In the context of climate change and the circular economy, biochar agricultural and envi-
ronmental applications have attracted a good deal of attention. Biochar has unique characteristics
like surface area, porosity, water-holding capacity, pH, surface charge, and nutrients. This study
reviews the biochar production from olive pomace (OP) and olive stone (OS) byproducts, its chemical
and physical characterization, and its environmental application. The current review highlights the
conditions for biochar production, the effects of pyrolysis temperature, and feedstock type on the
physicochemical properties of biochar. High pyrolysis temperature (>500 ◦C) promotes a high specific
surface area, high porosity (especially for OS biochars), and pH as well as the content of ash and fixed
carbon, but generates low cation exchange capacity (CEC) and electrical conductivity (EC) and high
values of O/C and H/C ratio. OP biochar also presents a high C amount, and ash content, i.e., rich in
nutrients and high alkalizing capacity. OP biochar serves as an important source of plant nutrients,
especially potassium. After adding both types of biochar, aggregate stability and the amount of water
held in soil increase, and bulk density and bioavailability of trace elements decrease. Thus, biochar
from olive mill wastes can be a potential plant nutrient reservoir, a good amendment to improve
soil properties and long-term carbon sequestration. Results presented in this review can be used to
build designer biochars from olive mill wastes to help solve environmental issues (water purification
and pollutant remediation) and are suitable for improving soil physical chemistry characteristics and
crop growth.
