Boron in Soils: Dynamics, Nutritional Roles, and Environmental Interactions, a Review

This review addresses the persistent knowledge gap arising from the fragmented treatment of boron fractions, mobility, and bioavailability in soil-plant-environment systems. The purpose of this work is to provide an integrated synthesis of current knowledge on boron dynamics in soils, with particular emphasis on its biogeochemical cycling, soil fractions, adsorption-desorption processes, and environmental controls. The review highlights that only a small proportion of total soil boron, mainly the soluble and specifically adsorbed pools, contributes directly to plant nutrition. At the same time, the majority is retained in oxide-bound, organic-bound, or residual fractions that regulate long-term availability. Key synthesized findings show that boron mobility and bioavailability are strongly governed by soil pH, texture, organic matter, calcium carbonate content, salinity, and climatic conditions, leading to high susceptibility to leaching in humid or coarse-textured soils and to accumulation and toxicity risks in arid and irrigated agroecosystems. A distinctive contribution of this review is the integration of boron fractionation with adsorption-desorption behavior to explain contrasting nutritional outcomes under similar total boron contents. The review further outlines advances in analytical techniques, particularly ICP-OES and ICP-MS, which enable more accurate assessment of boron pools and fluxes. Overall, this synthesis identifies critical challenges related to irrigation water quality, soil salinity, and climate variability, and provides a conceptual basis for improved boron management strategies to balance productivity, environmental sustainability, and nutritional health.