Tea Bags Tell Story of Soil Health

Soil health is trending, there’s no doubt about that! But perhaps expensive soil tests aren’t your cup of tea.

Look no further than the Soil Decomposition Index: a simple, straightforward, citizen science approach to evaluating soil health that utilizes buried tea bags. Learn more about this novel approach to soil health from Dr. Marshall McDaniel, assistant professor of agronomy at Iowa State University, in his recent Iowa Learning Farms webinar titled Burying Tea to Dig Up Soil Health.

Microbes are the engines that drive the biology of our soils, especially the cycling of nitrogen, phosphorus, and sulfur. Under the umbrella of soil health, McDaniel points out that biological indicators are the most sensitive to changing management practices, so this tea bag concept is built upon evaluating one aspect of the biology going on right beneath our feet.

The tea serves as food for the smallest soil microorganisms, including bacteria, actinomycetes, and fungi, that are able to squeeze through the tiny openings in the mesh tea bag. As the tea is consumed over time, the bags are dug up and weighed, providing an indication of the biological activity within the soil, particularly the decomposition activity of the smallest soil organisms.

In each field, McDaniel’s team is comparing two types of teas side-by-side: green tea, which simulates a high quality (low C:N) residue, and rooibos tea, which simulates a lower quality (high C:N, nitrogen-limited) residue. Based on how much of each tea is remaining, you can calculate a Soil Decomposition Index value.  Values range from 0 to 1, and the closer to 1, the healthier the soil is! Using two teas side-by-side lets you calculate a standardized Soil Decomposition Index value which accounts for temperature and soil moisture variability, as well as allowing results to be readily compared between different sites – so you can compare apples to apples.

Check out the full webinar, Burying Tea to Dig Up Soil Health, on the Iowa Learning Farms webinars page, to hear more details of this novel soil health test and preliminary results from on-farm studies evaluating the Soil Decomposition Index with cover crops.

For those active on Twitter, you can follow the McDaniel lab, @ Soil_Plant_IXNs, as they continue to evaluate this unique tea bag concept and many other aspects related to soil-plant interactions and agricultural sustainability.

Ann Staudt

River Stomping with ILF

As Dr. Tom Isenhart, Iowa State University Professor of Natural Resource Ecology and Management, tells his students,

“You can’t understand the health of our rivers by driving by in a car. You have to get down to the bank. Better still, get in the river…”

So we partnered with Tom this week to do just that with a group of our farmer leaders on a section of the Skunk River north of Ames.

The dozen farmer leaders from across the state were joined by members of our Iowa Learning Farms Steering Committee and our summer college interns. Tom divided the group into four teams, upon which they donned boots and waders and got to work looking for the biological indicators of river health.

SouthSkunkRiverThe group was told to explore under branches along the bank, stir up the bottom, and capture the insects that might call that location home…

MattWaders

… pick up rocks and search the moss for insects…

Annie

Participants like southwest Iowa farmer Seth Watkins were not afraid of getting wet and going to deeper sections of the river where the little creatures would make their home.

SethIowa doesn’t get any prettier than the Skunk River was that day as intern Kate Sanocki and farmer leaders Craig Fleishman and Tim Smith would tell you. The water was clear and the bottom was rocky. Rumor has it that there are good smallmouth bass to be found here!

CraigTimKateParticipants were told to put their finds in insect collection receptacles (i.e. ice cube trays).

TrayJakeJim Gillespie, Director of IDALS-Division of Soil Conservation and Water Quality, was heard to comment that he hadn’t done something like this since he was in college — that was a long time ago!

MattJimAfter about 45 minutes, it was with big smiles that the group left the river with their finds. Their job was not yet done.

SteveHTom put them to work identifying the insects using tools from IOWATER.

InsectIDThe group was happy to learn that they found macroinvertebrates such as caddisfly and stonefly that are pollution intolerant. Their presence suggested that this section of the South Skunk River is fairly healthy.

RickNathanThe crawdads they found belong in the “somewhat pollution tolerant” category. Tom pointed out that they make good smallmouth bass bait.

CrawdadsThis damselfly was as curious about us as we were about her. Damselflies belong to the somewhat pollution tolerant group and are good to find at our rivers, lakes, and wetlands.

DamselflyTom told the group that the health of a stream or river fluctuates by season and rainfall. During times of drought and floods, life on the river can be stressed. The Iowa DNR has put a lot of resources into making the Skunk River a healthier body of water.

While the group would have been content to stay at this beautiful stretch of the South Skunk River for the day, we headed on to our next stop at one of the Conservation Reserve Enhancement Program (CREP) wetlands where Dr. Matt Helmers discussed the use of these wetlands as part of our new Conservation Learning Labs project (stay tuned to the blog for further information).

WetlandWe ended at the site of the very first saturated buffer in Iowa (possibly the world) along Bear Creek. Here the group asked Tom many detailed questions about how the buffers worked.

SaturatedBufferAll in all, the group had fun and asked great questions at every stop of the field day. The participants went away with a better understanding of river ecosystems and its relationship to our land management choices. Everyone returned to Ames grateful for the quality time spent near (and in) an Iowa river!

Jacqueline Comito