Data from: The impact of black soil degradation on saturated hydraulic conductivity

Severe soil degradation represents a critical threat to agricultural
productivity and ecological sustainability in the black soil region of
Northeast China. Prolonged anthropogenic cultivation has induced varying
degrees of degradation, markedly impairing soil hydraulic
properties—particularly saturated hydraulic conductivity (Ksat). As Ksat
is governed by multiple interrelated pedological processes, its temporal
dynamics under long-term cultivation remain poorly understood, especially
with respect to the relative influence of key controlling factors across
degradation stages. This study investigates how cultivation history and
progressive soil degradation jointly regulate Ksat in black soils of
Northeast China. Results indicate that soil organic matter (SOM) declines
exponentially with cultivation duration, approaching a carbon equilibrium
state after approximately 150 years of continuous farming. Across
degradation gradients, Ksat exhibits a non-linear, unimodal response to
both the soil structural stability index (SSI) and SOM—initially
increasing and subsequently declining. Crucially, the dominant control on
Ksat shifts from nutrient-related properties (e.g., SOM content) during
early degradation to structural and textural attributes (e.g., aggregate
stability, clay dispersion, pore continuity) under severe degradation.
Separate regression models were developed for mildly and severely degraded
soils to quantify these divergent controls. Collectively, these findings
elucidate the dynamic hydrological mechanisms underlying soil degradation
and offer a robust scientific foundation for improving hydrological
modeling, land-use planning, and targeted soil conservation strategies in
the black soil region.