In this project, we are proposing to determine if soil amended with coproducts from the biofuel industry, namely biochar and digestate, can suppress soybean diseases caused by soilborne pathogens. We will focus our research on the pathogens that cause soybean sudden death syndrome (SDS) and soybean root rot (SRR) due to their economic importance and their soilborne nature.

We expect to learn if soil amendments with biochar or digestate have the potential to create a suppressive environment for soybean soilborne pathogens. This would be an added benefit to the use of these coproducts in agricultural fields.

The greenhouse experiments with pasteurized soil will allow us to test how the soil amendments affect disease development in more controlled conditions and to start gaining insights on how those effects vary with the rate and the physical/chemical characteristics of the amendments. The progression to greenhouse trials with natural field soil will determine if the effects on plant disease persists in soil with a complex microbiome and other interacting soil factors.

Finally, assessments of disease development in field trials with digestate and biochar amendments will provide insights into the potential impact of these amendments on farmer fields.

Oct 1, 2023 – Mar 30, 2024
Conduct greenhouse experiments to test 3 biochar types (from ISU Biocentury farm) for SDS suppression
Conduct greenhouse experiments to test different rates of solid digestate (from ISU research production) for SDS suppression

Apr 1 – Sept 30, 2024
Continue greenhouse experiments testing applications of biochar and digestate
Conduct field ratings of soybean diseases at grower fields with on-farm produced digestate amendments
Collect soil samples from grower fields with and without digestate soil amendments
Summarize data and prepare annual report

Oct 1, 2024 – Mar 30, 2025
Continue greenhouse experiments to test effect of different biochar types and solid digestate for suppression of Pythium root rot
Conduct greenhouse experiments to compare the most effective biochar and digestate treatments, based on standardized carbon amendment rate.

Apr 1 – Sept 30, 2025
Collect year 2 field data on soybean diseases with on-farm produced digestate amendments
Summarize data and prepare annual report
Share project results through diverse extension and research venues

The pressing need for biofuels will generate large amounts of valuable coproducts that are likely to be amended into agricultural fields. It is critical to soybean farmers and the soybean industry to understand on how these amendments will affect soybean health and productivity. This study will provide initial insights into the potential for biochar and digestate amendments to improve management of soybean diseases.