The Announcements
View the full set of September announcements by clicking here. As more activities open up, more volunteer opportunities are coming into the chapter calendar. Opportunities and contacts, websites, and other details are available in the announcements.
COVID-19 update: With Dallas County’s return to Level Red precautions, we shifted our chapter meeting back to virtual. We’re tracking with CDC guidance and continue to encourage wearing masks indoors and social distancing. Details here.
Highlights of the meeting
This month’s camera roll featured your photos from a busy summer. Thanks to all for your contributions!
Talking Dirt
Many thanks to Lorelei Stierlen for leading us to a better understanding and appreciation of soils – in general and those of our own Blackland Prairie. She is an environmental scientist, Blackland Prairie pedology subject matter expert, and very active Master Naturalist.
Lorelei began with background on the young science of Pedology, how it has developed over the last 150 years. To frame the discussion she offered this soil definition: naturally occurring…mineral particles and organic material covering the surfaces of terrestrial domains. Soil development is influenced by climate, organisms, relief, parent material and time. Illustrating the importance of time in relation to topsoil loss, she noted that 200-400 years are needed to build one centimeter of soil, and that fertile soil takes much longer.
Lorelei discussed the valuable environmental services that soil provides:
• a medium for plant growth, sustaining wildlife & feeding us • nutrient cycling
• regulates water quality & supply • soil organisms habitat • major carbon sink. She encourages us to see soil “not as a thing underfoot but a thriving community of interconnected, interrelated macroscopic and microscopic life.”
Turning to our region, Lorelei discussed the geological history leading to the parent materials we have: limestone, shale, chalk, marl. She focused on marine deposits, with some volcanic ash, during the Cretaceous period as building the Austin Chalk. She also showed how formation of the Ouachita Mountains led to these layers being tilted. Glacial melt during the Cenozoic era deposited distant sands and gravels to make our riparian areas unique.
Regarding soils of the Blackland Prairie, Lorelei showed how three soil orders are present here: vertisols, mollisols, and alfisols. Though common here, vertisols are relatively rare in the U.S. They include Houston Black, our very fertile state soil. Lorelei provided details of clay chemistry, stressing how the aforementioned volcanic ash helped create our extremely expansive montmorillonite clay.
Concluding the lecture portion, Lorelei discussed caring for our soil by mending it, rebuilding the organic and nutrient content. That, in contrast to “amending” (attempting to alter) the soil, as is often elsewhere advised.
The last portion of the evening was a virtual soil lab, where we worked with our own soil samples, determining pH, texture and how a sample can be shaped (into a ball or U), then relating these to the soil flow chart and pyramid. These help identify soil type. Lorelei discussed finding our soil on the Web Soil Survey.
Key takeaways: Lorelei recommends feeding your soil with 1/8 to 1/4” compost annually, feeding soil organisms with dry molasses, and giving the process time. If mulching, she prefers double-shred hardwood mulch. She discussed soil as an engineering medium – what we build on – reminding us that in North Texas we shouldn’t need to water our native plants but we do need to water our foundations.
Going deeper: Downloadable resources Lorelei mentioned in her talk
Rodale Institute Lorelei recommended on organic practices
USDA Interactive Web Soil Survey
Soil testing at Texas A&M lab
Soil Science Society of America educational material on Houston Black Soil
Contact Lorelei Stierlen with your soil questions
We have posted the recording of the meeting here.
Thanks to our guests and members for participating in this month’s meeting. I hope all feel welcome at NTMN.
Take care,
Scott Hudson
President
North Texas Master Naturalist