• Authors:
    • Beegle, D. B.
    • Duiker, S. W.
  • Source: Soil & Tillage Research
  • Volume: 88
  • Issue: 1-2
  • Year: 2006
  • Summary: In permanent no-till (NT), soil nutrients are no longer mixed into the topsoil as with moldboard plow/disking (MD), whereas chisel/disking (CD) does limited mixing. Surface broadcast and/or banded nutrient applications may result in high and low fertility zones in permanent NT, with possible implications for soil sampling and nutrient placement.We investigated effects of 25 years of continuous NT, CD and MD with corn planted in the same row locations on organic matter (SOM), pH-H2O and Mehlich-3 extractable phosphorus (P), potassium (K), calcium (Ca) and magnesium (Mg). Vertical distribution at 0-5, 5-10 and 10-15 cm depths was measured as well as horizontal distributions across corn rows. We observed higher SOM and P in NT and CD than in MD in the 0-15 cm layer. SOM content was greatest in the top 5 cm in NT, but declined sharply with depth. SOM content in CD was not as high at the surface as in NT, but did not decline as fast as in NT. SOM was uniform but low throughout the 0-15 cm depth of MD. In all tillage systems, SOM did not vary across rows. Soil pH was higher in the 0-5 cm layer of NT than the deeper layers but the reverse was true in the CD or MD treatments. Concentrations of P, K and Ca were higher in the surface 0-5 cm than 10-15 cm depth of all tillage systems, but most strikingly in NT and CD. Starter fertilizer injection resulted in higher P and lower pH in the injection zone of all tillage treatments, but most notably in NT. The pH was depressed under the band of side-dressed nitrogen with all tillage systems. Potassium accumulated in the rows of the previous crop, probably because it leached from crop residue that accumulated there. Tillage did not affect Mg distribution. Optimal nutrient management in NT should take account of horizontal and vertical nutrient and pH distributions. Samples in long-term NT could potentially be taken to a shallower depth if calibration curves are available. To avoid underestimating P and K availability or overestimate lime needs, high P or decreased pH bands should be avoided, as well as crop rows. Possibilities to reduce P and K applications with banding need more investigation. Results show the importance of regular liming in NT to maintain surface pH in the optimum range, but also show that lime does not have to be incorporated.
  • Authors:
    • Bourbonniere, R. A.
    • Warner, B. G.
    • Robarts, R. D.
    • Murkin, H. R.
    • McDougal, R. L.
    • Olness, A.
    • Gleason, R. A.
    • Euliss, N. H. Jr.
  • Source: Science of the Total Environment
  • Volume: 361
  • Issue: 1-3
  • Year: 2006
  • Summary: We evaluated the potential of prairie wetlands in North America as carbon sinks. Agricultural conversion has resulted in the average loss of 10.1 Mg ha(-1) of soil organic carbon on over 16 million ha of wetlands in this region. Wetland restoration has potential to sequester 378 Tg of organic carbon over a 10-year period. Wetlands can sequester over twice the organic carbon as no-till cropland on only about 17% of the total land area in the region. We estimate that wetland restoration has potential to offset 2.4% of the annual fossil CO2 emission reported for North America in 1990. (c) 2005 Elsevier B.V. All rights reserved.
  • Authors:
    • Tanaka, D. L.
    • Liebig, M. A.
    • Frank, A. B.
  • Source: Soil & Tillage Research
  • Volume: 89
  • Issue: 1
  • Year: 2006
  • Summary: Soil respiration is a process influenced by land use, management practices, and environmental conditions. Our objectives were to evaluate relationships between management-induced differences in soil organic carbon (SOC) and soil CO2 efflux from continuous no-till spring wheat (Triticum aestivum L.), spring wheat-fallow under no-till, and a native mixed-grass prairie with grazing near Mandan, ND. A Werner-Sen-Chama soil complex (Entic Haplustoll, Typic Haplustoll, and Typic Calciustoll) was present at the grassland site and a Wilton silt loam (Pachic Haplustoll) at the cropping sites. Soil chambers were used to measure soil CO2 effluxes about every 21 days starting 14 May 2001 to 1 April 2003. Soil water and soil temperature were measured at time of CO2 efflux measurements. Soil organic carbon, microbial biomass carbon (MBC), and above and belowground plant biomass were measured in mid-July each year. Root biomass to 0.3 m depth of the undisturbed grassland was significantly greater (12.3 Mg ha-1) than under continuous wheat (1.3 Mg ha-1) and wheat-fallow (0.3 Mg ha-1). Grassland SOC content of 84 Mg ha-1 to 0.3 m soil depth was 1.2 times greater than continuous wheat and 1.3 times greater than wheat-fallow. The MBC of the grassland was 2.2 Mg ha-1, or 3.6 times greater than continuous wheat and 7.2 times greater than wheat-fallow treatments. Soil CO2 efflux averaged 2.8 g CO2-C m-2 day-1 for grassland, compared to 1.9 g CO2-C m-2 day-1 for wheat fallow and 1.6 g CO2-C m-2 day-1 for continuous wheat treatments. Although these CO2 efflux rates were based on measurements made at intervals of about 21 days, the differences among treatments with time were rather consistent. Differences in soil CO2 efflux among treatments could be attributed to differences in SOC and MBC, suggesting that land use plays a significant role in soil CO2 efflux from respiration.
  • Authors:
    • Robertson, G. P.
    • Parr, S.
    • Loecke, T. D.
    • Grandy, A. S.
  • Source: Journal of Environmental Quality
  • Volume: 35
  • Issue: 4
  • Year: 2006
  • Summary: No-till cropping can increase soil C stocks and aggregation but patterns of long-term changes in N2O emissions, soil N availability, and crop yields still need to be resolved. We measured soil C accumulation, aggregation, soil water, N2O emissions, soil inorganic N, and crop yields in till and no-till corn-soybean-wheat rotations between 1989 and 2002 in southwestern Michigan and investigated whether tillage effects varied over time or by crop. Mean annual NO3- concentrations in no-till were significantly less than in conventional till in three of six corn years and during one year of wheat production. Yields were similar in each system for all 14 years but three, during which yields were higher in no-till, indicating that lower soil NO3- concentrations did not result in lower yields. Carbon accumulated in no-till soils at a rate of 26 g C m-2 yr-1 over 12 years at the 0- to 5-cm soil depth. Average nitrous oxide emissions were similar in till (3.27 {+/-} 0.52 g N ha d-1) and no-till (3.63 {+/-} 0.53 g N ha d-1) systems and were sufficient to offset 56 to 61% of the reduction in CO2 equivalents associated with no-till C sequestration. After controlling for rotation and environmental effects by normalizing treatment differences between till and no-till systems we found no significant trends in soil N, N2O emissions, or yields through time. In our sandy loam soils, no-till cropping enhances C storage, aggregation, and associated environmental processes with no significant ecological or yield tradeoffs.
  • Authors:
    • Puurveen, H.
    • Kryzanowski, L. M.
    • Goddard, T. W.
    • Pattey, E.
    • Grant, R. F.
  • Source: Soil Science Society of America Journal
  • Volume: 70
  • Issue: 1
  • Year: 2006
  • Summary: The attribution of N2O emission factors to N inputs from chemical fertilizers requires an understanding of how those inputs affect the biological processes from which these emissions are generated. We propose a detailed model of soil N transformations as part of the ecosystem model ecosys for use in attributing N2O emission factors to fertilizer use. In this model, the key biological processes--mineralization, immobilization, nitrification, denitrification, root, and mycorrhizal uptake--controlling the generation of N2O were coupled with the key physical processes--convection, diffusion, volatilization, dissolution--controlling the transport of the gaseous reactants and products of these biological processes. Physical processes controlling gaseous transport and solubility caused large temporal variation in the generation and emission of N2O in the model. This variation limited the suitability of discontinuous surface flux chambers measurements used to test modeled N2O emissions. Continuous flux measurements using micrometeorological techniques were better suited to the temporal scales at which variation in N2O emission occurred and at which model testing needed to be conducted. In a temperate, humid climate, modeled N2O emissions rose nonlinearly with fertilizer application rate once this rate exceeded the crop and soil uptake capacities for added N. These capacities were partly determined by history of fertilizer use, so that the relationship between N2O emissions and current N inputs depended on earlier N inputs. A scheme is proposed in which N2O emission factors rise nonlinearly with fertilizer N inputs that exceed crop plus soil N uptake capacities.
  • Authors:
    • Trettin, C. C.
    • Bliss, N. B.
    • Keller, J. K.
    • Megonigal, J. P.
    • Bridgham, S. D.
  • Source: Wetlands
  • Volume: 26
  • Issue: 4
  • Year: 2006
  • Summary: We examine the carbon balance of North American wetlands by reviewing and synthesizing the published literature and soil databases. North American wetlands contain about 220 Pg C, most of which is in peat. They are a small to moderate carbon sink of about 49 Tg C yr(-1), although the uncertainty around this estimate is greater than 100%, with the largest unknown being the role of carbon sequestration by sedimentation in freshwater mineral-soil wetlands. We estimate that North American wetlands emit 9 Tg methane (CH4) yr(-1); however, the uncertainty of this estimate is also greater than 100%. With the exception of estuarine wetlands, CH4 emissions from wetlands may largely offset any positive benefits of carbon sequestration in soils and plants in terms of climate forcing. Historically, the destruction of wetlands through land-use changes has had the largest effects on the carbon fluxes and consequent radiative forcing of North American wetlands. The primary effects have been a reduction in their ability to sequester carbon (a small to moderate increase in radiative forcing), oxidation of their soil carbon reserves upon drainage (a small increase in radiative forcing), and reduction in CH4 emissions (a small to large decrease in radiative forcing). It is uncertain how global changes will affect the carbon pools and fluxes of North American wetlands. We will not be able to predict accurately the role of wetlands as potential positive or negative feedbacks to anthropogenic global change without knowing the integrative effects of changes in temperature, precipitation, atmospheric carbon dioxide concentrations, and atmospheric deposition of nitrogen and sulfur on the carbon balance of North American wetlands.
  • Authors:
    • Amon, B.
    • Weiland, P.
    • Trimborn, M.
    • Clemens, J.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 112
  • Issue: 2-3
  • Year: 2006
  • Summary: Biogas treatment of animal manures is an upcoming technology because it is a way of producing renewable energy (biogas). However, little is known about effects of this management strategy on greenhouse gas (GHG) emissions during fermentation, storage, and field application of the substrates compared to untreated slurries. In this study, we compared cattle slurry and cattle slurry with potato starch as additive during the process of fermentation, during storage and after field application. The addition of potato starch strongly enhanced CH4 production from 4230 l CH4 m-3 to 8625 l CH4 m-3 in the fermenter at a hydraulic retention time (HRT) of 29 days. Extending the HRT to 56 days had only a small effect on the CH4 production.Methane emissions from stored slurry depended on storage temperature and were highest from unfermented slurry followed by the slurry/starch mixture. Gas emissions from untreated and fermented slurry during storage were further analyzed in a pilot-scale experiment with different levels of covering such as straw cover, a wooden lid and no cover. Emissions of greenhouse gases (CH4,N2O, NH3) were in the range of 14.3-17.1 kg CO2 eq. m-3 during winter (100 day storage period) and 40.5-90.5 kg CO2 eq. m-3 during summer (140 day storage period). A straw cover reduced NH3 losses, but not overall GHG emissions, whereas a solid cover reduced CH4 and NH3 emissions. After field application, there were no significant differences between slurry types in GHG emissions (4.15-8.12 kg CO2 eq. m-3a-1). GHG emissions from slurry stores were more important than emissions after field application. Co-digestion of slurry with additives such as starch has a large potential to substitute fossil energy by biogas. On a biogas plant, slurry stores should be covered gas-tight in order to eliminate GHG emissions and collect CH4 for electricity production.
  • Authors:
    • Pazsiczki, I.
    • Brunsch, R.
    • Berg, W.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 112
  • Issue: 2-3
  • Year: 2006
  • Summary: Liquid manure storage facilities are sources of methane, nitrous oxide and ammonia emissions. Different materials for covering liquid manure storage facilities to reduce gaseous emissions were investigated on laboratory scale (65 l): perlite (Pegu¨ litTM), lightweight expanded clay aggregate (LecaTM) and chopped straw—both individually and combined with lactic acid or saccharose, respectively. Methane is the predominant greenhouse gas emitted from liquid manure storage facilities. Nitrous oxide plays a role when surfaces become encrusted when it occurs by using the cover materials investigated. Common cover materials have good reduction effects on ammonia but less on greenhouse gas emissions. Straw can increase emissions of methane and nitrous oxide, as can granules. Lowering the pH value of the slurry can reduce both methane and nitrous oxide emissions. Combinations of covering and acidifying should cause a pH value below 6.0 to reduce methane and nitrous oxide emissions effectively. Lower pH value seems to be necessary also to reduce ammonia emissions effectively.
  • Authors:
    • Janzen, H. H.
    • Angers, D. A.
    • Gregorich, E. G.
    • VandenBygaart, A. J.
    • Bolinder, M. A.
  • Source: Canadian Journal of Soil Science
  • Volume: 86
  • Issue: 3
  • Year: 2006
  • Summary: Modelling soil organic carbon (SOC) stock changes in agroecosystems can be performed with different approaches depending on objectives and available data. Our objective in this paper is to describe a scheme for developing a dynamic SOC algorithm for calculating net greenhouse gas emissions from Canadian farms as a function of management and local conditions. Our approach is flexible and emphasizes ease of use and the integration of available knowledge. Using this approach, we assessed the performance of several SOC models having two or more compartments for some common agroecosystems in Canada. Analysis of long-term data for conventional management practices at different sites (n = 36) in Canada, including recent model applications in the literature on some of those data, indicated that the results obtained with two-compartment models, such as the Introductory Carbon Balance Model (ICBM) and Modified Woodruff Model (MWM), yielded results comparable to those of a multi-compartment model (CENTURY). The analysis also showed that a model such as ICBM need stuning to be applied to management and conditions across Canada. Two-compartment models programmable in a simple spreadsheet format, though they may not supplant more complex models in allapplications, offer advantages of simplicity and transparency in whole-farm analyses of greenhouse gas emissions. Key words: Virtual Farm, soil organic carbon, soil disturbance, C inputs, Introductory Carbon Balance Model (ICBM), CENTURY, Modified Woodruff Model (MWM).
  • Authors:
    • Solberg, E. D.
    • Nyborg, M.
    • Malhi, S. S.
    • Izaurralde, R. C.
    • Jakas, M. C. Quiroga
  • Source: Agronomy Journal
  • Volume: 98
  • Issue: 5
  • Year: 2006
  • Summary: Field experiments were conducted from 1991 to 1995 at Josephburg (Orthic Black Chernozem, Typic Cryoboroll) and Cooking Lake (Orthic Gray Luvisol, Typic Cryoboralf), Alberta, to determine the impact of topsoil removal on selected soil properties, N-mineralization potential, and crop yield, and the effectiveness of various amendments for restoring the productivity of eroded soils. The simulated-erosion levels were established in the autumn of 1990 by removing 20 cm of topsoil in 5-cm depth increments. The four amendments were: control, addition of 5 cm of topsoil, fertilizers to supply 100 kg N ha(-1) and 20 kg P ha(-1), and cattle manure at 75 Mg ha(-1). Topsoil and manure were applied once in the autumn of 1990, while fertilizers were applied annually from 1991 to 1995. Available N and P; total C, N, and P; and N-mineralization potential decreased, while bulk density increased with increasing depth of topsoil removal. Tiller number, plant height, spike density, thousand-kernel weight, and leaf area index decreased with simulated erosion. Grain yield reductions due to simulated soil erosion were either linear or curvilinear functions of nutrient removal. Application of N and P fertilizers and manure improved grain yield and reduced the impact of yield loss due to erosion. Return of 5 cm of topsoil also increased grain yield, but to a lesser extent than manure or fertilizers. Grain yields were maximized when fertilizers were also applied to organic amendment treatments. Our findings suggest the importance of integrated use of organic amendments and chemical fertilizers for best crop yields on severely eroded soils.