Helping growers improve their soil health is an important part of the role we play at Truterra. While carbon and carbon programs seem to be stealing the spotlight in the media, it is not lost on us that increasing carbon sequestration leads to better soil health, which can lead to higher yields, yield stability and numerous other positive attributes that could be worth more than a carbon asset. When talking with agronomists and soil scientists about soil health, you will often hear them mention the Haney Test as the first step in the soil health journey. What is the Haney Test? What does it tell a grower about their soil? Is it important for successfully increasing soil health?
What is the Haney Test?
The Haney test was developed by Rick Haney of the United States Department of Agriculture-Ag Research Service in Temple, Texas, as a way of testing for soil health and viewing soil as a living biological entity. The Haney test is actually a series of tests providing over a dozen data points and an overall soil health score derived by calculations from the data points. The test is available at multiple soil testing labs around the United States for a cost of approximately $50.
What does the Haney test tell a grower about their soil?
One of the key measurements in the Haney test is soil respiration, or biological activity over a 24hour period. Soil microbes breathe in oxygen and release carbon dioxide, just like humans. The Haney test measures how much CO2 the soil is releasing. Higher CO2 levels indicate more microbial activity. Higher microbial activity is tied to many functions of a healthy soil, such as increasing nutrient cycling, increasing organic matter and stimulating plant growth.
A water extract is another part of the Haney Soil Health Test. The water-extractable organic carbon is a measure of the organic carbon or food that is most readily available to the microbes. Likewise, water-extractable organic nitrogen is the pool of organic N that is most available to the microbes as well. Generally speaking, carbon is the energy source for microbes and nitrogen is the protein source. The carbon to nitrogen (C:N) ratio is used to calculate several of the data points in the test results.
Another unique element to the Haney test is the use of H3A as a soil extractant for nutrient testing. H3A mimics organic acids produced by living plant roots to temporarily change soil pH to increase nutrient availability. This method is used to measure nitrate, ammonium, orthophosphate, and ICAP phosphorus (total P), potassium, calcium, magnesium, sulfur, zinc, iron, manganese, copper, and aluminum.
The Haney test includes soil pH and organic matter, which are evaluated in the same way as more traditional soil tests. In addition, plant-available nutrients such as NPK are evaluated with the same instrumentation and protocol as a standard soil test.
From these data points, the Haney test calculates several metrics. It uses the C:N ratio and soil respiration scores for the overall soil health score. The water-extractable nitrogen, C:N ratio and soil respiration results are used to give a grower an estimate of available nitrogen or nitrogen credit in the soil. Water-extractable carbon and soil respiration are used to determine the % microbial active carbon. And finally, a very general cover crop recommendation is included based on the various data points of the Haney test.
Is the Haney test important for successfully increasing soil health?
While it is not imperative to the process, the Haney test provides a very good way to benchmark and document a grower’s soil health journey. It provides unique insights that you won’t get from any other test. For example, in a time of very high-cost nitrogen, knowing the available nitrogen in your soil could help a grower reduce their N rate and save some money without sacrificing yield. Knowing how active your soil is respiring and the food availability for microbes will give you a benchmark of where a grower is in the soil health journey. Then, yearly testing at the same time of year can provide a grower with metrics that show how their practice adoptions are affecting their soil health.
To learn more about Truterra and our role helping growers improve their soil health, visit our website at www.truterraag.com
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