19832015
  • Authors:
    • Thomazini,A.
    • Spokas,K.
    • Hall,K.
    • Ippolito,J.
    • Lentz,R.
    • Novak,J.
  • Source: Agriculture, Ecosystems and Environment
  • Volume: 207
  • Year: 2015
  • Summary: One potential strategy to abate increasing atmospheric carbon dioxide (CO 2) levels is to sequester CO 2 as biochar, a structural form of carbon created through the pyrolysis of various biomass materials. Biochar may be applied to soils, but has resulted in variable impacts on net soil greenhouse gas (GHG) emissions, with results spanning from suppression to stimulation. This laboratory incubation study examined the impacts of the same hardwood biochar (fast pyrolysis at 550°C) to elucidate driving variables affecting previously observed carbon dioxide (CO 2) fluctuations as well as nitrous oxide (N 2O), and methane (CH 4) production impacts across ten different US soils with and without biochar (10% w/w). Biochar application significantly impacted CO 2 ( P=0.04) and N 2O ( P=0.03) production following amendment across all soils, but there were no differences observed in CH 4 production/oxidation rates ( P=0.90). Interestingly, the induced biochar GHG alterations were significantly correlated to the original GHG production activity in the control soil, suggesting a more universal response across various soils to the same biochar than has been previously hypothesized. After correcting for the amount of CO 2 released from the biochar itself [24 g C g BC-1 d -1], there was no statistically significant alteration in the actual soil CO 2 mineralization rate for any soil. This suggests that the observed increase in CO 2 production was solely attributed to the abiotic CO 2 releases from the biochar. On the other hand, there was an average suppression of 63% in the N 2O production across all soils following biochar addition, which was again correlated to initial N 2O production activity. For this particular biochar, there are predictable impacts on the GHG production potential across various soils despite differences in soil chemistry, texture, and microbial communities.
  • Authors:
    • Winchester,N.
    • Reilly,J. M.
  • Source: Energy Economics
  • Volume: 51
  • Year: 2015
  • Summary: What are the feasibility, costs, and environmental implications of large-scale bioenegry? We investigate this question by developing a detailed representation of bioenergy in a global economy-wide model. We develop a scenario with a global carbon dioxide price, applied to all anthropogenic emissions except those from land use change, that rises from $25 per metric ton in 2015 to $99 in 2050. This creates market conditions favorable to biomass energy, resulting in global non-traditional bioenergy production of ~. 150 exajoules (EJ) in 2050. By comparison, in 2010, global energy production was primarily from coal (138 EJ), oil (171 EJ), and gas (106 EJ). With this policy, 2050 emissions are 42% less in our Base Policy case than our Reference case, although extending the scope of the carbon price to include emissions from land use change would reduce 2050 emissions by 52% relative to the same baseline. Our results from various policy scenarios show that lignocellulosic (LC) ethanol may become the major form of bioenergy, if its production costs fall by amounts predicted in a recent survey and ethanol blending constraints disappear by 2030; however, if its costs remain higher than expected or the ethanol blend wall continues to bind, bioelectricity and bioheat may prevail. Higher LC ethanol costs may also result in the expanded production of first-generation biofuels (ethanol from sugarcane and corn) so that they remain in the fuel mix through 2050. Deforestation occurs if emissions from land use change are not priced, although the availability of biomass residues and improvements in crop yields and conversion efficiencies mitigate pressure on land markets. As regions are linked via international agricultural markets, irrespective of the location of bioenergy production, natural forest decreases are largest in regions with the lowest barriers to deforestation. In 2050, the combination of carbon price and bioenergy production increases food prices by 3.2%-5.2%, with bioenergy accounting for 1.3%-3.5%. © 2015.
  • Authors:
    • He, X.
    • Guan, Q.
    • Lu, X.
    • Lu, M.
    • Wu, H.
  • Source: Biology Article
  • Volume: 88
  • Year: 2015
  • Summary: Soil fauna can significantly affect soil CO2 and N2O emissions, but little is known about interactions between faunal groups and their relative contribution to such emissions. Over a 64-day microcosm incubation, we studied the effects of an epigeic earthworm (Eisenia fetida), mesofauna (Collembola plus oribatid mites) and their combinations on soil CO2 and N2O emissions under two faunal densities. Earthworms significantly enhanced soil CO2 and N2O emissions, while mesofauna only increased N2O emissions. Soil CO2 and N2O emissions were significantly affected by earthworm density, but not by mesofauna density. No significant interactive effects between earthworms and mesofauna were found on soil CO2 and N2O emissions. Our results indicate that earthworms probably play the dominant roles in determining soil CO2 and N2O emissions where they coexist with soil mesofauna. (C) 2015 Elsevier Ltd. All rights reserved.
  • Authors:
    • Banger,Kamaljit
    • Tian,Hanqin
    • Tao,Bo
    • Ren,Wei
    • Pan,Shufen
    • Dangal,Shree
    • Yang,Jia
  • Source: Climatic Change
  • Volume: 132
  • Issue: 4
  • Year: 2015
  • Summary: India is very important but relatively unexplored region in terms of carbon studies, where significant environmental changes have occurred in the 20th century that can alter terrestrial net primary productivity (NPP). Here, we used a process-based, Dynamic Land Ecosystem Model (DLEM), driven by land cover and land use change (LCLUC), climate change, elevated atmospheric CO2 concentration, atmospheric nitrogen deposition (NDEP), and tropospheric ozone (O-3) pollution to estimate terrestrial NPP in India during 1901-2010. Over the country, terrestrial NPP showed significant inter-annual variations ranging 1.2 Pg C year(-1) to 1.7 Pg C year(-1) during the 1901-2010. Overall, multiple environmental changes have increased terrestrial NPP by 0.23 Pg C year(-1). Elevated atmospheric CO2 concentration has increased NPP by 0.29 Pg C; however climate change has offset a portion of terrestrial NPP (0.11 Pg C) during this study period. On an average, terrestrial NPP reduced by 0.12 Pg C year(-1) in drought years; when precipitation was 100 mm year(-1) lower than long term average, suggesting that terrestrial carbon cycle in India is strongly linked to climate change. LCLUC, including land conversions and cropland management practices, increased terrestrial NPP by 0.043 Pg C year(-1) over the country. Tropospheric O-3 pollution reduced terrestrial NPP by 0.06 Pg C year(-1) and the decrease was comparatively higher in croplands than other biomes after the 1980s. Our results have shown that climate change and tropospheric O-3 pollution may partially offset terrestrial NPP increase caused by elevated CO2 concentration, LCLUC, and NDEP over India.
  • Authors:
    • Jones, L. E.
    • Maddison, A. L.
    • Castle, M.
    • Barraclough, T. J. P.
    • Purdy, S. J.
    • Cunniff, J.
    • Shield, I. F.
    • Gregory, A. S.
    • Karp, A.
  • Source: Science Article
  • Volume: 80
  • Year: 2015
  • Summary: Willows ( Salix spp.) grown as short rotation coppice (SRC) are viewed as a sustainable source of biomass with a positive greenhouse gas (GHG) balance due to their potential to fix and accumulate carbon (C) below ground. However, exploiting this potential has been limited by the paucity of data available on below ground biomass allocation and the extent to which it varies between genotypes. Furthermore, it is likely that allocation can be altered considerably by environment. To investigate the role of genotype and environment on allocation, four willow genotypes were grown at two replicated field sites in southeast England and west Wales, UK. Above and below ground biomass was intensively measured over two two-year rotations. Significant genotypic differences in biomass allocation were identified, with below ground allocation differing by up to 10% between genotypes. Importantly, the genotype with the highest below ground biomass also had the highest above ground yield. Furthermore, leaf area was found to be a good predictor of below ground biomass. Growth environment significantly impacted allocation; the willow genotypes grown in west Wales had up to 94% more biomass below ground by the end of the second rotation. A single investigation into fine roots showed the same pattern with double the volume of fine roots present. This greater below ground allocation may be attributed primarily to higher wind speeds, plus differences in humidity and soil characteristics. These results demonstrate that the capacity exists to breed plants with both high yields and high potential for C accumulation.
  • Authors:
    • Cabral, F.
    • Surgy, S.
    • Bichana, A.
    • Pereira, J.
    • Fangueiro, D.
    • Coutinho, J .
  • Source: Research Article
  • Volume: 162
  • Year: 2015
  • Summary: Cattle-slurry (liquid manure) application to soil is a common practice to provide nutrients and organic matter for crop growth but it also strongly impacts the environment. The objective of the present study was to assess the efficiency of cattle-slurry treatment by solid-liquid separation and/or acidification on nitrogen dynamics and global warming potential (GWP) following application to an acidic soil. An aerobic laboratory incubation was performed over 92 days with a Dystric Cambisol amended with raw cattle-slurry or separated liquid fraction (LF) treated or not by acidification to pH 5.5 by addition of sulphuric acid. Soil mineral N contents and NH 3, N 2O, CH 4 and CO 2 emissions were measured. Results obtained suggest that the acidification of raw cattle-slurry reduced significantly NH 3 emissions (-88%) but also the GWP (-28%) while increased the N availability relative to raw cattle-slurry (15% of organic N applied mineralised against negative mineralisation in raw slurry). However, similar NH 3 emissions and GWP were observed in acidified LF and non-acidified LF treatments. On the other hand, soil application of acidified cattle-slurry rather than non-acidified LF should be preferred attending the lower costs associated to acidification compared to solid-liquid separation. It can then be concluded that cattle-slurry acidification is a solution to minimise NH 3 emissions from amended soil and an efficient strategy to decrease the GWP associated with slurry application to soil. Furthermore, the more intense N mineralisation observed with acidified slurry should lead to a higher amount of plant available N and consequently to higher crop yields.
  • Authors:
    • Franklin,D.
    • Bender-Özenç,D.
    • Özenç,N.
    • Cabrera,M.
  • Source: Soil Science Society of America Journal
  • Volume: 79
  • Issue: 5
  • Year: 2015
  • Summary: composts and soil conditioners may be useful soil amendments to provide organic matter as well as nutrients such as n and P, but net n mineralized and P released can vary greatly among materials. consequently, it is important to identify the material characteristics that control these processes. Furthermore, the magnitude of these processes may be affected by particle size. we conducted two laboratory studies at 30°c to: (i) identify variables that can be used to estimate n mineralized and Mehlich-1 P released from 14 composts and soil conditioners; and (ii) evaluate net n mineralized from three size fractions (<1.0 mm, 1.0-2.0, and 2.0-4.0 mm) of five different composts. organic n content and c/n ratio explained 83% of the variability in the amount of net n mineralized or immobilized per unit of material from the 14 composts or conditioners in 214 d. similarly, organic n content and total P content explained 99% of the variability in the amount of Mehlich-1 P released per unit of material. in the study with size fractions, we found that larger size fractions (1-4 mm) mineralized more n (4% of applied n) than the 0-to 1-mm size fraction (0.5%). these results indicate that sieving composts to obtain specific size fractions may affect the rate of n mineralization. © Soil Science Society of America, 5585 Guilford Rd., Madison WI 53711 USA. All Rights reserved.
  • Authors:
    • Ho,A.
    • Reim,A.
    • Kim SangYoon
    • Meima-Franke,M.
    • Termorshuizen,A.
    • Boer,W. de
    • Putten,W. H. van der
    • Bodelier,P. L. E.
  • Source: Global Change Biology
  • Volume: 21
  • Issue: 10
  • Year: 2015
  • Summary: Intensification of agriculture to meet the global food, feed, and bioenergy demand entail increasing re-investment of carbon compounds (residues) into agro-systems to prevent decline of soil quality and fertility. However, agricultural intensification decreases soil methane uptake, reducing, and even causing the loss of the methane sink function. In contrast to wetland agricultural soils (rice paddies), the methanotrophic potential in well-aerated agricultural soils have received little attention, presumably due to the anticipated low or negligible methane uptake capacity in these soils. Consequently, a detailed study verifying or refuting this assumption is still lacking. Exemplifying a typical agricultural practice, we determined the impact of bio-based residue application on soil methane flux, and determined the methanotrophic potential, including a qualitative (diagnostic microarray) and quantitative (group-specific qPCR assays) analysis of the methanotrophic community after residue amendments over 2 months. Unexpectedly, after amendments with specific residues, we detected a significant transient stimulation of methane uptake confirmed by both the methane flux measurements and methane oxidation assay. This stimulation was apparently a result of induced cell-specific activity, rather than growth of the methanotroph population. Although transient, the heightened methane uptake offsets up to 16% of total gaseous CO 2 emitted during the incubation. The methanotrophic community, predominantly comprised of Methylosinus may facilitate methane oxidation in the agricultural soils. While agricultural soils are generally regarded as a net methane source or a relatively weak methane sink, our results show that methane oxidation rate can be stimulated, leading to higher soil methane uptake. Hence, even if agriculture exerts an adverse impact on soil methane uptake, implementing carefully designed management strategies (e.g. repeated application of specific residues) may compensate for the loss of the methane sink function following land-use change.
  • Authors:
    • Karlen,D. L.
    • Beeler,L. W.
    • Ong,R. G.
    • Dale,B. E.
  • Source: Journal of Soil and Water Conservation
  • Volume: 70
  • Issue: 5
  • Year: 2015
  • Authors:
    • Hierold, W.
    • Miller, B. A.
    • Koszinski, S.
    • Haelbich, H.
    • Sommer, M.
  • Source: Soil Science Society of America Journal
  • Volume: 79
  • Issue: 5
  • Year: 2015
  • Summary: Spatial variation of c stocks within peatlands is an overall challenge for monitoring global c cycle processes, which is critical for responding to climate change induced by greenhouse gases (GHGs). the objective of this study was to evaluate the ability of high-resolution, minimally invasive sensor data to predict spatial variation of soil organic c (soc) stocks within highly degraded peatland soils in northeast Germany. within the rhin-Havelluch, a paludification mire that has been cultivated and drained for about 300 yr, seven fields were sampled by soil cores up to 2 m in depth, nine points for each field. soil horizons were examined for dry bulk density, soil organic c content (socc), and thickness to calculate soc stocks and to test for relationships with overall peat thickness, elevation, and electrical conductivity (eca). elevation was determined by light detection and ranging (LIDAR) and eca by an eM38dd, both producing maps of high resolution (1 m). soil organic c density (socd) was related to elevation, eca, and peat thickness. Based on these relationships, maps of socd were produced. within field variation of socd was high, which could be modeled by use of the covariate maps. if available, eca maps can improve the prediction of socd based on elevation. Modeling peat thickness based on sensor data needs additional research, but seems to be a valuable covariate in digital soil mapping. © Soil Science Society of America, 5585 Guilford Rd., Madison WI 53711 USA. All Rights reserved.