Evaluation of methane production from maize silage by harvest of different plant portions Marco Negri a , Jacopo Bacenetti a,* , Andrea Manfredini b , Daniela Lovarelli a , Marco Fiala a , Tommaso Maria Maggiore a , Stefano Bocchi a a Department of Agricultural and Environmental Sciences e Production, Landscape, Agroenergy, Universit  a degli Studi di Milano, Via G. Celoria 2, 20133 Milano, Italy b Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia Romagna “Bruno Ubertini”, Strada Campeggi 59/61, 27100 Pavia, Italy article info Article history: Received 21 February 2014 Received in revised form 15 May 2014 Accepted 17 May 2014 Available online Keywords: Anaerobic digestion Biomethane potential Maize Plant portions Corn ear silage abstract Biogas production is mainly based on the anaerobic digestion of cereals silages and maize silage is the most utilized. Regarding biogas production, the most important portion of the plant is the ear. The corn ear, due to high starch content, is characterized by a higher biogas production compared to the silage of the whole plant. In this paper, we present the results of experimental field tests carried out in Northern Italy that aim to evaluate the anaerobic methane potential (BMP) of different portions of ensiled maize hybrids. The BMP production is evaluated considering the possibility of harvesting and ensiling: the whole plant; the plant cut at 75 cm of height; the ear only; the plant without the ear. For the different solutions, the results are reported as specific BMP and as average biogas production achievable per hectare. The methane production by harvesting and ensiling the whole plant (10,212 and 10,605 m 3 ha 1 , for maize class 600 and 700, respectively) is higher than the ones achievable by the other plant portions (7961 and 7707 m 3 ha 1 , from the ear; 9523 and 9784 m 3 ha 1 , from the plant cut at 75 cm; 3328 and 3554 m 3 ha 1 , from the plant without the ear, for maize class 600 and 700, respectively). The harvest of the whole plant, although it is the most productive solution, could not be the best solution under an economic and environmental point of view. Harvesting only the ear can be interesting considering the new Italian subsidy framework and for the biogas plants fed by biomass transported over long distances. © 2014 Elsevier Ltd. All rights reserved. 1. Introduction The agricultural contribution to greenhouse gases (GHGs) emissions is undeniable [1]. Agricultural activities play a significant role in increasing the concentration of GHG in the atmosphere and, hence, agriculture contributes to global warming and climate change [2]. The two most important GHGs emitted by primary sector are methane from livestock breeding and nitrous dioxide from fertilizer application [3]. In * Corresponding author. Tel.: þ39 02 50316869; fax: þ39 02 50316845. E-mail address: jacopo.bacenetti@unimi.it (J. Bacenetti). Available online at www.sciencedirect.com ScienceDirect http://www.elsevier.com/locate/biombioe biomass and bioenergy 67 (2014) 339 e346 http://dx.doi.org/10.1016/j.biombioe.2014.05.016 0961-9534/© 2014 Elsevier Ltd. All rights reserved.