• Authors:
    • Lorenz, N.
    • Eastridge, M. L.
    • Dick, R. P.
    • Barker, D. J.
    • Sulc, R. M.
    • Fae, G. S.
  • Source: Agronomy Journal
  • Volume: 101
  • Issue: 5
  • Year: 2009
  • Summary: The benefits of cover crops within crop rotations are well documented, but information is limited on using cover crops for forage within midwestern United States cropping systems, especially under no-tillage management. Our objective was to evaluate plant, animal, and soil responses when integrating winter cover crop forages into no-till corn (Zea mays L.) silage production. Three cover crop treatments were established no-till after corn silage in September 2006 and 2007 at Columbus, OH: annual ryegrass (Lolium multiflorum L.), a mixture of winter rye (Secale cereale L.) and oat (Avena sativa L.), and no cover crop. Total forage yield over autumn and spring seasons was 38 to 73% greater (P <= 0.05) for oat + winter rye than for annual ryegrass. Soil penetration resistance (SPR) in May 2007 was 7 to 15% greater (P <= 0.10) in the grazed cover crops than in the nongrazed no cover crop treatment; however, subsequent silage corn yield did not differ among treatments, averaging 10.4 Mg ha(-1) in August 2007. Compared with the no cover crop treatment, cover crops had three- to fivefold greater root yield, threefold greater soil microbial biomass (MB) in spring 2008, and 23% more particulate organic carbon (POC) concentrations in the 0- to 15-cm soil depth. integration of forage cover crops into no-till corn silage production in Ohio can provide supplemental forage for animal feed without detrimental effects on subsequent corn silage productivity, with the added benefit of increasing labile soil C.
  • Authors:
    • Stuedemann, J. A.
    • Franzluebbers, A. J.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 129
  • Issue: 1-3
  • Year: 2009
  • Summary: Soil organic C (SOC) and total soil N (TSN) sequestration estimates are needed to improve our understanding of management influences on soil fertility and terrestrial C cycling related to greenhouse gas emission. We evaluated the factorial combination of nutrient source (inorganic, mixed inorganic and organic, and organic as broiler litter) and forage utilization (unharvested, low and high cattle grazing pressure, and hayed monthly) on soil-profile distribution (0-150 cm) of SOC and TSN during 12 years of pasture management on a Typic Kanhapludult (Acrisol) in Georgia, USA. Nutrient source rarely affected SOC and TSN in the soil profile, despite addition of 73.6 Mg ha-1 (dry weight) of broiler litter during 12 years of treatment. At the end of 12 years, contents of SOC and TSN at a depth of 0-90 cm under haying were only 82 ± 5% (mean ± S.D. among treatments) of those under grazed management. Within grazed pastures, contents of SOC and TSN at a depth of 0-90 cm were greatest within 5 m of shade and water sources and only 83 ± 7% of maximum at a distance of 30 m and 92 ± 14% of maximum at a distance of 80 m, suggesting a zone of enrichment within pastures due to animal behavior. During 12 years, the annual rate of change in SOC (0-90 cm) followed the order: low grazing pressure (1.17 Mg C ha-1 year-1) > unharvested (0.64 Mg C ha-1 year-1) = high grazing pressure (0.51 Mg C ha-1 year-1) > hayed (-0.22 Mg C ha-1 year-1). This study demonstrated that surface accumulation of SOC and TSN occurred, but that increased variability and loss of SOC with depth reduced the significance of surface effects.
  • Authors:
    • Wong, C. P.
    • Neely, C. L.
    • Schohr, T.
    • Oldfield, J. T.
    • Laca, E. A.
    • Kustin, C.
    • George, M. R.
    • Brown, J. R.
    • Alvarez, P.
    • Fynn, A. J.
  • Year: 2009
  • Authors:
    • Grinnell, J. L.
    • Baker, J. S.
    • Galik, C. S.
  • Source: Climate Change Policy Partnership
  • Year: 2009
  • Summary: Transaction costs are one of the key challenges that private forest landowners may face in participating in emerging carbon markets. As most forestlands in the United States occur in the form of small, privately held landholdings, the supply of forest carbon offsets could be constrained by high transaction costs. Using a custom spreadsheet model, this study examines the transaction costs of different forest offset projects operating in different forest types under different accounting methodologies or protocols. Our results suggest that transaction costs can be significant for small forest management offset projects. We find that transaction costs likewise vary by protocol and tend to decrease with project size and length of rotation extension. While transaction costs can be an important driver in total project revenue, they appear to be less of a factor than the actual accounting scheme under which the project is being operated.
  • Authors:
    • Jordan, D.
    • Owen, M. D. K.
    • Wilson, R. G.
    • Young, B. G.
    • Weller, S. C.
    • Johnson, W. G.
    • Kruger, G. R.
    • Shaw, D. R.
    • Givens, W. A.
  • Source: Weed Technology
  • Volume: 23
  • Issue: 1
  • Year: 2009
  • Summary: A phone survey was administered to 1,195 growers in six states (Illinois, Indiana, Iowa, Mississippi, Nebraska, and North Carolina). The survey measured producers' crop history, perception of glyphosate-resistant (GR) weeds, past and present weed pressure, tillage practices, and herbicide use as affected by the adoption of GR crops. This article describes the changes in tillage practice reported in the survey. The adoption of a GR cropping system resulted in a large increase in the percentage of growers using no-till and reduced-till systems. Tillage intensity declined more in continuous GR cotton and GR soybean (45 and 23%, respectively) than in rotations that included GR corn or non-GR crops. Tillage intensity declined more in the states of Mississippi and North Carolina than in the other states, with 33% of the growers in these states shifting to more conservative tillage practices after the adoption of a GR crop. This was primarily due to the lower amount of conservation tillage adoption in these states before GR crop availability. Adoption rates of no-till and reduced-till systems increased as farm size decreased. Overall, producers in a crop rotation that included a GR crop shifted from a relatively more tillage-intense system to reduced-till or no-till systems after implementing a GR crop into their production system.
  • Authors:
    • Euliss, N. H. Jr.
    • Browne, B. A.
    • Tangen, B. A.
    • Gleason, R. A.
  • Source: Soil Biology and Biochemistry
  • Volume: 41
  • Issue: 12
  • Year: 2009
  • Summary: It has been well documented that restored wetlands in the Prairie Pothole Region of North America do store carbon. However, the net benefit of carbon sequestration in wetlands in terms of a reduction in global warming forcing has often been questioned because of potentially greater emissions of greenhouse gases (GHGs) such as nitrous oxide (N2O) and methane (CH4). We compared gas emissions (N2O, CH4, carbon dioxide [CO2]) and soil moisture and temperature from eight cropland and eight restored grassland wetlands in the Prairie Pothole Region from May to October, 2003, to better understand the atmospheric carbon mitigation potential of restored wetlands. Results show that carbon dioxide contributed the most (90%) to net-GHG flux, followed by CH4 (9%) and N2O (1%). Fluxes of N2O, CH4, CO2, and their combined global warming potential (CO2 equivalents) did not significantly differ between cropland and grassland wetlands. The seasonal pattern in flux was similar in cropland and grassland wetlands with peak emissions of N2O and CH4 occurring when soil water-filled pore space (WFPS) was 40-60% and >60%, respectively; negative CH4 fluxes were observed when WFPS approached 40%. Negative CH4 fluxes from grassland wetlands occurred earlier in the season and were more pronounced than those from cropland sites because WFPS declined more rapidly in grassland wetlands; this decline was likely due to higher infiltration and evapotranspiration rates associated with grasslands. Our results suggest that restoring cropland wetlands does not result in greater emissions of N2O and CH4, and therefore would not offset potential soil carbon sequestration. These findings, however, are limited to a small sample of seasonal wetlands with relatively short hydroperiods. A more comprehensive assessment of the GHG mitigation potential of restored wetlands should include a diversity of wetland types and land-use practices and consider the impact of variable climatic cycles that affect wetland hydrology.
  • Authors:
    • Wyse, D. L.
    • Buckley, D. H.
    • DeHaan, L. R.
    • Crews, T. E.
    • Mai, J. G.
    • Mangan, M. E.
    • Young, L.
    • Broussard, W.
    • DuPont, S. T.
    • Culman, S. W.
    • Glover, J. D.
    • Reynolds, H. L.
    • Turner, R. E.
    • Ferris, H.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 137
  • Issue: 1-2
  • Year: 2009
  • Summary: Perennial vegetation can provide multiple ecosystem services essential for sustainable production more effectively than production systems based on annual crops. However, the ability of annually harvested, unfertilized perennial systems to sustain long-term yields while also maintaining ecosystem services has not been widely studied. Here we compare the impacts of harvested perennial grass and annual crop fields on ecosystem functioning in KS, USA. Despite the lack of mineral fertilizer applications, the aboveground harvests of perennial fields yielded similar levels of N compared to those of conventional high-input wheat (Triticum aestivum) fields and at only 8% of the in-field energy costs. Their 75-yr cumulative N yield per ha was approximately 23% greater than that from the region's wheat fields. In terms of aboveground food webs, perennial fields harboured greater numbers and/or diversity of insect pollinators, herbivores and detritivores. Belowground, perennial grass fields maintained 43 Mg ha-1 more soil carbon and 4 Mg ha-1 more soil nitrogen than annual crop fields in the surface 1 m. Soil food webs in perennial fields, as indicated by nematode communities, exhibited greater food web complexity and stability than did those in annual crop fields. In surrounding watersheds, increased annual cropland was correlated with higher riverine nitrate-nitrogen levels. Given their benefits, harvested perennial grasslands provide valuable ecological benchmarks for agricultural sustainability.
  • Authors:
    • Greaves, T.
  • Source: Fiscal Fact No. 164
  • Year: 2009
  • Authors:
    • Gurwick, N.
    • Gurian-Sherman, D.
  • Source: UCS Food and Environment Program
  • Year: 2009
  • Summary: from exec summary: "At this point, the prospects for GE contributing substantially to improved NUE are uncertain...At this point, the prospects for GE contributing substantially to improved NUE are uncertain..."
  • Authors:
    • Al-Kaisi, M. M.
    • Guzman, J. G.
  • Source: Journal of Environmental Quality
  • Volume: 39
  • Issue: 1
  • Year: 2009
  • Summary: In addition to their aesthetic and environmental qualities, reconstructed prairies can act as C sinks and potentially offset rising atmospheric CO2 concentration. The objective Of this Study was to quantify C budget components of newly established prairies on previously cultivated land. Net ecosystem production (NEP) was estimated using a C budgeting approach that assessed SOC content, soil surface CO2-C emission, and above- and belowground plant biomass. Study was conducted in southern Iowa, in 2005 to 2007. Results show that differences between sites for potential total C input were primarily due to root biomass contributions, which ranged from 0.8 to 5.4 Mg C ha(-1). Average potential aboveground biomass C input was 2.7 Mg C ha(-1) in 2006 and 5.5 Mg C ha(-1) in 2007. Total soil CO2-C emissions from heterotrophic respiration increased as prairie age increased from 2.9 to 4.0 Mg C ha(-1) and 3.1 to 4.7 Mg C ha(-1) in 2006 and 2007, respectively. Determination of NEP showed that the 1998 and 2003 reconstructed prairie sites had the greatest potential for soil C sequestration at 4.1 and 4.4 Mg C ha(-1). Increases in SOC content were only observed in the youngest established prairie site (2003) and the no-till site in 2003 at 2.1 and 2.6 Mg C ha(-1) yr(-1), respectively. Declines of SOC sequestration rates occurred when potential C equilibrium was reached (R-h = NPP) within 10 yr since prairie establishment.