Structural stabilization of soil backfill with quicklime

The application of quicklime (CaO) to soil backfill for the amelioration of poorly aerated grave soils (sandy loam) was tested in a cemetery in Germany. Two grave simulations (soil pits 9 m × 2 m × 1.6 m, l × w × d) were set up. Variation sans was only excavated and refilled, while in variation qlm, 20 kg quicklime per m³ soil were added to the backfill. Soil matric potential and gas composition were recorded over a period of 24 months in the two refilled pits and in the surrounding undisturbed soil (ref) at the 50 cm and 135 cm depths, respectively. Soil samples were taken in the beginning from ref and in three‐month intervals from the treatments sans and qlm. Soil pH and CaCO₃ content, as well as bulk density (ρB), air capacity (AC), air conductivity (kₗ), and saturated hydraulic conductivity (kₛ) were measured. Excavation and backfill of the untreated soil (sans) led to an increase in ρB at the 50 and 90 cm depths and decreases in AC, kₗ, and kₛ when compared to ref. Quicklime application led to an increase in pH, the formation of CaCO₃ in the formerly carbonate‐free soil, consistently reduced ρB, and increased AC, kₗ and kₛ. Although the quicklime application did not lead to notably more negative matric potentials, it increased the O₂ concentration in the soil air and reduced the CO₂ concentration to zero. The results show that the application of quicklime helps the structural amelioration of cemetery soils even at relatively low clay contents.