Year One ___ Haney Test:
Since this is the first years we have taken over this farm I wanted a good benchmark to go off of to track the improvements we are making to the soil. At first, I was content with just a basic soil sample that would give us a result for Nitrogen, Phosphorous, and Potassium. I also wanted to know the pH and amount of soil organic matter (SOM). After some consideration this will be the only chance I get and a benchmark assessment, I decided to go with the Haney test. The Haney test is a comprehensive soil test that measures the inorganic and organic compounds that conventional soil tests do not.
I separated our property into 3 different management systems. The first is the fescue pasture which was used as a hay meadow and for grazing. I did find a little bit of legumes scattered throughout the pasture. I would like to interseed a warm season cover crop mix and graze it during the fall. Here is a picture of the path I took to collect soil samples on the fescue pasture:
The next pasture I took samples from was a native hay meadow that has also be grazed. Repeated over grazing and haying late has resulted in a severely weakened native plant community and structure. Our goal is to properly graze the pasture and allow adequate regrowth during the late season growing period.
The third and final sample I took is from a pasture that was historically native and may have been seeded to fescue. It is on a Eram-eroded soil and the Sericea lespedeza has infested the entire pasture. This pasture is by far in the worst condition. I would like to first control the Sericea then use a cover crop mix to re-introduce the fungi back into the soil and to add some biomass. After the cover crop it grazed off I am going to try to seed it back to native. As I said it is an eroded soil so getting around with a tractor and drill may be a bit of a challenge.
The Results: (These are just the result to get to the soil health number. There is 2 pages of information when get the results back!)
Soil Respiration CO2-C, ppm C
“This result is one of the most important numbers in this soil test procedure. This number in ppm is the amount of CO2-C released in 24 hours from soil microbes after your soil has been dried and rewetted (as occurs naturally in the field). This is a measure of the microbial biomass in the soil and is related to soil fertility and the potential for microbial activity. In most cases, the higher the number, the more fertile the soil.” Ward Laboratories Inc.
Water extractable organic C (WEOC):
“This number (in ppm) is the amount of organic C extracted from your soil with water. This C pool is roughly 80 times smaller than the total soil organic C pool (% Organic Matter) and reflects the energy source feeding soil microbes. A soil with 3% soil organic matter when measured with the same method (combustion) at a 0-3 inch sampling depth produces a 20,000 ppm C concentration. When we analyze the water extract from the same soil, that number typically ranges from 100-300 ppm C. The water extractable organic C reflects the quality of the C in your soil and is highly related to the microbial activity. On the other hand, % SOM is about the quantity of organic C. In other words, soil organic matter is the house that microbes live in, but what we are measuring is the food they eat (WEOC and WEON).”
Water extractable organic N (WEON):
“This number is the amount of the total water extractable N minus the inorganic N (NH4-N + NO3-N). This N pool is highly related to the water extractable organic C pool and will be easily broken down by soil microbes and released to the soil in inorganic N forms that are readily plant available.”
Mix 20.0 (Sericea may have something to do with this...)
Organic C: Organic N (C:N):
“This number is the ratio of organic C from the water extract to the amount of organic N in the water extract. This C:N ratio is a critical component of the nutrient cycle. Soil organic C and soil organic N are highly related to each other as well as the water extractable organic C and organic N pools. Therefore, we use the organic C:N ratio of the water extract since this is the ratio the soil microbes have readily available to them and is a more sensitive indicator than the soil C:N ratio. A soil C:N ratio above 20:1 generally indicates that no net N and P mineralization will occur, meaning the N and P are “tied up” within the microbial cell until the ratio drops below 20:1. As the ratio decreases, more N and P are released to the soil solution which can be taken up by growing plants. We apply this same mechanism to the water extract, as the C:N falls; we credit more N and P mineralization on a sliding scale. We like to see this number between 8:1 and 15:1.”
Putting it all together
Soil Health Calculation:
“This number is calculated as 1-day CO2-C/10 plus WEOC/50 plus WEON/10 to include a weighted contribution of water extractable organic C and organic N. It represents the overall health of your soil system. It combines 5 independent measurements of your soil’s biological properties. The calculation looks at the balance of soil C and N and their relationship to microbial activity. This soil health calculation number can vary from 0 to more than 50. We like to see this number above 7 and increase over time. This number indicates your current soil health and what it needs to reach its highest sustainable state. Keeping track of this soil health number will allow you to gauge the effects of your management practices over the years.”
I was surprised to see the Mix pasture have a higher soil health score than the Fescue pasture. I assume this had to so with the organic N available and the amount of Sericea in the Mix pasture (Sericea is a legume which fixes N).
I'm curious what changes will occur with our improved management. I encourage anyone interested in soil tests to try the Haney test.
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