A multi-criteria evaluation of organic amendments used to transform an unproductive shrubland into a Mediterranean dehesa

• Published in: Journal of environmental management Vol. 82; no. 4; pp. 446 - 456
• Main Authors: Tarrasón, David, Ortiz, Oriol, Alcañiz, Josep M.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.03.2007; Elsevier; Academic Press Ltd
• Subjects: Animal, plant and microbial ecology; Applied ecology; Applied sciences; Biological and medical sciences; Composted sludge; composts; Conservation of Natural Resources - methods; Conservation, protection and management of environment and wildlife; Decision making; dehesa; digested sewage sludge; dry matter accumulation; drying; ecotoxicology; Environmental management; Evaluation Studies as Topic; Exact sciences and technology; Fertilizers; Fundamental and applied biological sciences. Psychology; General aspects; Global environmental pollution; grasses; Information systems; land restoration; Land use; Mediterranean Region; Multi-criteria decision-support tool; Planning Techniques; plant growth; Poaceae - growth & development; Pollution; rangelands; Sewage - analysis; sewage sludge; Sewage sludge management; Sewage treatment plants; shrublands; Sludge; Soil - analysis; Soil amendment; soil amendments; Soil conservation; soil fertility; soil organic matter; Soil rehabilitation; Soils; Spain; vegetation cover; Waste Disposal, Fluid - methods; Waste management; Spain; Mediterranean Area; Composted sludge; Multi-criteria decision-support tool; Sewage sludge management; Soil rehabilitation; Soil amendment; Compost; Land reclamation; Sewage sludge; Environmental management; Soil management; Shrubbery; Organic amendment
• ISSN: 0301-4797; 1095-8630
• DOI: 10.1016/j.jenvman.2006.01.002

Environmental and health problems associated with the use of digested sewage sludge hinder its application and encourage the introduction of additional treatments such as composting and thermal drying. The aim of this paper is to assess the possibility of using three different types of sewage sludge (digested, composted and thermally dried) to improve soil fertility and enhance the transformation of an unproductive shrub land into a Mediterranean dehesa for grazing purposes and also to reduce wildfire risk. In total, 10 t ha −1 of dry matter of three types of sewage sludge were spread on the soil surface of 4×5 m field plots, and then seeded with a mixture of grasses. Effects on soil fertility and plant growth were monitored over 2 years. The results show that all three types of sludge application had a significant effect on vegetation cover, herbaceous biomass (2767.7±716.1 and 1735.0±299.7 kg ha −1 for digested sludge amended and control plots, respectively) and tree growth (0.41±0.108 cm year −1 on amended trees, 14.6% more than control trees). This study proposes the use of multi-criteria analysis to identify the most suitable fertilization alternatives and to assist in the decision-making process of sludge recycling. Because of the high degree of uncertainty and conflicting objectives associated with these decisions, multi-criteria evaluation tools make a valuable contribution to decision-making processes concerning sewage sludge applications. According to multi-criteria results, the composted sludge alternative is the most suitable. This is because all the objectives are achieved: an improvement in the properties and functions of the soil with a positive vegetation response as well as minimal economic cost and risk of toxicity.