In this webinar we go in-depth and learn more about how aggregates are an important part of a healthy soil. We’ll start with the basics of how aggregates form, what stabilizes them and how they naturally turnover with time. We’ll also talk about how to evaluate aggregation using a shovel in the field along with options for analyses in the lab. The benefits of stable aggregation are not just physical, but also biological. This is part of why aggregation can be a great indicator of a healthy soil. Knowing what aggregates can do for you and how to manage for this part of the system when it comes to achieving on-farm goals really shows the importance of this soil property.
1 CEU in Soil and Water Management.
Presenter: Abbey Wick, Soil Health Extension Specialist, North Dakota State University
Sponsors: Illinois Soybean Association, North Dakota Soybean Council and North Dakota Corn Utilization Council
Aggregates: Groups of soil particles that bind to each other more strongly than to adjacent particles.
Respond to changes in management
Combination of sand, silt, clay, animal-derived debris and other organic material
Functional vs. Non-functional Aggregates
Functional create great habitats for microbes
Functional give more stability to the soil, have more pore space, and more water-holding capacity and air space
Aggregates Based on Function
Microaggregates are primary soil particles that are pulled together by physical-chemical forces
Macroaggregates are greater than 250 microns—form from organic debris and microaggregates
Fine roots and fungal hyphae will wrap around and stabilize
Microaggregates are held together by microbial glues; macroaggregates are held together by fungal hyphae
Aggregates Based on Size
Dr. Johan Six – for western U.S.
Less divisions because western U.S. doesn’t form aggregates as easily because it’s drier
Dr. Julie Jastrow – out of Illinois
Aggregates and Farm Systems
More large macroaggregates in pasture converted to corn system
More microaggregates in conventional tillage row crop system—create really tight pore spaces, not a lot of room for water to infiltrate soil
Balance of aggregates in no-till, cover crop, row crop system
Aggregate Formation, Stabilization and Disintegration
Aggregates are meant to turn over
Formation happens when primary soil particles and organic matter are held together by fungal hyphae
Fungal hyphae and roots pull particles into stable aggregates
When aggregates are stable, wet-dry cycles pull aggregate closer together
Microbes eat organic matter and aggregate disintegrates
When the aggregate breaks down it releases organic matter into the soil
Tillage shortens aggregate cycle
Aggregates can also form from earthworms. The soil minerals mix in their digestive system and are excreted
The Illinois Soybean Association (ISA) checkoff and membership programs represent more than 43,000 soybean farmers in Illinois. The checkoff funds market development, soybean production and government relations efforts, while the membership program, Illinois Soybean Growers (ISG) and the Illinois Soybean Growers PAC actively advocates for positive and impactful legislation for farmers at local, state and national levels. ISA upholds the interests of Illinois soybean farmers through promotion, advocacy, research and education with the vision of becoming a trusted partner of Illinois soybean farmers to ensure their profitability now and for future generations.