Cover crop inter-seeding in organic corn production to reduce resource inputs and soil disturbance and enhance pest control and farm profitability

A Young Scholar Enhancement Grant was awarded to this project in 2025.

View the project final report

Commodities

• Agronomic: buckwheat, clovers, corn, peas (field, cowpeas)

Practices

• Crop Production: cover crops, intercropping
• Production Systems: organic agriculture
• Soil Management: soil quality/health

The practice of “intercropping,” or companion crop production, creates a mutually beneficial ecosystem and functionally diverse plant community to increase individual plant production. This approach entails a multi-layered agroecosystem where different crops fill different functional niches. Two major benefits of this technique would be lower input costs and better crop protection from pests and diseases. In this project, we evaluated a similar approach for organic corn, namely cover crop interseeding, to enhance the utilization of unused functional niches in corn production systems, improve soil-plant interactions, reduce resource inputs, and enhance cropping system productivity. We engaged growers from diverse communities to assess potential risks/benefits of cover crop inter-seeding and barriers to acceptance. Overall, the results indicate that while farmers and agents can come across as knowledgeable, when discussing the benefits of cover crops, farmers sharing this information (more so than agents) can be perceived to be trustworthy sources, be more effective in improving their attitude towards adopting cover crops, and can make the benefits of carbon sequestration seem more concrete. Together, these can positively impact farmers’ intentions to adopt cover crops. In our experiments, we compared four cover crops (buckwheat, pigeonpea, white clover, and their mix) interseeded with organic corn at three seeding rates (standard, low, and high) under two tillage systems (tilled and no-till) at Clemson and Florence in South Carolina. Buckwheat was the best-performing interseeded cover crop in terms of biomass production. Interseeded cover crops did not reduce corn biomass, grain yield, and soil water content under conventional or reduced tillage conditions. Interseeding appeared to have a positive impact on corn grain yield; e.g., corn yield and biomass were increased when interseeded with buckwheat- at standard seeding rate, buckwheat increased corn grain yield up to 43 %, and at low seeding rate, it increased corn biomass up to 52%. Our results did not support the possibility of interseeded cover crops reducing the available soil water to the cash crops. Buckwheat and pigeon pea appeared to have a weed-suppression effect as well. Interseeded cover crops also enhanced soil function in terms of nitrogen cycling enzyme activity and active soil carbon content. The results from our study indicate a positive impact of cover crop interseeding on corn performance, soil moisture retention, soil health, and weed suppression. The economic analysis of cover crop interseeding under conventional and reduced tillage systems highlights the financial dynamics involved in adopting these practices. Economic advantage of cover crop inter-seeding across treatments was primarily driven by seeding rates. Increased seeding rates typically result in higher seed costs, which has a substantial effect on the economic viability of cover crops. Treatments with high seeding rates, particularly those utilizing pigeon pea, frequently resulted in significant losses, indicating that such treatments may require more tuning to be economically viable. While interseeded cover crops generally resulted in a net negative effect, the magnitude of economic loss was relatively lower for buckwheat when interseeded at standard or low seeding rates. As part of the project, university researchers worked with a team of collaborators including extension agents, NRCS, nonprofit, commodity board, and 1890 university personnel, point-persons for American Indians and small, diversified farmers to ensure outreach to diverse communities and effective farmer engagement. Results were disseminated to producers and stakeholders through field days, presentations at regional farming conferences and producer meetings, and print/online media.

1. Engage growers from diverse communities to assess potential risks/benefits of cover crop inter-seeding and barriers to acceptance and determine the impact of project results in addressing these barriers and improving the community quality of life.
2. Evaluate different cover crops (white clover, buckwheat, pigeon pea, and their mixture) inter-seeded with corn at multiple seeding rates and under conventionally tilled or no-tilled conditions to identify cover crops and their management practices that alleviate soil compaction, suppress weed infestation, and enhance microbial communities that improve nutrient availability and soil health.
3. Quantify natural pest control benefits conferred by inter-seeded cover crops aboveground and belowground.
4. Evaluate economic consequences of inter-seeding based on monetary benefits, and management costs.
5. Develop a collaborative outreach program to catalyze the integration of a regionally-specific inter-seeding system.