This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process which may lead to differences between this version and the Version of Record. Please cite this article as doi: 10.1002/ldr.2830 This article is protected by copyright. All rights reserved. ORGANIC AMENDMENTS AND MULCHES MODIFY SOIL POROSITY AND INFILTRATION IN SEMIARID MINE SOILS Luna, L. a , Vignozzi, N. b , Miralles, I. a,c , Solé-Benet, A. a a EEZA-CSIC, Estación Experimental de Zonas Áridas, Consejo Superior de Investigaciones Científicas, Carretera de Sacramento s/n, 04120, La Cañada de San Urbano, Almería, Spain b CREA-AA, Consiglio per la ricerca in agricoltura e l'analisi dell'economia agraria, Centro di ricerca Agricoltura e Ambiente, Via Lanciola 12/A, 50125 Firenze, Italy c Georges Lemaître Earth Sciences Center, Université Catholique de Louvain, Place Louis Pasteur 3, Louvain-La-Neuve, Belgium. ABSTRACT The restoration of soils affected by mining activities depends on the improvement of soil physical quality. This study aimed to determine the medium-term effects of organic amendments and mulches on soil physical properties and soil hydrological response. The experimental restoration was conducted in a homogeneous slope using a factorial design (organic amendments x mulches). The organic amendments consisted of compost from domestic organic residues, sewage sludge from an urban water treatment facility and a control without amendment. The mulches consisted of gravel, woodchips and a control without mulch. Modifications of the soil structure induced by the combinations of techniques were quantified by micromorphometric analysis of 2D-porosity. Undisturbed soil cores were collected to determine the soil bulk density. Soil hydrological behavior was determined by rainfall simulations. Samples from natural undisturbed soils surrounding the quarry were also taken as a reference. Restored soils with organic amendments have a higher total porosity than non-amended substrates. Each restoration treatment combination resulted in a different pore system with very diverse hydrological responses. Organic amendments resulted in infiltration improvement and water erosion reduction. The woodchip mulch was more effective at trapping runoff and sediment, although this type of mulch did not favor vertical water movement towards deeper horizons. Therefore, the use of organic amendments should be encouraged in mine soil restoration and should be strongly recommended for its proven environmental benefits (enhancement of soil structure and infiltration and reduction of soil losses). However, the mulches did not produce the expected results in the tested arid-semiarid area.