269 Am. J. Enol. Vitic. 63:2 (2012) Mulching consists of spreading a protective layer of ma- terial, either natural or synthetic, on top of the soil. Several materials can be used for mulching: synthetic, biomass, and living vegetation. Synthetic mulches include black polyeth- ylene and geotextile, whereas organic (biomass) mulches include straw, bark, compost, and various loose materials. Living mulches consist of low-growing annual or perennial plants (cover crops), which provide a groundcover inhibiting the growth of weeds. Black polyethylene and other synthetic mulches (i.e., polypropylene ilms) are able to ilter out the photosynthetically active radiation and are used for weed con- trol in a range of crops under an organic growing system and can also stimulate growth and yield of trees because of soil moisture conservation. Unfortunately, these mulches do not add organic matter and nutrients to the soil and can present some problems in their disposal (Verdú and Mas 2007). Loose organic materials such as straw, bark, and compost may provide effective weed control but the thickness of the mulch layer needed for weed control can be costly. Weed suppression by organic mulches can involve physical action (the thickness of the layer) and/or release of phytotoxic com- pounds. Organic mulches decompose over time and require periodic reapplications, but they provide organic matter and nutrients to the soil and enhance soil particle aggregation and water-holding capacity (Merwin et al. 1995, Verdú and Mas 2007). Soil management practices involving organic wastes have been advocated to improve the quality and to maintain the productivity of agricultural soils. In some cases vines grown under mulches outperformed those under clean cultiva- tion or cover crops (Van Huystteen and Weber 1980). Concerns over how cover crops and mulches might ad- versely affect vines have slowed down the adoption of these management systems. Potential problems include increased disease problems, vertebrate and invertebrate pests, and com- petition with vines for nutrients. Mulching with organic materials has reportedly had posi- tive effects not only on the soil but also on yield/grapevine, Brix, and leaf mineral elements (Pool et al. 1990, Pinamonti 1998, Jacometti et al. 2007). The use of mulching materials should also be considered as a tool for economical and sustain- able use of waste materials. Olive mill waste disposal is an issue of extreme importance in the Mediterranean area. Recent investigations on agronomic use of olive mill residue as soil amendment material, as it is or after composting, showed posi- tive effects on soil aggregate stability (Brunetti et al. 2005, López-Piñeiro et al. 2008). In a more recent study in a high- density olive orchard in southeastern Italy, the exhausted olive 1 Dipartimento di Scienze Agro-Ambientali e Territoriali, University of Bari ‘Aldo Moro’, via Amendola 165/A, 70126 Bari, Italy; and 2 CIHEAM, Mediter- ranean Agronomic Institute of Bari, via Ceglie, 9, 70010 Valenzano (Bari), Italy. *Corresponding author (email: ferrara.g@agr.uniba.it; tel.: +39 080 5442979; fax: +39 080 5442979) Manuscript submitted Sept 2011, revised Dec 2011, accepted Dec 2011. Publica- tion costs of this article defrayed in part by page fees. Copyright © 2012 by the American Society for Enology and Viticulture. All rights reserved. doi: 10.5344/ajev.2011.11092 Effects of Mulching Materials on Soil and Performance of cv. Nero di Troia Grapevines in the Puglia Region, Southeastern Italy Giuseppe Ferrara, 1 * Mariano Fracchiolla, 1 Ziad Al Chami, 2 Salvatore Camposeo, 1 Cesare Lasorella, 1 Andrea Paciico, 1 Adel Aly, 2 and Pasquale Montemurro 1 Abstract: The responses in soil conditions, vine growth, and physiological, yield, and composition components of cv. Nero di Troia to the application of synthetic and organic mulches were studied for two years (2006–2007 and 2007–2008). The effects of the application in the vine rows of two synthetic mulches (geotextile as polypropylene and black polyethylene) and an organic mulch (exhausted olive pomace 3- and 6-cm thick) were compared to a control (weed mowing) in an organic vineyard. Throughout the trial, we conducted soil and leaf analyses, weed surveys, and phytotoxicity tests and measured vegetative activity, leaf gas exchange and water status, yield, and composi- tion components. The exhausted olive pomace showed positive effects on some soil fertility variables and on vine physiology (stomatal conductance, transpiration, and net assimilation). Black polyethylene and geotextile provided good control of the weeds, especially in the irst year, but positive results were also obtained with the exhausted olive pomace. Yield and composition components of grape were unaffected by any of the organic and synthetic mulches compared to weed mowing. The exhausted olive pomace provided good control of weeds, improved the fertility of the soil, and could be acceptable in terms of sustainability. The mode of action of the exhausted olive pomace was both physical and phytochemical through the release of phytotoxic compounds. Key words: exhausted olive pomace, mulch, black polyethylene, geotextile as polypropylene, weeds, yield