- Crop Production: conservation tillage, cover crops, no-till
Natural plant-based indigo was once a major cash crop in the U.S., used around the world for dyeing textiles a blue color. Today, 147 million pounds of synthetic indigo dye are sold annually, primarily for the $61 billion denim market to color blue jeans blue. Its synthesis from benzene and other toxic precursors uses large quantities of oil derivatives and toxic non-renewable chemicals and requires high energy. Consumers are demanding more environmentally friendly production processes in the textile industry. Meanwhile, row crop farmers in the mid-south region of Tennessee and Kentucky are seeking profitable alternatives to broad-acre crops, to replace the high margin per acre role tobacco once played in their crop rotation.
Stony Creek Colors, an agricultural producer and processor based in northern Tennessee, has developed a new crop production and plant processing method that allows natural, plant derived indigo to compete with synthetic indigo. SCC has secured contracts with textile mills and thus the once small-scale market for plant dyes is opening to U.s. and global dyehouses as well as textile, cloth, and yarn manufacturers. Natural indigo has the capacity to be a widely accepted and valuable specialty crop for producers in the Southeast U.S. In addition to producing the indigo-containing crops on its own farm, SCC contracts with tobacco producers to plant and grow indigo biomass for the company's processing facility.
As well as providing new, diversified income stream for producers, two varieties of indigo plants have the potential to increase sustainability in a diversified cropping system and have few pest problems. The Indigofera tinctoria plants are leguminous plants that supply their own nitrogen and are a nematode suppressant. Persicaria tinctoria, in the buckwheat family, uses less than half of the nitrogen fertilizer commonly used for tobacco or corn. It provides excellent pollinator habitat, especially for domesticated and wild honey bees during the fall months when the crop has set flower and there is little wild forage available to bees preparing for winter.
Currently, SCC indigo is grown as transplant in a method similar to tobacco production, where seed is germinated in a greenhouse or float bed, and then transplanted in the field via mechanical transplanter. Since there are no listed herbicides for indigo, weed control is managed through pre-planting tillage and mechanical cultivation of teh crop during the growing season, especially in early summer prior to crop canopy closure. This manual cultivation process takes time, equipment and fuel away from the farmer during the busy spring and summer season. Farmers in the mid south use no-till in conjunction with direct seeding of soy and corn. However, these systems often rely on pre-plant and in-season herbicide applications for weed control and do not integrate with high biomass winter cover crops. Using no-till for transplanted crops without a chemical weed control regime will take different systems of field and management if indigo is produced with low tillage. Little information exists on indigo in a conservation production system setting using no-till management and cover crops.
Farmers in the region seem open to adopting cover crop and no-till combination systems, however the declining market for tobacco makes them unlikely to invest additional resources into this type of system. We see this research as an opportunity to integrate conservation systems in not just indigo but other transplant crops. Validating that comparable yields to conventional farming practices is possible with these techniques, along with reduced labor and input costs like energy savings through decreased tractor time, would help expand use of these systems across the Southeast, with a variety of crops.
Project objectives from proposal:
The project is designed to overcome the key challenges still existent in adoption of conservation systems using no-till and cover crops, especially as it relates to transplant production and alternative crops.
We will evaluate the growth and yields of indigo after transplanting in different winter cover crop configurations. These configurations differ in cover crop blend, termination method and date, and volume and rate of residue decomposition during the summer. To demonstrate the success of each result, researchers will evaluate labor and input costs, yield of biomass, yield of indigotin (a chemical extracted in the SCC lab which represents the final product), cover crop residue throughout summer, and number and severity of weeds.