Biochar, a carbon-rich by-product of organic matter pyrolysis, has a variety of physiochemical properties beside a variety of applications. This review highlights some physical and chemical characteristics of herbaceous, woody, and sewage waste biochar under different pyrolysis conditions, as well as soil and foliar applications of biochar. The controlling role of pyrolysis temperature was the reason for selecting the discussed biochar types in the study. This review concludes that increasing pyrolysis temperature mainly raised the values of some chemical properties of the biochar, such as pH, electrical conductivity (EC), ash content, total phosphorus (TP), and a few values of physical properties like porosity and specific surface area (SSA). On the other hand, yield and total nitrogen (TN) decreased with rising pyrolysis temperature. Among biochar application methods to soil, mixing biochar with soil before planting is one of the best methods of application, and in most cases, biochar reapplication improved soil properties, while foliar application of biochar has positive effects on plant growth and yield parameters, ranging from low rates to the highest ones.

One of the most critical problems facing countries in the Mediterranean basin and posing restrictions on agricultural production is poor soil quality caused by low organic matter content (OM). Biochar, a carbon-enriched material obtained by pyrolysis of agricultural wastes proved to be efficient in soil improvement. On the other hand, olive mill wastewater (OMWW) is a byproduct of olive oil production. The combined use of these materials will reduce environmental damage paving the way to sustainable agriculture and may also offer a practical solution for enhancing soil physical properties. This research aimed to evaluate the effect of biochar and OMWW on the physical and hydrodynamic characteristics of a loam soil in the syrian coast. A field experiment was carried out using four rates of biochar (0, 1, 3, and 6 t ha-1) and three levels of OMWW (0, 50, and 100 m3 ha-1). Results showed that with increasing the levels of biochar and OMWW the soil bulk density (BD) and pores containing unavailable water 10 μm (9.2%v) after adding 100 m3 ha-1 of OMWW and soil biochar addition at 6 t ha-1, also soybean productivity rose by (%222.187).

Using biochar as a soil amendment is suggested to be a win/win technology for enhancing physical and chemical soil properties, yet little is known about the effects of biochar on soil microorganisms. This review underscores twofold of soil microbiological features studied in short-term experiments. 1) microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), and basal soil respiration (BSR). 2) β-glucosidase, dehydrogenase, and urease enzymes activities under different doses and types of biochar and soil. MBC, MBN, BSR β-glucosidase, dehydrogenase, and urease and enzymes activities responded to biochar application depending on biochar dose, type, inorganic fertilizer application, soil type and cultivated plant. MBC, MBN, and BSR increased linearly after gradual amendments of cotton straw biochar while just low doses were effective for raising β-glucosidase, and dehydrogenase activities. Only high doses of wheat and corn straw biochar were effective to increase MBC while linear increments were witnessed under swine manure biochar. Across all biochar types, MBN showed an upward trend with increasing biochar rates hitting the heyday at the highest doses. On the other side, wheat straw and apple branch biochar caused gradual increments in β-glucosidase and urease activity with NPK (nitrogen-phosphorous-potassium) amendment after 72 months.