ABSTRACT Subsoil acidification is an intractable agronomic challenge worldwide, and its amelioration is costly and often practically infeasible. Because most studies are confined to the topsoil, acidity development in subsoil commonly remains undetected until it becomes severe. This review presents a bibliometric analysis of Web of Science and Scopus records (1984–2025) to identify research trends and patterns, and integrates evidence on the extent, causes, consequences and remediation of acidity at depth. The highest research active country on subsoil acidity is United States, contributing approximately 30.9% of total publications over the study period, followed by Australia (23.9%) and Brazil (14.0%). Mechanisms for subsoil acidification differ from topsoil acidification and imbalance in plant cation‐anion uptake may dominates as a contributor for subsoil acidification. Surface liming often corrects topsoil pH however leaves acidic subsoil layers and Al toxicity unresolved due to slow alkalinity movement. Evidence indicates that rapid subsoil remediation requires strategic deep incorporation or placement of alkalinity, sometimes combined with complementary amendments to enhance base cation (i.e., Ca/Mg) supply and alkalinity movement, while avoiding over‐liming risks. However, many proposed amendments and technologies still need thorough field‐scale evaluation to support their implementation in the agriculture sector. Overall, key priorities are depth‐resolved diagnostics and integrated field‐scale interventions that address co‐occurring constraints to prevent further acidification and sustain long‐term yields.
Hettithanthri et al. (Thu,) studied this question.