• Authors:
    • Marvinney,E.
    • Kendall,A.
    • Brodt,S.
  • Source: Journal of Industrial Ecology
  • Volume: 19
  • Issue: 6
  • Year: 2015
  • Summary: This is the second part of a two-article series examining California almond production. The part I article describes development of the analytical framework and life cycle-based model and presents typical energy use and greenhouse gas (GHG) emissions for California almonds. This part II article builds on this by exploring uncertainty in the life cycle model through sensitivity and scenario analysis, and by examining temporary carbon storage in the orchard. Sensitivity analysis shows life cycle GHG emissions are most affected by biomass fate and utilization, followed by nitrous oxide emissions rates from orchard soils. Model sensitivity for net energy consumption is highest for irrigation system parameters, followed by biomass fate and utilization. Scenario analysis shows utilization of orchard biomass for electricity production has the greatest potential effect, assuming displacement methods are used for co-product allocation. Results of the scenario analysis show that 1 kilogram (kg) of almond kernel and associated co-products are estimated to cause between -3.12 to 2.67 kg carbon dioxide equivalent (CO2-eq) emissions and consume between 27.6 to 52.5 megajoules (MJ) of energy. Co-product displacement credits lead to avoided emissions of between -1.33 to 2.45 kg CO2-eq and between -0.08 to 13.7 MJ of avoided energy use, leading to net results of -1.39 to 3.99 kg CO2-eq and 15.3 to 52.6 MJ per kg kernel (net results are calculated by subtracting co-product credits from the results for almonds and co-products). Temporary carbon storage in orchard biomass and soils is accounted for by using alternative global warming characterization factors and leads to a 14% to 18% reduction in CO2-eq emissions. Future studies of orchards and other perennial cropping systems should likely consider temporary carbon storage. © 2015 The Authors. Journal of Industrial Ecology, published by Wiley Periodicals, Inc., on behalf of Yale University.
  • Authors:
    • Michalsky,M.
    • Hooda,P. S.
  • Source: Environmental Science and Policy
  • Volume: 48
  • Year: 2015
  • Summary: Today considerable efforts are being made in identifying means of further energy efficiencies within the UK food system. Current air importation of fruit and vegetables (FVs) generates large amounts of greenhouse gas (GHG) emissions part of which could be avoided. Local food production has been recognized as an environmentally feasible alternative production option and could help reduce GHG emissions, as required under the legally binding emissions targets stipulated by the UK Climate Change Act 2008. Climate change impacts of FVs importation were determined for a selection of five indigenous FV commodities, namely: apples, cherries, strawberries, garlic and peas. Carbon dioxide equivalents (CO 2e) emissions associated with the production and transport stages were calculated using the sample of selected fruit and vegetables (SFVs). The latter stage includes three diverse geographic locations/regions for emissions comparison, namely the UK, Europe and non-European (NE) countries. On average (across the five SFVs), NE commodities, all in fresh/chilled state, were found to contain embedded (arising from production, air freighting and distribution within the UK) GHG emissions of 10.16 kg CO 2e/kg. This is 9.66 kg more CO 2e emissions compared to a kilogram of these commodities produced and supplied locally. A scenario-based approach determined the level of emissions savings that could be achieved by local FVs production in the UK. The least dramatic change of SCENARIO-1 (25% reduction in NE SFVs imports by increasing their local production by the same amount) could save 28.9 kt CO 2e/year, while SCENARIO-2 (50% reduction in NE SFVs imports) and SCENARIO-3 (75% reduction in NE SFVs imports) could result in saving of 57.8 kt and 86.7 kt, respectively.
  • Authors:
    • Monteleone,M.
    • Garofalo,P.
    • Cammerino,A. R. B.
    • Libutti,A.
  • Source: Italian Journal of Agronomy
  • Volume: 10
  • Issue: 2
  • Year: 2015
  • Summary: Climate change mitigation is the most important driving force for bioenergy development. Consequently, the environmental design of bioenergy value chains should address the actual savings of both primary energy demand and greenhouse gases (GHG) emissions. According to the EU Renewable Energy Directive (2009/28/EC), no direct impacts and no GHG emissions should be attributed to crop residues (like cereal straws) when they are removed from agricultural land for the purpose of bioenergy utilisation. The carbon neutral assumption applied to crop residues is, however, a rough simplification. Crop residues, indeed, should not be viewed simply as a waste to be disposed, because they play a critical role in sustaining soil organic matter and therefore have an inherent C-capturing value. Moreover, considering straws as an energy feedstock, its status of co-product is clearly recognised and its availability could be obtained according to different cropping systems, corresponding to different primary energy costs and GHG emissions. This paper highlights some hidden features in the assessment of agricultural energy and carbon balance, still very difficult to be detected and accounted for. Although they are frequently disregarded, these features (such as long term dynamic trend of soil organic carbon and annual nitrous oxide emissions from the soil) should be carefully considered in assembling the energy and emission balance. By using a crop simulation model, the long-term soil organic matter and annual N2O soil emissions were estimated. Consequently, a comprehensive energy and GHG balance was determined in accordance with the life cycle assessment methodology. Contrasting methods of straw management and wheat cultivation were compared: straw retention vs removal from the soil; conventional vs conservation tillage; wheat cropping system as a single-crop or in rotation. The resulting carbon footprint of straws has different magnitudes with respect to the several experimental conditions. By selecting the best agricultural practices, energy from straw can be optimally coupled with grain productions, without detrimental effects on soil fertility. An improved and specifically tailored cropping system is designed to obtain an optimal trade-off. © M. Monteleone et al., 2015.
  • Authors:
    • O'Leary,G. J.
    • Christy,B.
    • Nuttall,J.
    • Huth,N.
    • Cammarano,D.
    • Stockle,C.
    • Basso,B.
    • Shcherbak,I.
    • Fitzgerald,G.
    • Luo QunYing
    • Farre-Codina,I.
    • Palta,J.
    • Asseng,S.
  • Source: Global Change Biology
  • Volume: 21
  • Issue: 7
  • Year: 2015
  • Summary: The response of wheat crops to elevated CO 2 (eCO 2) was measured and modelled with the Australian Grains Free-Air CO 2 Enrichment experiment, located at Horsham, Australia. Treatments included CO 2 by water, N and temperature. The location represents a semi-arid environment with a seasonal VPD of around 0.5 kPa. Over 3 years, the observed mean biomass at anthesis and grain yield ranged from 4200 to 10 200 kg ha -1 and 1600 to 3900 kg ha -1, respectively, over various sowing times and irrigation regimes. The mean observed response to daytime eCO 2 (from 365 to 550 mol mol -1 CO 2) was relatively consistent for biomass at stem elongation and at anthesis and LAI at anthesis and grain yield with 21%, 23%, 21% and 26%, respectively. Seasonal water use was decreased from 320 to 301 mm ( P=0.10) by eCO 2, increasing water use efficiency for biomass and yield, 36% and 31%, respectively. The performance of six models (APSIM-Wheat, APSIM-Nwheat, CAT-Wheat, CROPSYST, OLEARY-CONNOR and SALUS) in simulating crop responses to eCO 2 was similar and within or close to the experimental error for accumulated biomass, yield and water use response, despite some variations in early growth and LAI. The primary mechanism of biomass accumulation via radiation use efficiency (RUE) or transpiration efficiency (TE) was not critical to define the overall response to eCO 2. However, under irrigation, the effect of late sowing on response to eCO 2 to biomass accumulation at DC65 was substantial in the observed data (~40%), but the simulated response was smaller, ranging from 17% to 28%. Simulated response from all six models under no water or nitrogen stress showed similar response to eCO 2 under irrigation, but the differences compared to the dryland treatment were small. Further experimental work on the interactive effects of eCO 2, water and temperature is required to resolve these model discrepancies.
  • Authors:
    • Pereira,E. I. P.
    • Suddick,E. C.
    • Mansour,I.
    • Mukome,F. N. D.
    • Parikh,S. J.
    • Scow,K.
    • Six,J.
  • Source: Biology and Fertility of Soils
  • Volume: 51
  • Issue: 5
  • Year: 2015
  • Summary: We investigated the effect of biochar type on plant performance and soil nitrogen (N) transformations in mesocosms representing an organic lettuce ( Lactuca sativa) production system. Five biochar materials were added to a silt loam soil: Douglas fir wood pyrolyzed at 410°C (W410), Douglas fir wood pyrolyzed at 510°C (W510), pine chip pyrolyzed at 550°C (PC), hogwaste wood pyrolyzed between 600 and 700°C (SWC), and walnut shell gasified at 900°C (WS). Soil pH and cation exchange capacity were significantly increased by WS biochar only. Gross mineralization increased in response to biochar materials with high H/C ratio (i.e., W410, W510, and SWC), which can be favorable for organic farming systems challenged by insufficient N mineralization during plant growth. Net nitrification was increased by W510, PC, and WS without correlating with the abundance of ammonia oxidizing gene ( amoA). Increases in N transformation rates did not translate into increases in plant productivity or leaf N content. WS biochar increased the abundance of amoA and nitrite reductase gene ( nirK), while SWC biochar decreased the abundance of amoA and nitrous oxide gene ( nosZ). Decreases in N 2O emissions were only observed in soil amended with W510 for 3 days out of the 42-day growing season without affecting total cumulative N 2O fluxes. This suggests that effects of biochar on decreasing N 2O emissions may be transient, which compromise biochar's potential to be used as a N 2O mitigation strategy in organic systems. Overall, our results confirm that different biochar materials can distinctively affect soil properties and N turnover.
  • Authors:
    • Cardenas-Galindo, P.
    • Prosperi, P.
    • Flammini, A.
    • Jacobs, H.
    • Golec, R. D. C.
    • Biancalani, R.
    • Rossi, S.
    • Federici, S.
    • House, J.
    • Ferrara, A. F.
    • Salvatore, M.
    • Tubiello, F. N.
    • Schmidhuber, J.
    • Sanchez, M. J. S.
    • Nalin, S.
    • Smith, P.
  • Source: Research Article
  • Volume: 21
  • Issue: 7
  • Year: 2015
  • Summary: We refine the information available through the IPCC AR5 with regard to recent trends in global GHG emissions from agriculture, forestry and other land uses (AFOLU), including global emission updates to 2012. Using all three available AFOLU datasets employed for analysis in the IPCC AR5, rather than just one as done in the IPCC AR5 WGIII Summary for Policy Makers, our analyses point to a down-revision of global AFOLU shares of total anthropogenic emissions, while providing important additional information on subsectoral trends. Our findings confirm that the share of AFOLU emissions to the anthropogenic total declined over time. They indicate a decadal average of 28.71.5% in the 1990s and 23.62.1% in the 2000s and an annual value of 21.21.5% in 2010. The IPCC AR5 had indicated a 24% share in 2010. In contrast to previous decades, when emissions from land use (land use, land use change and forestry, including deforestation) were significantly larger than those from agriculture (crop and livestock production), in 2010 agriculture was the larger component, contributing 11.20.4% of total GHG emissions, compared to 10.01.2% of the land use sector. Deforestation was responsible for only 8% of total anthropogenic emissions in 2010, compared to 12% in the 1990s. Since 2010, the last year assessed by the IPCC AR5, new FAO estimates indicate that land use emissions have remained stable, at about 4.8 Gt CO 2 eq yr -1 in 2012. Emissions minus removals have also remained stable, at 3.2 Gt CO 2 eq yr -1 in 2012. By contrast, agriculture emissions have continued to grow, at roughly 1% annually, and remained larger than the land use sector, reaching 5.4 Gt CO 2 eq yr -1 in 2012. These results are useful to further inform the current climate policy debate on land use, suggesting that more efforts and resources should be directed to further explore options for mitigation in agriculture, much in line with the large efforts devoted to REDD+ in the past decade.
  • Authors:
    • Akhtar,Saqib Saleem
    • Andersen,Mathias Neumann
    • Liu,Fulai
  • Source: Agricultural Water Management
  • Volume: 158
  • Year: 2015
  • Summary: Salinity is one of the major threats to global food security. Biochar amendment could alleviate the negative impacts of salt stress in crop in the season. However, its long-term residual effect on reducing Na+ uptake in latter crops remains unknown. A pot experiment with wheat was conducted in a greenhouse. The soil used was from an earlier experiment on potato where the plants were irrigated with tap water (S0), 25 mM (S1) and 50 mM (S2) NaCl solutions and with 0 and 5% (w/w) biochar amendment. At onset of the experiment, three different EC levels at S0, S1 and S2 were established in the non-biochar control (2.3, 7.2 and 10.9 dS m(-1)) and the biochar amended (2.8, 8.1 and 11.8 dS m(-1)) soils, respectively. A column leaching experiment was also conducted in the greenhouse to study the adsorption capacity of biochar to Na+. The results indicated that biochar addition reduced plant sodium uptake by transient Na+ binding due to its high adsorption capacity, decreasing osmotic stress by enhancing soil moisture content, and by releasing mineral nutrients (particularly K+, Ca++, Mg++) into the soil solution. Growth, physiology and yield of wheat were affected positively with biochar amendment, particularly under high salinity level. It was concluded that addition of biochar had significant residual effect on reducing Na+ uptake in wheat under salinity stress. However, more detailed field studies should be carried out to evaluate the long-term residual effects of biochar for sustaining crop production in saline soils. (C) 2015 Elsevier B.V. All rights reserved.
  • Authors:
    • Antille,D. L.
    • Chamen,W. C. T.
    • Tullberg,J. N.
    • Lal,R.
  • Source: Transactions of the ASABE
  • Volume: 58
  • Issue: 3
  • Year: 2015
  • Summary: The drive toward adoption of conservation agriculture to reduce costs and increase production sustainably causes concern due to the potentially negative effects of increased soil compaction. Soil compaction reduces aeration, water infiltration, and saturated hydraulic conductivity and increases the risk of waterlogging. Controlled traffic farming (CTF) is a system in which: (1) all machinery has the same or modular working and track width so that field traffic can be confined to the least possible area of permanent traffic lanes, (2) all machinery is capable of precise guidance along those permanent traffic lanes, and (3) the layout of the permanent traffic lanes is designed to optimize surface drainage and logistics. Without CTF, varying equipment operating and track widths translate into random traffic patterns, which can cover up to 85% of the cultivated field area each time a crop is produced. Nitrous oxide (N2O) is the greatest contributor to agriculture's greenhouse gas (GHG) emissions from cropping, and research suggests that its production increases significantly under conditions of high (>60%) water-filled porosity when nitrate (mainly from fertilizer N) and carbon (usually from crop residues) are available. Self-amelioration of soils affected by compaction occurs slowly from the surface downward; however, the rate of amelioration decreases with increase in depth. Consequently, all soils in non-CTF systems in mechanized agriculture are prone to some degree of compaction, which compromises water infiltration, increases the frequency and duration of waterlogged conditions, reduces gaseous exchange between soil and the atmosphere, inhibits root penetration and exploitation of nutrients and water in the subsoil, and enhances N2O emissions. Adoption of CTF increases soil porosity in the range of 5% to 70%, water infiltration by a factor of 4, and saturated hydraulic conductivity by a factor of 2. The greater cropping opportunity and enhanced crop growth for given fertilizer and rainfall inputs offered by CTF, coupled with no-tillage, provide potential for enhanced soil carbon sequestration. Reduced need and intensity of tillage, where compaction is avoided, also helps protect soil organic matter in stable aggregates, which may otherwise be exposed and oxidized. There is both circumstantial and direct evidence to suggest that improved soil structural conditions and aeration offered by CTF can reduce N2O emissions by 20% to 50% compared with non-CTF. It is not compaction per se that increases the risk of N2O emissions but rather the increased risk of waterlogging and increase in water-filled pore space. There may be an elevated risk of GHG emissions from the relatively small area of permanent traffic lanes (typically <20% of total cultivated area) if these are not managed appropriately. Quantification of the benefits of compaction avoidance in terms of GHG emissions may be possible through the use of well-developed models. © 2015 American Society of Agricultural and Biological Engineers.
  • Authors:
    • Buckley,Cathal
    • Wall,David P.
    • Moran,Brian
    • Murphy,Paul N. C.
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 102
  • Issue: 3
  • Year: 2015
  • Summary: This study uses a national farm survey which is part of the European Union (EU) Farm Accountancy Data Network (FADN) to develop environmental sustainability indicators in the use of nitrogen (N) and phosphorus (P) across a range of farm systems in the Republic of Ireland. Farm level micro data were used to calculate all inputs and outputs of N and P that cross the farm gate and to derive balances (kg ha(-1)) and overall use efficiencies across 827 farms in 2012. The sample is populated weighted to represents 71,480 farms nationally. Results indicated an average N balance of 71.0 kg ha(-1) and use efficiency of 36.7 % across the nationally representative sample. Nitrogen balances were between two and four times higher across specialist dairy farms compared to livestock rearing and specialist tillage systems. Nitrogen use efficiency was generally lowest across milk producing systems compared to livestock rearing and tillage systems. Phosphorus balance and use efficiency averaged 4.7 kg ha(-1) and 79.6 % respectively across the sample. Specialist tillage and dairying farms had higher average P balances compared to other livestock based systems. The approach developed in this analysis will form the benchmark for temporal analysis across these indicators for future nutrient balance and efficiency trends and could assist other members of the EU FADN to develop similar nationally representative indicators.
  • Authors:
    • Meyer-Aurich, A.
    • Kern, J.
    • Ammon, C.
    • Andert, J.
    • Dicke, C.
    • Kaupenjohann, M.
  • Source: Science Article
  • Volume: 524
  • Year: 2015
  • Summary: Field studies that have investigated the effects of char materials on the emission of nitrous oxide (N2O) are still scarce. Therefore, we conducted a field trial with bio- and hydrochars and measured N2O emissions for one whole year. It was hypothesised that the incorporation of chars reduces the emissions of N2O. Chars were produced by pyrolysis and hydrothermal carbonisation (HTC) using either maize silage or wood residues as feedstock. In addition, after production chars were post-treated with digestate in order to accelerate the ageing process of the chars. Chars and digestate were applied to the soil to raise the C content. Emissions of N2O were measured weekly and soil samples for inorganic nitrogen (N) and soil water-content were taken once a month. Additionally, the abundance of functional marker genes from denitrification (nosZ) was determined in October 2012 and in June 2013. The treatment with pure digestate emitted the most N2O compared to the control and char treatments. However, this was significant only in one case. There were no great differences between the char treatments due to high spatial variability and gene abundance of nosZ did not differ between treatments. Overall, emissions of N2O were relatively low. This was attributed to the heterogeneous distribution of the chars and the sandy soils that did not favour the production of N2O. To conclude, the emissions of N2O were mainly influenced by temperature and precipitation and to a minor extent by the type of char and post-treatment. (C) 2015 Elsevier B.V. All rights reserved.