Many current organic arable agriculture systems are challenged by a dependency on imported livestock manure from conventional agriculture. At the same time organic agriculture aims at being climate ...friendly. A life cycle assessment is used in this paper to compare the carbon footprints of different organic arable crop rotations with different sources of N supply. Data from long-term field experiments at three different locations in Denmark were used to analyse three different organic cropping systems (‘Slurry’, ‘Biogas’ and ‘Mulching’), one conventional cropping system (‘Conventional’) and a “No input” system as reference systems. The ‘Slurry’ and ‘Conventional’ rotations received slurry and mineral fertilizer, respectively, whereas the ‘No input’ was unfertilized. The ‘Mulching’ and ‘Biogas’ rotations had one year of grass-clover instead of a faba bean crop. The grass-clover biomass was incorporated in the soil in the ‘Mulching’ rotation and removed and used for biogas production in the ‘Biogas’ rotation (and residues from biogas production were simulated to be returned to the field).
A method was suggested for allocating effects of fertility building crops in life cycle assessments. The results showed significantly lower carbon footprint of the crops from the ‘Biogas’ rotation (assuming that biogas replaces fossil gas) whereas the remaining crop rotations had comparable carbon footprints per kg cash crop. The study showed considerable contributions caused by the green manure crop (grass-clover) and highlights the importance of analysing the whole crop rotation and including soil carbon changes when estimating carbon footprints of organic crops especially where green manure crops are included.
•Carbon footprints of crops from organic and conventional crop rotations were assessed.•The contributions caused by the green manure crop were considerable.•Highlights the importance of analysing the whole crop rotation and to include soil carbon changes.•Carbon footprint of organic compared to conventional varied depending on production practice.•Indicates a potential for improving the carbon footprint of organic produce.
Joint implementation of Life Cycle Assessment (LCA) and Data Envelopment Analysis (DEA) has recently showed to be a suitable tool for measuring efficiency in agri-food systems. In the present study, ...LCA + DEA methodologies were applied for a total of 94 soybean farms in Iran to benchmark the level of operational input efficiency of each farmer. Likewise, potential reductions in the consumption levels of the physical inputs were determined, while estimating the environmental improvements linked to these reduction targets. Our results indicate that 46% of the farms studied operated efficient. The estimated Global Warming Potential (GWP) reduction for the whole sample was obtained∼11% according to DEA model results. Among the field operations, the contribution of irrigation to the total GWP reduction was the highest (63%) followed by fertilization (34%). The results also revealed that farms which burnt crop residue in the field generate significantly more greenhouse gas emissions than other farms. The raising of operational input efficiency and limiting of crop residue burning in the field are recommended options to ensure more environmental friendly soybean farming systems in the region.
•The DEA results show that 46% of the studied farms operated efficient.•Fertilizing agents generated the highest GHG emissions among the farm operations.•Irrigation is the main contribution to the total GWP reduction.•Limiting of crop residue burning has a significant impact on improving GHGs performance.•The potential GWP reduction for the whole sample was found around 11%.
The aim of this paper is to examine the environmental consequences of beef meat production in the EU, using a life cycle approach. Four beef production systems were studied – three from intensively ...reared dairy calves and one from suckler herds. According to the results of the analysis, the contributions from the production of 1
kg beef meat (slaughter weight) to global warming, acidification, eutrophication, land use and non-renewable energy use were lower for beef from dairy calves than from suckler herds (16.0–19.9 versus 27.3
kg
CO
2e, 101–173 versus 210
g
SO
2e, 622–1140 versus 1651
g
NO
3e, 16.5–22.7 versus 42.9
m
2year, and 41.3–48.2 versus 59.2
MJ, respectively). The breakdown analysis helped identify the key areas in the “cradle to farm gate” beef production system where sustainable management strategies are needed to improve environmental performance. The study also included a sensitivity analysis to preliminarily estimate GHG emissions from beef production systems if land opportunity cost and land use change related to grazing and feed crop production for beef were taken into account. If so, the contribution from the production of 1
kg beef to global warming would increase by a factor of 3.1–3.9, based on a depreciation period of 20 years. This highlights the importance of taking into account the impacts of land use in assessing the environmental impacts of livestock production.
This paper assesses the environmental performance of biomass gasification for electricity production based on wheat straw and compares it with that of alternatives such as straw-fired electricity ...production and fossil fuel-fired electricity production. In the baseline simulation, we assume that the combustion of biomass and fossil fuel references for electricity production takes place in a combined heat and power plant, but as a sensitivity analysis, we also consider combustion in a condensing mode power plant where only electricity is produced. Our results show that the production of 1 kWh of electricity from straw through gasification would lead to a global warming potential of 0.08 kg CO2e, non-renewable energy use of 0.2 MJ primary, acidification of 1.3 g SO2e, respiratory inorganics of 0.08 g PM2.5e and eutrophication potential of −1.9 g NO3e. The production of electricity from straw based on gasification technology appears to be more environmentally friendly than straw direct combustion in all impact categories considered. The comparison with coal results in the same conclusion as that reached in the comparison with straw direct combustion. The comparison with natural gas shows that using straw gas as an alternative energy source reduces global warming, non-renewable energy use and eutrophication but increases acidification and respiratory inorganics. The relative performance of straw gasification versus direct combustion and fossil fuel references does not change with varying assumptions about whether or not heat recovery is considered.
► This paper assesses the environmental performance of wheat straw as an energy source. ► Coal and natural gas (NG) are selected as references for comparison with straw. ► Straw has a better ...performance than coal and NG in some midpoint impact categories. ► The single score results show that straw is better than coal but worse than NG. ► Potential improvements lie in reducing NOx emissions and increasing power output.
This paper aims to address the question, “What is the environmental performance of crop residues as an alternative energy source to fossil fuels, and whether and how can it be improved?”. In order to address the issue, we compare electricity production from wheat straw to that from coal and natural gas. The results on the environmental performance of straw for energy utilization and the two fossil fuel references are displayed first for different midpoint categories and then aggregated into a single score. The midpoint impact assessment shows that substitution of straw either for coal or for natural gas reduces global warming, non-renewable energy use, human toxicity and ecotoxicity, but increases eutrophication, respiratory inorganics, acidification and photochemical ozone. The results at the aggregate level show that the use of straw biomass for conversion to energy scores better than that of coal but worse than natural gas. In order to investigate the question of whether and how a reduction in the single score per kWh of electricity produced from straw is feasible, we perform a scenario analysis where we consider two approaches. The first one is a potential significant reduction in emissions of nitrogen oxides (NOx) by implementing selective catalytic reduction technology and the second is a potential increase in power generation efficiency. The results of the scenario analysis show that both approaches are effective in enhancing the competitiveness of straw as an alternative energy source, though the second approach “increasing efficiency” is somewhat less attractive than the first “reducing NOx emissions”.
This paper documents and illustrates a model to estimate the greenhouse gas (GHG) emissions and land use on commercial dairy farms. Furthermore, a method of allocating total farm emissions into meat ...and milk products was developed and, finally, potential mitigation options at farm scale were identified. The GHG emission at farm gate using a Life Cycle Approach (LCA) was estimated based on data from 35 conventional dairy farms with an average 122 cows and 127ha, and 32 organic dairy farms with an average 115 cows and 178ha. There was a significant (p<0.05) higher emission in kg CO2-eq. per kg energy corrected milk (ECM) in the organic system (1.27) compared to conventional (1.20) before allocation into milk and meat. In the conventional system 88% was on-farm emission vs. 98% in the organic production system. Based on a mathematical model, an average of 15% of total farm GHG emissions was allocated to meat. This level was low compared with four other methods traditionally used to allocate between milk and meat, with the amounts allocated to meat ranging from 13% for economic value, 18% for protein mass, 23% for system expansion and up to 26% for biological allocation. The allocation method highly influenced the GHG emission per kg meat (3.41 to 7.33kg CO2-eq. per kg meat), while the effect on the GHG emission per kg milk was lower (0.90 to 1.10kg CO2-eq. per kg ECM). After allocation there was no significant effect of production system on GHG emission per kg ECM. Land requirement, including imported feed, was highest in the organic system at 2.37 m2 per kg ECM against 1.78m2 in the conventional system. Farming strategies based on low stocking rate or with focus on high efficiency in the herd were identified as the most promising for reducing GHG emissions per kg milk at farm gate after allocation between meat and milk. It was concluded that the model can estimate relevant variation in GHG emissions between commercial farms without intensive data registration.
Estimates of soil carbon changes, biodiversity and ecotoxicity have often been missing from life cycle assessment based studies of organic dairy products, despite evidence that the impacts of organic ...and conventional management may differ greatly within these areas. The aim of the present work was therefore to investigate the magnitude of including these impact categories within a comprehensive environmental impact assessment of organic and conventional dairy systems differing in basic production conditions. Three basic systems representative of a range of European approaches to dairy production were selected for the analysis, i.e. (i) low-land mixed crop-livestock systems, (ii) lowland grassland-based systems, (iii) and mountainous systems. As in previous publications, this study showed that when assessing climate change, eutrophication and acidification impact organic milk has similar or slightly lower impact than conventional, although land-use is higher under organic management. Including soil carbon changes reduced the global warming potential by 5–18%, mostly in organic systems with a high share of grass in the ration. The impacts of organic milk production on freshwater ecotoxicity, biodiversity and resource depletion were 2, 33 and 20% of the impacts of conventional management, respectively, across the basic systems considered. The study highlights the importance of including biodiversity, ecotoxicity and soil carbon changes in life cycle assessments when comparing organic and conventional agricultural products. Furthermore, the study shows that including more grass in the ration of dairy cows increases soil carbon sequestration and decreases the negative impact on biodiversity.
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•The importance of including soil carbon changes, ecotoxicity and biodiversity in LCA is highlighted.•Including soil carbon changes reduced global warming potential of milk by 5–18%.•For ecotoxicity, organic milk had only 2% of the impacts of conventional milk.•Impacts on biodiversity of organic milk was only 33% of the conventional milk impacts.•Including more grass decreases impacts on biodiversity and increases soil C sequestration.
The combined implementation of Life Cycle Assessment (LCA) and Data Envelopment Analysis (DEA) has been identified as a suitable tool for the evaluation of the environmental and economic performance ...of multiple similar entities. In this study, a total of 82 rice paddy fields for spring and summer growing seasons in north of Iran were assessed using a combined LCA and DEA methodology to estimate the technical efficiency of each farmer. Furthermore, the environmental consequences of operational inefficiencies were quantified and target performance values benchmarked for inefficient units so that eco-efficiency criteria were verified. Results showed average reduction levels of up to 20% and 25% per material input for spring and summer systems, leading to impact reductions which ranged from 8% to 11% for spring farms and 19% to 25% for summer farms depending on the chosen impact category. Additionally, the potential economic savings from efficient farming operations were also determined. The economic results indicate that an added annual gross margin of 0.045 $ per 1 kg rice paddy could be achieved if inefficient units converted to an efficient operation.
•Analysis of 82 rice paddy farms by LCA + DEA method for spring and summer systems.•Summer fields have higher values for all impacts.•Mean impact reductions from 8% to 11% (spring farms), and 19% to 25% (summer farms).•Identification the best performing units was carried out via a super-efficiency analysis.
Life Cycle Assessment (LCA) is a widely used tool to assess environmental sustainability of products. The LCA should optimally cover the most important environmental impact categories such as climate ...change, eutrophication and biodiversity. However, impacts on biodiversity are seldom included in LCAs due to methodological limitations and lack of appropriate characterization factors. When assessing organic agricultural products the omission of biodiversity in LCA is problematic, because organic systems are characterized by higher species richness at field level compared to the conventional systems. Thus, there is a need for characterization factors to estimate land use impacts on biodiversity in life cycle assessment that are able to distinguish between organic and conventional agricultural land use that can be used to supplement and validate the few currently suggested characterization factors. Based on a unique dataset derived from field recording of plant species diversity in farmland across six European countries, the present study provides new midpoint occupation Characterization Factors (CF) expressing the Potentially Disappeared Fraction (PDF) to estimate land use impacts on biodiversity in the ‘Temperate Broadleaf and Mixed Forest’ biome in Europe. The method is based on calculation of plant species on randomly selected test sites in the biome and enables the calculation of characterization factors that are sensitive to particular types of management. While species richness differs between countries, the calculated CFs are able to distinguish between different land use types (pastures (monocotyledons or mixed), arable land and hedges) and management practices (organic or conventional production systems) across countries. The new occupation CFs can be used to supplement or validate the few current CF's and can be applied in LCAs of agricultural products to assess land use impacts on species richness in the ‘Temperate Broadleaf and Mixed Forest’ biome.
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•New characterization factors (CF) for land use impacts on biodiversity in LCA•Provides CFs for different land use types and management (organic or conventional)•Shows significant differences in CFs between organic and conventional fields•Compares the new characterization factors with other studies•Useful for assessing land use impacts on biodiversity in agricultural LCA studies
► A challenging issue in LCA is how to account for co-products’ environmental burdens. ► The two most commonly used procedures are system expansion and allocation. ► System expansion appears to be ...more appropriate than allocation. ► Indirect land use change is a consequence of diverting molasses from feed to fuel. ► The inclusion of land use change worsens the GHG balance of molasses ethanol.
This study aims to establish a procedure for handling co-products in life cycle assessment (LCA) of a typical sugar cane system. The procedure is essential for environmental assessment of ethanol from molasses, a co-product of sugar which has long been used mainly for feed. We compare system expansion and two allocation procedures for estimating greenhouse gas (GHG) emissions of molasses ethanol. As seen from our results, system expansion yields the highest estimate among the three. However, no matter which procedure is used, a significant reduction of emissions from the fuel stage in the abatement scenario, which assumes implementation of substituting bioenergy for fossil-based energy to reduce GHG emissions, combined with a negligible level of emissions from the use stage, keeps the estimate of ethanol life cycle GHG emissions below that of gasoline. Pointing out that indirect land use change (ILUC) is a consequence of diverting molasses from feed to fuel, system expansion is the most adequate method when the purpose of the LCA is to support decision makers in weighing the options and consequences. As shown in the sensitivity analysis, an addition of carbon emissions from ILUC worsens the GHG balance of ethanol, with deforestation being a worst-case scenario where the fuel is no longer a net carbon saver but carbon emitter.
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