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

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Commodities

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

Practices

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

Sometimes looking to the past for answers is meaningful. An ancient cropping practice called “intercropping,” or companion crop production, created a mutually beneficial ecosystem and functionally diverse plant community to increase individual plant production. This approach entailed a multi-layered agroecosystem where different crops filled different functional niches. Two major benefits of returning to this technique would be lower input costs and better crop protection from pests and diseases. While American Indians used "three sister crops," including squash, corn, and beans for companion cropping, the underlying principles can be utilized for improving the sustainability of larger and commercial farming operations with positive results for producers. We propose cover crop inter-seeding into corn (one of the most resource-intensive crops) to enhance utilization of unused functional niches in corn production systems, improve soil-plant interactions, reduce resource inputs, and improve cropping system productivity. Our systematic approach includes Social Science research that will engage growers from diverse communities (certified organic, small diverse, African American, American Indian, other underserved, and conventional) to assess potential risks/benefits of cover crop inter-seeding and barriers to acceptance. Our experiments will compare four cover crops inter-seeded with corn at three seeding rates (standard, low and high) under two tillage systems (tilled or no-tilled). The experiments adopt the basic principles of ‘companion cropping’, where success is based on choosing the right combinations of nitrogen-fixing legumes, rapidly establishing land-covers, and crops that occupy different functional niches aboveground and belowground. Our agronomist will evaluate cover crops and their management practices (seeding rate and tillage type) for their potential for bio-drilling, soil compaction alleviation, and weed suppression. Our soil scientist will identify cover crops and their management practices that optimize microbial activity and enhance soil health. Our entomologist will quantify natural pest control benefits conferred by inter-seeded cover crops aboveground and belowground. Our economist will conduct a cost-benefit analysis based on monetary benefits, management costs, and potential disadvantages of inter-seeding. We will work with farmers to conduct on-farm trials based on their preferred treatments and assessments of on-station research. Project key personnel will work 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 will be disseminated to producers and stakeholders through a training workshop, field days, presentations at regional farming conferences and producer meetings, and print/online media. By optimizing management and removing technical barriers to adoption of cover cropping, farmers will benefit from: reducing compaction; building healthier soils; reducing inputs for weed, fertility, and pest management; strengthening resilience to climate extremes; and stabilizing their economic viability. Reducing resource inputs will help protect natural resources; increasing crop, insect, and microbial diversity in the system will promote climate/weather-related risk management strategies and resilient agriculture; and including woman- and family-farmers as cooperators will help strengthen the family farm system of agriculture, the backbone of rural communities. Finally, our social scientist will assess how these outcomes improve the community’s quality of life.

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, buck wheat, 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.

Rationale for selection of cover crop species

Legume-based cover crops, when inter-seeded into organic systems, can lead to economic and environmental efficiency because of nutrient supply and control of soil erosion and nutrient leaching (Sanders et al., 2017). White clover may be a good option because it can be as effective as herbicides to control weeds (Hartwig and Ammon, 2002) and demonstrates shade tolerance (NRCS, 2011). White clover also encourages the association between mycorrhizal fungi and corn plants to assist in nutrient supply from soils with high phosphorous fixation capabilities (Deguchi et al., 2007). Buckwheat is another cover crop that has been shown to work well as an inter-seeded cover crop with corn (Loran Steinlage- row crop farmer, Presentation at the Conference on Building Soil Health: Principles, Practices and Profitability, Clemson, SC, 10/28/2019). Its benefits include rapid establishment and land cover, strong weed suppression, phosphorous scavenging, and ability to thrive in low fertility soils and attract beneficial insects (Clark, 2012). It produces abundant fine roots, which makes soil friable (Clark, 2012), which in turn makes this species a good choice for compacted soils in the Southeast. Another species, pigeon pea produces a deep root system with a strong taproot. It is moderately shade tolerant (Aniela, 2018) and well-suited for intercropping as it draws water from deeper soil profiles than most legumes, so will not interfere with the water uptake of other crops and grasses (Sheahan, 2012). This crop has been valued for its bio-drilling ability in many other parts of the world (Valenzuela, 2011). However, its potential for compaction alleviation when used as an inter-seeded cover crop has never been tested in the U.S. Testing a mixture of the three species (white clover, buck wheat, and pigeon pea) will allow us to evaluate any complimentary interactions among these functionally distinct species. The same cover crops were tested in our preliminary research as well (results given under “preliminary research” in the “Problem, Rationale and Significance” section).