How We Test
Our growers sample their own soil, using our Soil Sampling Protocol. We retrieve the soil samples from our growers, freeze the samples, and then ship the samples to Regen Ag Lab in Pleasanton Nebraska. Regen has been great to work with, and has been very responsive in answering our questions. They have conducted a workshop to help our growers understand their soil health test results, provided individual soil health consults for 19 growers, and helped us develop our User Friendly Haney and PLFA Results Report.
We use the Haney and PLFA tests to monitor our growers’ progress at improving their soil’s health, because these two tests seem more widely accepted in the West.
- The Haney test is similar to a standard soil test in that it measures pH, NPK, trace and more.
- The PLFA test gives our growers an overview of which classes of microbes are living in their soil.
The Haney test also includes a Soil Health Score, which is computed from the number of microbes in your soil, as measured indirectly by soil respiration, PLUS the amount of carbon-rich food (organic carbon) they have to eat PLUS the amount of nitrogen (organic nitrogen) they can supply to other living things. So the Soil Health Score is a quick way to measure the health of your soil’s microbial life.
But the Soil Health Score is a bit of a blunt instrument, and it’s important to notice what is does NOT measure. It does not tell you anything about nutrient deficiencies, or pH problems, or compaction issues, or fungal bacterial ratios for example. The Soil Health Score is just one slice of a much bigger picture of a soil.
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The Haney Soil Health Test measures the nutrient needs and overall health of a 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 balance the C: N ratio and feed the soil microbes, to improve the soil’s health.
Finally, if a “crop to be grown” and “yield goal” is provided at the time of sampling, the lab will provide recommended application rates of N, P, K and trace.
The Haney test provides values for:
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 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 the 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: