Historical Perspective of Soil Balancing Theory and Identifying Knowledge Gaps: A Review

Abstract

Core Ideas A soil with an ideal basic cation saturation ratio (BCSR) is said to maximize crop yields. Previous studies concluded higher crop yields are possible over a wide range of ratios. Scientific community generally disregards BCSR theory. Soil balancing effects on weeds, soils, and crop quality are critical knowledge gaps. The common philosophies that contextualize soil test results and fertilizer recommendations are sufficiency level of available nutrients (SLAN), buildup and maintenance, and basic cation saturation ratio (BCSR). The BCSR approach postulates maintaining an ideal ratio of basic cation (Ca2+, Mg2+, and K+) saturations on the soil exchange sites to maximize crop yields. The practice of adding amendments to alter the ratios of basic cation saturations in soils is called “soil balancing.” Bear, Graham, and Albrecht promoted this concept, with each suggesting a desired saturation ratio of Ca:Mg:K for optimum crop yields. Several researchers have tried to validate this theory with both greenhouse and field experiments but could not conclude that an ideal cation saturation ratio existed and found that crop yields were similar across a wide range of ratios. While the scientific community disregards this theory, some farmers, crop consultants, and commercial soil‐testing laboratories still use BCSR to guide their fertilizer recommendations. It is believed that soil balancing effectively controls weeds, insects, and pests and improves overall soil health for better plant growth, ultimately producing better crop yields. Some even argue that soil balancing improves nutritional quality of the harvested crop. However, contemporary research to objectively demonstrate such perceived benefits of practicing soil balancing is missing. This review presents a holistic overview of soil balancing, presents a literature review on BCSR, and identifies knowledge gaps, which need to be addressed to better understand the merits and limitations of soil balancing.