Soil management legacy provides resiliency to salinization: Insights of soil processes and indicators from a case study

Abstract

While individual management practices affecting soil salinity are well-documented, empirical evidence of their combined long-term protective effects under field conditions remains limited, and critical gaps persist in understanding how soil processes confer resilience. In 2018, a salinized soybean (Glycine max (L) Merr.) field from a persistently high-water table provided a unique opportunity to investigate this issue. Most of the field suffered severe plant damage and death, whereas a precise rectangular area in the southeast corner sustained healthy growth. This area corresponded exactly to decommissioned research plots managed with subsurface drains, no-till, gypsum, and cover crops (soil-health-legacy managed), which were absent elsewhere in the field (conventionally managed). In 2019, soil sampling along replicated transects between dead/damaged and living/thriving plants within each zone were analyzed for salinity, fertility, aggregation, and microbial community indices. No significant difference was observed in the conventionally managed zone between damaged and living areas. Within the soil-health-legacy zone, most chemical properties (6 out of 9), some microbial indicators (5 out of 14) and no physical properties significantly differed among areas with dead, damaged, or dying plants vs areas with living plants. These findings suggest that while some soil indicators may hint at salinization risk, they lack clear thresholds for practical interpretation. Therefore, we advise producers against over-reliance on soil health indices; instead, management processes should be targeted directly. This case study demonstrates that a history of combined subsurface drainage, no-till, gypsum, and cover crops protects crops from salinization through soil processes that soil indices alone do not reveal.