The use of biochar as soil amendment: effects on nitrogen and water availability for potted grapevines

Biochar use as soil amendment represents an interesting mitigation practice against the CO₂ increases in the atmosphere (carbon sequestration in the soil), combined with a potential enhancement of physicochemical properties of treated soils. The available literature related to the use of biochar in agriculture is nevertheless not univocal, the effect of biochar being strongly dependent from several aspects, such as the characteristics of the feedstock material, the technology used for biochar production and the original properties of the amended soil. This paper reports about the main outcomes of experiments conducted on potted vines under semi-controlled conditions aiming to evaluate if the presence of biochar (alone or mixed with compost) affects i) the availability of N fertilizers for Pinot noir grapevines and ii) the soil water properties and water availability for the vines. N uptake and distribution in the different grapevine organs was not affected by biochar in the soil as demonstrated after the application of a 15N labelled fertilizer and quantification by IRMS (Isotopic Ratio Mass Spectrometer). Biochar enhanced the amount of soil water available for the plants by approximately 30% as compared to not amended soil, therefore allowing significantly higher vine physiological performances during periods of water shortage. Overall, biochar addition to the soil did not affect the N availability for the vines, while it increased the soil water holding capacity therefore postponing the onset of the negative physiological effects caused by water shortage.

DOI: 10.26353/j.itahort/2020.2.2840

Keywords: soil water retention; water stress; photosynthetic rate; nitrogen isotope; Vitis vinifera