Soil amendment with biochar from slaughterhouse waste bones enhances soil quality and promotes the growth of crop plants

This study investigated the effects of different concentrations of bone char (2 and 5%, B2 and B5, respectively), a by-product of the pyrolysis of slaughterhouse waste animal bones, on the growth of lettuce (Lactuca sativa) plants, evaluating biometric (i.e. fresh weight), biochemical (i.e. chlorophyll, starch, soluble sugars, antioxidants (i.e. polyphenols and flavonoids), and mineral (i.e. Ca, Cu, Fe, K, Mn, P, S, Zn) parameters. Changes in the physio-chemical properties (i.e. pH, electrical conductivity, and mineral content) of the soil in which the plants were grown were also evaluated. Bone char amendment raised the soil levels of Ca and especially P. Lettuce plants grown in soils amended with bone char showed a remarkable increase in Ca, fresh weight (B2: +14%; B5: +17%), and biochemical parameters. Specifically, bone char increased the leaf content of chlorophyll, starch, and soluble sugars. Notably, the addition of 5% bone char also significantly boosted total polyphenols and the uptake of Mn and P.