Changes in soil aeration and soil respiration of simulated grave soils after quicklime application

Abstract

AbstractThe decomposition of buried human remains on cemeteries can be delayed in poorly aerated graves due to high water levels and a low permeable pore system for oxygen and water transport. With aim to improve the soil aeration properties in the burial environment, the addition of quicklime (CaO) to the grave backfill was tested. Quicklime is expected to promote a stronger aggregation and stabilization of the backfilled soil mainly by forcing an immediate dehydration and particle cementation processes.Two different grave simulations (without buried corpses) were prepared: (1) mixing the grave backfill with 20 kg m−3 quicklime (“CaO”) and (2) backfill without CaO (“NIL”) on a cemetery in Northern Germany. The soil type was a Terric Anthrosol (Stagnic) with a loamy sand texture. Undisturbed soil cores were taken from two depths before and after excavation and backfill at regular intervals of 3 months in order to analyze changes in (1) gaseous transport functions expressed by air‐filled porosity, air permeability (air permeameter), gas diffusivity (double chamber method) and related pore continuity indices as well as in (2) soil respiration (alkali trap method) representing microbial activity.Results clearly demonstrated a more conductive pore system in the CaO variant reflected by higher gas diffusivity and air permeability over 1 year compared to the NIL variant. Pore continuity indices also indicated a more connective pore system for the CaO variant. Effects of CaO application on soil respiration rate differed between the quarterly sampling times. Results indicated that microorganism were still active under alkaline soil conditions induced by CaO application, but the quantitative determination of biologically produced CO2 is influenced by chemical reactions when hydrated quicklime [Ca(OH)2] was reformed to limestone under consumption of CO2. The experiments indicate that the application of quicklime is a promising approach to improve aeration properties of grave soils and is therefore proposed as an adequate method to improve the aeration of burials on cemeteries.