Biochar production has gained significant attention lately due to its potential to sequester carbon,                improve soil fertility and mitigate climate change. Various production technologies have been developed to convert biomass into biochar, each with its unique characteristics and advantages. This review provides a comprehensive overview of the current biochar production technologies aiming to synthesize existing knowledge and identify research gaps with a focus on their potential to contribute to the United Nations Sustainable Development Goals (SDGs) 2, 12, 13 and 15. The scope of this review encompasses various biochar production techniques including slow pyrolysis, fast pyrolysis, gasification and torrefaction. The effects of production conditions such as temperature, residence time, and feedstock types on biochar properties and yields are discussed. The prospects of using biochar in the agricultural system were discussed.  Additionally, challenges and opportunities associated to scaling up biochar production technologies are highlighted. The findings of this review have implications for the development of sustainable biochar production practices and environmental management strategies.

In search for an efficient means of building up the carbon stock, improving the fertility levels and aggregate stability of tropical soils for optimum crop yield, a field study was carried using different biochars and comparing the effects with inorganic fertilizer. The biochars were palm bunch biochar (PBB), saw dust biochar (SDM) and rice mill husk biochar (RMHB). Treatments consisted of 10 t/ha palm bunch biochar + 0.25t/ha poultry manure (T1), 10 t/ha rice mill husk biochar + 0.25t/ha poultry manure (T2), 10 t/ha saw dust biochar + 0.25t/ha poultry manure (T3), 500kg/ha N.P.K 15:15:15 fertilizer + 0.25t/ha poultry manure (T4) and plot without biochar + 0.25t/ha poultry manure (T5) (control plot). These were replicated five times on experimental plots of 4m2 in a randomized complete block design. Maize (Zea mays) was used as a test crop and data obtained were statistically analyzed using analysis of variance and correlation. Soils amended with biochars significantly improved soil pH, organic carbon, exchangeable bases and base saturation than non biochar fertilized soils. Saw dust biochar increased soil carbon stock by 95.1% against NPK fertilizer plots and control. There was 19% decrease in soil bulk density and 17% increase in soil pH with application of palm bunch biochar. Amending soils with palm bunch biochar increased soil organic carbon by 51.5%. The biochars increased the values of critical level of soil organic matter, modifies clay ratio and reduced the value of clay flocculation index more than NPK fertilized soils or control. Among the treatments, rice mill husk biochar recorded the highest maize cob weight though not significant with palm bunch biochar. Therefore, applying biochars on eroded soil is an effective measure of improving the stability, soil carbon stock as well as enhancing higher maize yield than inorganic fertilizer.

Soil moisture has a vital role in the cultivation of crops. Its sufficiency and availability to crop- water supplies depends on the management practices of soil and amount of available water to the soil. This study examines the influence of rice husk biochar on the water holding capacity of soil in the savannah ecological zone of Ghana. Increasing rate of rice husk biochar increased water-holding capacity of soils. 4t/ha rice husk biochar showed higher significant differences among the treatments. It is recommended that 4t/ha rice husk biochar should be applied to increase the water-holding capacity of the soil.