S13 - Session P1 - Biochar-compost and cover crop use for enhancing soil carbon and nitrogen contents in an irrigated vineyard in Okanagan Valley, British Columbia, Canada

Authors: Mehdi Sharifi *, Monireh Hajiaghaei-Kamrani

Effects of biochar-compost mixture (BICOM) and cover crop (CC) were assessed on soil and wine grape productivity in an irrigated Merlot ( Vitis vinifera L.) vineyard in Okanagan Valley, British Columbia from 2017 to 2020.The experimental set up was a factorial arrangement of control (CON; no BICOM or CC), BICOM, CC and their combination (CCBICOM) treatments in alleys with 4 replications.The BICOM comprised a 1:1 ratio of biochar, and compost and was applied at a rate of 22 Mg ha -1 dry-weight basis in May 2017 and 2019. The CC consisted of a dryland forage mixture plus birds foot trefoil ( Lotus corniculatus L.) sown at rates of 22.4 and 6.7 kg ha -1 , respectively. Biochar-compost and CCBICOM significantly increased the soil C content by 11 and 17% only at the 0-15 cm soil depth compared with the CON averaged across sampling dates, respectively. Cover crop treatment did not affect soil C content at the 0-15 or 15-30 cm soil depths in all sampling dates. The soil N content was not affected by BICOM, decreased by CC by average of 12.5% in both soil depths, and increased by CCBICOM by 4% only at the 0-15 cm soil depth averaged across sampling dates. Biochar-compost treatment did not affect CC biomass or tissue C and N concentrations except for a 12% reduction in 2019 biomass. Grape yield was not affected by treatments except for a 32% increase by CCBICOM relative to CON in 2020. The CC reduced petiole N and pruning weights in 1 or 2 years out of 3. In semiarid light-textured vineyard soils the use of BICOM in combination with a high C/N ratio CC can be recommended to increase C and N residence time and consequently C sequestration in the soil.