Comparing activated charcoal and biochar for carbon-seeding in grass seed production

Authors: Mattox, Clint; Trippe, Kristin

Submitted to: Crop, Forage & Turfgrass Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/14/2025
Publication Date: 6/5/2025
Citation: Mattox, C.M., Trippe, K.M. 2025. Comparing activated charcoal and biochar for carbon-seeding in grass seed production. Crop, Forage & Turfgrass Management. 11(1). Article e70049. https://doi.org/10.1002/cft2.70049.
DOI: https://doi.org/10.1002/cft2.70049

Interpretive Summary: A field study compared the use of activated charcoal (AC) and conifer-based biochar across six pre-emergent herbicides for carbon-seeding perennial ryegrass seed in western Oregon. Among the six herbicides tested, both AC and biochar protected perennial ryegrass plants during establishment when diuron, rimsulfuron, pronamide, and a combination of pyroxasulfone and flumioxazin were used. This suggests that conifer-based biochars with similar characteristics could be used instead of AC under similar circumstances. When indaziflam was used, AC protected perennial ryegrass better than biochar at the carbon rate tested; however, AC did not always provide equivalent crop safety as when no herbicides were applied. When EPTC was used, neither AC nor biochar protected perennial ryegrass. These findings suggest that more testing is merited regarding carbon rates in this system when using indaziflam or EPTC.

Technical Abstract: Perennial ryegrass seed production fields in western Oregon are often established using carbon-seeding, which consists of applying a band of activated charcoal (AC) over the seed row at the time of sowing. A preemergent herbicide is then broadcast applied to the field prior to rainfall or irrigation. In the seed row, the herbicide that encounters AC is absorbed, which allows the seed to germinate and establish. Biochar has similar characteristics to AC and is a potential alternative for carbon-seeding. Conifer-based biochars are produced in western Oregon, use less energy to make, and are less expensive than AC, providing potential benefits to stakeholders. To compare the seed safening effects of conifer-based biochar to AC, we tested seven herbicide treatments: EPTC, diuron, indaziflam, rimsulfuron, pronamide, a combination of pyroxasulfone and flumioxazin, and a no herbicide check in a field study repeated four times in western Oregon. Results suggest that perennial ryegrass establishment was equivalent when either biochar or AC were used in combination with diuron, rimsufluron, pronamide, and a combination of pyroxasulfone and flumioxazin signifying that biochar could be used in place of AC for these herbicides. Perennial ryegrass establishment was greater when activated charcoal was used compared to biochar when indaziflam was used. When EPTC was used, neither AC nor biochar led to perennial ryegrass establishment that was equal to the no herbicide check plots. Findings provide data on the use of biochar for carbon seeding and an update on crop safety expectations across multiple herbicides in this system.