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I am a soil health fan. I like learning more about it and discovering ways to improve it on our family farm. The challenge is measuring progress and being able to measure it myself without breaking the bank.
In the first part of this series of articles I encouraged growers to think of the soil as an engine. The productivity (horsepower) of that engine can be improved, but first we need to measure the existing horsepower. The Solvita test is an affordable tool growers can use to estimate the size of soil's engine by measuring respiration or carbon dioxide (CO2) release.
Most of us think we are doing what is good for crops. "The normal practice is to provide crops with nitrogen, phosphorus and potassium," said Will Brinton, the environmental scientist who developed the Solvita test and founded Woods End Soil Lab, which distributes the test. "We take it for granted that our crops will get the CO2 they need from the surrounding air. But things have changed over the years. Soils have fallen so low in organic carbon that they no longer produce enough CO2 to feed vigorously growing plants."
Brinton said active soil can release a lot of CO2 and it can be measured. "Today the atmosphere contains about 400 ppm (parts per million), crop canopy about 800 ppm, the layer of litter on the soil surface has about 1500 ppm and the soil as much as 4000 ppm CO2," he said.
Very healthy soils will have CO2 bursts of 150 ppm or more. Keep in mind that microbes feed on carbon, respire CO2 and recycle nutrients to feed roots and humic compounds to improve the soil structure. The bigger the burst, the bigger the engine.
There are two Solvita tests. The Solvita Basal Respiration Test is used on-farm and can be done at home. The Solvita Soil CO2-Burst Test is run in a commercial laboratory that does soil analysis under more precise conditions. With both methods, the user purchases specially designed paddles that collect CO2 and a meter that will read the paddles. With the basal test, users have the option of reading color change off a color chart.
While the basal test measures CO2 release under natural field conditions on any given day, the burst test measures the potential of that soil to release carbon dioxide. "The CO2-Burst test works because when you dry and rewet the soil, it will give off a burst of carbon dioxide. This burst is an indicator of (potential) biological activity," Britton said.
With the CO2-Burst test, the soil is dried and ground like a conventional soil sample in a laboratory. The rewetting procedure is standardized with a special soil-capillary moistening beaker to conveniently add the correct amount of water for the test without over-wetting the soil.
"No one test will evaluate all the components of soil health, as it is tedious," said Brinton. "However, the CO2-Burst is a good indicator. It integrates everything related to soil quality and health and can monitor incremental improvements in soil from better management.
"Yields are stagnating for many growers globally, because of climate change, salinization, erosion, pests and diseases and depletion of biology and soil fertility. Soil fertility is not just about applying more fertilizer," he added. "Soil biology is an important component. Unfortunately, growers don't see that they are depleting their soil's biology."
In 2013, I collected samples and sent them to a laboratory to run the Solvita CO2-Burst Test. I wanted to understand the technology and investigate its potential.