Evaluation of organic spring cover crop termination practices to enhance rolling/crimping

Authors: Price, Andrew; Duzy, Leah; MCELROY, SCOTT - Auburn University; XI, STEVE - Auburn University

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/3/2019
Publication Date: 9/6/2019
Citation: Price, A.J., Duzy, L.M., Mcelroy, S., Xi, S. 2019. Evaluation of organic spring cover crop termination practices to enhance rolling/crimping. Agronomy Journal. 9(9):519. https://doi.org/10.3390/agronomy9090519.
DOI: https://doi.org/10.3390/agronomy9090519

Interpretive Summary: Cover crops provide valuable agronomic services in numerous production systems, especially in organic agriculture. With organic farming hecterage and cover crop interest increasing throughout the United States (U.S.), effectively timed cover crop termination practices are needed that can be utilized throughout the growing season. A two-year cover crop termination experiment was established in Alabama. Results indicate that organic producers needing to terminate winter covers would most likely be successful using a broadcast flamer in most any winter cover or utilizing clear plastic in hairy vetch, winter peas, or cereal rye as ambient temperature increase along with solar radiation, both in combination with a roller/crimper. Commercially available vinegar and clove/cinnamon oil solutions provided little predictable termination and producers are likely to resort to tillage if no other material or practice is readily available.

Technical Abstract: Cover crops provide valuable agronomic services in numerous production systems, especially in organic agriculture. With organic farming hecterage and cover crop interest increasing throughout the United States (U.S.), effectively timed cover crop termination practices are needed that can be utilized throughout the growing season. A two-year cover crop termination experiment was established in Alabama in fall, 2013. Four commercially available termination treatments were evaluated immediately following mechanical termination with a cover crop roller/crimper: 1) 20% vinegar solution, 2) 2.84 L/ha 45% clove oil/45% cinnamon oil mixture, 3) solarization using 0.15mm clear polyethylene sheeting with edges manually tucked into soil for 28 days over the entire plot, and 4) broadcast flaming emitting 1,100°C (approximately 7.3 million kj) applied at 1.2 km/h. A rolled/crimped alone treatment, and the synthetic herbicide glyphosate applied at 1.12 kg/ae ha, were included for comparison. Five cover crop species were evaluated: 1) hairy vetch, 2) crimson clover, 3) cereal rye, 4) Austrian winter peas, and 5) rape. Three termination timings occurred at four week intervals beginning mid-March each year. In 2013, a maximum May biomass of 8,838 kg/ha was attained with cereal rye, followed by Austrian winter peas (7,177 kg/ha), hairy vetch (6,213 kg/ha), and crimson clover (5,124 kg/ha); rape provided the least biomass (1,657 kg/ha). Terminating covers in April resulted in approximately half biomass in all comparisons, while terminating covers in March resulted in less than 1,000 kg/ha regardless of cover species. Similar biomass trends were observed in 2014 although biomass totals were lower. Clove/cinnamon oil and vinegar were generally non-effective at termination over rolling/crimping alone in either year. In March, rye and rape was not terminated by any practice, while solarization was effective in April. By May, rolling/crimping alone terminated vetch 90%, peas 96%, and clover, rye 99%. Solarization was effective in March for vetch termination (95%) while solarization provided 72% termination of clover and 93% pea termination. In 2014 due to warmer winter and spring temperatures, similar termination results were observed for March 2014 as were observed in April 2013. Organic producers needing to terminate winter covers would most likely be successful using a broadcast flamer for most winter covers or utilizing clear plastic for hairy vetch, winter peas, or cereal rye as ambient temperature increases along with solar radiation, both in combination with a roller/crimper. Commercially available vinegar and clove/cinnamon oil solutions provided little predictable termination and producers are likely to resort to tillage if no other material or practice is readily available.