Polk Soil and water conservation district
Biology for Soil health workshop
July 10, 2024, Indianola, Iowa
Coordinated by Michael James
Soil Biology is the Foundation of Healthy Soils
Polk SWCD and Midwest Soil Restore hosted a ‘Biology for Soil Health Workshop’ this summer, giving participants insights and information on the soil microbiome. The field day was organized by Polk SWCD WQI Coordinator Michael James, along with interns Tess Kerns and Courtney Strauser. James brought in experts to talk about the roles soil organisms play in driving soil function.
This article and workshop videos highlight key takeaways from the educational sessions. Additional links are included throughout the article for more information, but you are encouraged to do more research and ‘dig deeper’ into the topics that interest you!
Workshop Sessions
Session 1: Soil Biology, The Basics with Jared Flater, Post-Doctorate, Iowa State University
Session 2: Soil Under the Microscope with Zach Wright, Director of Living Soil Compost Lab
Session 3: Multispecies Cover Crops are a Feast for the Soil with Davis Behle, Green Cover Seed
Session 4: How to Build a Johnson-Su Compost Reactor with Steve Shivvers, Midwest Soil Restore
Session 5: NRCS Soil Carbon Amendment with Hilary Olson, State Soil Health Specialist
Session 1: Soil Biology, The Basics
Jared Flater, Post Doctorate, Iowa State University
The workshop was opened by Jared Flater from Iowa State University. Jared highlighted the roles of soil organisms in healthy, functioning soils. They are responsible for building soil structure, cycling nutrients, and helping to suppress pathogens.
Compost can be applied to help build robust soil microbial communities. It has all the food microbes need to thrive and it adds organic material to the soil. Compost can also serve as a biological inoculant for the soil.
Healthy robust microbial communities build soil structure and organic matter, improving water use efficiency and creating more resilient cropping systems. They reduce inputs by improving nutrient cycling and suppressing pests and disease. Farmers can improve profitability and resiliency as they build soil biology and realize these benefits.
Session 2: Soil Under the Microscope
Zach Wright, Director of Living Soil Compost Lab
Zach Wright took a deeper look at building soils using a biological approach. He did a demonstration showing soils from different management systems under a microscope. Throughout his demonstration he talked about conclusions he has drawn from evaluating hundreds of different samples of soil and compost under the microscope. Some of his thoughts are featured here:
- Humus is an artifact of biological function. Organisms take organic matter, which is a complex blend of Carbon, Hydrogen, and Nitrogen, decompose it further, and recompose it with even greater bonds. The result is stable carbon substances such as humin, humic acid, and fulvic acid. The half life of these substances can range from decades to centuries. Converting organic matter into humus is a long-term investment in the soil.
- Soil is never dead. Even in degraded soils, bacteria always find a way to survive. Bacterial dominated soils are prone to high nitrates, and high nitrates favor weeds.
- Soils are like a digestive tract and most agricultural soils are constipated. The don’t have a healthy microbial population so they can’t achieve optimal soil function.
- Commercial fertilizers and chemicals do have a collateral impact on the ecosystem. Viewing soils under the microscope after an application of herbicide shows the soils respond with a bacterial bloom.
- Biological applications are NOT like fertilizers. They are non-leachable and won’t volatilize.
- ‘Bugs in a jug’ products typically have only 30 to 80 species of biology. Making your own compost extracts can yield 100s to 1000s of species.
- The recommended rate for compost extracts is 1-2 lbs per acre with 5 to 20 gallons of water but you could potentially see a boost in microbial communities with as little as 1/10 of a lb/acre.
Session 3: Multispecies Cover Crops are a Feast for the Soil
Davis Behle, Green Cover Seed
Davis Behle says that if you are focusing on ‘farming with biology’, multispecies cover crop mixes are the way to go. Multispecies mixes incorporate a variety of flavors in the form of root exudates, to meet the needs of a wide array of soil organisms.
With multiple cover crop species, you aren’t putting ‘all your eggs in one basket’. The needs of the soil will vary from year to year. While we can’t predict the needs of the soil, having a variety of plants means there is a greater chance at least one of the species will provide the exudates the soil needs. Furthermore, one species might thrive in certain years where others suffer. Adding cool and warm season species can ensure a healthy supply of root exudates in the soil for the duration of the growing season.
Behle said that cereal rye is still a good option as a cover crop. It meets goals such as weed suppression and erosion prevention, and it captures sunlight and provides and supply of fresh root exudates in the soil. But, if the goal is to drive biological farming, more species is better than one. In a quote borrowed from the first session with Jared Flater from Iowa State University, “one species is better than none, but more is better than one.” Producers should focus on incorporating different plant families for the greatest diversity.
Session 4: How to Build a Johnson-Su Compost Reactor
Steve Shivvers, Midwest Soil Restore
Steve Shivvers believes that biological farming will help to restore our soils. He started making Johnson-Su compost to provide an option for locally sourced, high quality compost. The Johnson-Su process is a compost made in a static system that remains aerated without needing to be turned. The process allows for complete biological breakdown of the compost materials, and results in a microbially diverse, fungal dominant compost product.
Steve shared a demonstration on how to build a Johnson-Su compost at the workshop. There was good discussion and questions through the demonstration.
- Compost Teas vs Compost Extracts
- Extracts are shelf stable. Teas are given a food source like molasses, and this causes the stability to go WAY down. Teas must be used immediately. Extracts can be good for several days, or perhaps even longer, depending on conditions and aeration.
- Worms should be added in the compost process.
- First, the compost will heat up during a thermal phase to greater than 130 degrees F.
- After cooling back down to 80 degrees, worms should be added. Add at least 100 red wigglers per tote.
- One tote of compost will yield approximately 120 lbs. of finished product. This can treat about 200 – 250 acres as extract.
- If you are using city water, it must be treated to remove the chlorine.
- Use smell to determine the quality. If the compost or the extract smells bad, it has likely gone anaerobic. This is NOT the biological inoculant that you want. You want a biological product that has been aerobic through the entire process.
Session 5: NRCS Soil Carbon Amendment
Hillary Olson, State Soil Health Specialist
The day concluded with an overview of the NRCS Code 336 Soil Carbon Amendment Standard with the NRCS State Soil Health Specialist, Hillary Olson.
The new practice allows for application of a carbon-based amendment to help improve organic matter, sequester carbon, improve aggregate stability, or improve habitat for soil organisms.
Biochar is a type of carbon amendment. It is a high surface area charcoal like substance created by burning in a temperature controlled, low oxygen environment. It is a very stable carbon source, and because of the high surface area, it can be thought of like a ‘condo’ for organisms. It is recommended to inoculate biochar with compost. The compost will act as a food source for the organisms.
The recalcitrant carbon that is a primary ingredient in all types of biochar can persist in soils for years, decades, even millennia. Biochar can be used to amend soils on its own, but it can also be combined with other soil amendments to address a wider range of environmental challenges.
The Soil Carbon Amendment (336) is commonly applied with practices such as Nutrient Management (590); Conservation Crop Rotation (328); Cover Crop (340); Residue and Tillage Management, No Till (329), Residue and Tillage Management, Reduced Till (345), and Critical Area Planting (342).
For further information, contact the USDA-NRCS Service Center.
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