• Authors:
    • Luna-Guido, M.
    • Dendooven, L.
    • del Rosario Cardenas-Aquino, M.
    • Diaz-Rojas, M.
    • Aguilar-Chavez, A.
  • Source: Soil Biology and Biochemistry
  • Volume: 52
  • Issue: September
  • Year: 2012
  • Summary: Applying biochar to soil is an easy way to sequester carbon in soil, while it might reduce greenhouse gas (GHG) emissions and stimulate plant growth. The effect of charcoal application (0, 1.5, 3.0 and 4.5%) on GHG emission was studied in a wastewater sludge-amended arable soil (Typic Fragiudepts) cultivated with wheat (Triticum spp. L) in a greenhouse. The application of charcoal at >= 1.5% reduced the CO2 emission rate significantly >= 37% compared to unamended soil (135.3 g CO2 ha(-1) day(-1)) in the first two weeks, while the N2O emission rate decreased 44% when 4.5% charcoal was added (0.72 g N2O ha(-1) day(-1)). The cumulative GHG emission over 45 days was 2% lower when 1.5% charcoal, 34% lower when 3.0% charcoal and 39% lower when 4.5% charcoal was applied to the sludge-amended soil cultivated with wheat. Wheat growth was inhibited in the charcoal-amended soil compared to the unamended soil, but not yields after 135 days. It was found that charcoal addition reduced the emissions of N2O and CO2, and the cumulative GHG emissions over 45 days, without altering wheat yield. (C) 2012 Elsevier Ltd. All rights reserved.
  • Authors:
    • Recous, S
    • Cadoux, S.
    • Bertrand, I.
    • Amougou, N.
  • Source: GCB Bioenergy
  • Volume: 4
  • Issue: 6
  • Year: 2012
  • Summary: Energy crops are currently promoted as potential sources of alternative energy that can help mitigate the climate change caused by greenhouse gases (GHGs). The perennial crop Miscanthus x giganteus is considered promising due to its high potential for biomass production under conditions of low input. However, to assess its potential for GHG mitigation, a better quantification of the crop's contribution to soil organic matter recycling under various management systems is needed. The aim of this work was to study the effect of abscised leaves on carbon (C) and nitrogen (N) recycling in a Miscanthus plantation. The dynamics of senescent leaf fall, the rate of leaf decomposition (using a litter bag approach) and the leaf accumulation at the soil surface were tracked over two 1-year periods under field conditions in Northern France. The fallen leaves represented an average yearly input of 1.40 Mg C ha-1 and 16 kg N ha-1. The abscised leaves lost approximately 54% of their initial mass in 1 year due to decomposition; the remaining mass, accumulated as a mulch layer at the soil surface, was equivalent to 7 Mg dry matter (DM) ha-1 5 years after planting. Based on the estimated annual leaf-C recycling rate and a stabilization rate of 35% of the added C, the annual contribution of the senescent leaves to the soil C was estimated to be approximately 0.50 Mg C ha-1yr-1 or 10 Mg C ha-1 total over the 20-year lifespan of a Miscanthus crop. This finding suggested that for Miscanthus, the abscised leaves contribute more to the soil C accumulation than do the rhizomes or roots. In contrast, the recycling of the leaf N to the soil was less than for the other N fluxes, particularly for those involving the transfer of N from the tops of the plant to the rhizome.
  • Authors:
    • Matthews, R.
    • Balana, B. B.
    • Bakam, I.
  • Source: Journal of Environmental Management
  • Volume: 112
  • Issue: December
  • Year: 2012
  • Summary: Market-based policy instruments to reduce greenhouse gas (GHG) emissions are generally considered more appropriate than command and control tools. However, the omission of transaction costs from policy evaluations and decision-making processes may result in inefficiency in public resource allocation and sub-optimal policy choices and outcomes. This paper aims to assess the relative cost-effectiveness of market-based GHG mitigation policy instruments in the agricultural sector by incorporating transaction costs. Assuming that farmers' responses to mitigation policies are economically rationale, an individual-based model is developed to study the relative performances of an emission tax, a nitrogen fertilizer tax, and a carbon trading scheme using farm data from the Scottish farm account survey (FAS) and emissions and transaction cost data from literature metadata survey. Model simulations show that none of the three schemes could be considered the most cost effective in all circumstances. The cost effectiveness depends both on the tax rate and the amount of free permits allocated to farmers. However, the emissions trading scheme appears to outperform both other policies in realistic scenarios. (C) 2012 Elsevier Ltd. All rights reserved.
  • Authors:
    • Klakegg, O.
    • Janzen, H. H.
    • Skjelvag, A. O.
    • Bonesmo, H.
    • Tveito, O. E.
  • Source: Agricultural Systems
  • Volume: 110
  • Issue: July
  • Year: 2012
  • Summary: To increase food production while mitigating climate change, cropping systems in the future will need to reduce greenhouse gas emission per unit of production. We conducted an analysis of 95 arable farms in Norway to calculate farm scale emissions of greenhouse gases, expressed both as CO2 eq per unit area, and CO2 eq per kg DM produced and to describe relationships between the farms' GHG intensities and heir economic efficiencies (gross margin). The study included: (1) design of a farm scale model for net GHG emission from crop production systems; (2) establishing a consistent farm scale data set for the farms with required soil, weather, and farm operation data; (3) a stochastic simulation of the variation in the sources of GHG emission intensities, and sensitivity analysis of selected parameters and equations on GHG emission intensities; and (4) describing relationships between GHG emission intensities and gross margins on farms. Among small seed and grain crops the variation in GHG emissions per kg DM was highest in oilseed (emission intensity at the 75th percentile level was 1.9 times higher than at the 25th percentile). For barley, oats, spring wheat, and winter wheat, emissions per kg DM at the 75th percentile levels were between 1.4 and 1.6 times higher than those at the 25th percentiles. Similar trends were observed for emissions per unit land area. Invariably soil N2O emission was the largest source of GHG emissions, accounting for almost half of the emissions. The second largest source was the off farm manufacturing of inputs (similar to 25%). Except for the oilseed crop, in which soil carbon (C) change contributed least, the on farm emissions due to fuel use contributed least to the total GHG intensities (similar to 10%). The soil C change contributed most to the variability in GHG emission intensities among farms in all crops, and among the sensitivity elasticities the highest one was related to environmental impacts on soil C change. The high variation in GHG intensities evident in our study implies the potential for significant mitigation of GHG emissions. The GHG emissions per kg DM (intensity) decreased with increasing gross margin in grain and oilseed crops, suggesting that crop producers have economic incentives to reduce GHG emissions. (c) 2012 Elsevier Ltd. All rights reserved,
  • Authors:
    • Fitt, B. D. L.
    • Smith, P.
    • West, J. S.
    • Carlton, R. R.
  • Source: European Journal of Plant Pathology
  • Volume: 133
  • Issue: 1
  • Year: 2012
  • Summary: Crop disease not only threatens global food security by reducing crop production at a time of growing demand, but also contributes to greenhouse gas (GHG) emissions by reducing efficiency of N fertiliser use and farm operations and by driving land use change. GHG emissions associated with adoption of reduced tillage, organic and integrated systems of field crop production across the UK and selected regions are compared with emissions from conventional arable farming to assess their potential for climate change mitigation. The reduced tillage system demonstrated a modest (< 20%) reduction in emissions in all cases, although in practice it may not be suitable for all soils and it is likely to cause problems with control of diseases spread on crop debris. There were substantial increases in GHG emissions associated with the organic and integrated systems at national level, principally due to soil organic carbon losses from land use change. At a regional level the integrated system shows the potential to deliver significant emission reductions. These results indicate that the conventional crop production system, coupled to reduced tillage cultivation where appropriate, is generally the best for producing high yields to minimise greenhouse gas emissions and contribute to global food security, although there may be scope for use of the integrated system on a regional basis. The control of crop disease will continue to have an essential role in both maintaining productivity and decreasing GHG emissions.
  • Authors:
    • Allen, R. B.
    • Mason, N. W. H.
    • Hall, G. M. J.
    • Burrows, L. E.
    • Carswell, F. E.
  • Source: New Zealand Journal of Ecology
  • Volume: 36
  • Issue: 2
  • Year: 2012
  • Summary: Natural regeneration of new forests has significant potential to mitigate greenhouse gas emissions, but how strong is the potential biodiversity co-benefit? We quantified carbon accumulation and biodiversity gain during secondary succession of two New Zealand lowland forests. The rate of carbon sequestration was the same for the kanuka-red beech succession as for the coastal broadleaved succession (c. 2.3 Mg C ha(-1) year(-1)) over the first 50 years of succession. Mean above-ground carbon stocks were 148 +/- 13 Mg C ha(-1) for kanuka-red beech forests and 145 +/- 19 Mg C ha(-1) for tall coastal broadleaved forests after at least 50 years of succession. Biodiversity gain was investigated through the quantification of 'ecological integrity', which comprises dominance by indigenous species, occupancy of indigenous species or a group of species fulfilling a particular ecological role, and gain in representation of lowland forests within each ecological region. All components of ecological integrity increased with carbon accumulation for both successions. In addition, above-ground carbon stocks were correlated with the Shannon and Simpson diversity indices and species richness for both successions, suggesting that conventional metrics of diversity also show biodiversity gain with above-ground carbon during succession of recently non-forested lands to secondary forest.
  • Authors:
    • Schmidt, J. E.
    • Thomsen, S. T.
    • Jensen, M.
    • Heiske, S.
    • Hauggaard-Nielsen, H.
    • Carter, M. S.
    • Johansen, A.
    • Ambus, P.
  • Source: GCB Bioenergy
  • Volume: 4
  • Issue: 4
  • Year: 2012
  • Summary: One way of reducing the emissions of fossil fuel-derived carbon dioxide (CO2) is to replace fossil fuels with biofuels produced from agricultural biomasses or residuals. However, cultivation of soils results in emission of other greenhouse gases (GHGs), especially nitrous oxide (N2O). Previous studies on biofuel production systems showed that emissions of N2O may counterbalance a substantial part of the global warming reduction, which is achieved by fossil fuel displacement. In this study, we related measured field emissions of N2O to the reduction in fossil fuel-derived CO2, which was obtained when agricultural biomasses were used for biofuel production. The analysis included five organically managed feedstocks (viz. dried straw of sole cropped rye, sole cropped vetch and intercropped ryevetch, as well as fresh grassclover and whole crop maize) and three scenarios for conversion of biomass into biofuel. The scenarios were (i) bioethanol, (ii) biogas and (iii) coproduction of bioethanol and biogas. In the last scenario, the biomass was first used for bioethanol fermentation and subsequently the effluent from this process was utilized for biogas production. The net GHG reduction was calculated as the avoided fossil fuel-derived CO2, where the N2O emission was subtracted. This value did not account for fossil fuel-derived CO2 emissions from farm machinery and during conversion processes that turn biomass into biofuel. The greatest net GHG reduction, corresponding to 700800 g CO2 m(-2), was obtained by biogas production or coproduction of bioethanol and biogas on either fresh grassclover or whole crop maize. In contrast, biofuel production based on lignocellulosic crop residues (i.e. rye and vetch straw) provided considerably lower net GHG reductions (=215 g CO2 m(-2)), and even negative numbers sometimes. No GHG benefit was achieved by fertilizing the maize crop because the extra crop yield, and thereby increased biofuel production, was offset by enhanced N2O emissions.
  • Authors:
    • Lorentz, S.
    • Manson, A.
    • Mchunu, C. N.
    • Chaplot, V.
    • Jewitt, G.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 159
  • Issue: September
  • Year: 2012
  • Summary: The acceleration of soil erosion by water in most regions of the world in response to the anthropogenic modification of landscapes is a serious threat to natural ecosystem functionalities because of the loss of invaluable constituents such as soil particles and organic carbon (OC). While soil OC erosion is likely to be a major component of the global C cycle, water erosion-induced CO2 emissions remain uncertain. In this study, our main objective was to compare the release of CO2 from eroded topsoils and from the sediments exported by diffuse erosion during an entire rainy season. Conventional tillage (CT) and no-tillage (NT) maize treatments were considered in an attempt to set up best management practices to mitigate gaseous OC losses from agricultural soils. The study was conducted in the KwaZulu-Natal province in South Africa, whereas in many other areas of the developing world, erosion is severe and crop residue scarcity is the main challenge. CO2 emissions from undisturbed 0-0.02 m soil samples collected within 2.25 m x 10 m runoff plots and from exported sediments by water erosion, were evaluated continuously at the laboratory over a 140-day period and compared to soil OC stocks. NT significantly reduced CO2 emissions from both soils and sediments. Overall NT, which exhibited a greater carbon density than CT (17.70 vs 13.19 kg C m(-3)), reduced soil gaseous emissions by 4.4% (10.40 vs 10.88 gCO(2)-C m(-2), P < 0.05) but had a much greater impact on the release of CO2 from eroded sediments (0.185 vs 0.778 gCO(2)-C m(-2)), which corresponded to a 76.3% decrease. For CT, cumulative 141-day emissions were, 19% greater in sediments (0.048 g CO2-C g C-1) compared to soils (0.040 gCO(2)-C g C-1), while for NT, emissions were 33% lower in sediments (0.024 g CO2-C g C-1) compared to soils (0.032 g CO2-C g C-1), these differences being significant at P < 0.05. The lower erosion-induced CO2 emissions under NT could be explained by a high soil aggregate stability (mean weight diameter of 2.29 +/- 0.05 mm for NT vs 1.59 +/- 0.07 mm for CT, P < 0.05) and the associated enhanced protection of SOC from the decomposers. These results on a land management control of water erosion-induced CO2 emissions, might allow improving the impact of terrestrial ecosystems on greenhouse gases concentration in the atmosphere and associated climate change. (C) 2012 Elsevier B.V. All rights reserved.
  • Authors:
    • Vasquez-Murrieta, S.
    • Gutierrez-Miceli, F. A.
    • Montes-Molina, J.
    • Marsch, R.
    • Luna-Guido, M.
    • Verhulst, N.
    • Ramirez-Villanueva, D. A.
    • Patino-Zuniga, L.
    • Gutierrez-Oliva, V. F.
    • Dendooven, L.
    • Govaerts, B.
  • Source: Science of The Total Environment
  • Volume: 431
  • Issue: August
  • Year: 2012
  • Summary: In 1991, the 'International Maize and Wheat Improvement Center' (CIMMYT) started a field experiment in the rain fed Mexican highlands to investigate conservation agriculture (CA) as a sustainable alternative for conventional maize production practices (CT). CT techniques, characterized by deep tillage, monoculture and crop residue removal, have deteriorated soil fertility and reduced yields. CA, which combines minimum tillage, crop rotations and residue retention, restores soil fertility and increases yields. Soil organic matter increases in CA compared to CT, but increases in greenhouse gas emissions (GHG) in CA might offset the gains obtained to mitigate global warming. Therefore, CO2, CH4 and N2O emissions, soil temperature, C and water content were monitored in CA and CT treatments in 2010-2011. The cumulative GHG emitted were similar for CA and CT in both years, but the C content in the 0-60 cm layer was higher in CA (117.7 Mg C ha(-1)) than in CT (69.7 Mg C ha(-1)). The net global warming potential (GWP) of CA (considering soil C sequestration, GHG emissions, fuel use, and fertilizer and seeds production) was -7729 kg CO2 ha(-1) y(-1) in 2008-2009 and -7892 kg CO2 ha(-1) y(-1) in 2010-2011, whereas that of CT was 1327 and 1156 kg CO2 ha(-1) y(-1). It was found that the contribution of CA to GWP was small compared to that of CT. (C) 2012 Elsevier B.V. All rights reserved.
  • Authors:
    • Marsch, R.
    • Luna-Guido, M.
    • Verhulst, N.
    • Patino-Zuniga, L.
    • Dendooven, L.
    • Govaerts, B.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 152
  • Issue: May
  • Year: 2012
  • Summary: Conservation agriculture based on (1) minimal soil movement, (2) retention of rational amounts of crop residue, (3) economically viable crop rotations restores soil fertility. Conservation agriculture improves soil characteristics, but it remains to be seen how zero tillage (ZT) affected greenhouse gas emissions (GHG) and the global warming potential (GWP) compared to conventional tillage (Cr) when crop residue was kept or removed in a maize-wheat crop rotation since 1991. The soil organic C content in the 0-60 cm layer was larger in ZT (117.7 Mg C ha(-1)) compared to CT (76.8 Mg C ha(-1)) when residue was retained, but similar when it was removed. Tillage and residue management had only a small effect on GWP of the GHG emissions. However, the C sequestered in the 0-60cm was affected by tillage and crop residue management, resulting in a negative net GWP for ZT with crop residue retention (-6.277 Mg CO2 ha(-1) y(-1)) whereas in the other management practices it ranged from 1.288 to 1.885 Mg CO2 ha(-1) y(-1). It was found that cultivation technique had little effect on the GWP of the GHG, but had a large effect on C sequestered in the 0-60cm layer and the net GWP. (C) 2012 Elsevier B.V. All rights reserved.