NEXUS Involve & Partner: impacts of biochar supplementation on livestock productivity, profitability and GHG emissions : Milestone 4

The NEXUS project is a multi-party program that explores the nexus between profitability, productivity, greenhouse gas mitigation, carbon sequestration and consumer perceptions of livestock businesses in an increasingly variable climate. The Involve and Partner (I&P) activities associated with the Tasmanian NEXUS project is trialling biochar as a feed supplement to a cohort of livestock on a commercial beef cattle farm in northern Tasmania, Australia. The I&P farm are implementing pasture renovation activities aimed at increasing soil carbon and have been formally registering their activities under the Emissions Reduction Fund (ERF). Supplementation of a commercial grade biochar 'FeedChar' to Wagyu-cross calves (biochar treatment) commenced in May 2022. A second cohort of calves (control treatment) rotationally grazing paddocks of the same farm to allow a comparison of liveweight gain over the duration of the project. The project began with 200 animals, however in line with his commercial trading operation, the farmer sold a number of animals in winter 2022. As such, the present experiment now has 60 calves in each cohort. This change removed some of the smaller (late birth) calves and will improve statistical rigour in this experiment. Measurements of pasture quality and availability indicates little difference between the control and biochar treatment cohorts. While mean liveweight of the biochar treatment was greater than that of the control in early 2023, the difference was not significant. We have also shown that seasonal variation in manure organic carbon has been greater than variation between (control and biochar) treatments, suggesting minimal enrichment of organic carbon in manure due to biochar consumption. Three on-farm workshops have been completed; the first on the I&P farm in November 2022, the second on a dairy farm in the north-east of the state and the third on a beef farm in the north-west of the state. Two workshops were conducted on farms that have used biochar as a feed supplement for several years, and are thus further along the sustainability journey compared with the I&P farm. Across workshops there were 72 attendees, comprising a blend of producers and industry representatives. The aim of these workshops was to promote awareness of the biochar supplementation project, implications for soil carbon, enteric methane and liveweight gain. In these, we assessed participant knowledge, attitudes, skills and aspirations to commence feeding biochar on their own properties through a survey process. Awareness, knowledge and skills related to biochar increased substantially between pre-and post-workshops, with the majority of participants reporting improved ability to make more informed decisions on the use of biochar. The majority of survey participants indicated a willingness to use biochar as a feed supplement after attending the workshops, primarily to assist in improving soil carbon and animal health, while reduce greenhouse gas emissions (enteric methane). We will interview of survey participants in late 2023 to gauge practice change and propensity for impact