Using Bone Char as a Renewable Resource of Phosphate Fertilizers in Sustainable Agriculture and its Effects on Phosphorus Transformations and Remediation of Contaminated Soils as well as the Growth of Plants

Recycling slaughterhouse waste such as bone and converting it into bone char is a promising environmentally friendly, low-cost strategy in a circular economy and an important source of phosphorus. Therefore, this review focused on the impacts of bone char on the availability, dynamics, and transformations of phosphorus in soils as well as plant growth and utilizing bone char in remediating contaminated soils by heavy metals. Bone char is material produced through bone pyrolysis under limited oxygen at 300–1050 °C. Bone char applications to the soils significantly increased phosphorus availability and plant growth. Agricultural practices such as co-applying organic acids or sulfur or nitrogen fertilizers with bone char in some soils played an important role in enhanced phosphorus availability. Also, co-applying bone char with phosphate-solubilizing microorganisms enhanced plant growth and phosphorus availability in the soils. Applying bone char to the soils changed the dynamics and redistribution of phosphorous fractions, enhanced fertility, promoted crop growth and productivity, reduced heavy metals uptake by plants in contaminated soil, and decreased heavy metals bioavailability. Bone char has shown positive performance in remediating soils contaminated by heavy metals. Bone char proved its efficiency in sustainable agriculture and practical applications as an alternative source of phosphate fertilizers, it is safe, cheap and helps in remediating contaminated soils by heavy metals. Using bone char as a slow-release fertilizer is potentially beneficial because it reduces the hazard of excessive fertilizing and nutrient leaching which have negative impacts on the ecosystem.