Lance Gunderson Explains the Haney and PLFA Soil Health Tests, February 13 2020

Lance Gunderson explains the science behind the Haney and PLFA soil health tests, and how to interpret test results.
Soil is a complex ecosystem that provides habitat for all kinds of micro-organisms. These include bacteria, fungi, protozoa, nematodes, earthworms and more. These organisms control much of the nutrient cycling in your soil. They breakdown crop residues, store plant nutrients, create stable organic matter in the form of humic acid, and help build soil structure, thus reducing compaction and erosion, while increasing water holding capacity and allowing for deeper root structures.
The relationship between different microorganisms and plants is dynamic. Predatory protozoa eat bacteria which releases nitrogen into the soil. Symbiotic bacteria and fungi aid the plant in acquiring more nutrients.
Phospholipid fatty acids (PLFA) are found in the cell membranes of living organisms, and are used to estimate the living microbial biomass in your soil. Different kinds of cells have unique biomarkers, or signature fatty acids, which helps identify the presence or absence of various microbial groups of interest.
PLFA test results are a snapshot of your microbial community structure and abundance at the time of sampling. As environmental conditions such as pH, temperature, and moisture change, so does your microbial community. These communities are also influenced by soil type, organic matter, intensity and type of tillage, crop rotations, cover crops, and herbicide or pesticide applications. You can use the ability of microbial communities to change rapidly as a tool to compare different management decisions, to see how your decisions affect soil health and fertility.
Since there is no baseline “normal range” for biological testing like there is for chemical analysis, this test is most useful for making comparisons between management conditions: till vs. no-till, different fertilizer applications, crop rotations, grazing vs. no grazing, etc.
The PLFA test provides values for: Total Living Microbial Biomass; Total Bacteria; Gram (+) and (-) Bacteria; Actinomycetes; Rhizobia; Total Fungi; Arbuscular Mycorrhizae; Saprophytes; Protozoa; Fungal: Bacterial ratio; Predator: Prey ratio; Gram (+): Gram (-) ratio; Stress and Community Activity ratios.
The Haney Soil Health Test measures the nutrient needs and overall health of your soil. Some Haney measurements are similar to traditional soil tests. Soil pH and organic matter, for example, are measured in the same way as traditional soil tests. But the Haney test uses different extracts than traditional soil tests use, to measure nutrients like N, P, K and trace. Haney’s special extracts (H2O -water, and H3A, similar to acids produced by plant roots to break down soil minerals) are meant to mimic nature, and more accurately measure the amount of nutrients that your plants can actually access.
For some nutrients like nitrate, Haney tests and traditional soil tests might have quite similar values, because their different extracts pull nitrate out of the soil at the same rate. But for other nutrients like phosphorus or trace, Haney test values will be quite different from values in traditional soil tests, because their different extracts pull phosphorus or trace out of the soil at different rates.
The Haney Test also evaluates soil health indicators such as soil respiration, the water-soluble fractions of organic carbon and organic nitrogen and the ratios between them. A soil health score is calculated based on a combination of these different soil health indicators. The Haney test then recommends a cover crop mix (% legumes: %grasses), to help you balance your C: N ratio and feed your soil microbes, to improve your soil health.
Finally, if you provide a “crop to be grown” and “yield goal” at the time of sampling, you will be provided with recommended application rates of N, P, K and trace.
We do NOT recommend that you discard your traditional soil testing and just rely on Haney test results for fertilizing. Rather, continue using both tests for several years to learn how they match up or disagree, and to figure out which tests are most useful for you.
Provides values for:
• pH
• Soluble Salts
• Excess Lime
• Organic Matter
• Soil Respiration
• Nitrogen: Total, Organic, Inorganic, Release, Reserve
• Phosphorus: Total, Organic, Inorganic, Release, Reserve
• Potassium
• Trace: Zinc, Iron, Manganese, Copper, Sulfur, Calcium, Magnesium, Sodium, Aluminum
• Carbon: Organic, Active
• C : N ratio
• Organic N : Inorganic N ratio
• Soil Health Score
• Cover Crop Suggestion
• N, P, K Quantity Available for next crop
• Fertilizing Recommendations, pounds of plant nutrients/acre (if you provide crop and yield goal)