Carbon sequestration in a limestone quarry mine soil amended with sewage sludge

Abstract

To reclaim a limestone quarry, 200 and 400 Mg/ha of municipal sewage sludge were mixed with an infertile calcareous substrate and spread as mine soil in 1992. Soil samples were taken 1 week later and again after 17 yr of mine soil rehabilitation so as to assess changes in the amount and persistence of soil organic carbon (SOC). Sludge application increased SOC as a function of the sludge rate at both sampling times. Seventeen years after the sludge amendments, the nonhydrolysable carbon was increased in the 400 Mg/ha of sludge treatment. The recalcitrance of SOC was less in sludge-amended soils than in the control treatment at the initial sampling, but 17 yr later this trend had reversed, showing qualitative changes in soil organic carbon. The CO 2 -C production had not differed between treatments, yet the percentage of mineralized SOC was less in the high sludge dose. When the size of active (C active ) and slow (C slow ) potentially mineralizable C pools was calculated by curve fitting of a double-exponential equation, the proportion of C active was observed to be smaller in the 400 Mg/ha sludge treatment. Soil aggregate stability, represented by the mean weight diameter of water-stable soil aggregates, was significantly greater in mine soil treated with the high dose of sludge (18.5%) and SOC tended to be concentrated in macro-aggregates (5-2 mm). Results suggest that SOC content in sludge-amended plots was preserved due by (i) replacement of the labile organic carbon of sludge by more stable compounds and (ii) protection of SOC in aggregates.

Mid‐term effects on ecosystem services of quarry restoration with Technosols under Mediterranean conditions: 10‐year impacts on soil organic carbon and vegetation development

“…The storage efficiency of the different pools of organic matter is highly influenced by its biochemical recalcitrance, its stabilization as organomineral aggregates, the occlusion in soil aggregates, or its transportation into the subsoil (Lal ). Sewage sludge, as a biomass derived residue, may directly contribute to soil carbon sequestration through its stabilization in soil, and indirectly through the increase in plant biomass production and litter intake (Ojeda et al ). However, the relatively low stability of sewage sludge (Mattana et al ) is expected to cause transient effects on soil organic matter pools, as mid‐term soil organic carbon (SOC) sequestration relies more on the subsequent evolution of OC inputs from plant debris intake to soil rather than on the OC provided by the sludge (Ojeda et al ).…”

“…Sewage sludge, as a biomass derived residue, may directly contribute to soil carbon sequestration through its stabilization in soil, and indirectly through the increase in plant biomass production and litter intake (Ojeda et al ). However, the relatively low stability of sewage sludge (Mattana et al ) is expected to cause transient effects on soil organic matter pools, as mid‐term soil organic carbon (SOC) sequestration relies more on the subsequent evolution of OC inputs from plant debris intake to soil rather than on the OC provided by the sludge (Ojeda et al ). Organic matter improvements, in turn, can contribute to other relevant ecosystem services in rehabilitated land such as raw materials production (for fuel, construction materials, etc.…”

“…), nutrient cycling, climate regulation, or improving soil as habitat for organisms (Baveye et al ). However, little is known about the efficiency of Technosol approaches in terms of soil carbon storage (Ojeda et al ), and especially in the mid and long term, which could be of interest for offsetting the emissions of mining activities closely linked to the cement industry, one of the main contributors to industrial CO 2 emissions (Imbabi et al ).…”

Carbon balance as affected by biosolid application in reforestations

“…Attending to the carbon cycle, sludge applications imply a direct input of exogenous carbon to the soils. Then the behaviour of the SOM depends on his physicochemical composition and the distribution between labile and recalcitrant pools of C determining the portion used by microorganisms as energy and the portion that contribute to the pool of humiclike soil stable substances (González-Ubierna, Jorge-Mardomingo, Carrero-González, de la Cruz, & Casermeiro, 2012;Ojeda, Ortiz, Medina, Perera, & Alcañiz, 2015). The increase of activity of soil microbial populations promotes the rate of organic matter decomposition and mineralization and, hence, the amount of CO 2 emitted to the atmosphere (Fontaine, Bardoux, Abbadie, & Mariotti, 2004), but at the same time it increases plant productivity and C fixation both at medium and in a long term (Hernández, Garcia, & García, 2015;Pascual et al, 2000).…”

Técnicas de restauración de suelos basadas en el uso de residuos orgánicos: seis años de beneficios sobre las propiedades de un suelo forestal

“…A largo plazo, se espera un aumento del porcentaje de agregados estables y el aumento el espacio poroso (Ojeda et al, 2015;Luna et al, 2016). A su vez, las implicaciones que estos cambios tendrían sobre la hidrología del sistema podrían suponer un aumento para los umbrales de escorrentía y el descenso de las tasas de erosión (Lavee et al, 1998).…”