what’s measured and why it matters:
1. Microbial Respiration
Measures CO₂ released after a dry-rewet cycle.
Reflects microbial reactivation potential.
2. Water-Extractable Organic Carbon & Nitrogen
Represents the energy and nitrogen supply for microbes.
These values directly feed into the soil health score.
- Using water extractable organic N provides insight into an additional source of N that isn’t often considered but can provide 50% of the overall N supply. This study found that nitrogen rates could be reduced by 30-50% without significantly affecting corn, wheat, oat and sorghum yields.
3. H3A Nutrient Extraction
Uses malic, citric and oxalic acids—mimicking natural root exudates.
Accurately assesses phosphorus, nitrogen, and other nutrients across variable soil types and pH levels. For example, in this study, they found that the H3A extractant preformed the best than the Mehlich-3 extractant for determining P availability, when compared to the FeAlO strips (Gold Standard for P availability)
Ideal levels for The Haney Soil Test
Haney Soil Health Score
A composite score combining microbial activity, carbon, and nitrogen to benchmark overall soil health. This score ranges from 0 to 50 with a score over 25 being ideal. A typical score is around 7.
Soil Respiration
Measures how actively soil microbes respond after a dry–rewet cycle, indicating biological potential. Ideally soil respiration should be above 100ppm. See the guide to interpret your results.
Water-Extractable Organic Carbon (WEOC)
Represents the easily available food source (like sugars and acids) that fuels soil microbes.
Total Water-Extractable Nitrogen (WEN)
Indicates the nitrogen readily available to microbes and plants, including both organic and inorganic forms.
Water Extr C:N
This is the ratio of water extractable carbon to water extractable Nitrogen and gives a good idea of the limiting factor for microbial growth. Ideally C:N is 11:1, above this N becomes locked and below this C can be released.
Organic Nitrogen
This is the amount of organic nitrogen in the water extractable nitrogen component and contains amino acids, amino sugars, proteins, etc. This form of nitrogen is very beneficial as it requires less energy for the plant to convert into proteins when compared to inorganic forms. Ideally, this should be greater than 60ppm and the higher the better.
Soil Carbon
Ideally total soil organic matter should be greater than 3%, with labile soil carbon making up 50% of that and the water extractable carbon making up 5% of total carbon
Haney Extractable Minerals
Compare each mineral’s found concentration to it’s ideal level. When minerals are below the ideal level, a deficiency is likely.
How to Read a Haney Soil Test
Here’s how to interpret the key data and what actions it may suggest:
Step 1: Check Soil Metadata
Ensure sample ID, location, and date are noted for tracking purposes.
Step 2: Look at the Soil Health Score
Scores below 25 suggest the need for increased biological activity through cover crops or stimulants.
Step 3: Review Microbial Indicators
Low respiration = dormant biology.
High carbon and nitrogen = good microbial food supply.
Step 4: Nutrient Assessment
Compare your levels to ideal ranges.
Watch for nutrient imbalances or deficiencies—e.g. high sodium may antagonise calcium uptake.
Step 5: Calculate Fertiliser Requirements
Subtract your test result from the desired level.
Convert from mg/kg to kg/ha.
Include organic N in your calculations for accurate nitrogen budgeting.
Step 6: Watch for Limitations
Haney test may overestimate N in drought due to reduced mineralisation and underestimate N in wet years due to increased mineralisation as suggested by this study.
Pair it with SAP tests for in-season adjustments.
Conclusion
The Haney Soil Test provides a more holistic and realistic picture of soil nutrient availability and biological function. It’s especially valuable in regenerative systems where biology drives nutrient cycling. By using root-mimicking extractions and including organic nitrogen in its analysis, it allows farmers to fine-tune fertiliser inputs and boost efficiency.
Need Help With A Haney Soil Test?
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