Agricoltura biologica: è la strada giusta per affrontare i cambiamenti climatici?

The contribution to climate change of the organic versus conventional wheat farming: A case study on the carbon footprint of wholemeal bread production in Italy

Maria Vincenza Chiriac
o ^{a , *} , Giampiero Grossi ^a , Simona Castaldi ^{a , b , c} , Riccardo Valentini ^{a , c}

a

Division on Impacts on Agriculture, Forests and Ecosystem Services, Fondazione Centro Euro-Mediterraneo sui Cambiamenti Climatici (CMCC), Viterbo, Italy

b

Dipartimento di Scienze e Tecnologie Ambientali, Biologiche e Farmaceutiche, Universit
a degli Studi della Campania “Luigi Vanvitelli”, via Vivaldi, 43, 81100 Caserta, Italy

c

Far East Federal University (FEFU), Vladivostok, Russky Island, Russia

a r t i c l e i n f o

Article history:

Received 6 November 2016 Received in revised form 15 March 2017 Accepted 17 March 2017 Available online 29 March 2017

Keywords:

Organic and conventional farming Life Cycle Assessment (LCA) Carbon footprint (CF) Climate change Wheat cultivation Bread

a b s t r a c t

Despite many studies in literature demonstrate the environmental sustainability of organic food, a debate is still open in the scientific community on the effect of organic farming on global warming and climate change mitigation. This paper aims to contribute to a more informed debate on the actual contribution to climate change in terms of GHG emissions of organic and conventional agriculture. For this purpose, the production process of an organic vs conventional wholemeal bread locally produced in central Italy by a small-medium bakery enterprise was compared and the carbon footprint (CF) was assessed by means of the life cycle assessment (LCA) methodology.

We found that the CF of 1 kg of the conventional wholemeal bread was 24% less respect to the same organic bread, with 1,18 and 1,55 kg CO

eq respectively. On the contrary, if the CF is assessed per unit of cultivated area (hectare), wheat organic cultivation showed a better performance in terms of GHG emissions than conventional by 60%, with 1,15 and 2,87 Mg CO

eq ha

respectively. The higher CF per unit of organic product is due to the lower yield per unit of area cultivated with organic farming and to the consequent attribution to a smaller amount of products of the GHG emissions generated in the field phase of the life cycle. Whereas, the CF per hectare is higher when conventional practices are applied due to the higher use of raw materials (higher seed density, agrochemicals for fertilization and plant pro- tection) respect to the same organic system.

Results of the study demonstrate that organic farming for wheat cultivation in Italy is a low-carbon agriculture with a lower contribution to climate change in terms of GHG emissions per hectare respect to the conventional wheat cultivation, although implications of the reduced productivity and the consequent need of more cultivated land should be considered. However, more research is needed to better explore the potential of organic farming and to improve organic food production, optimizing the balance between the use of resources and yields, to ensure sufficient organic food supply at global level.

A more comprehensive assessment of the actual GHG emitted in the atmosphere from both organic and conventional agricultural systems can be provided when the CF is assessed per unit of area, in addition to the CF per product unit, especially if also the carbon sink of the agrosystem is included.

© 2017 Elsevier Ltd. All rights reserved.

1. Introduction

Food production plays an important role in the context of climate change and agriculture in particular is a major driver of climate change representing a major source of anthropogenic GHG emissions. About 10% of the European GHG emissions in 2013 (EU-

* Corresponding author.

E-mail address: mariavincenza.chiriaco@cmcc.it (M.V. Chiriac
o).

Contents lists available at ScienceDirect

Journal of Cleaner Production

j o u r n a l h o me p a g e : w w w .e l se v i e r. co m/ lo ca t e / jc le p r o

http://dx.doi.org/10.1016/j.jclepro.2017.03.111

0959-6526/© 2017 Elsevier Ltd. All rights reserved.

NIR, 2015) and about 24% of global GHG emissions in 2010 were attributed to the agricultural activities, as cultivation of crops and livestock, and deforestation for agricultural purposes (IPCC, 2014).

These values rise if raw materials and agrochemical production, industrial process for food transformation, transport and trade of agricultural and food products are attributed to the sector. The main international agreements as the Kyoto Protocol and the Paris Agreement under the United Nations Framework Convention on Climate Change (UNFCCC), as well as the main related European Decisions and Regulations, ask for concrete actions to mitigate global climate change and reduce GHG emissions. Consequently, substantial mitigation efforts in the agricultural sector are needed in order to meet the global climate goals.

On the other hand, in the last years food consumers are paying more and more attention to their choices opting for healthy, local and fresh food, with growing interest also about the sustainability of food chain (Galli et al., 2015; Renzulli et al., 2015). In this regard, the production and consumption of organic food is increasing worldwide and will increase in the future to the point that global organic food market is projected to grow of over 16% by 2020 (Techsci, 2015). In Italy, the organic farming involved about 1,4 million of hectare in 2014, corresponding to the 11% of the total cultivated land (SINAB, 2015). This trend is projected to increase considering also the considerable support to organic production provided by the main European financial instrument for the agri- culture sector represented by the Common Agricultural Policy (CAP) for the period 2014e2020.

One of the most well-known and appreciated characteristics of organic food is the lower pesticide residual (Crinnion, 2010) which reduces the human health risk. Moreover, the main bene fit clearly recognized to the organic farming practices is the environmental sustainability compared to conventional ones (Caporali et al., 2003;

Birkhofer et al., 2008; Gomiero et al., 2011; Tuomisto et al., 2012), with a minor pressure of chemicals on environmental compart- ments and trophic chains, reduced negative impacts on biodiversity and improved agricultural soil and water quality and vitality.

However, the effect of organic farming on global warming and climate change mitigation is instead a still open debate in the sci- enti fic community. Some studies in literature try to review findings for the main agricultural productions on the environmental impact of the two systems, with regards also to global warming potential (GWP) and effects on climate change, resulting in a large variability of outcomes (Tuomisto et al., 2012; Venkat, 2012; Meier et al., 2015). Depending on the boundary of the study, the adopted methodology, the soil and climatic characteristic of the agrosystem, the analyzed crops and the availability of primary data, organic farming is considered to perform better in some cases (Kavargiris et al., 2009; Litskas et al., 2011; Za firiou et al., 2012 ) and worse in other cases (Williams et al., 2006; Venkat, 2012) in terms of GWP, compared to conventional farming. This is due often to the fact that different studies refer to different site conditions, soil and climate characteristic, methodological approach and management prac- tices, therefore they are not easily comparable to assess the dif- ference of impacts in organic vs conventional systems. The discussion is even more interesting especially if considering the robust evidence of long term enhancement of the soil organic carbon (SOC) of organic practices compared to conventional man- agement (Robertson et al., 2000; Wright and Hons, 2005) and the apparently disadvantageous carbon footprint of most organic products compared to similar ones based on conventional agriculture.

The carbon footprint (CF) represents the overall GHG emissions associated to a unit of product, including its overall life cycle from cradle to grave (ISO, 2006b; Finkbeiner et al., 2006). The main point of weakness in the analysis of the carbon footprint of organic versus

conventional products comes from the fact that the yield per unit of cultivated area is generally signi ficantly lower when organic prac- tices are applied compared with conventional farming. Conse- quently, in the organic farming production the environmental pressures and the GHG emissions generated in the field phase of the life cycle will be attributed to a smaller amount of products, resulting in an higher impact per unit of product, thus outweighing the general bene fits of organic farming ( Tuomisto et al., 2012).

Although this is a general view, it is quite dif ficult to find real case studies where the same product is compared, differing solely for the organic or conventional farming practices and for the organic and non-organic labeling of its raw material.

To contribute to a more informed debate about the actual contribution to climate change in terms of GHG emissions of organic versus conventional farming, this study aims at analyzing and comparing the carbon footprint of the wholemeal bread pro- duced with organic or conventional wheat flour by a small-medium bakery enterprise of central Italy.

Despite several CF analyses of bread are available either for organic or conventional bread, studies are not easily comparable as they refer to different kinds of bread, produced in different coun- tries and at different scales (Andersson and Ohlsson, 1999;

Espinoza-Orias et al., 2011; Jensen and Arlbjørn, 2014; Galli et al., 2015) and with various forms of agricultural management (Meisterling et al., 2009; Williams et al., 2010; Kulak et al., 2015).

This work represents indeed an optimal case study for a correct and scienti fically sound comparison of organic and conventional wholemeal bread production. In fact, both the organic and con- ventional wholemeal bread are produced using the same proced- ure, which hence differs only for the origin of the flour that comes from the same variety of soft wheat (Triticum aestivum L.) cultivated by organic and conventional local producers in the same geographical area (see methods). The comparison is therefore possible as the overall cultivation phase differs only for the man- agement practices applied in the organic and in the conventional plots in the same geographical area, being yield and crop man- agement strongly dependent on climate, soil characteristics, plant variety.

Despite the analyzed wheat-to-bread production process is representative of the average conditions of the national small- medium bakery enterprises of the Italian agrofood sector, the findings of this study could be of wide interest to different readers, ranging from the policy makers to scientists dealing with crop science and climate change, up to the final consumers, considering the global relevance of the wheat-to-bread chain. In fact, wheat is widely cultivated and traded in many areas of the world and bread is daily consumed in many countries worldwide, although wheat processing and baking are often in fluenced by local traditions and consumption patterns, particularly in Europe and in Italy where gastronomy represents a cultural heritage (Galli et al., 2015).

2. Methodology to assess the carbon footprint

The analyzed wholemeal bread production process, starting from the cultivation of wheat, takes place in the area of the Vulsino volcanic apparatus of central Italy, where the geological formation consists in volcanoclastic deposits, predominantly ignimbrites composed by tuffs, lapilli and inconsistent ash. The soils are clas- si fied as Entisols, Xeropsamments group in Soil Taxonomy ( USDA, 2010); they are slightly acidic and well drained as a consequence of the xeric moisture regime, texture and slight inclination of the ground (generally less than 5%). The climatic conditions are char- acterized by average annual precipitations of about 1200 mm and average daily temperatures around 23

C during the hottest month of July and around 5

C during the coldest month of January.

310

To contribute to the assessment of the actual contribution to climate change in terms of GHG emissions of agricultural produc- tion, we assessed the carbon footprint associated to the life cycle of an organic versus conventional wholemeal bread locally produced in central Italy by a small-medium bakery enterprise and sold in retail shops as packaged loafs of 1 kg. In a first methodological approach, we identi fied the functional unit of the carbon footprint as 1 kg of wholemeal bread (FU

).

The Life Cycle Assessment (LCA) was applied to the organic versus conventional wholemeal bread production process with a

“cradle to retail” approach: the production and transport of raw materials, the field operations, the direct and indirect N

O soil emissions, the milling process, the bakery process and the final distribution to retail shops were included in the boundary system (Fig. 1). The LCA applied in this study follows an attributional approach where the environmental impacts in terms of GHG emissions are detected and quanti fied in relation to the life cycle of the two organic and conventional production process. However, the comparison of the two attributional LCAs applied to the two pro- cesses (organic versus conventional wholemeal bread production) allows also for a possible consequential LCA approach, where it is possible to appreciate how the environmental impacts in terms of GHG emissions will change in response to possible decisions (organic vs conventional practices) related to the farming phase.

The methodology we adopted follows the Product Category Rules (PCR) for Bakery Products (EPD, 2015) based on the ISO 14025 standard on Environmental Product Declaration (ISO, 2006a) and in accordance with the international standards ISO 9001 “Quality management systems ”; ISO 14001 “Environmental management systems ”; ISO 14040 “LCA - Principles and procedures”; ISO 14044

“LCA - Requirements and guidelines” ( ISO, 2006b; Finkbeiner et al., 2006) and ISO 14067 “Greenhouse gases - Carbon footprint of products - Requirements and guidelines for quanti fication and communication ”. The data were processed by the LCA software SimaPro 7.3.3.

For the assessment of the CF, the GHG emissions resulting from the LCA of the wholemeal bread production process were converted into global warming potential (GWP) according to the CO

-equiv- alent emission factors with a time horizon of 100 years (IPCC, 2006) which assigned 1 GWP to 1 kg of CO

, 25 GWP to 1 kg of CH

and 298 GWP to 1 kg of N

O.

3. Life cycle inventory (LCI) and analysis

The data used to compile the inventory refer to the production year 2013 ( Tables 2e6 ) and were directly collected on site from invoices, registries, measures and archives of the farmers, the

operators of the flour milling plant and the manager of the bakery.

Only when primary data were not available, conservative data were derived from literature and international databases which support environmental assessments (i.e. Ecoinvent database) or calculated using appropriate models (IPCC, 2006). Table 1 summarizes the main emission factors used in this study.

3.1. Organic wheat farming

The wheat organic farming system of the analyzed case study includes the following field operations: incorporation of green manure with alfalfa (Medicago Sativa L.) (7 tons ha

of above- ground biomass and 1,4 tons ha

of belowground biomass) before the wheat cultivation; soil tillage at 0,4 m depth; two soil har- rowing; sowing with a seed density of 250 kg ha

; harvest with a crop yield of 1,5 tons ha

. No irrigation occurs and no chemicals for fertilization or weed control are applied, according to the organic farming criteria (Reg. EU n. 834/2007). The total consumption of diesel for organic agricultural operations was 206 L ha

. The production, packaging and transport of raw materials, such as seeds and fuel, were also included in this phase (Tables 2 and 6).

The direct and indirect N

O emissions from soil management were estimated with a Tier 2 approach according to IPCC (2006), using crop-soil modeling simulation data and country-speci fic factors to improve the robustness of the analysis (Williams et al., 2010). Soil incorporation of alfalfa implies a total N input to the soil of 194 kg N ha

, corresponding to 170 and 24 kg N ha

(dry mass basis) for the above and belowground biomass, respectively.

We calculated direct emissions of N

O from decomposition/

mineralization of alfalfa using an emission factor derived from two years field direct GHG emission monitoring in Italian crops ( Rees et al., 2013; Castaldi et al., 2015) and gap- filling modeling ( Lugato et al., 2010). Indirect N

O emissions from N deposition were calculated applying the emission factor (EF

) reported in IPCC guidelines (2006), whereas NH

and NOx emissions were estimated taking into account soil characteristics (texture, pH, CEC, Corg, drainage class) and fertilizer form as indicated in Bouwman et al.

(2002a, 2002b) respectively. Indirect N

O emissions from N leaching were calculated estimating N losses via leaching (EF

) as indicated by the IPCC guidelines (IPCC, 2006), while a N

O emission factor (N

O-N emitted per unit of N leached) of 0,0125 was used based on Laini et al. (2011) and Australian Methodology (2006). The effect of wheat residues on N

O emissions were assumed to be negligible, based on scienti fic evidences which show that, in absence of combined mineral fertilization/straw incorporation, the wheat residues, characterized by very high C/N ratios ( >70) tend to immobilize rather than release mineral N in soil, with consequent

Fig. 1. Boundaries system of the Life Cycle Assessment of organic and conventional wholemeal bread produced in central Italy by a small-medium bakery and sold in retail shops as packaged loafs of 1 kg (T is transport).

311

minimal or no losses of N in form of leaching or gaseous emissions (Aulakh et al., 1991; Delgado et al., 2010; Wu et al., 2015; Palmieri et al., 2017).

Furthermore, as wheat was cultivated on land which has been used for agricultural purposes for longer than 20 years, we didn ’t consider the GHG emissions from land use change, according to IPCC (2006).

To allocate GHG emissions from field management and raw materials, different methods were considered. Allocation assigns a proper share of impacts to the main product and co-products and is crucial in LCA of agricultural products where impacts of their co- products are particularly sensitive to the allocation methods (Notarnicola et al., 2015; Palmieri et al., 2017). An economic allo- cation is based on market prices, while a mass allocation consider the quantitative aspects of the co-products and ignores qualitative characteristics, i.e. the nutritive components of food, which is considered instead in allocation methods based on the nutritional value.

As suggested by ISO 14040 and by the Product Category Rules for Arable Crops (EPD, 2016), when a process results in multiple products that are harvested and sold as byproducts, an allocation between the main product (i.e. grains) and the byproducts (i.e.

straw) shall be done using an economic method. Therefore, an economic allocation was considered for the grain production ac- cording to the economic average value of 50 V ton

for the straw and 300 V ton

for the organic wheat grains (Borsa Merci Roma, 2013). Considering these economic values applied to the amount of produced grains and straw, calculated with the straw/grains ratio for organic wheat cultivation assumed as 0,81 according to Nemecek and Kagi (2007), we allocated the GHGs emitted from field management as 89% to the grains and 11% to the straw.

A mass allocation was applied to the amount of plastic (high- density polyethylene, HDPE) used for the packaging of organic wheat seeds in relation to the weight of seeds needed for the production of 1FU

.

Table 1 Emission factors.

Input Unit Emission factor

(kg CO

eq)

Data source (Ecoinvent database)

Conventional wheat seed kg 0,58 Nemecek and Kagi, 2007

Organic wheat seed kg 0,53 Nemecek and Kagi, 2007

Fertilizers - N kg 12,43 Nielsen et al., 2003; Lugato et al., 2010; Castaldi et al., 2015

Fertilizers - P

O

kg 1,18 Nielsen et al., 2003

Fertilizers - K

O kg 0,66 Nielsen et al., 2003

Pesticide (Triazine-compounds) kg 9,95 Nemecek and Kagi, 2007

Fungicide (Dimethenamide) kg 15,2 Nemecek and Kagi, 2007

Herbicides kg 10,2 Nemecek and Kagi, 2007

Green manure (alfalfa) t 65,4 IPCC, 2006; Laini et al., 2011; Rees et al., 2013; Castaldi et al., 2015

Diesel for farming (fuel production) kg 0,51 Jungbluth, 2007

Diesel for farming (fuel combustion) kg 3,1 Nemecek and Kagi, 2007

Hydropower energy kWh 0,005 Dones et al., 2007

Italian energetic mix kWh 0,65 Dones et al., 2007

Kraft paper unbleached kg 0,84 Hischier, 2007

High-Density-Polyethylene (HDPE) kg 1,93 Hischier, 2007

Combustion of paper kg 0,8 Doka, 2003

Transport van < 3,5 t tkm 1,9 Spielmann et al., 2007

Transport lorry 3,5e20 t tkm 0,28 Spielmann et al., 2007

Transport lorry > 28 t tkm 0,14 Spielmann et al., 2007

Table 2

Data of the LCI per 1 kg of wholemeal bread (FU

) and per hectare (FU

) of the organic wheat farming for the year 2013.

Organic farming Quantity per FU

Quantity per FU

Type of data Data source

Cultivated area 8,52 m

1 ha Primary Farm registry

Organic wheat seeds 213 g 250 kg Primary Farm registry

Packaging of seeds (HDPE) 0,2 g 235 g Primary Directly measured

Green manure (alfalfa) 7,16 kg 8,4 tons Primary Farm registry

Fuel consumption 147 g 206 L Primary; Secondary Farm registry; Specific weight of diesel 0,84 kg/l (Nemecek and Kagi, 2007)

Grains yield 1,28 kg 1,5 tons Primary Farm registry

Straw 1,04 kg 1,2 tons Secondary Ecoinvent databse (Nemecek and Kagi, 2007)

Table 3

Data of the LCI per 1 kg of wholemeal bread (FU

) and per hectare (FU

) of the conventional wheat farming for the year 2013.

Conventional farming Quantity per FU

Quantity per FU

Type of data Data source

Cultivated area 2,13 m

1 ha Primary Farm registry

Conventional wheat seeds 60 g 280 kg Primary Farm registry

Packaging of seeds (HDPE) 0,06 g 182 g Primary Directly measured

Fertilizer (N)-(P

O

)-(K

O) 37-15-33 g 175-70-155 kg Primary Farm registry

Fungicide 0,04 g 0,2 kg Primary Farm registry

Insecticide 0,04 g 0,2 kg Primary Farm registry

Herbicide 0,06 g 0,3 kg Primary Farm registry

Fuel consumption 41 g 226 L Primary; Secondary Farm registry; Specific weight of diesel 0,84 kg/l (Nemecek and Kagi, 2007)

Grains yield 1,28 kg 6 tons Primary Farm registry

Straw 0,78 kg 3,7 tons Secondary Ecoinvent databse (Nemecek and Kagi, 2007)

312

3.2. Conventional wheat farming

Data related to the conventional cultivation of wheat refer to an adjacent experimental site, which hence presented comparable soil characteristics and exposure to climatic and meteorological con- ditions as the organic field. The agricultural operations considered for the conventional cultivation of wheat include: soil tillage at 0,4 m depth; soil harrowing (twice in the cultivation season);

sowing with a seed density of 280 kg ha

; three fertilizer appli- cations for total of 175 kg ha

of N, 70 kg ha

of P

O

and 155 kg ha

of K

O; one plant protection application with 0,2 kg ha

of chemical active principle of pesticide (Triazine compounds) and 0,2 kg ha

of chemical active principle of fungi- cide (Dimethenamide); one weed control with 0,3 kg ha

of chemical active principle of herbicide; harvest of the grains yielded 6 tons ha

.

Diesel consumption for management practices was 226 L ha

. The production, packaging and transport of raw materials, such as seeds, fuel, fertilizers and chemical compounds, were also included in this phase, while we excluded from the boundaries of the study the GHG emissions related to the packaging of fertilizers and of other chemical compounds, due to their low incidence. (Tables 3 and 6).

Direct and indirect N

O emissions were calculated as indicated in section 3.1. In this case N

O emissions were attributed to the application of mineral N fertilizer. Direct N

O emissions from

fertilizer application were calculated using more speci fic EFs for non-irrigated crops under Mediterranean climate (Lugato et al., 2010; Castaldi et al., 2015). Such EFs are sensibly lower than the Tier 1 IPCC EFs for N

O emission from fertilizer application.

Also in this case the effect of land use change on GHG emissions was considered irrelevant due to the age of the agricultural site ( >20 years since conversion).

The same methods used in the organic farming were applied for the allocation of GHG emissions to grains (90%) and straw (10%) on the basis of the economic product value of 50 V ton

for the straw and 260 V ton

for the conventional wheat grains (Borsa Merci Roma, 2013) referred to the amount of produced grains and straw, calculated with the straw/grains ratio for conventional wheat cultivation assumed as 0,61 according to Nemecek and Kagi (2007), as well as for plastic (high-density polyethylene, HDPE) of seed packaging.

3.3. Flour milling

The energy required by the milling process was about 7,5 kWh per 0,1 tons of wheat grains and is provided exclusively by a hy- dropower plant. According to Dones et al. (2007), an emission factor of 5 g CO

eq is assigned per kWh of hydroelectricity pro- duced by Italian reservoirs and run-of-river power plants.

The final packaging of the flour is a paper bag (135 g) of 30 kg capacity, produced within an average distance of 30 km far from the Table 4

Data of the LCI per 1 kg of wholemeal bread (FU

) of the flour milling process.

Flour milling Quantity per FU

Type of data Data source

Wheat 1,28 kg Primary Mill registry

Electricity from Hydro Electric 0,08 kWh Primary Mill archive

Packaging of flour (paper) 5,75 g Primary Directly measured

Wholemeal flour 1,15 kg Primary Mill registry

Bran 0,13 kg Primary Mill registry

Table 5

Data of the LCI per 1 kg of wholemeal bread (FU

) of the bakery.

Bakery Quantity per FU

Type of data Data source

Wholemeal flour 1,15 kg Primary Bakery registry

Electricity (IT energetic mix) 0,26 kWh Primary Invoices

Shellnuts 4,38 kg Primary Bakery registry

Bread bags (paper) 7 g Primary Directly measured

Bread bags (HDPE) 1 g Primary Directly measured

Salt 1 g Primary Bakery registry

Waste paper combusted 8 g Primary Bakery registry

Table 6

Data of the LCI per 1 kg of wholemeal bread (FU

) of the transport of raw materials, fuel, packaging and packaged loaf, based on the distance travelled and load of the truck including an empty return trip.

Type of transport From To Type of vehicle Distance (km) Kgkm per FU

kg CO

eq per FU

Wheat seeds regional storehouse field van<3,5 t 13 0,78

- 2,77

0,001

- 0,005

Fuel regional storage field lorry 3,5e20 t 45 1,85

- 6,62

0,0005

- 0,002

Chemical products (fertilizers, pesticides and herbicides) regional storehouse field van<3,5 t 20 1,7

0,003

Packaging of flour (paper) regional storehouse mill van<3,5 t 30 0,17 0,0003

Wheat grains field mill lorry 3,5e20 t 32 41 0,01

Wholemeal flour mill bakery van<3,5 t 82 94,3 0,18

Shellnuts hazelnut field bakery lorry >28 t 33 145 0,02

Packaging of bread (paper bags with plastic strip) regional storehouse bakery van<3,5 t 20 0,16 0,0003

Salt retail bakery van<3,5 t 18 0,02 0,00003

Packaged bread bakery retail van<3,5 t 20e120 110

0,21

a

Data referred to conventional farming.

b

Data referred to organic farming.

c

Distribution is in a range from 20 to 120 km; weighted average distance was considered.

313

flour milling plant. The transport of wheat from the field to the mill as well as the production, packaging and transport of raw materials (such as paper for flour packaging, fuel, etc.) were also included in this phase (Tables 4 and 6). We excluded from the boundaries of the study the GHG emissions related to detergents used in the flour milling plant, due to their low incidence.

As explained in the organic wheat farming section, since the analyzed process results in multiple output products (i.e. whole- meal flour and bran) that are harvested and sold as byproducts, an economic allocation was considered for the amount of wholemeal flour (90%) and bran (10%) resulting from the flour milling process.

According to the economic value of 157 V ton

assigned to the bran (Borsa Merci Roma, 2013) and to the market price of 1.900 V ton

of the wholemeal flour directly declared by the grinding plant, we attributed the 99% of the GHG emissions of the flour milling process to the wholemeal flour and the 1% to the bran. The amount of paper used for the packaging of the flour in bags of 30 kg of capacity was allocated by mass in relation to the amount of flour needed for the production of 1FU

.

3.4. Bakery

The bakery is located 83 km far from the flour milling plant and works through a sustainable process: the cooking takes place exclusively from the combustion of nutshells which are an agri- cultural residue very common in the surrounding area. The overall amount of nutshells used in 2013 in the bakery for the total annual production of about 41 tons year

of different kinds of bakery products was 200 tons. We considered an average distance of 33 km for the nutshells supply. According to the IPCC guidelines (2006) and to Petersen Raymer (2006), we assumed that the CO

emitted during the combustion equals the CO

absorbed by nut- shells, therefore the GHG emissions of the cooking process were assumed to be zero. Other energy consumptions for the manage- ment of the bakery facilities were derived from the invoices of the electric energy company in 2013 and accounted for about 11.000 kWh for all the year round, which result in about 0,26 kWh per kg of produced bread. According to Dones et al. (2007), an emission factor of 0,65 kg CO

eq is assigned per kWh of consumed electricity derived by the Italian energy mix at medium voltage.

The paper of the packaging resulting from the flour bags was used as fire starter of nutshells in the oven during the cooking process. The yeast used for the dough was self-produced while the salt came from a distance of 18 km considering the site of pro- duction, even if the packaging of the salt was not considered due to the low incidence of the resulting GHG emissions. The final pack- aging of the wholemeal bread is a virgin paper bag with a central plastic band. The production site of the packaging is 20 km far from the bakery. The production, packaging and transport of raw mate- rials and other ingredients for baking such as the wholemeal flour, the nutshell for combustion, the salt and the bags for the bread packaging were included in this phase (Tables 5 and 6).

As described in the previous sections, since the analyzed process results in multiple output products (i.e. different kinds of bakery products), an economic allocation was applied for the energy consumption for the management of the bakery facilities, consid- ering that the 13% of the total production costs of the bakery was computed to the production of the wholemeal bread in 2013. The same economic allocation was applied to the amount of nutshell needed for the cooking process; while an allocation by mass was considered for the emissions of the waste paper used as fire starter.

3.5. Retail

The transport distance of 110 km from the bakery to the retail

shops was considered in relation to a weighted average distance between the two main points of distribution (province of Rome and province of Viterbo), taking into account the total amount of wholemeal bread annually delivered (Table 6).

4. Results and discussion

The contribution to climate change in terms of GHG emissions of the analyzed organic wholemeal bread sold in retail shops as packaged loafs of 1 kg was of 1,55 kg CO

eq, while the GHG emis- sions of the same wholemeal bread produced using conventional wheat were lower (1,18 kg CO

eq FU

). The GHG emissions of each phase of the analyzed wholemeal bread production and distribu- tion are reported in Table 7 .

According to the other studies existing in literature (Andersson and Ohlsson, 1999; Espinoza-Orias et al., 2011; Jensen and Arlbjørn, 2014; Renzulli et al., 2015), we found that the farming phase for the wheat cultivation is the main hotspot in the life cycle that mostly contributes in terms of GHG emissions, both in the organic and conventional production, with a contribution to the total carbon footprint of 0,98 kg CO

eq FU

(63%) and 0,61 kg CO

eq FU

(52%) respectively (Fig. 2). The bakery phase was the second hotspot, with a contribution to the total carbon footprint of 0,35 kg CO

eq FU

corresponding to the 22% and the 29% of GHG emissions in the organic and conventional wholemeal bread production respec- tively. The third hotspot is the retail phase, with a contribution of 0,2 kg CO

eq FU

corresponding to 13% and 18% of the total carbon footprint in the organic and conventional wholemeal bread pro- duction respectively. The flour milling operations accounted only for 1% with only 0,01 kg CO

eq FU

(Fig. 2).

Fig. 3 shows the share of the main sources of GHG emissions in each phase of the life cycle of the studied wholemeal bread pro- duction and distribution. Within the organic farming phase, the

Table 7

GHG emissions of each phase of the life cycle of organic and conventional whole- meal bread production and distribution, per functional unit (FU

) of wholemeal bread and per unit of area (hectare). The wheat cultivation for the production of 1 kg of wholemeal bread (1 FU

is 8,52 m

in organic farming and 2,13 m

in conven- tional farming.

Life cycle phases kg CO

eq FU

Mg CO

eq ha

Organic wheat seeds 0,1 0,12

Packaging of wheat seeds 0,001 0001

Direct and indirect soil emissions 0,42 0,5

Fuel production and consumption 0,46 0,5

Transport 0,005 0006

Total organic farming 0,98 1,15

Conventional wheat seeds 0,02 0,10

Packaging of wheat seeds 0,00005 0,0002

Fertilizers production 0,34 1,6

Fungicide, pesticides and herbicide 0,002 0008 Direct and indirect soil emissions 0,13 0,6

Fuel production and consumption 0,11 0,5

Transport 0,004 0,02

Total conventional farming 0,61 2,87

Hydro Electric Power 0,0004

Packaging of flour (paper) 0,004

Transport 0,01

Total milling 0,015

Electricity (IT energetic mix) 0,174

Salt 0,0002

Packaging (paper, HDPE) 0,008

Transport 0,16

Total Bakery 0,35

Transport of the FU 0,21

Total Retail 0,21

314

fuel used for the agricultural equipment in the field operations for wheat cultivation represents the main impact in terms of GHG emissions, with a share of about 47%. The soil emissions, including the direct and indirect N

O soil emissions, cover a share of 42% of the GHG emissions of the organic farming phase, followed by the production of raw materials that has a share of about the 10%. The production and waste treatment of the packaging as well as the transport of raw materials, packaging and fuel have a minor impact with a share of less than 1% of the GHG emissions of this phase (Fig. 3).

When considering the conventional farming phase, the main share of GHG emissions is represented by the production and use of the raw materials (59%). The soil emissions, including direct and indirect N

O soil emissions, covers a share of about 21% of the total GHG emissions of the conventional farming phase, followed by the fuel used for the farming operations that has a share of about 19%.

The production and waste treatment of the packaging as well as the transport of raw materials, packaging and fuel have a minor impact with a share of about 1% of the GHG emissions of the farming phase (Fig. 3).

In the milling phase, transport was the main GHG source with a share of 69%. The production of flour packaging has a share of about 28% while hydropower energy accounts for less than 3% of the GHG emissions of the flour milling phase ( Fig. 3).

In the bakery phase, the main impact is due to the electricity consumption for the management of the bakery facilities which represents a share of 51% of the GHG emissions within this phase, followed by the transport of the nutshells used for the cocking process and other raw materials, packaging and fuel that covers a share of about 47%. The contribution to climate change of the cooking process was accounted as zero considering that the CO

emitted during the combustion is assumed to equal the CO

absorbed by nutshells (IPCC, 2006). The production and use of packaging and raw materials have a minor impact with a share of about 2% of the GHG emissions of the bakery phase. The retail phase includes only the transport of the packaged wholemeal bread to the retail shops which covers the 100% of the GHG emissions within this phase (Fig. 3).

As previously reported, the wheat cultivation is the main hot- spot that mostly contributes in terms of GHG emissions, both in the organic and conventional investigated bread production. Namely, the organic wheat cultivation for the production of 1 kg of wholemeal bread needs a cultivated area of 8,52 m

and contrib- utes to the total carbon footprint of the FU

with 0,98 kg CO

eq, while the conventional wheat cultivation needs a cultivated area of 2,13 m

for the production of 1 kg of wholemeal bread and con- tributes to the total carbon footprint of the FU

with 0,61 kg CO

eq.

If these values are extended to 1 ha of wheat farming, we found that the total GHG emissions per hectare of land cultivated with organic wheat are considerably lower than the total GHG emissions per hectare of land cultivated with conventional wheat, corresponding to 1,15 and 2,87 Mg CO

eq ha

respectively (Fig. 4, Table 7). A similar average value of 2,28 Mg CO

eq ha

was found for durum wheat in central Italy by Casolani et al. (2016) based on an elabo- ration of data derived by a literature review, although the study doesn ’t distinguish between organic and conventional practices.

Although the CF of 1 kg (FU

) of the conventional wholemeal bread was 24% less respect to the organic one (Fig. 2), when the GHG emissions are evaluated per hectare the CF is 60% lower per

0,61 (52%) 0,35 (22%)

0,35 (29%) 0,21 (13%)

0,21 (18%) 0,01 (1%)

0,01 (1%)

0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60

Organic Conventional

kg C O

eq kg

loaf o f bread

Milling Retail Bakery Farming 1,55

1,18

Fig. 2. Carbon footprint of organic and conventional wholemeal bread produced in central Italy by a small-medium bakery and sold in retail shops as packaged loafs of 1 kg.

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

CONVENTIONAL

FARMING ORGANIC

FARMING MILLLING BAKERY RETAIL

Transport Packaging Diesel for farming Electricity Raw materials Soil emissions

Fig. 3. Percentage distribution of the main sources of GHG emissions in each phase of the life cycle of organic and conventional wholemeal bread produced in central Italy by a small-medium bakery and sold in retail shops as packaged loafs of 1 kg.

315

unit of land cultivated with organic wheat respect to conventional wheat (Fig. 4). These findings demonstrate that organic farming for wheat cultivation in Italy is a low-carbon agriculture with a lower contribution to climate change in terms of GHG emissions per hectare respect to the conventional wheat cultivation, although productivity is considerably reduced. In fact, crop yield of con- ventional wheat farming is higher than organic (6 tons ha

in the conventional farming respect to 1,5 tons ha

in organic) with a consequent lower land used for the production of the same quan- tity of wholemeal bread, resulting in lower GHG emissions per FU

in the conventional wholemeal bread. Similar findings in terms of land use and contribution to global warming potential were detected also by Williams et al. (2010) in a comparison between organic and non-organic bread wheat production in Europe. Also Kulak et al. (2015) in a comparison of different systems and scales of bread production at European level found that in the agricultural stage of cereal cultivation some low yielding systems can be even more eco-ef ficient in terms of GHG emissions than high input agriculture, much depending on the in fluence of site conditions and the management. Meisterling et al. (2009) found even a lower GWP in organic than in conventional bread also when comparing the functional unit of 1 kg loaf in United States, although results are strongly in fluenced by the soil carbon accumulation and nitrous oxide emissions from the two systems.

In this study, the main difference in GHG emissions related to 1 ha of organic and conventional wheat farming is due to the higher use of raw materials in the conventional wheat farming, especially if considering seed density and agrochemical compounds for fertilization or plant protection, respect to the same organic system (Figs. 4 and 5). In fact, the GHG emissions related to the production and use of the needed amount of seeds (280 kg/ha) and of the agrochemical compounds applied for fertilization and plant pro- tection in conventional wheat farming are more than thirteen times higher than the GHG emissions related to the production and use of the organic seeds (250 kg/ha) which are the only raw materials used in the organic wheat farming. Also soil GHG emissions, including the direct and indirect N

O soil emissions, are higher in conventional wheat farming due to the use of synthetic N fertilizer, making the alfalfa green manure applied in organic wheat farming a more sustainable technique in terms of GHG emissions per hectare of cultivated land, compared to the conventional chemical

fertilization. In particular, indirect NH

emissions due to the use of synthetic N fertilizer were more than five times higher than indi- rect NH

emissions from alfalfa green manure, while N

O emissions from N leaching and NOx emissions were two times higher in conventional farming respect to the organic.

If the results of this study in terms of GHG emissions per hectare of land cultivated for organic and conventional wheat production are extended to the total area cultivated with Triticum aestivum L. in Italy, that in 2014 accounted for 634.272 ha (ISMEA, 2014) of which 24.676 ha were cultivated with organic farming (SINAB, 2014), the total national annual GHG emissions for the Italian wheat farming sector would be of about 1.800 Mg CO

eq per year. If the whole Italian wheat farming system is converted to the organic farming, the annual value of GHG emissions of the sector could be sensibly reduced to about 731 Mg CO

eq per year, although implications of the consequent decrease of total potential productivity should be faced.

Hence, what is clear is that while conventional farming provides more food but with higher impact on climate and environment, organic farming produces less quantity of food per unit of area but more sustainable in terms of GHG emissions with a consequent 0.0

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1

ORGANIC

FARMING CONVENTIONAL

FARMING kg C O

eq k g

loaf of bread

0,98

0,61

0.0 0.5 1.0 1.5 2.0 2.5 3.0

ORGANIC FARMING

CONVENTIONAL FARMING

Mg C O

eq ha

Transport

Packaging Diesel for farming Raw materials Soil emissions 1,15

2,87

Fig. 4. Comparison of the main sources of GHG emissions related solely to the wheat cultivation phase in organic and conventional farming per functional unit (FU

) of wholemeal bread and per unit of area (hectare).

0.0 0.3 0.5 0.8 1.0 1.3 1.5 1.8 2.0 2.3 2.5 2.8 3.0

Diesel for farming

Raw materials Soil emissions Transport Total field emissions

ORGANIC FARMING CONVENTIONAL FARMING

Fig. 5. Comparison of the main sources of GHG emissions per unit of area (hectare) of wheat cultivated with organic and conventional farming.

316

lower impact on climate.

The results of the study demonstrate that organic farming could represent a pathway to produce healthy food with a lower impact per unit of area in terms of GHG emissions, contributing at the same time to mitigate climate change that represents also one of the causes of food insecurity. The challenge is to understand if organic methods alone could produce enough food on a global basis to feed the current human population and potentially an even larger population. An attempt to demonstrate this was carried out by Badgley et al. (2007) that found that organic production is already suf ficient, without increasing cultivated areas. However, organic farming is still not widely applied with only 43,7 million hectares in the world, representing a share of about 1% of the global agricul- tural land and 5,7% in the European Union (EUROSTAT, 2016; Willer and Lernoud, 2016). Thus, organic production has probably room for improvement in yields if more experience is accrued and organic areas are expanded with the creation of organic territorial districts where the overall agro-ecosystem stability is increased.

The aim of organic agriculture is, in fact, to produce food in an ecological balance to prevent soil fertility and pest problems, through a proactive approach (FAO, 2007) that could improve with time and experience. Nevertheless, more research is needed to better explore and con firm the potential of organic farming of as- suring adequate food supply at global level.

Another important issue to consider is that, as established by the Product Category Rules followed for the assessment of the carbon footprint for bakery products and arable crops (EPD, 2015, 2016), GHG emissions offset cannot be included in the assess- ment of the life cycle GHG emissions of the product. Therefore, the contribution to climate change in terms of GHG emissions of the organic and conventional wholemeal bread analyzed in this study does not take into account the effects on soil carbon content of the organic and conventional practices. Many studies demonstrate that organic practices (Robertson et al., 2000; Wright and Hons, 2005) and more conservative practices as reduced-tillage (West and Post, 2002; Smith et al., 2008) can both increase the carbon content of soils (Meisterling et al., 2009), compared to conventional tillage. If the effects on soil carbon content of the farming systems are included into the LCA approach for the carbon footprint, the full carbon balance is likely to be even more favorable in terms of GHG emissions per hectare with a lower contribution to climate change in organic farming respect to conventional. A comprehensive assessment of the contribution to climate change of food products should take into account both the carbon footprint assessed trough the traditional LCA approach and the possibility to include GHG emission offsets provided by the analyzed ecosystem itself. In this sense, a land-based GHG accountability system for the assessment of the carbon footprint of products or processes whose life cycle involves the land use of managed ecosystems, would be more comprehensive than the carbon footprint assessment based solely on the unit of product. In fact, as demonstrated in the present study and in other cases in literature (Renzulli et al., 2015), a comparison of CF based on the product units for agricultural products is not always fair as the GHG emissions of product units are much related to the yields and more intense management per hectare can overshadow the higher productivity. This factor underlines the need to identify an appropriate FU - or, better, several FUs, including the land area functional unit - for comparing the envi- ronmental impacts of crops, as considered in many studies in literature (Charles et al., 2006; Harada et al., 2007; Kavargiris et al., 2009; Ferng, 2011; Litskas et al., 2011; Nalley et al., 2011; Michos et al., 2012; Notarnicola et al., 2012; Roer et al., 2012; Za firiou et al., 2012; Eshun et al., 2013; Hayashi, 2013; Murphy and Kendall, 2013; Meier et al., 2015). Especially for agricultural areas where agronomic practices can in fluence the organic carbon

content in soils and/or in woody perennial biomass, the carbon footprint based on the unit of land used for the food production (FU

), including also the carbon sink provided by the agrosystem itself, in addition to the product unit (FU

), would actually provide explicit information on the intensity of use of agricultural inputs (Renzulli et al., 2015) and increase the relevance of the LCA sus- tainability, allowing for a more comprehensive assessment of the real contribution to climate change.

5. Conclusions

According to the other studies found in literature, the farming phase for the wheat cultivation was identi fied as the main hotspot in the life cycle of the analyzed wholemeal bread production, that mostly contributes in terms of GHG emissions both in the organic and conventional production. These findings indicate that it is of fundamental importance to concentrate efforts in reducing the environmental impacts and GHG emissions of agricultural practices to contribute to climate change mitigation.

When comparing the carbon footprint of the analyzed organic and conventional wholemeal bread production, results demon- strate that organic farming has a lower contribution in terms of GHG emissions per hectare of cultivated land, but these results are overturned when assessed per unit of product. This is attributed to the fact that organic wheat cultivation has still lower crop yields per unit of area and, consequently, the GHG emissions generated in the field phase of the life cycle refer to a smaller amount of products, resulting in a higher CF per unit of product. Whereas, the higher use of raw materials in conventional farming (higher seed density, agrochemicals for fertilization and plant protection) results in a higher CF per hectare, respect to the same organic system. In this sense, a land-based accountability of the CF per unit of area, in addition to the CF per unit of product, can provide a more comprehensive assessment of the actual GHG emissions from organic and conventional agrosystems, with the possibility to detect the overall net exchange with the atmosphere of fluxes of GHG per unit of land, if also the carbon sink of the ecosystem itself is included. A LCA tailored to such crop systems with appropriate FU or several FUs, including the land area functional unit, could represent a more suitable mean to identify the negative environ- mental effects of agricultural production and highlight possible pathways for the agricultural land use pursuing the goal of global climate change mitigation.

The study demonstrates that organic farming for wheat culti- vation in Italy has the potential for reducing the impact on climate change in terms of GHG emissions per hectare, even if implications of reduced productivity of organic agriculture should be consid- ered. However, intensive agriculture with high level of crop yields and consequent high impacts on climate and environment, is not necessarily the solution to eradicate hunger and feed the 9 billion people expected in 2050. In fact, the current agricultural produc- tion supplies enough food to global population (FAO, 2015a, 2015b), but food security is not ensured due to a range of causes as poverty, con flicts, food waste and climate change.

Organic farming could represent a pathway to produce healthy food responding at the same time to the need of global climate change mitigation. However, more research is needed to better explore the potential of organic farming and to improve organic food production, optimizing the balance between the use of re- sources and yields, to ensure suf ficient organic food supply at global level.

Acknowledgements

The authors wish to thank the bakery “Soc. Coop. Il Sambuco”

317

located in Celleno (Viterbo, Italy) for the contribution in data pro- vision. We would also like to thank the anonymous reviewers for their constructive comments. The study presented in this paper was partially developed under the project “LCA EcoInTeverina”

co financed by “Gruppo di Azione Locale In Teverina e Programma di Sviluppo Rurale della Regione Lazio 2007e2013 e Asse IV LEADER Fondo europeo agricolo per lo sviluppo rurale: l ’Europa investe nelle zone rurali. Mis. 4.1.1.124 - Prog. n. 94752003510 ”.

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