Biochar and biochar-compost as soil amendments to a vineyard soil: Influences on plant growth, nutrient uptake, plant health and grape quality

Most European vineyard soils exhibit low soil fertility. They are highly vulnerable to erosion, low in soil organic matter content and, therefore, in water holding capacity and nitrate retention. The applications of biochar and biochar-compost are said to address some of these issues. We tested the ability of these amendments to improve soil quality and plant production quality in a 30-year-old vineyard in Valais, Switzerland. The amendments of biochar alone (8 t ha−1, produced from wood at 500 °C), aerobic compost (55 t ha−1) and biochar-compost (8 t ha−1 + 55 t ha−1, mixed before the composting process) were compared to an un-amended control soil. During the years 2011, 2012 and 2013 various vine and green cover growth, vine health and grape quality parameters were monitored. Biochar and biochar-compost treatments induced only small, economically irrelevant and mostly non-significant effects over the three years. We concluded that topsoil application of higher amounts of biochar has no immediate economic value for vine growing in poor fertility, alkaline, temperate soil.