Industrial Crops and Products 85 (2016) 167–173 Contents lists available at ScienceDirect Industrial Crops and Products jo ur nal home p age: www.elsevier.com/locate/indcrop Poplar short rotation coppice is not a ﬁrst choice crop for cattle slurry fertilization: Biomass yield and nitrogen-use efﬁciency Enrico Ceotto a,∗ , Fabio Castelli b , Anna Moschella a , Michele Diozzi a , Mario Di Candilo a a Consiglio per la ricerca in agricoltura e l’analisi dell’economia agraria, Via Di Corticella 133, 40128 Bologna, Italy b Consiglio per la ricerca in agricoltura e l’analisi dell’economia agraria, Via Canton 14, 37051 Bovolone, Verona, Italy a r t i c l e i n f o Article history: Received 3 November 2015 Received in revised form 14 January 2016 Accepted 16 February 2016 Available online 11 March 2016 Keywords: Woody perennial crop N agronomic efﬁciency N recovery efﬁciency N physiological efﬁciency C to N ratio a b s t r a c t Little is known about the effect of cattle slurry fertilization on poplar short rotation coppice (SRC). This study addresses the following research questions: (i) is the biomass productivity of poplar SRC responsive to slurry application? (ii) what is the efﬁciency with which poplar SRC utilizes the N applied in the form of cattle slurry? (iii) does the ratio of carbon (C) to N (C/N) in harvested dry matter vary with rates of N fertilization? Fertilization treatments were: (i) no fertilization (control); (ii) cattle slurry 10 mm, i.e. 10 L m -2 (CS10); (iii) cattle slurry 20 mm, i.e. 20 L m -2 (CS20); and (iv) industrial fertilizers, consisting in 120 kg N ha -1 in the form of urea and 120 kg P 2 O 5 in the form of superphosphate (IF). The agronomic efﬁciency of applied N (AE N ) varied from 5 to 14 kg yield dry matter per kg N applied. The recovery efﬁciency of applied N (RE N , kg N uptake per kg N applied) was merely 7.3–10.6%. The physiological efﬁciency of N uptake (PE N ) was 79–123 kg yield dry matter per kg N uptake. The threshold of 0.6% N, which is considered the guide value for high-quality biomass feedstock for combustion, was exceeded with the treatment CS20 in the ﬁrst harvest cycle. Overall, our ﬁndings suggest that poplar SRC is not a ﬁrst choice crop for cattle slurry application. In fact, N supply determined poor agronomic efﬁciency, a modest fraction of the N applied was recovered by the crop, and the rise of N concentration in the harvested biomass was detrimental for the quality of the feedstock product for combustion. © 2016 Elsevier B.V. All rights reserved. 1. Introduction In the Region Emilia-Romagna, Northern Italy, the management of livestock efﬂuents is a critical issue. This is due to the presence of 1.5 million pigs and 620,000 cows, producing about 10 million Mg of liquid slurries and 5 million Mg of solid manure (Bonazzi, 2009). In the view of reducing the use of the energy-intensive industrial fertilizers, the huge amounts of plant nutrients contained in these efﬂuents can be regarded as a valuable resource. Liquid manure is a complex organic fertilizer, because it supplies, along with nitrogen (N), phosphorus (P), potassium (K) and microele- ments. However, its rate of application is normally determined on the basis of its N content because this element has major inﬂu- ence of crop yield. A crop suited to receive manure should possess high nitrogen-use efﬁciency (NUE) in order to reduce N losses and related environmental concerns (Connor et al., 2011). NUE is a com- ∗ Corresponding author. Fax: +39 051 374857. E-mail addresses: enrico.ceotto@crea.gov.it (E. Ceotto), fabio.castelli@crea.gov.it (F. Castelli), anna.moschella@crea.gov.it (A. Moschella), michele.diozzi@crea.gov.it (M. Diozzi), mario.dicandilo48@gmail.com (M. Di Candilo). plex, comprehensive efﬁciency that can be thoroughly evaluated by considering the contributions from indigenous soil N supply, the fraction of N applied that is taken up by the crop plant, and the efﬁciency with which N uptake is converted into crop dry matter production (Cassman et al., 2003). Because livestock manure is predominantly applied to maize (Zea mays L.), there is the need to identify alternative crops, well suited for receiving slurry applications, in areas unsuited to maize cultivation. Poplar (Populus ssp.) is a well adapted, widely grown crop in Northern Italy (Spinelli et al., 2011). A recent report of the International Poplar Commission (FAO, 2012) indicates that planted poplars occupy 101,400 ha in Italy, of which 65,900 ha are dedicated to industrial roundwood, 6,100 ha to fuelwood biomass, and 29,400 to environmental protection. In addition, 42,200 ha of indigenous poplar forests are also present in the country, hence the total poplar area in Italy amounts to 143,600 ha. Short rotation coppice (SRC) of poplar is a well-suited energy crop for Northern Italy. Beside to the high quality of the feedstock product for combustion, poplar can provide valuable environmen- tal services, in particular soil carbon sequestration (Ceotto and Di Candilo, 2011; FAO, 2012; Zenone et al., 2007). Little is known about the effect of cattle slurry fertilization on poplar SRC. Therefore, a http://dx.doi.org/10.1016/j.indcrop.2016.02.042 0926-6690/© 2016 Elsevier B.V. All rights reserved.