Overview of biochar role in remediating soil salinity stress in crops

Salt stress has been a major problem in the soils of the world. Semi-arid and arid soils are the most affected and bring about adverse crop productivity and yield especially in susceptible species. Salinity is usually denoted with electrical conductivity (EC) equal to or greater than 4 deci Siemens per meter (dS/m). With expanding areas affected by salinity, especially with increasing sea water level and incursion of land, rise in salty water table is eminent as consequences of climate change. Sustainable remediation of soil salinity is becoming a major concern, especially in the field of agriculture and climate change mitigation. Remediation of saline soil with application of organic amendments has shown positive results with the added advantage of carbon build up in the soil. Recently with the focus on biochar as one of the recent soil conditioners and amendment, many researchers have tried to find out its remediating capacity on soil salinity. This article will focus on how biochar affects soil salinity with much emphasis on cation exchange capacity (CEC) and anion exchange capacity (AEC). Results from researchers showed that biochar remediates soil salinity due to its inherent characteristics like high CEC and possession of AEC that deprives both cations and anions that form salt in the soil. This positively favour the thrival of crops under salt stress by boosting K+ availability, high salt sorption capacity, increased plant water intake, accelerated transpiration, lowered soil EC, increased soil accessible nutrients, increased soil moisture saving, optimizes the water-salt balance of the soil during saline irrigation, extended life span of plant which all favour crop performance. Future studies should explore synergistic effects of combining biochar with other soil management practices like drainage systems to enhance salinity mitigation and crop performance. Additionally, nano-biochar represents a promising direction in biochar development, with more possible potential for salinity amelioration due to higher surface area compared to biochar. While biochar has the potential to mitigate this issue, research on its application in African contexts is limited. More localized studies are needed to develop effective biochar solutions tailored to specific African environments and agricultural practices.