Long term effect of biochar on soil plant water relation and fine roots: Results after 10 years of vineyard experiment

Biochar is widely suggested to improve soil physical properties and soil-water-plant interactions. Furthermore, the application of biochar to the soil can alter the dynamics of the roots and, in turn, affect the performance of the plant. Nevertheless, the long-term evolution of these effects is unknown and of critical importance because biochar persists in soil for centuries. The results of this work are part of a long-term study in the vineyard started in 2009 and still ongoing. In this work, the effect of applying biochar to soil on the plant-water relationships of Vitis vinifera, soil properties and fine root traits is evaluated 10 years after application. Even after 10 years, the ecophysiological measurements indicated an increase in soil water content and a significant increase in the water status of the plants in the plots treated with biochar. Independently of the diameter class considered, both doses of biochar led in the entire 40 cm of soil to a general reduction of the fine-root standing biomass and length, which is probably due to the lower need for fine root foraging. Moreover, the SRL did not show differences among different treatments. When fine-root traits were analysed along the soil depth at 10 cm intervals, we noted that both length and biomass were significantly higher in the control plant only in the upper soil layers (20 cm) and SRL was significantly higher only in the upper 10 cm of soil. These findings underscore how control plants plastically respond to the lower content of water in the soil by decreasing the fine-root cost-to-benefit ratio, especially in the topsoil layer. Research on the effect of biochar in viticulture can provide an effective contribution to the mitigation of climate change by increasing the water status of the soil and plants even 10 years after its application.