- Agronomic: rye, soybeans
- Crop Production: conservation tillage
- Education and Training: demonstration, on-farm/ranch research, workshop
- Energy: energy conservation/efficiency
- Natural Resources/Environment: soil stabilization
- Pest Management: allelopathy, chemical control, mulches - killed, physical control, mulching - vegetative
- Production Systems: transitioning to organic, organic agriculture
- Soil Management: soil analysis, nutrient mineralization, organic matter, soil quality/health
- Sustainable Communities: local and regional food systems, sustainability measures
Demand for organic corn and soybeans in North Carolina is growing. Braswell Milling in Nashville, NC estimates they need at least 500,000 bushels of organic corn and 7,000 tons of organic soybean meal each year to supply their organic egg farms. A group of farmers in eastern North Carolina have incorporated as Eastern Carolina Soy Products, LLC to build a soybean crusher that will process up to 400,000 bushels of organic soybeans each year. Five dairies in our state transitioned to organic in 2007 and more are expected in 2008. The state currently imports a majority of its organic corn and soybeans to meet market demand and imports will increase as additional buyers move in. This new market is an opportunity for grain farmers who are prepared for the challenges involved with organic production.
Currently, weed management in organic soybean production relies heavily upon multiple secondary tillage passes over the field each season. Increased tillage can result in increased soil erosion (Beale et al., 1955) and soil compaction (Raper et al., 2000), increased fossil fuel requirements (Hargrove, 1990), increased CO2 release (Paustian et al., 1998), increased labor costs (Weersink et al., 1992), increased equipment costs (Weersink et al., 1992) and decreased soil residue cover (Hargrove, 1990).
Some cover crops such as rye have demonstrated allelopathic (releases weed inhibiting chemicals) properties (Barnes et al., 1987). A newly designed chevron roller can be utilized to effectively kill the rye and create a thick biomass layer on the soil surface. By planting soybeans into such a biomass layer, weed growth can be greatly inhibited. This system has been successful at the Rodale Institute in the Northeast, but it has not been investigated for the Southeast region. With the increased research and development of organically certified herbicides (Tworkoski, 2002), use of corn gluten (shown to possess weed suppressive qualities (Christians 1993)) and high residue cultivation equipment (Paarlberg et al., 1998), more options have become available to successfully implement no-till organic grain production.
Most of NC's organic grain farmers are located in the Tidewater region; an area of poorly drained, high organic matter soils. These farmers would like a cover crop to contribute significantly to the nitrogen budget of their corn crop. In organic systems, reliance on manures for nitrogen is not sustainable due to increasing phosphorus levels and concerns of environmental contamination (Bulter et al., 2005). Crimson clover is typically recommended for adding large amounts of biomass with high nitrogen content. However, crimson clover is inhibited on poorly drained soils (Yenish et al., 1996; Cavigelli et al., 2007). Hairy vetch is also a significant contributor of nitrogen and known to tolerate wet soils (Anderson et al., 1990). In an attempt to incorporate no-till into a full rotation system, farmers have identified the need to further investigate the limitations of crimson clover on poorly drained soils and the potential use of hairy vetch, a cover crop more tolerant to wet soils but rarely used in North Carolina grain rotations.
Project objectives from proposal:
We propose an on farm trial to compare no-till organic soybean systems utilizing different combinations of the following tactics: planting soybeans into a rye cover crop compared to planting into no cover crop; planting soybeans into a rolled down rye cover crop compared to planting into an undercut rye cover crop; planting soy with a 7 inch band of corn gluten over the crop row, use of post crop emergence vinegar organic herbicides with sprays directed under crop foliage and the use of one pass of a high residue cultivator to control weeds between crop rows.
We also propose a multi-location investigation of nitrogen contribution by crimson clover and hairy vetch cover crops grown on poorly drained soils preceding corn as part of the no-till organic grain rotation.