Ecological Engineering 40 (2012) 117–120 Contents lists available at SciVerse ScienceDirect Ecological Engineering j ourna l ho me page: www.elsevier.com/locate/ecoleng Short communication Stump grinding on a poplar plantation: Working time, productivity, and economic and energetic inputs Rodolfo Picchio a,∗ , Stefano Verani b,1 , Giulio Sperandio c,2 , Raffaello Spina a,3 , Enrico Marchi d,4 a Tuscia University, Department of Science and Technology for Agriculture, Forests, Nature and Energy (DAFNE), Via S. Camillo de Lellis, 01100 Viterbo, Italy b Agricultural Research Council (CRA), Research Unit for Wood Production Outside Forests, Periferic Operative Structure of Roma, Via Valle della Questione, 27, 00166 Roma, Italy c Agricultural Research Council (CRA), Research Unit for Agricultural Engineering, Via della Pascolare, 16, 00016 Monterotondo (Roma), Italy d University of Florence, Department of Agricultural and Forest Economics, Engineering, Sciences and Technologies, Via S. Bonaventura 13, 50145 Firenze, Italy a r t i c l e i n f o Article history: Received 5 July 2011 Received in revised form 30 September 2011 Accepted 21 November 2011 Keywords: Stump grinder Productivity Mechanization Poplar plantation Costs Energetic input a b s t r a c t After poplar plantation harvesting, the agricultural land should be restored for further cultivation. Stump wood grinding or extraction is completed in conjunction with agroforestry and some forest plantations. The main aims of this study were to determine the technical, economical and energetic results of a stump grinding operation in a plantations of Populus × euramericana (Dode) Guinier “Luisa Avanzo” and to com- pare these results to data from other similar works on stump extraction operations. Through working time analysis, productivity, energy inputs and costs were calculated. The stump grinding machine was installed behind an agricultural tractor. This working system showed a higher output (gross productivity PHS 15 172 stumps h -1 and net productivity PHS 0 227 stumps h -1 ) than stump extraction (gross produc- tivities lower of 37–62% in the compared yards); a lower operating cost per hectare (182.01 D ha -1 ) than stump extraction (higher 18–71% in the compared yards); and lower energetic inputs (2334.1 MJ ha -1 ) than stump extraction (3651.2–7251.9 MJ ha -1 in the compared yards). In the comparison of the cost of grinding and extraction, it was not considered that an income is possible in stump extraction by selling the woody material recovered. This fact may considerably affect the balance between the cost of the two methods. © 2011 Elsevier B.V. All rights reserved. 1. Introduction Stump wood grinding or extraction is completed in conjunction with agroforestry and forest plantations (Saarinen, 2006). In har- vested agroforestry plantations, in particular, in poplar stands, the removal of the stumps is the last step performed before plowing in order to return the soil to cultivation. Normally, there are two approaches: extraction or grinding. Stump extraction may be car- ried out using two methods: (i) a large metal “cap” cylinder bottom edge, connected to the tractor Power Take Off (PTO), the cylinder is externally equipped with a sharp metal rim with a diameter rang- ing from 350 to 500 mm (Spinelli and Verani, 2000; Spinelli et al., ∗ Corresponding author. Tel.: +39 0761357400; fax: +39 0761357250. E-mail addresses: r.picchio@unitus.it (R. Picchio), stefano.verani@entecra.it (S. Verani), giulio.sperandio@entecra.it (G. Sperandio), rspina@unitus.it (R. Spina), emarchi@unifi.it (E. Marchi). 1 Tel.: +39 0661571021; fax: +39 0661571030. 2 Tel.: +39 0690675218; fax: +39 0690625591. 3 Tel.: +39 0761357400; fax: +39 0761357250. 4 Tel.: +39 0553288609; fax: +39 055319179. 2005; Danilovic et al., 2009) and (ii) a ripper or a bucket mounted on an excavator (Spinelli et al., 2005; Tolosana et al., 2011). Addressing logging residues and stump recovery creates a favorable environment for agroforestry and forest plantations by reducing the difficulty of the regeneration work and improving the quality and productivity of the site preparation and planting work (Saksa et al., 2002; Saarinen, 2006). Stump grinding is based on a grinder that allows the complete destruction of the stump, leaving its fragments on the ground. It consists of a drilling device that bores the stump in the center and two knives that cut most of the wood and the roots that branch off the stump itself. At the end of the operation, the wood remains inside the ground but is totally shredded, so that the soil can be worked without difficulty. In Italy, poplar plantations cover approximately 66,000 hectares (INFC, 2005) while in Europe the potential productive growth area of poplar covers 547,054 km 2 (33.6% of the European arable land) (Reisner et al., 2007) and have a great potential for biomass recov- ery because of the abundance of the residue, the ease of access and the industrial character of management (Spinelli et al., 2005). In recent years, renewed interest in the woody biomass for energy production has made stump extraction in artificial plantations 0925-8574/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.ecoleng.2011.11.012