• Authors:
    • Lafond, J.
    • ParĂ©, M. C.
    • Pageau, D.
  • Source: Soil and Tillage Research
  • Volume: 150
  • Year: 2015
  • Summary: In the northern agroecosystem of Saguenay-Lac-Saint-Jean, cash crops such as barley, canola, and field pea are gaining popularity over traditional perennial crops like alfalfa. However, very little information is available on the relatively long-term effect of different crop rotations and soil tillage practices on crop yields and soil quality parameters. This study was conducted at the Normandin Research Farm of Agriculture and Agri-Food Canada. Five rotation types [1: Canola-Barley-Barley-Pea (C-B-B-P); 2: Canola-Pea-Barley-Barley (C-P-B-B); 3: Canola-Barley-Pea-Barley (C-B-P-B); 4: Pea monoculture; and 5: Barley monoculture] and two soil tillage practices [1: Chisel plough (CP) and 2: Moldboard plough (MP)] were evaluated. Canola monoculture of was not included. The study began in 1999 on a former alfalfa field and ended in 2010 after three four-year rotation cycles. Barley monoculture decreased yields by 600kgha-1 in the last five years, whereas field pea monoculture decreased yields by about 1000kgha-1 in most years. Barley monoculture did not significantly reduce grain yields compared to C-B-B-P and C-P-B-B, highlighting the importance of alternate crops every year. Soil tillage (CP versus MP) did not significantly affect yields for all crops in most years; and when it did have an effect, it showed inconsistencies by either increasing or decreasing grain yields. Soil tillage also had insignificant impact regardless of the rotation type involved. Rotation type and soil tillage had insignificant effect on soil organic matter content, whereas CP increased nitrate and phosphorus content in the 0-20cm soil layer. Rotation type had insignificant impact on soil physical properties, whereas CP improved soil water conductivity by 0.03cmh-1 for C-B-B-P and barley monoculture. Compared to MP, CP improved soil macro-aggregate (2-6mm) stability to water as well as aggregate mean weight diameter by about 15% for most of the rotations.
  • Authors:
    • Austin,K. G.
    • Kasibhatla,P. S.
    • Urban,D. L.
    • Stolle,F.
    • Vincent,J.
  • Source: Web Of Knowledge
  • Volume: 10
  • Issue: 5
  • Year: 2015
  • Summary: Our society faces the pressing challenge of increasing agricultural production while minimizing negative consequences on ecosystems and the global climate. Indonesia, which has pledged to reduce greenhouse gas (GHG) emissions from deforestation while doubling production of several major agricultural commodities, exemplifies this challenge. Here we focus on palm oil, the world's most abundant vegetable oil and a commodity that has contributed significantly to Indonesia's economy. Most oil palm expansion in the country has occurred at the expense of forests, resulting in significant GHG emissions. We examine the extent to which land management policies can resolve the apparently conflicting goals of oil palm expansion and GHG mitigation in Kalimantan, a major oil palm growing region of Indonesia. Using a logistic regression model to predict the locations of new oil palm between 2010 and 2020 we evaluate the impacts of six alternative policy scenarios on future emissions. We estimate net emissions of 128.4-211.4 MtCO 2 yr -1 under business as usual expansion of oil palm plantations. The impact of diverting new plantations to low carbon stock land depends on the design of the policy. We estimate that emissions can be reduced by 9-10% by extending the current moratorium on new concessions in primary forests and peat lands, 35% by limiting expansion on all peat and forestlands, 46% by limiting expansion to areas with moderate carbon stocks, and 55-60% by limiting expansion to areas with low carbon stocks. Our results suggest that these policies would reduce oil palm profits only moderately but would vary greatly in terms of cost-effectiveness of emissions reductions. We conclude that a carefully designed and implemented oil palm expansion plan can contribute significantly towards Indonesia's national emissions mitigation goal, while allowing oil palm area to double.
  • Authors:
    • Brookes,G.
    • Barfoot,P.
  • Source: GM Crops & Food
  • Volume: 7
  • Issue: 2
  • Year: 2015
  • Summary: This paper updates previous assessments of how crop biotechnology has changed the environmental impact of global agriculture. It focuses on the environmental impacts associated with changes in pesticide use and greenhouse gas emissions arising from the use of GM crops since their first widespread commercial use in the mid 1990s. The adoption of GM insect resistant and herbicide tolerant technology has reduced pesticide spraying by 553 million kg (-8.6%) and, as a result, decreased the environmental impact associated with herbicide and insecticide use on these crops (as measured by the indicator the Environmental Impact Quotient (EIQ)) by 19.1%. The technology has also facilitated important cuts in fuel use and tillage changes, resulting in a significant reduction in the release of greenhouse gas emissions from the GM cropping area. In 2013, this was equivalent to removing 12.4 million cars from the roads.
  • Authors:
    • Hou,Yong
    • Ma,Lin
    • Sardi,Katalin
    • Sisak,Istvan
    • Ma,Wenqi
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 102
  • Issue: 3
  • Year: 2015
  • Summary: Nitrogen (N) emissions from food production can cause serious environmental problems. Mitigation strategies require insights of N cycles in this complex system. A substance flow analysis for N in the Hungary food production and processing chain over the period 1961-2010 was conducted. Our results show that the history of the total N input and output for the Hungary food chain consists of four distinct periods: 1961-1974 a rapid increase; 1974-1988 a steady increase; 1988-1992 a sharp decrease; 1992-2010 a period of large annual variations. The total N input to the food chain largely depended on N fertilizer input (on average 83 % of total input). Nitrogen losses were the largest outflows, particularly via ammonia emissions and denitrification from agricultural systems. The N use efficiency (NUE) for crop production sharply decreased from 1961 to 1974, but went up since the late 1980s. The NUE of animal production increased from 11 % in 1961 to 20 % in 2010. The N cost of food production in Hungary largely varied from 3 to 10 kg kg(-1) during 1961-2010, which was related to changes in fertilizer use and human dietary preferences. Increased dependence of crop yield on weather was observed since the early 1990s where large decrease in N fertilizer use occurred. The observed weather-dependence has resulted in large yearly variations in crop yields, the NUE of crop production and also the food N cost, which may pose a threat to food security of Hungary.
  • Authors:
    • Goglio,Pietro
    • Smith,Ward N.
    • Grant,Brian B.
    • Desjardins,Raymond L.
    • McConkey,Brian G.
    • Campbell,Con A.
    • Nemecek,Thomas
  • Source: Journal of Cleaner Production
  • Volume: 104
  • Year: 2015
  • Summary: Soil carbon sequestration, a climate change mitigation option for agriculture, can either increase or decrease as a result of land management change (LMC) and land use change (LUC). To estimate all greenhouse gas (GHG) exchanges associated with various agricultural systems, life cycle assessments (LCAs) are frequently undertaken. To date LCA practitioners have not had a well-defined procedure to account for soil C in their assessments and as a consequence it is often not included. In this study, various methods used to estimate soil C changes due to (i) LMC and (ii) LUC are examined to assess soil C accounting methodologies in the life cycle inventory (LCI) of agricultural LCAs. A compromise between accuracy and completeness in LCA methods is necessary. A ranking of the preference of soil C accounting methods is suggested based on user expertise and data quality. For large scale assessment, the timing of soil CO2 emissions should be taken into account. If indirect LUC is relevant, a sensitivity analysis of assessment methods should be conducted because the methods highly affect assessment results. A common soil C accounting method that can be easily applied in agricultural LCA needs to be established and an agreement on indirect LUC methods will facilitate the assessment of LMC and LUC within agricultural LCAs. Crown Copyright (C) 2015 Published by Elsevier Ltd. All rights reserved.
  • Authors:
    • Herridge, D.
    • Guppy, C.
    • Begum, N.
    • Schwenke, G.
  • Source: Biology and Fertility of Soils
  • Volume: 50
  • Issue: 3
  • Year: 2014
  • Summary: Few studies have compared emissions of nitrous oxide (N2O), the potent greenhouse gas associated with decomposition of both below-ground (root) and above-ground (shoot) residues. We report a laboratory incubation experiment to evaluate effects of root and shoot residues from wheat, canola, soybean, and sorghum, incorporated into a naturally fertile acidic Black Vertisol, on N2O and carbon dioxide (CO2) emissions. The residue-amended Vertisol samples were incubated at 25 A degrees C and 70 % water-filled pore space (WFPS) to facilitate denitrification activity for a total period of 56 days. The incubated soils were periodically sampled for N2O, CO2, mineral N, and dissolved organic carbon (DOC). In general, shoot residues emitted more CO2 than roots, while N2O emissions were 50-70 % higher in cereal root residues than those in shoots. Surprisingly, the highest N2O emissions were associated with soils amended with the more inert high C/N ratio residues (wheat and sorghum roots), and to some extent, lowest emissions were associated with low C/N ratio (more labile) residues, particularly during the early stages of incubation (0-22 days). During this stage, there was a significant (p < 0.01) and negative correlation between N2O emissions and microbial respiration (CO2 efflux) and a positive (p < 0.001) correlation between microbial respiration and DOC. These results suggest that residue decomposition linked to N immobilization reduced N2O emissions during this early stage. Only, later in the study (23-56 days), did the high %N, low C/N ratio residues of soybean shoot and canola roots release at least twice as much N2O as the majority of the other treatments. We concluded that the unexpected patterns of N2O emissions were a result of the initially high mineral N content of the incubated soils and that root residues are likely to contribute substantially to emissions from cropping soils.
  • Authors:
    • Dyer, J. A.
    • Worth, D. E.
    • McConkey, B. G.
    • Desjardins, R. L.
    • Shrestha, B. M.
    • Cerkowniak, D. D.
  • Source: Renewable Energy
  • Volume: 63
  • Issue: March
  • Year: 2014
  • Summary: Accounting for greenhouse gas (GHG) emissions at the production stage of a bioenergy crop is essential for evaluating its eco-efficiency. The objective of this study was to calculate the change in GHG emissions for canola (Brassica napus L.) production on the Canadian Prairies from 1986 to 2006. Net GHG emissions in the sub-humid and semi-arid climatic zones were estimated for fallow-seeded and stubble-seeded canola in intensive-, reduced- and no-tillage systems, with consideration given to emissions associated with synthetic nitrogen (N) fertilizer input, mineralized N from crop residues, N leaching and volatilization, farm operations, the manufacturing and transportation of fertilizer, agrochemicals and farm machinery, and emission and removal of CO2 associated with changes in land use (LUC) and land management (LMC). The GHG emissions on an area basis were higher in stubble-seeded canola than in fallow-seeded canola but, the opposite was true on a grain dry matter (DM) basis. Nitrous oxide emissions associated with canola production, CO2 emissions associated with farm energy use and the manufacturing of synthetic N fertilizer and its transportation contributed 49% of the GHG emissions in 1986 which increased to 66% in 2006. Average CO2 emissions due to LUC decreased from 27% of total GHG emissions in 1986 to 8% in 2006 and soil C sequestration due to LMC increased from 8% to 37%, respectively. These changes caused a reduction in net GHG emission intensities of 40% on an area basis and of 65% on a grain DM basis. Despite the reduction in GHG emission intensities, GHG emissions associated with canola in the Prairies increased from 3.4 Tg CO2 equiv in 1986 to 3.8 Tg CO2 equiv in 2006 because of the more than doubling of canola production. Crown Copyright (C) 2013 Published by Elsevier Ltd. All rights reserved.
  • Authors:
    • Skaracis, G. N.
    • Mariolis, N. A.
    • Vlachos, C. E.
  • Source: The Journal of Agricultural Science
  • Volume: 152
  • Issue: 2
  • Year: 2014
  • Summary: Sunflower (Helianthus annuus L.) and rapeseed (Brassica napus L.) are considered as the most suitable crops for biodiesel production in the Mediterranean basin. Soybean (Glycine max L.) could also be used, under certain conditions. In Greece, the farming practice adopted in each region varies significantly, leading to significant differences in the levels of emitted greenhouse gases (GHG). Greenhouse gas emissions were estimated during the cultivation phase as grams of carbon dioxide equivalents (g CO 2e) per megajoule (MJ), followed by emission savings (%) estimation when fossil fuels are replaced by biodiesel. Crop and region comparisons provided important information towards promoting sustainability. Overall, sunflower demonstrated the lowest average emissions, 53.8 g CO 2e/MJ, followed by rapeseed and soybean. Furthermore, rapeseed achieved the lowest emission saving level required by European legislation in most cases studied, with an average value of 37%. Irrigation and nitrogen fertilization were the operations mostly contributing to the total quantity of GHG emissions. More specifically, the highest GHG emissions were found for soybean irrigation (34%) and rapeseed nitrogen fertilization (68%).
  • Authors:
    • Zhu, Y. G.
    • Su, J. Q.
    • Yao, H. Y.
    • Li, H.
    • Wang, . H.
    • Xu, H. J.
  • Source: ENVIRONMENTAL SCIENCE & TECHNOLOGY
  • Volume: 48
  • Issue: 16
  • Year: 2014
  • Summary: Biochar has been suggested to improve acidic soils and to mitigate greenhouse gas emissions. However, little has been done on the role of biochar in ameliorating acidified soils induced by overuse of nitrogen fertilizers. In this study, we designed a pot trial with an acidic soil (pH 4.48) in a greenhouse to study the interconnections between microbial community, soil chemical property changes, and N2O emissions after biochar application. The results showed that biochar increased plant growth, soil pH, total carbon, total nitrogen, C/N ratio, and soil cation exchange capacity. The results of high-throughput sequencing showed that biochar application increased alpha-diversity significantly and changed the relative abundances of some microbes that are related with carbon and nitrogen cycling at the family level. Biochar amendment stimulated both nitrification and denitrification processes, while reducing N2O emissions overall. Results of redundancy analysis indicated biochar could shift the soil microbial community by changing soil chemical properties, which modulate N-cycling processes and soil N2O emissions. The significantly increased nosZ transcription suggests that biochar decreased soil N2O emissions by enhancing its further reduction to N-2.
  • Authors:
    • Carboni, G.
    • Virdis, A.
    • Sulas, L.
    • Ledda, L.
    • Deligios, P. A.
    • Cocco, D.
  • Source: ENERGIES
  • Volume: 7
  • Issue: 10
  • Year: 2014
  • Summary: This paper reports outcomes of life cycle assessments (LCAs) of three different oleaginous bioenergy chains (oilseed rape, Ethiopian mustard and cardoon) under Southern Europe conditions. Accurate data on field practices previously collected during a three-year study at two sites were used. The vegetable oil produced by oleaginous seeds was used for power generation in medium-speed diesel engines while the crop residues were used in steam power plants. For each bioenergy chain, the environmental impact related to cultivation, transportation of agricultural products and industrial conversion for power generation was evaluated by calculating cumulative energy demand, acidification potential and global warming potential. For all three bioenergy chains, the results of the LCA study show a considerable saving of primary energy (from 70 to 86 GJ.ha(-1)) and greenhouse gas emissions (from 4.1 to 5.2 t CO2.ha(-1)) in comparison to power generation from fossil fuels, although the acidification potential of these bioenergy chains may be twice that of conventional power generation. In addition, the study highlights that land use changes due to the cultivation of the abovementioned crops reduce soil organic content and therefore worsen and increase greenhouse gas emissions for all three bioenergy chains. The study also demonstrates that the exploitation of crop residues for energy production greatly contributes to managing environmental impact of the three bioenergy chains.