What is Solvita?

Solvita is a patented environmental measurement system with applications for soil, compost, manure and grain. The foundation of Solvita is a gel probe impregnated with chemistry that is sensitive to specific gaseous molecules, and changes color in proportion to their concentration. Two types of probes are available. One type measures carbon dioxide (CO2) in a low and high range, and the other type is for ammonia (NH3). The colors of the gel are visually compared to a color chart. The reaction follows the Beer-Lambert Law so it is quantifiable with the Solvita Digital Color Reader (DCR). The results can be used to assess soil health (soil biology), humic bound nitrogen, compost maturity (CO2+NH3 gas emissions), ammonia volatilization in manure, or grain spoilage due to fungal respiration.

Details on Using Solvita

At what temperature should I be testing? Do I need an incubator?

The reactions measured by Solvita are all temperature dependent and therefore temperature control is important. The kits are designed for room temp or about 20°C (68F). If your testing area has temperature shifts from day to night greater than + 3°C (5F), an incubator or closed room should be used.

Soil Microbe Temperature

Microbes respond significantly to temperature changes based on the Arrhenius rule which states that for each 10C increase, within a normal range, microbes will approximately double their rate of metabolism. Thus changes of only 5C can result in 50% difference in readings. The point here is that a range of temperatures can be used, but once a temperature is selected, all samples to be compared should be measured at that temperature. The research by Haney and Brinton is based on 22-25C readings.

Ammonia and SLAN Tests

The Solvita test for Ammonia is used for compost and now for soil (SLAN). It is not a microbial test so is less sensitive to temperature flux; volatilization of N, however, is influenced by changing temperature but not to the same extent as microbial response in the case of CO2.

How soon after opening the jar should I read the probe?

The probe should be read immediately after being removed from the jar.

Can I leave the probe in for longer or shorter periods of time?

No. It is important to adhere to the 4 hr read time for composts and the 24-hr time for soils since the test is calibrated for this time frame. In some cases with very active soils, the read time can be altered with suitable adjustments (contact the technical support team).

Use and storage of probes

The Solvita probes are specially packaged and sealed to assure freshness for up to 1 year under normal room-temperature <20C (<68F) storage conditions. High heat (>30C / >85F) reduces the storage life. For storage longer than 4 months, use cool or refrigerator (5-10C / 40-50F) conditions. Do not allow to freeze which will void the warranty. You can find the expiration date stamped on the individual silver pouch for each probe.

What to do when gel released from probe and remained in pouch?

Occasionally the Solvita gel can separate from the probe and remain in the pouch due to changes in temperature or pressure during shipment.  The gel can be carefully placed back onto the probe.  Avoid touching the gel while putting it back on.  For more information go to


Are probes reusable?

No. – Only the grain test may have an alternate application.

Are jars reusable? What about beakers?

Yes, both are reusable.

Are the probes toxic or do any of the tests require special reagents?

No. Solvita probes are non-toxic but contain strong preservatives, so should be handled with care, and definitely kept away from children. There are no additional special reagents needed.  Some Solvita tests require supplemental reagents in order to perform the test; as in the case of SLAN, and may require suitable lab experience. Solvita CO2 probes do not contain toxic barium chloride (BaCl2) which some alternate technologies do.

About the Digital Color Readers

Do I need a DCR?

A DCR reduces subjectivity in reading the gel color and provides significantly greater precision for the readings. Using a DCR should be mandatory if you are reporting research or offering the test commercially. There are two DCRs available from Solvita to be used to read Solvita probes. The yellow unit is applicable to all tests, however- if you are an individual grower, you can use the Field Unit (green DCR) as it reports just Basal Respiration. Color charts are still provided with all kits.

When do I need a DCR Model Upgrade?

The DCR programs are occasionally upgraded and owners will automatically receive information about the availability. Model numbers less than 700.6 should be updated to be applicable for the Soil CO2-Burst Test. The earlier units (Models 500, 600) can be returned to the factory and upgraded for a fee. All labs submitting data to the Solvita Soil Reference Program or Soil proficiency programs as ALP or NAPT need to be using version 700.8 or higher. Check with tech ervice for more details. 

Is the same DCR Button used for both CO2-Burst and Basal methods?

No. On the yellow DCR, CO2-Burst uses the Low-CO2 key and Basal uses the ALT key. The green Field Unit DCR only reads basal respiration.

How to use the Digital Color Reader

to download instructions for the Multi-Mode DCR (yellow) or for the (green). Instructions how to operate the DCR (both units) and how to use Solvita Reader Software can be downloaded .

Solvita Soil Respiration

What is Solvita Soil Respiration?

Solvita is a thin-gel technology that is used to assess soil health. Carbon dioxide (CO2) emissions from soil are primarily due to microbial respiration. The level of microbial activity is indicative of the amount of active organic matter that is being broken down and nutrients being released. By using either the Basal Respiration field method or CO2-Burst lab method, a quantitative level of your soil’s health can be obtained.

What is the distinction between Basal Respiration (Field Test) and CO2-Burst (Lab Test)?

Field or Basal Respiration is based on employing minimally-disturbed or unaltered soil taken directly from the field with no lab processing or drying. You should perform this test if you wish to observe native respiration and carbon emissions from unaltered soil.  “CO2-Burst” is a lab protocol based on pre-drying and sieving soil and then subjecting it to a rapid rewetting to capture the pulse of “flush” of CO2 that results.

Is the same probe used for CO2-Burst and Basal Respiration?

Yes. The Low-CO2 probe is used for both methods.

How do I take a minimally-disturbed soil sample in the field?

An optimal means to take a sample for any respiration test is to use a soil knife or similar spade that does not cause shearing of the surface as does small diameter soil-corers.

What equipment is required for the CO2-Burst test?

  • The ability to dry and sieve soil. Soil should be dried at temperatures no higher than 40°C , rolled then coarse-sieved (2-6mm). Hammermills disrupt the soil structure to such an extent as to obscure natural C-min and N-min results.
  • a scale or volume to accurately measure dried soil
  • a dispenser or auto-pipette with a range of 5-15cc  to easily dispense varied amounts of water to the soil sample

During my CO2-Burst test, the water is not being fully absorbed by the soil. What should I do?

You are likely dealing with a very clayey soil which wets slowly or a hydrophobic soil. Most hydrophobic soils will eventually absorb water but extra time may be needed to allow for absorption. Observe the soil and if the water is working its way fully through the soil, start the 24hr test.

All CO2 probes turned yellow quickly. What does this mean?

Such soils have very high biological activity, most likely a combination of very high organic content and high biological activity. The test can be altered by using larger jars or less soil. Try 25g soil as a first step. Please contact technical support for assistance and advice on these soils.

Solvita SLAN

What is Solvita SLAN?

SLAN means Solvita Labile Amino-N and is a new lab soil test that measures a pool of organic N that relates to past soil management. The nitrogen compounds being measured appear to be relatively labile amino groups as they readily release free NH3 upon addition of room-temperature alkali. Soils with very recent cover crops or organic matter additions often indicate significant reserves of this amino-N

Does the new SLAN test require a new DCR?

No. We have designed the SLAN test to be readable by current DCR models. It can be read with the NH3 button on the DCR.

Solvita Compost

What is Solvita Compost?

Solvita Compost measures carbon-dioxide (CO2) and ammonia (NH3) which are the two most common gases released during composting. The test requires both measurements to be performed simultaneously, and provides a Maturity Index value that is calculated by combining the two results. High release of either or both gases indicates an unstable and possibly odorous condition associated with very actively degrading compost.

What if both compost probes are yellow after 4 hours? How do I tell the difference?

Look closely at the probe just below the gel. You will see an “A” indicating the NH3 probe or a “C” indicating the CO2 probe.

How do I know if my compost is at the right moisture?

Refer to the manual and follow the instructions for the “squeeze test”.