Evaluation of Organic Spring Cover Crop Termination Practices to Enhance Rolling/Crimping

Abstract

With organic farming hectarage and cover crop interest increasing throughout the United States, effectively timed cover crop termination practices are needed that can be utilized in organic conservation tillage production systems. Four commercially available termination treatments approved by Organic Materials Review Institute (OMRI) were evaluated, immediately following mechanical termination with a cover crop roller/crimper and compared to a synthetic herbicide termination to access termination rates. Treatments included rolling/crimping followed by (1) 20% vinegar solution (28 L a.i. ha−1 acetic acid), (2) 2.5 L a.i. ha−1 45% cinnamon (Cinnamomum verum L.) oil (cinnamaldehyde, eugenol, eugenol acetate)/45% clove oil (eugenol, acetyl eugenol, caryophyllene) mixture, (3) 0.15 mm clear polyethylene sheeting applied with edges manually tucked into the soil for 28 days over the entire plot area (clear plastic), (4) broadcast flame emitting 1100 °C applied at 1.2 k/h (flame), (5) glyphosate applied at 1.12 kg a.i. ha−1 (this non-OMRI-approved, non-organic conservation tillage cover crop termination standard practice was included to help ascertain desiccation, regrowth, and economics), and (6) a non-treated control. Five cover crop species were evaluated: (1) hairy vetch (Vicia villosa Roth), (2) crimson clover (Trifolium incarnatum L.), (3) cereal rye (Secale cereale L.), (4) Austrian winter pea (Pisum sativum L.), and (5) rape (Brassica napus L.). Three termination timings occurred at four-week intervals beginning mid-March each year. In April or May, organic producers are most likely to be successful using a roller crimper as either a broadcast flamer for terminating all winter covers evaluated, or utilizing clear plastic for hairy vetch, winter peas, and cereal rye. Ineffectiveness and regrowth concerns following cover crop termination in March are substantial. Commercially available vinegar and cinnamon/clove oil solutions provided little predictable termination, and producers attempting to use these OMRI-approved products will likely resort to cover crop incorporation, or mowing, to terminate covers if no other practice is readily available.

Cover crop termination options and application of remote sensing for evaluating termination efficiency

“…Termination efficiency and biomass reduction with roller-crimping was 43 and 9% 28 DAT, respectively ( Table 6 ). Poor termination of rapeseed with roller-crimper is also reported by Price et al, [ 54 ].…”

Volunteer rapeseed infestation and management in corn

“…Price et al. (2019) reported greater than 90% termination efficiency with the combined use of a roller‐crimper and glyphosate as compared with the sole use of a roller‐crimper for the termination of a rapeseed cover crop. Poor termination of brassica species with a roller‐crimper alone has also been reported by Barbercheck and Borrelli (2020).…”

“…In a study conducted in Alabama, Price et al. (2019) found a 350% increase in rapeseed biomass by delaying the termination from mid‐April to mid‐May. More biomass accumulation under delayed termination has also been reported in other cover crop species (Otte et al., 2019; Wallace et al., 2017).…”

“…Termination of rapeseed 1 DBP with the sole use of the roller-crimper was 56%, which was significantly less than the termination achieved with the combined use of herbicides and rollercrimper at other timings. Price et al (2019) reported greater than 90% termination efficiency with the combined use of a roller-crimper and glyphosate as compared with the sole use of a roller-crimper for the termination of a rapeseed cover crop. Poor termination of brassica species with a rollercrimper alone has also been reported by Barbercheck and Borrelli (2020).…”

“…The temperature at the rapeseed termination timing (April-May) in both 2021 and 2022 (Figure 2) remained more than 4˚C, which explains the greater biomass accumulation by delaying the termination. In a study conducted in Alabama, Price et al (2019) found a 350% increase in rapeseed biomass by delaying the termination from mid-April to mid-May. More biomass accumulation under delayed termination has also been reported in other cover crop species (Otte et al, 2019;Wallace et al, 2017).…”