Soil Physical Properties and Their Role in Plant Growth: Texture, Structure, Porosity, Water Retention, Compaction, Aeration, and Root Responses

Abstract Soil physical properties regulate the soil environment experienced by plant roots by controlling water storage and movement, aeration, mechanical impedance, and the spatial arrangement of pores that determine where and how roots proliferate. This narrative review synthesizes key concepts and evidence on soil texture, structure, bulk density, porosity, water retention, compaction, and aeration, with a focus on how these properties affect root growth and, ultimately, plant productivity. Texture sets the foundational limits for water-holding capacity, aeration, and hydraulic conductivity, while structure—shaped by aggregation, biopores, and management—often determines the “effective” physical habitat for roots. Bulk density and penetration resistance are widely used indicators of compaction and mechanical constraints on root elongation. Compaction commonly reduces microporosity and gas exchange, increases soil strength, and alters root system architecture by restricting rooting depth and concentrating roots in surface layers. Root growth responses depend on interactions among soil moisture, oxygen availability, and soil strength, with evidence showing root elongation declines sharply above characteristic penetration-resistance thresholds under many conditions. The review highlights measurement approaches and practical thresholds used in soil physical assessment, and it synthesizes management strategies that improve soil structure and reduce compaction risk, including controlled traffic, organic matter management, reduced tillage, and cover crops. Finally, research gaps are identified, especially in linking pore-network characteristics to root traits under climate extremes. Keywords: soil physics, texture, structure, bulk density, porosity, water retention, compaction, aeration, root growth