Spanish Journal of Agricultural Research 17 (1), e0101, 16 pages (2019) eISSN: 2171-9292 https://doi.org/10.5424/sjar/2019171-12118 Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, O.A, M.P. (INIA) RESEARCH ARTICLE OPEN ACCESS Economic profitability of agroforestry in nitrate vulnerable zones in Catalonia (NE Spain) Simone Blanc1, Carles M. Gasol2,3, Julia Martínez-Blanco2,3, Pere Muñoz4, Jaime Coello5, Pere Casals5, Angela Mosso1 and Filippo Brun1 1 University of Torino, Dept. of Agricultural, Forest and Food Sciences (DISAFA), 10095 Grugliasco, Italy. 2Research Park of the Autonomous University of Barcelona (PRUAB), Inèdit Innovació SL, Bellaterra (Cerdanyola del Vallès) 08193 Barcelona, Spain. 3Autonomous University of Barcelona (UAB), Sostenipra (ICTA-IRTA-Inèdit), Institute of Environmental Science and Technology (ICTA) & Dept. of Chemical Engineering, Bellaterra (Cerdanyola del Vallès) 08193 Barcelona, Spain. 4Institute of Agrifood Research and Technology (IRTA), Environmental Horticulture Program, Ctra. De Cabrils s/n 08348 Cabrils, Spain. 5Forest Science and Technology Centre of Catalonia (CTFC), Solsona, 25280 Lleida, Spain. Abstract The impact of agricultural practices and the excess application of nitrogen can negatively impact the environment and cause human health problems. In Spain, the liquid manure applied in areas of intensive agriculture is creating groundwater nitrate pollution problems. The purpose of this paper is to evaluate the economic profitability of agroforestry practices in North East Spain. Therefore, it deals with an alternative land use that has attracted attention in recent years, considering its potential to reduce the negative impact of modern agriculture that combines concurrent forestry and agricultural production in the same area. Specifically, silvoarable practices, such as alley cropping (AC), edge row planting and riparian buffer (RB) strips were compared to conventional agricultural land use. Considering the current agricultural policy framework in Spain, which does not favour these practices, our results showed the economic profitability of alley-cropping practices in comparison to conventional barley production of 25 to 64 € ha-1 yr-1. However, AC systems presented negative results compared to the traditional wheat crop (-122 to -63 € ha-1 yr-1). The results for RB strips were strongly influenced by the high initial costs, both in irrigated and non-irrigated scenarios. Economic results were negative (between -137 and -85 € ha-1 yr-1) compared to the conventional crops, barley and corn. These figures could be greatly increased with a policy framework that promotes these practices based on the fundamental ecosystem services they provide. Moreover, these practices allow an economic diversification that could prove to be beneficial for the majority of farmers. Additional keywords: silvoarable practices; alley cropping; riparian buffer strips; N- leaching; economic evaluation. Abbreviations used: AC (alley cropping); CAP (common agricultural policy); EAV (equivalent annual value); NPV (net present value); NVZ (nitrate vulnerable zones); RB (riparian buffer). Authors’ contributions: SB was mainly responsible for the ideas, concept and research as well as writing the manuscript. FB and AM supported the research with regard to the economic assessment and revised the text. CMG, JMB, PM, JC and PC provided helpful feedback for composing the final document. All authors approved the final manuscript. Citation: Blanc, S.; Gasol, C. M.; Martínez-Blanco, J.; Muñoz, P.; Coello, J.; Casals, P.; Mosso, A.; Brun, F. (2019). Economic profitability of agroforestry in nitrate vulnerable zones in Catalonia (NE Spain). Spanish Journal of Agricultural Research, Volume 17, Issue 1, e0101. https://doi.org/10.5424/sjar/2019171-12118 Received: 04 Aug 2017. Accepted: 04 Feb 2019. Copyright © 2019 INIA. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International (CC-by 4.0) License. Funding: The authors received no specific funding for this work. Competing interests: The authors have declared that no competing interests exist. Correspondence should be addressed to Simone Blanc: simone.blanc@unito.it Introduction health problems (Leach et al., 2004; Giles, 2005; Gutierrez et al., 2016; Pacheco & Fernandes, 2016). Modern conventional and intensive agricultural The European Commission Council Directive prac­tices have an impact on the environment, causing 91/676/EEC (Nitrates Directive), integrated in Directive a re­duc­tion of biodiversity, an increase in soil erosion 2000/60/EC of the European Parliament and of the and pollution of underground and surface waters Council (Framework for the Community action in the (Palma et al., 2007; FAO, 2013). Excessive application field of water policy), indicates the need to introduce of nitrates in agriculture (inorganic N fertilisers and measures to protect waters from pollution caused by manures) can leach into groundwater and subsequently nitrates deriving from agricultural sources (Cerro et negatively impact the environment and pose human al., 2014; Lawniczak et al., 2016) and identifies Nitrate 2 Simone Blanc, Carles M. Gasol, Julia Martínez-Blanco, Pere Muñoz, Jaime Coello, Pere Casals, et al. Vulnerable Zones (NVZs) as areas of land or water at pork industry in Catalonia can be defined as intensive, risk of pollution (Arauzo & Valladolid, 2013), where totalling 6,045 farms in 2016, with a high concentration fertiliser application procedures should be reviewed. of stabled animals, equal to over 460 animals per farm In order to achieve the objective of these Directives, (Food & Water Europe, 2017). Member States are required to implement all necessary Pig manure used as a fertiliser is not the only measures to prevent or limit inputs of any hazardous cause of N contamination of ground water. Intensive substances into groundwater. agriculture, using mineral fertilisers, also produces In compliance with these directives, the Spanish contamination; however, a clear relationship between Royal Decree 261/1996 provides a list of “Codes pork producing areas, in Spain and Catalonia, and the of Good Agricultural Practices” for farmers, to be contamination of ground water exists. As a matter of implemented generically on a voluntary basis and fact, all the pork production areas in Spain (with the “Action Programmes” to be implemented specifically relevant exception of Galicia) report N contamination within the NVZs on a compulsory basis (Velthof et of groundwater and a part of their territory has been al., 2014). These measures limit the periods when N designated as nitrate vulnerable zones (Food & Water fertilisers can be applied, in order to prevent nutrient Europe, 2017). leaching and also limit the maximum amount of Studies on the quality of ground and surface waters livestock manure that can be applied, corresponding to of Catalonia, indicate that 38% is contaminated by 170 kg N ha-1 year-1 (Bayo et al., 2012). nitrates and that 34% of the surface has been designated Spain, Italy and the south of France are among as nitrate vulnerable zones; over the 2000-2010 period, the major pork producing countries of the EU more than 42M € was spent, in order to reduce or to Mediterranean area (EC, 2013), and they present similar prevent water pollution (CWA, 2016). The nitrate issues with N pollution of ground water due to the lack problem in Catalonia has led to the preparation of a of a correct management of manure originating from new regional decree regarding the management of the pork industry (INE, 2009). Although the majority soil fertilization and manure, which is due to become of the EU state members have decreased the number of effective within 2018 and various measures have also reared pigs, this has not occurred in the Mediterranean been implemented to reduce N leaching, including: catch countries. crops, agroforestry systems, wetlands and biogas plants Manure production in Spain, generated by stabled (Børgesen & Vinther, 2012). Currently, biogas plants animals, is 76 million tonnes per year (Bigeriego, are not operative due to their low feasibility and their 2001). This large volume of liquid manure, especially practicality is subject to an unstable policy of support in pig manure, applied to areas of intensive agriculture is Spain (Capodaglio et al., 2016). creating a significant nitrate pollution of groundwater Furthermore, over the last fifty years, Spain has lost problem (Prapaspongsa et al., 2010). 60% of its buffer areas (ditches, rows of trees, hedges, The number of farms and swine bred for the Spanish wetlands), which, combined with the evolution of pork industry has increased over the last decades agricultural practices, has led to a consequent increase according to MAPAMA (2016), reaching a total of in erosion, runoff and drainage of nutrients (Paris et al., 29M swine in 2016 and makes Spain the second largest 2002). pork producing country in the EU. In Spain, Catalonia The objectives of N management are both agrono­ represents the top-ranking region for swine with 7.6 mical and environmental and they obviously have million animals (26% of all Spanish stock). Catalonia eco­nomic consequences. Many authors (Grignani et produces 43% of all Spanish pork meat and represents al., 2009; Oenema et al., 2009; Cardenas et al., 2011; 64% of Spanish swine exports (almost 1 million tons). Oenema, 2012; Van der Straeten et al., 2012; Zavattaro The annual export revenue of pork meat in Catalonia et al., 2012) agree that N management measures require is approx. 2 billion € (DARPA, 2017). Although the additional activities (i.e. adjustment and reduction of number of intensive farms has decreased by 16% over the rate of N fertiliser applied, adjustment of stocking the last 10 years, it is still the most common method of rate and N surplus in animal diets, reduction of the pig rearing and fattening in Spain, with a total number of length of the grazing season, adoption of catch crops 68,980 intensive farms versus 14,213 extensive farms and irrigation control). (MAPAMA, 2016). Regions such as Andalucía, Ara­ Agroforestry, which is the concurrent cultivation of gón, Castilla León, Extremadura and Catalonia present trees and agricultural crops in the same area, can play a similar number of intensive farms. Conversely, of a key role in reducing the environmental impact of these regions, Extremadura and Andalusia are the only conventional modern agriculture (Eichhorn et al., 2006; areas where a significant number of extensive farms Rigueiro-Rodríguez et al., 2008; Dougherty et al., 2009; are also present (12,084) (MAPAMA, 2016). The Zamora et al., 2009; Christen & Dalgaard, 2013; Smith Spanish Journal of Agricultural Research March 2019 • Volume 17 • Issue 1 • e0101 3 Economic profitability of agroforestry in NVZs in Catalonia et al., 2013), however farmers’ willingness to adopt of profitability. In addition, farmers who choose to these practices depends on economic and management use their lands for agroforestry, consider profitability factors (Buckley et al., 2012). Recent estimates as the main prerequisite, followed by diversification, indicate that the cultivated territory, classified as environmental issues and landscape benefits. An in­ agroforestry in the EU 27, is approximately 15 million crease in productivity and economic outcomes has hectares (den Herder et al., 2017) and Spain, with 5.6 already been reported (Herzog, 1998; Colomb, million hectares, has the largest area. Thanks to an 2009; Sereke, 2012), but the latter strictly depend integrated land-use system, agroforestry can pro­vide on the legislative framework; for instance, in the a wide variety of ecosystem services (Torralba et al., last Common Agricultural Policy (CAP) reform, the 2016) and social and economic benefits (Graves et al., threshold of maximum tree density to maintain the 2007). Regarding ecosystem services, agroforestry land eligible for public funding increased from 50 to can contribute to climate change mitigation (Palma 100 trees ha-1. This is still a rather low value for new et al., 2015), by reducing CO2 emissions produced agroforestry systems, if age is not considered, and has by agricultural activities, by improving C fixation yet to be adopted in many countries, including Spain (Paolotti et al., 2016), by protecting the soil (both (Mosquera-Losada et al., 2015). Other potential physically and chemically), by improving water lines of subsidy in the most recent CAP were those quality and by protecting biodiversity (Liagre & related to greening practices (Regulation 1307/2013), Dupraz, 2008). including, among others, crop diversification and Agroforestry systems could provide a partial solu­ ecological focus areas. tion for N contamination (Mosquera-Losada et al., In the light of the above framework, the aim of this 2016); Palma (2006) estimates that an agroforestry paper was to evaluate the profitability of agroforestry system can reduce up to 28% of N leaching. According practices located in NVZs in a Mediterranean area, in to Briggs (2012), N leaching in silvoarable systems is Catalonia, NE Spain, evaluating the competitiveness reduced by 50% compared to monocultures, because of these practices in comparison to conventional the tree roots absorb the excess N not utilised by crops. The economic performance was assessed by the arable crop. A more optimistic study (Dupraz et exami­ ning the various experimental plots, which al., 2005), indicates an approximate 65% reduction differed in terms of agricultural cultivations (typical in leaching after 60 years and can be considered as of the examined area and representative for the Spa­ a theoretical maximum impact of agroforestry on N nish Mediterranean area), category of agroforestry, leaching. tree components, tree density and the presence or In accordance with several authors (Nair et al., absence of irrigation. In addition, the potential of 2007; Palma et al., 2007; Christensen et al., 2013), silvoarable systems was also evaluated in relation to the ability of agroforestry systems to reduce the loss the availability of subsidies for the studied area. of N can be conservatively estimated from 10% to 50%. Two types of agroforestry practices (Mosquera- Losada et al., 2009) are particularly efficient in this Methodology regard: alley-cropping (AC) and riparian buffer (RB) strips. Systems studied Alley cropping consists in combining an arable crop with trees planted in rows (Burgess et al., 2005; Catalonia is located in NE Spain, characterised by Cardinael et al., 2015), whereas RBs consist of groups a Mediterranean climate and continental influence in of high density trees, or shrubs, established between inland areas. The mean annual precipitation ranges the arable area and a body of water (Borin & Bigon, from 650 mm to 800 mm (summer precipitation from 2002), simulating the buffer effect of riparian forests. 90 to 150 mm yr-1), and the mean annual temperature In both cases, the tree component normally consists of ranges from 10 to 13°C. To all effects, Catalonia a species providing an income that is either frequent possesses many climatic and edaphic features (i.e. biomass) or significant (i.e. valuable timber) and representative of the Mediterranean area in general can be considered as an activity able to stimulate and of Spain in particular, in fact agroforestry practices rural development, by promoting the management of can be adopted in entire NVZ areas of Catalonia, marginal areas through sustainable revenues (Rois- where the study areas are located. All these areas Díaz et al., 2017). are dedicated to agriculture and a wide range of tree In fact, as demonstrated by Graves et al. (2017a) species exist, which are suited to the various site and and Rois-Diaz et al. (2017), the obstacles to the management conditions. Moreover, most of the cereal diffusion of agroforestry are mainly linked to the lack farming areas in Catalonia mainly focus on wheat Spanish Journal of Agricultural Research March 2019 • Volume 17 • Issue 1 • e0101 4 Simone Blanc, Carles M. Gasol, Julia Martínez-Blanco, Pere Muñoz, Jaime Coello, Pere Casals, et al. and barley production, which are often the main crops 1 m, for each tree. Cultivation included herbicide and rotated on a yearly basis. The cases studied are situated insecticide treatments with a sprayer, manual pruning in a hilly area, where the geology is characterised by from year 1 to 4 and pruning with a basket lift in years a predominance of carbonate materials and the soil is 5, 7, 9 and 11 respectively. primarily light clayey and light loamy (Conesa, 2007; The harvesting phase included thinning and final Casals et al., 2009). felling, performed by chainsaw, followed by timber Eight experimental plots, four AC cultivations and delivery, by tractor and trailer, to a storage yard inside four RB cultivations, were established in March 2014 the farm. Lastly, stump destruction using a drill and (Table 1). The AC plantation species are hybrid wal­ field restoration to the initial conditions was considered. nut (Juglans × intermedia) and ash (Fraxinus excelsior Timber transport from farm to sawmill was a service L.) and consider a rotation period of 50 years; the contract and transport distance was defined as 50 km. annual crop in the plots labelled AC1-AC2 was barley For operations that referred to the surface, a strip zone and in the plots labelled AC3-AC4 was wheat. The of 1 m width, flanking the tree rows was considered, implantation specifications were not chosen with an amounting to 0.055 ha in AC1-AC2 and 0.091 ha in exclusively economic objective. Rather, a high tree AC3-AC4. The four plots (Table 3) differed in the density was specifically chosen in order to reduce soil number of initial plants and type of thinning. The tree N content and leaching in the short and medium term in spacing plantation layout was 18 m between rows in NVZs, in accordance with Andrianarisoa et al. (2016). AC1-AC2 and 11 m in AC3-AC4 and then 4 m in AC1- The RBs involved a double annual crop with AC3 and 2.5 m in AC2-AC4 between rows. barley and corn and different biomass crop densities The production model utilised to estimate tree harvested every 3 years, the stumps to be removed and volume and timber production of different qualities re-planted at year 12; the plant species was Populus (veneer, sawnwood and firewood) was the one pro­po­sed spp. In the plots labelled RB1 and RB2, there was no by Coello et al. (2017) rendering a “good” quality for irrigation; in plots RB3 and RB4, both the barley and the site, complemented by allometric models proposed the corn were irrigated. by Cambria & Pierangeli (2012). All scenarios refer to a square plot of 1 ha. In order to reduce nitrate leaching in the short-medium term, Description of the riparian buffer crop the experimental plots have a higher than usual density for this type of production, in order to achieve a “safe- RB crops were planted on the side of the river, to net” zone as soon as possible. This high density implies a width of 7 m and covering a total area of 0.07 ha that a higher number of thinnings must be performed. for each plot. Plots RB1-RB3 were planted with a low density, amounting to 10,000 plants ha-1 (spacing 1 m Description of the alley cropping system × 1 m), whereas plots RB2 and RB4 featured a high density of 20,513 plants ha-1 (spacing 0.65 m × 0.75 The common operations (Table 2) typical of AC m). systems were defined for each experimental plot. Economic evaluation considered two main processes: Plantation included harrowing, with a 180 HP tractor, plantation/cultivation and harvesting/chipping phases hole preparation using a backhoe excavator, manual (Table 4). Plantation and cultivation included initial planting and placing plastic groundcover, sized 1 m × manual brush cutting, harrowing and ploughing, using a Table 1. Description of scenarios analysed. Altitude Initial tree density Irrigation[a] Scenario Arable crop Tree component (m a.s.l.) (plants ha-1) (m3 ha-1 year-1) AC1 455 barley walnut and ash 140 AC2 455 barley walnut and ash 220 AC3 821 wheat walnut and ash 227 AC4 821 wheat walnut and ash 364 RB1 538 barley and corn poplar 10,000 RB2 538 barley and corn poplar 20,513 RB3 270 barley and corn poplar 10,000 9,000 + 1,500 RB4 270 barley and corn poplar 20,513 9,000 + 1,500 [a] Irrigation includes both the arable crop and the tree component. Spanish Journal of Agricultural Research March 2019 • Volume 17 • Issue 1 • e0101 5 Economic profitability of agroforestry in NVZs in Catalonia Table 2. Summary of all the processes, number of repeats and operating rates for alley cropping (AC) scenarios. Operating rate Phases Operation Year Operation h ha-1 yr-1 h plant-1 yr-1 h m-3 yr-1 Plantation Harrowing 0 0.36 Preparation holes 0 0.02 Planting 0 0.08 Mulching 0 0.03 Cultivation Weed control from 1 to 50 0.50 Protection against insects from 1 to 50 0.50 Tree pruning 1, 2, 3, 4, 5, 7, 9, 11 0.08 Harvesting Thinning 2 times in AC1-AC2 Felling 1.00-0.67 Forwarding 1.00-0.67 3 times in AC3-AC4 Felling 1.00-0.67-0.25 Forwarding 1.00-0.67-0.33 Main felling 50 Felling 0.08 Forwarding 6.00 Stump removal and 50 Stump removal 0.03 chopping Stump 1.70 chopping Table 3. Description of harvesting activities and expected output in alley cropping (AC) scenarios. AC1 AC2 AC3 AC4 Initial density, 140 220 227 364 plants ha-1 Thinning, yr 33% trees ha-1, year 12 50% trees ha-1, year 8 50% trees ha-1, year 12 50% trees ha-1, year 8 33% trees ha-1, year 20 50% trees ha-1, year 17 33% trees ha-1, year 20 50% trees ha-1, year 17 33% trees ha-1, year 30 50% trees ha-1, year 30 Final density, 62 56 51 46 plants ha-1 Potential output, 32 veneer 29 veneer 26 veneer 24 veneer m3 ha-1 48 sawnwood 43 sawnwood 48 sawnwood 52 sawnwood 74 firewood 68 firewood 76 firewood 80 firewood Table 4. Summary of all the processes, number of repeats and operating rates for riparian buffer (RB, h ha-1 yr-1) scenarios. Phases Operation Year RB1-RB3 RB2-RB4 Plantation and Brush cutting 2 times in year 0 in RB5-RB6 48.00 48.00 cultivation 2 times in year 0 and 2 times in year 2 in RB7-RB8 Field preparation 0 0.95 0.95 Planting 0 10.98 19.39 Weed control 1, 4, 7, 10 1.50 1.50 Harvesting and Harvesting and chipping 3, 6, 9, 12 2.07 2.70 chipping Stump removal 12 2.49 5.10 180 HP tractor, planting and then herbicide application field to a storage yard inside the farm, where biomass (at years 1, 4, 7 and 10 respectively). Harvesting and will be sold with 30% water content. At year 12, field chipping phases were expected at 3rd, 6th, 9th and 12th restoration to the initial conditions with stump removal years. Biomass transport was considered from the and chopping was considered. Spanish Journal of Agricultural Research March 2019 • Volume 17 • Issue 1 • e0101 6 Simone Blanc, Carles M. Gasol, Julia Martínez-Blanco, Pere Muñoz, Jaime Coello, Pere Casals, et al. In plots RB1 and RB2, no irrigation was foreseen, Table 6. Crop yield decrease assumed in alley cropping whereas in RB3 and RB4, emergency irrigation using (AC) scenarios. 1,500 m3 ha-1 year-1 of water was considered. Scenarios Scenarios Biomass production for RB scenarios is shown in Year Year AC1 AC2 AC3 AC4 Table 5, relating to scenarios RB1 to RB4. Experimental Arable area, ha 1-50 0.94 0.94 1-50 0.91 0.91 data regarding the yield obtained during the first two Crop yield, % 1-6 100 100 1-6 100 100 years was complemented with Sevigne et al. (2011) and Miguel et al. (2015), in order to obtain the potential 7-20 90 88 7-20 88 81 yield over the four rotations. 21-36 80 83 21-30 77 72 37-50 70 74 31-50 73 76 Agricultural reference system barley production was 6 Mg grain ha-1 and 6 Mg straw The cultivation method of the baseline arable system, ha-1 and corn production was 11 Mg grain ha-1. used as a comparison, is the one typical of NE Spain, The sales prices utilised were the average prices in as described in Vilamanya (2014). The experimental Spain in 2015, 170 € Mg-1 for barley grain and corn data used in the analysis relates to the cultivation grain, 185 € Mg-1 for wheat grain, 27 € Mg-1 corn process and grain yield for barley, corn and wheat fodder (35% water content) and 60 € Mg-1 for straw crops. It is the average data of a two-year observation (MAGRAMA, 2015). period; the measured data is consistent with the average production reported in the literature for Catalonia Economic evaluation in Vilamanya & Piqué (2015). We assume that the agronomic practices remain unaltered throughout the The economic results were determined by comparing entire period considered. In AC1-AC2, the barley yield the direct costs and revenues of each scenario with the was 3 Mg grain ha-1 and 3 Mg straw ha-1, whereas in agricultural reference system. AC3-AC4 the arable crop was wheat and production In order to evaluate long-term investment, it is 4 Mg grain ha-1 and 4 Mg straw ha-1. The portion of common to compare Net Present Value (NPV) and cropped area was calculated by subtracting the area Equivalent Annual Value (EAV). The economic occupied by tree rows, considering a width of 1 m for com­parison of annual agricultural and multi-annual each row. The resulting area was 0.94 ha in AC1-AC2 silvoarable systems that last many years was based on and 0.91 ha in AC3-AC4. Furthermore, crop yields discounted cost benefit analysis (Dupraz et al., 2005; would progressively decrease due to shadowing by Testa et al., 2014); this method enables the comparison trees (Table 6). The agricultural yield reduction is of revenues obtained at different intervals of time. proposed in accordance with that described in Colomb The NPV (in € ha-1) is defined as the difference (2009), based on simulations with PlotSAFE software between all revenues and all costs, which are received for a case study in Central Catalonia. The trees in the and paid out during the complete production cycle, AC method have no impact on crop yields in the first discounted to year zero (De Benedictis & Cosentino, 6 years and very little impact over the first 20 years 1979) according to the equation below (Blanc et al., (Dupraz et al., 2005). Greater impact on crop yields 2019): can be assumed in the final 30 years, in relation to the density of the tree component. On the other hand, in RB plots the cultivated area was 0.93 ha, and crop yields did not change over the where Rt is the revenue from the system in year t (€ whole rotation period. In RB1-RB2, the barley yield ha-1), Ct are the costs in year t (€ ha-1), i is the discount was 5 Mg grain ha-1 and 5 Mg straw ha-1 and corn rate, n is the time horizon (year). fodder production was 33 Mg ha-1. In RB3-RB4, the In order to compare systems with different rotation lengths, it is useful to calculate the EAV, the infinitive Table 5. Description of potential output (Mg ha-1 yr-1) in net present value converted to an annual payment (€ riparian buffer (RB) scenarios. ha-1 yr-1). Item Rotation RB1 RB2 RB3 RB4 Potential 1st (years 1, 2, 3) 5.75 6.75 8.21 9.64 output 2nd (years 4, 5, 6) 6.32 7.42 9.03 10.60 The model takes into consideration the risks or 3rd (years 7, 8, 9) 6.67 7.83 9.52 11.18 unforeseen situations that may occur during the 50 4th (years 10, 11, 12) 6.67 7.83 9.52 11.18 years of crop rotation. After evaluating the interest Spanish Journal of Agricultural Research March 2019 • Volume 17 • Issue 1 • e0101 7 Economic profitability of agroforestry in NVZs in Catalonia rates typically used by other authors in forestry and by IRTA (Institute of Agrifood Research and Tech­ agriculture studies: i.e., Hauk et al. (2014) report nology). values between 1.5% and 6% for investments in short rotation coppice systems; Sgroi et al. (2015) Machinery costs. Machinery costs were calculated indicate a rate of 5% for agroforestry; whereas Blanc using a model created by the Ministry of Agriculture, et al. (2018a) propose a rate of 2.5% for investments Food and Environment of Spain (MAGRAMA, 2016). in pluri-annual crops in rural areas; a discount rate The model included both fixed costs (capital recovery, of 3.0% was chosen. An inflation rate of 0.0 % was interest and depreciation, taxes and insurance) and assumed, considering that in the reference period, the variable costs (fuel, lubricant, repair and maintenance average inflation rate for Spain was 0.02% (www. costs) (Sierra-Pérez et al., 2018). A cost of 0.6677 € inflation.eu). L-1 was assumed for Spanish diesel fuel for agricultural Other specific risks, such as disease, drought, machinery, based on the average cost in 2015 (DARP, phy­tosanitary problems, windblown, etc. were not 2015). explicitly taken into account in this study. The model assumed a continuous uninterrupted cultivation Land remuneration. In accordance with the Govern­ of those speci­fied crops with no modification. ment of Catalonia (GOC, 2015a), a value of 27,000 € With regard to drought risk in plantations in the ha-1 for irrigated land and 8,000 € ha-1 for non-irrigated Mediterranean area, non-irrigation in agroforestry land was assumed. Adopting an interest rate of 1%, an scenarios could be considered risky, even if the average annual land use cost of 270 € ha-1 yr-1 for irrigated land annual precipitation in the study area is sufficient to and 80 € ha-1 yr-1 for non-irrigated land was obtained. ensure no water deficit. In the case of extremely dry years, the tree species would be close to their water Timber sale price. The price of timber, meeting the requirement threshold, however it was not possible requirements for veneer industry (at least 3 m high, to take into account emergency irrigation over such 40-45 cm diameter, straight and free of visual de­fects), a long rotation period. In addition, the instalment of ranges from 500 to 900 € m-3 (Coello et al., 2009). The permanent irrigation systems in agroforestry would reference value utilised in this study was 650 € m-3. require a significant economic investment. Timber that does not reach veneer standards can be utilised for saw wood with prices ranging from 86 to Production costs. Production costs were calculated 119 € m-3 for high quality timber and from 72 to 86 € by taking into account service contracts, goods ac­ m-3 for low quality timber; in this study a price of 86 € qui­sition, labour costs, machinery costs and land m-3 was assumed. The remaining wood would be sent to remuneration. In AC scenarios, the production costs the biomass market, obtaining 32 € m-3 (COSE, 2015). of the tree component were specifically correlated to All prices refer to timber sold to the sawmill plant. the density of each plantation. In RB scenarios, the production costs were calculated in reference to 1 Biomass sale price. The reference price in the hectare and then reduced in proportion to the buffer Catalonia biomass market is the sale price of chipped surface of 0.07 ha. biomass, 55 € Mg-1 (30% water content) sold to a storage yard, inside the farm (pers. comm Biopoplar, Service contracts and goods acquisition. In AC 2016). a cost of 2.6 € per walnut plant and 1.2 € per ash plant including transport (pers. comm. Coello, Subsidies. Catalonia has not activated the sub- 2016) was assumed, together with timber transport measure 8.2 of the European Regulation No 1305 costs from farm to sawmill of 0.21 € Mg-1 km-1 (EAFRD) subsidising the introduction and maintenance (Marquez, 2014). The service contract assumed for of agroforestry systems. The range of subsidies for RB crops was stem purchase and shipping, according annual crops was between 120 and 150 € ha-1 yr-1 (pers. to Gasol et al. (2010), with a cost of 0.23 € stem-1 comm. Department of Agriculture, Livestock, Fisheries (pers. comm. BioPoplar, 2016). The irrigation cost and Food, 2016), in this study an average subsidy of assumed for scenarios RB3 and RB4 was 0.099 € m-3, 135 € ha-1 yr-1 was considered. The subsidy calculated corresponding to variable water supply costs from in proportion to the cultivated area was equal to 127 irrigation canals in Catalonia (GOC, 2015b). € ha-1 yr-1 in scenarios AC1-AC2 and 123 € ha-1 yr-1 in scenarios AC3-AC4; whereas the total RB scenario Labour costs. Labour costs, considered for opera­ subsidy was equal to 126 € ha-1 yr-1. The subsidies were tions carried out by the farmer, were established at calculated to be constant for rotations of both 12 and 10 € h-1, obtained from the standard costs provided 50 years. Spanish Journal of Agricultural Research March 2019 • Volume 17 • Issue 1 • e0101 8 Simone Blanc, Carles M. Gasol, Julia Martínez-Blanco, Pere Muñoz, Jaime Coello, Pere Casals, et al. Sensitivity analysis Economic results for alley cropping systems The sensitivity analysis enables the evaluation, within The results obtained in the economic assessment of a reasonable range, of how the changes in some of the the tree component (Table 7), show that the increase components of the model affect the comparison between in tree density leads to higher costs in each phase scenarios (Blanc et al., 2018b). Two sensitivity analyses of the crop management but does not guarantee a were carried out for the AC1 and AC3 scenarios using the higher income. following variables: timber price and annual crop yield. The total cost of the system increased when the Given the timber price uncertainty over the next initial density was higher. Scenario AC1 gave a total 50 years, a price range of 300 to 1,000 € m-3 in the cost of 2,239 € ha-1, compared with 2,790 € ha-1 for sensitivity analysis was considered. The relative yield of AC2 (25% higher), and AC3-AC4 respectively 48% an annual crop was calculated, in agreement with Dupraz and 92% higher than AC1. Plantation costs accounted et al. (2005), and Graves et al. (2007), for a range of for 25% in AC1 and rose to 32% in AC4. The highest productivity yields falling from 90% to 30%, over the costs for all scenarios were the cultivation activities, next 50 years. which represented on average 34% of total costs. Two other sensitivity analyses were carried out for the High cultivation costs, however, can lead to high RB1 and RB4 scenarios, producing a biomass ran­ge crop profits; in fact, appropriate and intensive pruning yield between 4.0 and 15.2 Mg ha-1 year-1 and a biomass management has a strong impact on the timber price range of 35 to 100 € Mg-1. quality. Thus, high cost scenarios do not necessarily match high revenues; in fact, low-density cultivation ensures higher quality timber. Results The results of the comparison between AC systems and arable crops also indicated that the The economic comparison of silvoarable systems best scenario was AC1 (Table 8). In scenarios AC1 and arable scenarios refers to EAV for long-term period and AC2, the silvoarable system was economically rotations and to profit for annual crops. viable compared to a barley crop. AC1 guaranteed an Table 7. Economic results, NVP and EAV, of tree component in alley cropping (AC) scenarios. AC1 AC2 AC3 AC4 NPV EAV NPV EAV NPV EAV NPV EAV Plantation (1) -568.25 -22.09 -858.00 -33.35 -892.08 -34.67 -1393.10 -54.14 Cultivation (2) -704.62 -27.39 -957.55 -37.22 -1146.40 -44.56 -1485.42 -57.73 Harvesting (3) -385.38 -14.98 -425.74 -16.55 -570.32 -22.17 -652.93 -25.38 Transport (4) -466.24 -18.12 -434.77 -16.90 -521.62 -20.27 -576.05 -22.39 Land benefit (5) -114.35 -4.44 -114.35 -4.44 -187.13 -7.27 -187.13 -7.27 Total costs (a) = 1+2+3+4+5 -2238.84 -87.01 -2790.40 -108.45 -3317.54 -128.94 -4294.63 -166.91 Incomes (b) 6371.68 247.64 5793.87 225.18 6031.80 234.43 6128.43 238.18 Benefits (c) = b-a 4132.84 160.62 3003.47 116.73 2714.26 105.49 1833.80 71.27 NPV: net present value, € ha-1. EAV: equivalent annual value, € ha-1 yr-1. Table 8. Comparison of EAV of alley cropping (AC, € ha-1 yr-1) scenarios and traditional crops. AC1 AC2 AC3 AC4 Alley cropping Forestry (1) 160.62 116.73 Forestry (1) 105.49 71.27 Barley (2) -115.03 -110.51 Wheat (2) 35.47 9.92 Subsidies (3) 127.00 127.00 Subsidies (3) 123.00 123.00 Total (a) = 1+2+3 172.60 133.22 Total (a) = 1+2+3 263.96 204.19 Arable Barley (4) -26.13 -26.13 Wheat (4) 191.48 191.48 Subsidies (5) 135.00 135.00 Subsidies (5) 135.00 135.00 Total (b) = 4+5 108.87 108.87 Total (b) = 4+5 326.48 326.48 Difference (c) = a-b 63.73 24.35 (c) = a-b -62.52 -122.29 Spanish Journal of Agricultural Research March 2019 • Volume 17 • Issue 1 • e0101 9 Economic profitability of agroforestry in NVZs in Catalonia EAV 59% higher than the annual profit of only arable and 15%, respectively. Furthermore, the low production crops, in AC2 this gap reduced to 22%. The AC3 and of biomass, also observed in scenarios with irrigation, AC4 scenarios both returned negative economic results determined reduced revenues. An additional factor that in comparison to an agricultural crop, and the profit was determined high production costs was the land benefit, respectively 19% and 37% less than a wheat crop. The which accounted for 10-15% in the scenarios without low profit margin of crop production in the final years irrigation, but increased up to 27% of costs in the of rotation caused the decrease in revenues. In scenarios scenarios with irrigation. AC1 and AC2, the barley crop profits became negative However, the limited cultivated area, 0.07 hectares, after the 20th year, while in AC3 and AC4, profit from guaranteed the economic viability of this crop in RB the wheat crop was reduced to 11 € ha-1 and 17 € scenarios, because the negative economic results did ha-1 respectively at year 50. The production costs of not significantly affect the total profit. Results for RBs annual crops were 728 € ha-1 for barley (242 € Mg-1) (Table 10), indicated a reduction in profits of 8-10%/ha and 821 € ha-1 for wheat (205 € Mg-1). These values in the scenarios without irrigation and 31-34% in the were consistent with the production costs recorded scenarios with irrigation. for traditional crops in Spain. The production costs of barley and corn were respectively 666 € ha-1 and 524 € ha-1 in non-irrigated Economic results for riparian buffer crops scenarios and 1285 € ha-1 and 1716 € ha-1 in irrigated scenarios. The results for RB crops were strongly influenced by the high initial costs (Table 9). In fact, the plantation Sensitivity analysis results and cultivation phases represented 77% of costs, in scenario RB1, and 83% in scenario RB2. These values The results of sensitivity analysis conducted for decreased to 54 and 63% in irrigated scenarios, RB3- scenarios AC1 and AC3 are provided in Figs. 1a RB4, where irrigation costs represented between 12 and 1b. Figure 1a illustrates that at the point with Table 9. Economic results, NPV (net present value, € ha-1) and EAV (equivalent annual value, € ha-1 yr-1) of the biomass component in riparian buffer scenarios. RB1 RB2 RB3 RB4 NPV EAV NPV EAV NPV EAV NPV EAV Plantation and cultivation (1) -4226.61 -424.61 -6931.31 -696.33 -5460.17 -548.54 -8164.87 -820.26 Harvesting and chipping (2) -435.74 -43.78 -629.42 -63.23 -435.74 -43.78 -629.42 -63.23 Irrigation (3) 0.00 0.00 0.00 0.00 -1493.10 -150.00 -1493.10 -150.00 Land benefit (4) -796.32 -80.00 -796.32 -80.00 -2687.58 -270.00 -2687.58 -270.00 Total costs (a) = 1+2+3+4 -5458.67 -548.39 -8357.06 -839.57 -10076.59 -1012.32 -12974.98 -1303.49 Incomes (b) 3355.93 337.14 3940.41 395.86 4362.60 438.28 5629.16 565.52 Benefits (c) = b-a -2102.74 -211.25 -4416.64 -443.70 -5713.99 -574.04 -7345.82 -737.98 Benefits × 0.07 ha [(d) = 0.07 × c] -147.19 -14.79 -309.16 -31.06 -399.98 -40.18 -514.21 -51.66 Table 10. Comparison of equivalent annual value (EAV, € ha-1 yr-1) in buffer sce- narios and traditional crops. RB1 RB2 RB3 RB4 Riparian buffer Biomass (1) -14.79 -31.06 -40.18 -51.66 Barley (2) 468.49 468.49 52.92 52.92 Corn (3) 341.74 341.74 143.03 143.03 Subsidies (4) 126.00 126.00 126.00 126.00 Total (a) = 1+2+3+4 921.44 905.16 281.77 270.29 Arable Barley (5) 503.75 503.75 118.97 118.97 Corn (6) 367.46 367.46 153.79 153.79 Subsidies (7) 135.00 135.00 135.00 135.00 Total (b) = 5+6+7 1006.21 1006.21 407.76 407.76 Difference (c) = a- b -84.77 -101.04 -125.99 -137.47 Spanish Journal of Agricultural Research March 2019 • Volume 17 • Issue 1 • e0101 10 Simone Blanc, Carles M. Gasol, Julia Martínez-Blanco, Pere Muñoz, Jaime Coello, Pere Casals, et al. a) b) Crop yield - % Crop yield - % Timber price m-3 Timber price m-3 Figure 1. Profitability of AC scenario: with 140 plants/ha tree density and barley crop (a) and with 227 plants/ha tree density and wheat crop (b). the default values used in the model, positive results price would have to exceed 85 € m-3 in order to achieve a were only slimly achieved, however a hypothetical positive economic result. In the case with irrigation (Fig. slight reduction of the timber price to 600 € m-3 or of the 2b), the break-even point was only reached in the upper crop yield production to 65% could produce negative right-hand area, assuming a production greater than 11.3 economic results. Figure 1b shows a greater economic Mg (dry matter) rotation-1 0.07 ha-1 and prices higher robustness of agroforestry systems in association with a than 75 € Mg-1. As a result, it does not seem possible to wheat crop. In this case, positive economic results were achieve positive economic results with this method. guaranteed even when the price of timber was reduced to 550 € m-3 and when agricultural production was reduced to 60%. However, in both scenarios it would Discussion be difficult to generate a significant increase in profits. Figures 2a and 2b show the sensitivity analysis results As stated by Sereke et al. (2016), there is a lack for the biomass component of RB1 and RB4 scenarios, of studies focussing on the socio-economic aspects referred to a 0.07 ha surface. In both cases, the results regarding profitability of agroforestry farming. The obtained with the default values were negative and a present study assessed the profitability of agroforestry very high biomass yield production and price would be at plot scale, as an income opportunity for farmers necessary to achieve economic viability of this crop. In located in rural areas with environmental problems. the scenario without irrigation (Fig. 2a) it was difficult In fact, one of the main drivers of abandonment to assume an increase in production, and the biomass and decline of rural areas is related to agriculture a) b) Figure 2. Profitability of RB scenario with a 10,000-tree density plantation without irrigation (a) and with a 20,513-tree density plantation with irrigation (b). Spanish Journal of Agricultural Research March 2019 • Volume 17 • Issue 1 • e0101 11 Economic profitability of agroforestry in NVZs in Catalonia profitability (Breustedt & Glauben, 2007; Renwick Patenaude (2012), who also achieved similar results et al., 2013), hence, the first motivation for farmers in Central Europe, reporting high production costs not to start agroforestry practices is of economic nature. offset by revenues, and highlighting the importance Therefore, agroforestry could represent an interesting of subsidies to encourage this type of agricultural opportunity, useful to stimulate rural areas by providing activity. The sensitivity analyses conducted for the additional revenues and employment opportunities two RB scenarios also expressed the difficulty of (Rancane et al., 2014; Rois-Díaz et al., 2017). With obtaining positive economic results. reference to the Mediterranean area, the main drivers Farmers consider that the major benefits of for practicing agroforestry are: diversification of silvoarable systems would be environmental (Pannell, products, improving the environment, life quality and 1999) and previous studies have demonstrated the subsidies (Mosquera-Losada et al., 2017; Rois-Díaz et environmental and social benefits of agroforestry al., 2017). (Palma et al., 2007). Both silvoarable agroforestry Many authors (i.e., Graves et al., 2017b) state systems studied, in addition to being a business the negative perceptions of silvoarable systems due opportunity, provide habitats and refuge zones for birds to intercrop production and timber quality. In our and other animals, and ensure ecological functions. simulation, the results in alley-cropping scenarios However, RBs provide important environmental confirmed the sharp decline of the agricultural crop functions, and the loss of profits may be comparable component after 20 years, and these results would to the cost of deployment of other systems for N only be offset by the profits from the tree component pollution reduction (i.e. reduction at source and at the end of the rotation. Furthermore, agroforestry treatment of slurry, artificial drainage). This solution only appeared to be applicable advantageously in AC could have a positive reception, particularly in rural with barley, while the scenarios with wheat indicated areas and where water is readily available. negative results. Moreover, the results show that to As highlighted, no decrease is expected for the achieve high profitability of the tree component, the number of stabled animals in the Mediterranean area, objective is not high productivity but rather high- and several manure management solutions are needed, quality timber, such as veneer. moreover farmers with environmental problems Other authors point out that, in a European are more receptive to the adoption of silvoarable environment, agroforestry systems become econo­ agroforestry (Graves et al., 2017b). Hence, for mically interesting by reducing the number of plants farmers located in Mediterranean area, the mitigation per hectare and with crops lasting between 30 and 60 of groundwater contamination and N leaching could years (Sereke et al., 2015), in other environments the be transformed from an environmental problem to an agroforestry system is economically viable over 20 opportunity. years (Martinelli et al., 2019). It is therefore necessary The main threats to the implementation of the to highlight that the economic results of the agroforestry examined practices appear to be high insecurity and system examined in this study are strongly influenced dependence on EU subsidies. As also reported by by the ecological and regulatory function for which Mosquera-Losada et al. (2017), in order to make this this type of activity is undertaken. The sensitivity possible, agroforestry has to be supported by policy analyses indicated that both AC scenarios only and actions, bearing in mind that agroforestry is a become a competitive option, compared to traditional land management option that delivers market and crops, when agricultural production is reduced by 40- non-market goods and services. In both the examined 45% and with higher timber prices at 800-850 € m-3. agroforestry categories, it appears that direct payments These conditions present a pessimistic scenario for of subsides for annual crops are fundamental for the the agricultural component and optimistic for the tree success of agriculture in rural contexts. Unlike other component, however when compared to the experience six Spanish regions, Catalonia has not activated gained in other contexts it could be considered realistic grants for agroforestry within its Regional Rural (Valdivia et al., 2012; Rancane et al., 2014). Development Programme (sub-measure 8.2) within Graves et al. (2017b) highlight that farmers could Pillar II of the CAP. In this regard, Spain operates possibly perceive the advantage of systems located in as a federal state in agricultural management and a Mediterranean context, where the annual crops are policies, meaning that Catalonia has the authority to obtained from the trees (i.e. firewood). In this study, develop its own policy. Thus, support in the form of the economic results for the RB scenarios indicated an annual grant would be justified by the potential that high-density crops involved high production of agroforestry systems to reduce N leaching. More costs that were not offset by the biomass yield. These generally, the access to forms of subsidies, such as results are in line with those obtained by Faasch & payments for ecosystem services, could be key to Spanish Journal of Agricultural Research March 2019 • Volume 17 • Issue 1 • e0101 12 Simone Blanc, Carles M. Gasol, Julia Martínez-Blanco, Pere Muñoz, Jaime Coello, Pere Casals, et al. encouraging farmers to provide environmental References service benefits. In Pillar I of the CAP, agroforestry is eligible for Andrianarisoa KS, Dufour L, Bienaime S, Zeller B, Dupraz basic payments, where the density of trees with a C, 2016. The introduction of hybrid walnut trees (Juglans crown diameter larger than 4 m is below 100 trees ha-1 nigra x regia cv. NG23) into cropland reduces soil mineral N (Coello et al., 2018). Moreover, agroforestry practices content in autumn in southern France. Agrofor Syst 90: 193- are eligible to receive payments linked to greening, 205. https://doi.org/10.1007/s10457-015-9845-3 as they have been activated by Spain as an eligible Arauzo M, Valladolid M, 2013. Drainage and N-leaching in Ecological Focus Area. Thanks to our simulation, alluvial soils under agricultural land uses: Implications an additional subsidy to that already granted, equal for the implementation of the EU Nitrates Directive. Agr to 122 € ha-1 year-1, could be sufficient to make AC Ecosyst Environ 179: 94-107. https://doi.org/10.1016/j. economically viable, where the annual crop is wheat, agee.2013.07.013 and a subsidy of 137 € ha-1 year-1 for RBs. A similar Bayo J, Gomez-Lopez MD, Faz A, Caballero A, 2012. picture emerges in other contexts (Buchholz & Volk, Environmental assessment of pig slurry management after 2013), where the profitability of this type of cultivation local characterization and normalization. J Clean Prod 32: is strongly affected by incentive programs. Therefore, 227-235. https://doi.org/10.1016/j.jclepro.2012.04.003 agroforestry can represent an opportunity in rural Bigeriego M, 2001. El sector ganadero y el medio ambiente en areas, where the value of agricultural land is low. España. [The livestock sector and the environment in Spain]. Furthermore, searching for a compromise through IV Congreso Nacional de Suinicultura, Lisboa. tree density reduction would reduce costs, without Blanc S, Accastello C, Girgenti V, Brun F, Mosso A, 2018a. losing significant profits and at the same time, limit Innovative strategies for the raspberry supply chain: An the negative impact on agricultural production. environmental and economic assessment. Quality - Access Considering the limitations in comparing the to Success 19: 139-142. eight scenarios, which involve rotations of 12 and 50 Blanc S, Brun F, Di Vita G, Mosso A, 2018b. Traditional years, to conventional farming, we can expect that beekeeping in rural areas: Profitability analysis and feasibility agroforestry will ensure a comparative advantage of pollination service. Quality - Access to Success 19: 72-79. in the future, whereby wood prices are not expected Blanc S, Accastello C, Bianchi E, Lingua F, Vacchiano G, to collapse and the demand for biomass energy will Mosso A, Brun F, 2019. An integrated approach to assess probably grow. The choice of agroforestry practices carbon credit from improved forest management. J Sustain creates great risks for the farmer, as climatic factors Forest 38 (1): 31-45. https://doi.org/10.1080/10549811.201 are particularly relevant in determining the capability 8.1494002 of forestry species to grow successfully at a specific Borin M, Bigon E, 2002. Abatement of NO3-N concentration site. Moreover, in 12 and 50-year scenarios, it is in agricultural waters by narrow buffer strips. Environ difficult to predict what risks these crops will be Pollut 117: 165-168. https://doi.org/10.1016/S0269- challenged by, and additionally, these systems must 7491(01)00142-7 consider the willingness of the farmers to accept the Breustedt G, Glauben T, 2007. Driving forces behind exiting risk of not seeing an income before 12-50 years, from farming in Western Europe. J Agr Econ 58: 115-127. against the typical annual revenue of agricultural https://doi.org/10.1111/j.1477-9552.2007.00082.x crops. In fact, the poor cash flow during most of the Briggs S, 2012. Agroforestry: A new approach to increasing rotation could be a demotivating factor for many farm production. Nuffield Farming Scholarships Trust farmers. Report. Stratford Upon Avon, UK. NFU Mutual Charitable The limitations that emerged from this study are Trust. 82 pp. still linked to the lower flexibility that agroforestry Buchholz T, Volk T, 2013. 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