Management of soil phosphorus for sustainable agriculture in South Asia: A review

South Asia (SA), one of the most densely populated regions in the world, relies heavily on agriculture for livelihoods. Although the region’s diverse climatic conditions and soil characteristics support agricultural intensification, high phosphorus (P) fixation in soils significantly limits P availability for plant uptake and consequently reduces crop productivity. Phosphorus fixation is strongly influenced by tropical and subtropical climatic conditions, dominant soil types such as Entisols and Aridisols, and anthropogenic activities including deforestation and crop residue burning. These factors contribute to the formation of highly weathered soils rich in kaolinitic clay and low in organic matter, which further enhance P fixation. Microorganisms such as Aspergillus, Penicillium, Bacillus, and Pseudomonas, as well as arbuscular mycorrhizal fungi (AMF) including Glomus, Gigaspora, and Acaulaspora, play important roles in P solubilization under varying agro-climatic conditions. However, low soil P availability and poor phosphorus use efficiency have led to excessive application of chemical P fertilizers, making South Asia one of the largest consumers of phosphorus fertilizers globally. Since rock phosphate, the primary raw material used in P fertilizer production, is a finite and rapidly depleting resource, sustainable phosphorus management is essential. This review critically examines phosphorus dynamics in South Asian soils and highlights sustainable strategies to improve P availability, enhance phosphorus use efficiency, and support long-term agricultural productivity.