Haney Test
The Haney Test, named after its developer Rick Haney from the USDA (United States Department of Agriculture), is an innovative method, recognized in the USA and gaining popularity among regenerative agriculture movements. There is no better analysis to evaluate the health status of your soil in a simple, economical, and precise way. It measures key indicators related to soil biology and plant nutrition.
This analysis allows:
- Measuring the levels of nutrients present in the soil,
- Evaluating biological activity and the organic quality of it,
- Identifying limiting factors to unlock biological activity,
- Measuring the nitrogen released by the plot to adjust nitrogen doses,
- Establishing a complete profile of macro and trace elements available for the crop.
Thanks to the Haney Test, one can obtain a global view of the health and functioning of a soil, enabling fertilization decisions while improving soil fertility through a range of indicators.
Understanding your soils with the key indicators of the Haney Test
Assessment of biological activity potential
When active, soil microorganisms respire and emit CO2. This microbial respiration is measured over 24 hours under controlled conditions to establish biological activity. Soil respiration, measured in ppm of CO2 using the Solvita test, indicates the potential biological activity of the soil:
- High respiration shows strong microorganism activity, essential for the decomposition of organic matter and nutrient release.
- Conversely, in degraded soils, respiration is often below 50 ppm CO2, indicating a lack of biological activity. In this case, it is important to try to understand the reasons for low respiration. Checking other potentially limiting indicators in the analysis, visiting the plot, and discussing with the producer helps find solutions to unlock these soils.
Mineral bioavailability
To measure the availability of macro and micronutrients, the Haney Test simulates root activity that releases weak acids to solubilize nutrients. This process is reproduced with an extraction solution using organic acids that simulate the action of plant root exudates; this solution is H3A. It is composed of citric, oxalic, and acetic acids. This allows an evaluation of nutrient bioavailability for plants and soil biology.
There are strong correlations between H3A bioavailability and sap analyses, which allows us to determine limiting factors for crops with greater precision.
Water-soluble organic nitrogen
This indicator is crucial to understand the amount of nitrogen readily available to microorganisms.
- A soil rich in water-soluble organic nitrogen supports active microbial life, promoting better nutrient cycling and improved soil fertility. Microorganisms need labile nitrogen for their cellular and metabolic functions.
- If the Haney Test shows low values, it is advisable to apply organic fertilizer rich in nitrogen or practice cover crops with more legumes, which will release nitrogen upon destruction or grazing.
The Haney Test does not measure just one criterion to arrive at available N.P.K elements; it uses an integrated approach. For example, the available N result depends both on the measured respiration and the C/N ratio to model nitrogen availability.
Water-soluble organic carbon
It represents the amount of carbon readily available to microorganisms, an essential energy source for them. This includes sugars and molecules containing easily accessible carbon (glucose, sucrose, organic acids, bacteria or bacterial fragments…).
The roots of plants present in soils exude up to half of the sugars produced in their leaves; this liquid carbon feeds the microorganisms. They can then access minerals, simple molecules, and water for the plants. It is a symbiosis between the plant, which produces sugar but depends on microbiology for minerals, and the microorganisms, which depend on plants for their energy supply.
Therefore, maximizing biomass production and improving the photosynthesis of plants is essential to generate more exudation, more sugar, for more microbiology and organic matter.
A plant’s photosynthesis capacity can be multiplied by 10 with a single foliar application, which can have a considerable impact in terms of energy produced per hectare, representing several tons of sugar.
Benefits for farmers
Input reduction
Thanks to precise measurements made with H3A (Haney Test extraction solution), the amount of nitrogen, phosphorus, and potassium available in soils is known. This allows fertilization plans to be rationalized based on what the analyzed soil can provide during the season.
Soil health monitoring
The Haney Test, more dynamic than conventional analyses, allows annual monitoring of soil health evolution. Unlike conventional analyses performed every five years, which are very stable, the Haney Test shows soil and practice changes each year.
A score on a 50-point scale allows tracking soil health evolution. This score is based on respiration, organic carbon, and nitrogen measured in the samples.
Prevention of mineral deficiencies and excesses
By analyzing not only nutrient quantities but also their bioavailability for crops, the Haney Test offers a clear view of soil status. With this information, it is possible to apply appropriate minerals to prevent deficiencies and rebalance the soil according to crop needs. This helps maintain healthy soil, maximize yields, and ensure crops get exactly what they need to develop well and avoid diseases.
Example of a barley plot from a farmer in the Loire
Organic matter and soil pH
Organic matter is the home of microorganisms. At 3.4%, microbiology is comfortably established but it is not a castle life. Continuing to return biomass through cover crops and manure inputs would increase the size of the habitat and promote stronger microbial activity.
The pH of 6.6 is slightly acidic and ideal for mineral availability.
Soil respiration
Soil respiration, at 98.20 ppm CO2, is adequate, indicating average microbial activity. Biology is well present but here it is limited by low labile organic nitrogen content and the limiting size of the home (OM).
Labile organic nitrogen
The labile organic nitrogen at 8.80 ppm is insufficient. This limits microorganism development. Legumes and nitrogen-rich organic fertilization in the rotation can help increase these levels and thus promote microbiology development.
Labile organic carbon (microbial fuel)
Labile organic carbon is good at 199 ppm. Microorganisms therefore have enough easily available sugars for their development.
Nutrient bioavailability
Here, magnesium, zinc, and boron are limiting. These deficiencies are also found in the sap analyses of the farmer’s barley, indicating a good correlation between the Haney Test and sap analyses. The farmer applied Kieserite, boron, and zinc to the soil on his plot, which helped prevent deficiencies to some extent, but foliar applications remain necessary for now.
Nutrients available for the next crop
To produce his 6 tons of barley, the crop needs 132 units of nitrogen, 45 of P2O5, and 60 of K2O. According to the analysis, the crop has 59 units of N, which is insufficient to reach the farmer’s goal of 6 tons of barley. The farmer must find 73 additional units to reach his target.
Low respiration/organic carbon
This shows that despite good levels of easily accessible sugars, microorganisms are not thriving. In this example, the sample was taken after a rapeseed cover crop. Although crucifers secrete sugars, the cover, made up of a single species, produces less diverse exudates. A multi-species cover would improve this indicator.
High organic C/N ratio
In this analysis, with a value of 22.70, the indicator is high due to lack of organic nitrogen and a high level of available sugar. It is as if bacteria consume only energy drinks without access to vitamins. It is all about balance, and to promote intense biological activity, both sugar and vitamins are needed.
Organic N / Inorganic N ratio
With a value of 0.70, the ratio is too low, caused by synthetic nitrogen fertilization applied to rapeseed and highly mineralizing mid-autumn conditions. Healthy soils have ratios that can exceed 5 or even 7. The higher this ratio, the less mineral nitrogen (nitrates, ammonium) the soil contains, which is always preferable.
Test availability
To date, this analysis is only available in the USA. It is therefore necessary to find a provider who has partnered with an American laboratory that can receive samples and send them to the USA. This is the case for Symbiotik Agroecologie.
