• Authors:
    • Jones, R.
    • Hatfield, J. L.
    • Chan, A. S. K.
    • Parkin, T. B.
    • Jarecki, M. K.
  • Source: Journal of Environmental Quality
  • Volume: 37
  • Issue: 4
  • Year: 2008
  • Summary: The interactive effects of soil texture and type of N fertility (i.e., manure vs. commercial N fertilizer) on N2O and CH4 emissions have not been well established. This study was conducted to assess the impact of soil type and N fertility on greenhouse gas fluxes (N2O, CH4, and CO2) from the soil surface. The soils used were a sandy loam (789 g kg-1 sand and 138 g kg-1 clay) and a clay soil (216 g kg-1 sand, and 415 g kg-1 clay). Chamber experiments were conducted using plastic buckets as the experimental units. The treatments applied to each soil type were: (i) control (no added N), (ii) urea-ammonium nitrate (UAN), and (iii) liquid swine manure slurry. Greenhouse gas fluxes were measured over 8 weeks. Within the UAN and swine manure treatments both N2O and CH4 emissions were greater in the sandy loam than in the clay soil. In the sandy loam soil N2O emissions were significantly different among all N treatments, but in the clay soil only the manure treatment had significantly higher N2O emissions. It is thought that the major differences between the two soils controlling both N2O and CH4 emissions were cation exchange capacity (CEC) and percent water-filled pore space (%WFPS). We speculate that the higher CEC in the clay soil reduced N availability through increased adsorption of NH4+ compared to the sandy loam soil. In addition the higher average %WFPS in the sandy loam may have favored higher denitrification and CH4 production than in the clay soil.
  • Authors:
    • Laird, D. A.
  • Source: Agronomy Journal
  • Volume: 100
  • Issue: 1
  • Year: 2008
  • Summary: Processing biomass through a distributed network of fast pyrolyzers may be a sustainable platform for producing energy from biomass. Fast pyrolyzers thermally transform biomass into bio-oil, syngas, and charcoal. The syngas could provide the energy needs of the pyrolyzer. Bio-oil is an energy raw material ([~]17 MJ kg-1) that can be burned to generate heat or shipped to a refinery for processing into transportation fuels. Charcoal could also be used to generate energy; however, application of the charcoal co-product to soils may be key to sustainability. Application of charcoal to soils is hypothesized to increase bioavailable water, build soil organic matter, enhance nutrient cycling, lower bulk density, act as a liming agent, and reduce leaching of pesticides and nutrients to surface and ground water. The half-life of C in soil charcoal is in excess of 1000 yr. Hence, soil-applied charcoal will make both a lasting contribution to soil quality and C in the charcoal will be removed from the atmosphere and sequestered for millennia. Assuming the United States can annually produce 1.1 x 109 Mg of biomass from harvestable forest and crop lands, national implementation of The Charcoal Vision would generate enough bio-oil to displace 1.91 billion barrels of fossil fuel oil per year or about 25% of the current U.S. annual oil consumption. The combined C credit for fossil fuel displacement and permanent sequestration, 363 Tg per year, is 10% of the average annual U.S. emissions of CO2-C.
  • Authors:
    • Thompson, M.
    • Wershaw, R. L.
    • Martens, D. A.
    • Chappell, M. A.
    • Laird, D. A.
  • Source: Geoderma
  • Volume: 143
  • Issue: 1-2
  • Year: 2008
  • Summary: Most models of soil humic substances include a substantial component of aromatic C either as the backbone of humic heteropolymers or as a significant component of supramolecular aggregates of degraded biopolymers. We physically separated coarse (0.2-2.0 [micro]m e.s.d.), medium (0.02-0.2 [micro]m e.s.d.), and fine (>0.02 [micro]m e.s.d.) clay subfractions from three Midwestern soils and characterized the organic material associated with these subfractions using 13 C-CPMAS-NMR, DTG, SEM-EDX, incubations, and radiocarbon age. Most of the C in the coarse clay subfraction was present as discrete particles (0.2-5 [micro]m as seen in SEM images) of black carbon (BC) and consisted of approximately 60% aromatic C, with the remainder being a mixture of aliphatic, anomeric and carboxylic C. We hypothesize that BC particles were originally charcoal formed during prairie fires. As the BC particles aged in soil their surfaces were oxidized to form carboxylic groups and anomeric and aliphatic C accumulated in the BC particles either by adsorption of dissolved biogenic compounds from the soil solution or by direct deposition of biogenic materials from microbes living within the BC particles. The biogenic soil organic matter was physically separated with the medium and fine clay subfractions and was dominated by aliphatic, anomeric, and carboxylic C. The results indicate that the biogenic humic materials in our soils have little aromatic C, which is inconsistent with the traditional heteropolymer model of humic substances.
  • Authors:
    • Hepperly, P.
    • LaSalle, T. J.
  • Year: 2008
  • Authors:
    • Plowden, Y.
    • Benham, E. C.
    • Franks, E. C.
    • Salon, P. R.
    • Dell, C. J.
  • Source: Journal of Soil and Water Conservation
  • Volume: 63
  • Issue: 3
  • Year: 2008
  • Summary: No-till (NT) crop production is expected to sequester soil C, but little data is available for dairy forage systems. Our objective was to quantify impacts of NT and rye (Secale cereale L.) cover crops on soil C and N pools and associated soil properties on Pennsylvania dairies. Samples were collected from seven fields following corn harvest. The NT fields had approximately 50% more C and N in particulate and mineral-associated pools in the upper 5 cm (2 in) compared to conventional tillage, but C and N accumulations below 5 cm were similar. This suggests a C sequestration rate of ~0.5 Mg ha-1 y-1 (~0.2 tn ac-1 yr-1) in the 8 to 13 years NT has been used. Soil aggregate stability and cation exchange capacity were proportional to C pool sizes. Rye cover crops had no clear impact. Findings show that expected increases in C sequestration and soil quality with NT can be achieved in dairy forage systems.
  • Authors:
    • Diamant, A.
    • Knipping, E.
  • Source: Handout for US EPA Integrated Nitrogen Committee
  • Year: 2008
  • Authors:
    • Lal, R.
    • Elder, J. W.
  • Source: Soil & Tillage Research
  • Volume: 98
  • Issue: 1
  • Year: 2008
  • Summary: As in other drained, intensively cultivated Histosols of the world, soil subsidence is a growing concern of vegetable farmers in the muck crops region of North Central, Ohio. Subsidence in organic soils is caused primarily by aerobic degradation of soil organic matter (SOM), which in turn makes available large quantities of once bound C and N. Upon drainage and cultivation, soil C and N dynamics shift drastically. Organic soils transition from CO2 and organic N sinks, to persistent sources, whereas CH4 uptake capacity increases. Therefore, this study was conducted to assess the short-term (within the first year) impact of conversion of intensively tilled organic soils to no-till management. The specific objectives of this study were to: (i) compare soil moisture content, soil temperature, and greenhouse gas (GHG) emission rates from moldboard/disking (MB), no-till (NT), and bare (B) treatments in cultivated organic soils, and (ii) estimate the rate of subsidence associated with these tillage practices. Over the year, soil moisture content (SMC) was significantly higher in MB (0.90 kg kg-1) than B (0.84 kg kg-1) treatments; however NT (0.87 kg kg-1) was not significantly different from either MB or B treatments. Mean annual temperatures at 5 cm depth were significantly higher in B (16.9 °C) compared to MB (16.2 °C) and NT (15.9 °C) treatments The CO2 emissions were not significantly different among treatments, while N2O emissions were significantly higher from MB (96.9 kg N2O-N ha-1 yr-1) than NT (35.8 kg N2O-N ha-1 yr-1) plots. Both CH4 uptake and CH4 emission exhibited low annual flux in all treatments.
  • Authors:
    • Euliss, N. H. Jr.
    • Laubhan, M. K.
    • Gleason, R. A.
  • Source: U.S. Geological Professional Paper 1745
  • Year: 2008
  • Summary: Chapter A: Background and Approach to Quantification of Ecosystem Services By Robert A. Gleason and Murray K. Laubhan Chapter B: Plant Community Quality and Richness By Murray K. Laubhan and Robert A. Gleason Chapter C: Carbon Sequestration By Robert A. Gleason, Brian A. Tangen, and Murray K. Laubhan Chapter D: Floodwater Storage By Robert A. Gleason and Brian A. Tangen Chapter E: Reduction of Sedimentation and Nutrient Loading By Brian A. Tangen and Robert A. Gleason Chapter F: Proposed Approach to Assess Potential Wildlife Habitat Suitability on Program Lands By Murray K. Laubhan, Kevin E. Kermes, and Robert A. Gleason
  • Authors:
    • D'Ordine, R.
    • Navarro, S.
    • Back, S.
    • Fernandes, M.
    • Targolli, J.
    • Dasgupta, S.
    • Bonin, C.
    • Luethy, M. H.
    • Heard, J. E.
    • Salvador, S.
    • Kumar, G.
    • Abad, M.
    • Stoecker, M.
    • Harrison, J.
    • Anstrom, D. C.
    • Bensen, R. J.
    • Warner, D.
    • Castiglioni, P.
    • Carpenter, J. E.
  • Source: Plant Physiology
  • Volume: 147
  • Issue: 2
  • Year: 2008
  • Summary: An article about bacterial RNA chaperones conferring abiotic stress tolerance in plants and improved grain yield in maize under water-limited conditions.
  • Authors:
    • Conklin, A. E.
    • Teasdale, J. R.
    • Cavigelli, M. A.
  • Source: Agronomy Journal
  • Volume: 100
  • Issue: 3
  • Year: 2008
  • Summary: Despite increasing interest in organic grain crop production, there is inadequate information regarding the performance of organically-produced grain crops in the United States, especially in Coastal Plain soils of the mid-Atlantic region. We report on corn (Zea mays L.), soybean [Glycine max (L.) Merr.], and wheat (Triticum aestivum L.) yields at the USDA-ARS Beltsville Farming Systems Project (FSP), a long-term cropping systems trial established in Maryland in 1996 to evaluate the sustainability of organic and conventional grain crop production. The five FSP cropping systems include a conventional no-till corn-soybean-wheat/soybean rotation (NT), a conventional chisel-till corn-soybean-wheat/soybean rotation (CT), a 2-yr organic corn-soybean rotation (Org2), a 3-yr organic corn-soybean-wheat rotation (Org3), and a 4- to 6-yr organic corn-soybean-wheat-hay rotation (Org4+). Average corn grain yield during 9 yr was similar in NT and CT (7.88 and 8.03 Mg ha-1, respectively) but yields in Org2, Org3, and Org4+ were, respectively, 41, 31, and 24% less than in CT. Low N availability explained, on average, 73% of yield losses in organic systems relative to CT while weed competition and plant population explained, on average, 23 and 4%, respectively, of these yield losses. The positive relationship between crop rotation length and corn yield among organic systems was related to increasing N availability and decreasing weed abundance with increasing rotation length. Soybean yield averaged 19% lower in the three organic systems (2.88 Mg ha-1) than in the conventional systems (3.57 Mg ha-1) and weed competition alone accounted for this difference. There were no consistent differences in wheat yield among cropping systems. Crop rotation length and complexity had little impact on soybean and wheat yields among organic systems. Results indicate that supplying adequate N for corn and controlling weeds in both corn and soybean are the biggest challenges to achieving equivalent yields between organic and conventional cropping systems.