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
Probes may be used for one year from date of manufacture. You will find the expiration date stamped on the individual silver pouch for each probe. They are sealed to assure freshness for up to one year under recommended storage conditions. It is best to store them in cool or refrigerated conditions, but do not allow to freeze.
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 Solvita Technical Data Sheet- Separation of Gel from Probe.
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 not toxic but contain strong preservatives, so should be handled with care, and definitely kept away from children. There are no additional special reagents needed. The new SLAN test does require NaOH, which the customer is responsible for obtaining, and only experienced technicians should perform such a test.
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 are not applicable for Soil CO2-Burst Test, due to recent improvements. 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 700.6 or higher. Download your free upgrade here
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
Click here to download instructions for the Multi-Mode DCR (yellow) or for the Field DCR (green). Instructions how to operate the DCR (both units) and how to use Solvita DCReader can be downloaded here.
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 an in-the-field test that provides a snapshot of soil health using unaltered soil directly from the field. You should perform this test if you’re looking for an easy method that you can perform yourself or if you’re trying to measure carbon emissions from unaltered soil. This test is a part of the USDA Soil Quality Educator’s Guide for respiration. CO2-Burst is generally deemed a lab protocol that uses a more standardized drying-rewetting method to assess the potential of your soil’s health and its ability to release nutrients. You should have a lab perform this method on your soils if you want a more quantitative evaluation of your soil’s health and its potential nitrogen release. This test is a part of the USDA Soil Health Tool that is offered by select labs.
Is the same probe used for CO2-Burst and Basal Respiration?
Yes. The Low-CO2 probe is used for both methods, and is read at 24 hrs for each.
Why do the two methods use different jars?
CO2-Burst uses glass jars, which are more reliable in terms of gas leakage and longevity. Since the Basal Respiration test is often performed in the field, we offer plastic jars which are less likely to be broken. The basal method can be run in either jar, but the CO2-Burst should only be run in glass jars. Both come with CO2-proof gaskets.
How do I take a soil sample in the field without too much disturbance?
We are finding that the best way to take a sample for a Basal Respiration test is to use a soil knife or something similar that will allow you to take a 6″ sample without shearing the surface.
What equipment is required for the CO2-Burst test?
- The ability to dry and sieve soil. Soil should be coarse-sieved (2-6mm) and dried at temperatures no higher than 40°C
- a scale to accurately measure 40 grams of dried soil
- an 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 absorbed by the soil. What should I do?
You are likely dealing with a hydrophobic soil. Most hydrophobic soils will eventually absorb water but extra time may be needed to allow for proper absorption. Carefully observe the soil and once the water has worked its way fully through the soil, insert the probe and 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. 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 appears to relate to soil management. Evidence suggests that the nitrogen compounds measured must be labile amino groups since they readily release free NH3 upon addition of alkali to the sample. 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”.
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