• Authors:
    • Bauer, P. J.
    • Watts, D. W.
    • Frederick, J. R.
    • Novak, J. M.
  • Source: Soil Science Society of America Journal
  • Volume: 73
  • Issue: 2
  • Year: 2009
  • Summary: Long-term disk tillage (DT) for cotton (Gossypium hirsutum L.) production in the southeastern U.S. Coastal Plain has resulted in soil organic C (SOC) content reductions. Conservation tillage (CT) management in some studies can rebuild SOC levels. A field study, with two adjacent 3.5-ha fields, both containing soil series formed in upland and depressional areas, was conducted using a 6-yr rotation of corn (Zea mays L.) and cotton to determine the CT and DT effects on SOC contents and residue characteristics returned to the soil. Annual soil samples were collected from 50 locations per field at 0- to 3- and 3- to 15-cm. After 6 yr under CT, residue accumulation promoted a significant SOC increase in the 0- to 3-cm depth in the upland soil series (about 0.7 Mg SOC ha(-1)). The lack of residue mixing in the 3- to 15-cm depth in upland Soils under CT however, resulted in a significant SOC content decline at this depth (1.25-2.51 Mg SOC ha(-1)). There was no significant SOC content change in soils under CT formed in depressional areas or in all soils under DT During 6 yr, 14.8 Mg ha(-1) of organic C from both corn and cotton residues was returned to Soils under CT but <4% was incorporated into the SOC pool. Levels of SOC in sandy upland soils can be increased at the surface after 6 yr of CT under a corn and cotton rotation, with the increase coming at the expense of an SOC decline at a deeper topsoil depth.
  • Authors:
    • Williams, S.
    • Vining, R.
    • Schuler, J.
    • Olson, C.
    • Ogle, S.
    • Killian, K.
    • Easter, M.
    • Brenner, J.
    • Paustian, K.
  • Source: Journal of Soil and Water Conservation
  • Volume: 64
  • Issue: 1
  • Year: 2009
  • Summary: US agriculture has much to offer as a participant in efforts to mitigate the buildup of GHGs in the atmosphere, and, in most cases, the adoption of practices that mitigate GHGs will provide additional environmental services and improved resource use efficiency on America's farms. Whether agriculture will reap the financial benefits possible as a provider of GHG offsets within the framework of a cap-and-trade market or other regulatory framework will depend to a large extenton the quantification, monitoring, andverification of these offsets.
  • Authors:
    • Jackson, R. B.
    • Murray, B. C.
    • Baker, J.
    • Jobbagy, E. G.
    • Pineiro, G.
  • Source: Ecological Applications
  • Volume: 19
  • Issue: 2
  • Year: 2009
  • Summary: Although various studies have shown that corn ethanol reduces greenhouse gas (GHG) emissions by displacing fossil fuel use, many of these studies fail to include how land-use history affects the net carbon balance through changes in soil carbon content. We evaluated the effectiveness and economic value of corn and cellulosic ethanol production for reducing net GHG emissions when produced on lands with different land-use histories, comparing these strategies with reductions achieved by set-aside programs such as the Conservation Reserve Program (CRP). Depending on prior land use, our analysis shows that C releases from the soil after planting corn for ethanol may in some cases completely offset C gains attributed to biofuel generation for at least 50 years. More surprisingly, based on our comprehensive analysis of 142 soil studies, soil C sequestered by setting aside former agricultural land was greater than the C credits generated by planting corn for ethanol on the same land for 40 years and had equal or greater economic net present value. Once commercially available, cellulosic ethanol produced in set-aside grasslands should provide the most efficient tool for GHG reduction of any scenario we examined. Our results suggest that conversion of CRP lands or other set-aside programs to corn ethanol production should not be encouraged through greenhouse gas policies.
  • Authors:
    • Hiatt, S.
    • Potter, C.
  • Source: Journal of Soil and Water Conservation
  • Volume: 64
  • Issue: 6
  • Year: 2009
  • Summary: The nonpoint source pollution model Soil and Water Assessment Tool (SWAT) was applied to understand management options that may improve water quality in the Laguna de Santa Rosa watershed in Sonoma County, California. Surface water quality in the Laguna watershed has been significantly impaired over recent years, as natural land cover has been urbanized or converted to agricultural uses. We first generated new maps of land cover and major land uses from satellite and airborne imagery for the watershed. The SWAT model output was checked against six streamflow gauges in the watershed. At the monthly time step, we found that the precalibrated model performed well at all gauges, with the coefficient of determination () values ranging from 0.81 to 0.92. Calibration by modifications of groundwater extraction in the watershed resulted in notable increases to correlation values at all gauges, except at upstream locations on Santa Rosa Creek and Mark West Creek. Measured seasonal trends in sediment concentrations were tracked closely by the SWAT model predictions. Highest sediment loading rates were associated in the model results with pasture, rangeland, and vineyard cover areas. Model scenarios were tested for vegetation filter strips and improved ground cover conditions applied in subbasins, where soil erosion was shown to be elevated in previous simulations.
  • Authors:
    • Bryant, R. B.
    • Schmidt, J. P.
    • Kleinman, P. J.
    • Dell, C. J.
    • Skinner, R. H.
    • Soder, K. J.
    • Rotz, C. A.
  • Source: Forage and grazinglands
  • Year: 2009
  • Summary: Incorporating managed rotational grazing into a dairy farm can result in an array of environmental consequences. A comprehensive assessment of the environmental impacts of four management scenarios was conducted by simulating a 250-acre dairy farm typical of Pennsylvania with: (i) a confinement fed herd producing 22,000 lbs of milk per cow per year; (ii) a confinement fed herd producing 18,500 lbs; (iii) a confinement fed herd with summer grazing producing 18,500 lbs; and (iv) a seasonal herd maintained outdoors producing 13,000 lbs. Converting 75 acres of cropland to perennial grassland reduced erosion 24% and sediment-bound and soluble P runoff by 23 and 11%, respectively. Conversion to all perennial grassland reduced erosion 87% with sediment-bound and soluble P lossess reduced to 80 and 23%. Ammonia volatilization was reduced 30% through grazing but nitrate leaching loss increased up to 65%. Grazing systems reduced the net greenhouse gas emission by 8 to 14% and the C footprint of an all grassland farm up to 80% during the transition from cropland. The environmental benefits of grass-fed dairy production should be used to encourage greater adoption of managed rotational grazing in regions where this technology is well adapted.
  • Authors:
    • Grau, R.
    • Baptista, S.
    • Birkenholtz, T.
    • Lambin, E. F.
    • Ickowitz, A.
    • Hecht, S.
    • Geoghegan, J.
    • Lawrence, D.
    • DeFries, R. S.
    • Turner, B. L.
    • Uriarte ,M.
    • Schneider ,L.
    • Rudel, T. K.
  • Source: Proceedings of the National Academy of Sciences of the United States of America
  • Volume: 106
  • Issue: 49
  • Year: 2009
  • Summary: Does the intensification of agriculture reduce cultivated areas and, in so doing, spare some lands by concentrating production on other lands? Such sparing is important for many reasons, among them the enhanced abilities of released lands to sequester carbon and provide other environmental services. Difficulties measuring the extent of spared land make it impossible to investigate fully the hypothesized causal chain from agricultural intensification to declines in cultivated areas and then to increases in spared land. We analyze the historical circumstances in which rising yields have been accompanied by declines in cultivated areas, thereby leading to land-sparing. We use national-level United Nations Food and Agricultural Organization data on trends in cropland from 1970-2005, with particular emphasis on the 1990-2005 period, for 10 major crop types. Cropland has increased more slowly than population during this period, but paired increases in yields and declines in cropland occurred infrequently, both globally and nationally. Agricultural intensification was not generally accompanied by decline or stasis in cropland area at a national scale during this time period, except in countries with grain imports and conservation set-aside programs. Future projections of cropland abandonment and ensuing environmental services cannot be assumed without explicit policy intervention.
  • Authors:
    • Beegle, D. B.
    • Dellinger, A. E.
    • Schmidt, J. P.
  • Source: Agronomy Journal
  • Volume: 101
  • Issue: 4
  • Year: 2009
  • Summary: Precision agriculture technologies provide the capability to spatially vary N fertilizer applied to corn (Zea mays L.), potentially improving N use efficiency. The focus of this study was to evaluate the potential of improving N recommendations based on crop canopy reflectance. Corn was grown at four field sites in each of 2 yr in Centre County, Pennsylvania. Preplant treatments included: zero fertilizer, 56 kg N ha(-1), and manure. Split-plot treatments included the following N sidedress rates as NH4NO3: 0, 22, 45, 90, 135, 180, and 280 kg N ha(-1), and one at-planting N rate of 280 kg N ha(-1). Light energy reflectance (590 and 880 nm), chlorophyll meter (SPAD) measurements, and the presidedress NO3 test (PSNT) results were obtained at sidedress. The late-season stalk NO3 (LSSN) test was determined. The economic optimum nitrogen rate (EONR) was determined based on grain yield response to sidedress N rates. Relative green normalized difference vegetation index (GNDVI) and relative SPAD were based on relative measurements from the zero sidedress treatment to the 280 kg N ha(-1) at-planting treatment. The EONR from 24 preplant treatment-site combinations was related to relative GNDV1 (R-2 = 0.76), the PSNT (R-2 = 0.78), relative SPAD (R-2 = 0.72), and the LSSN test (R-2 = 0.64), suggesting that relative GNDVI was as good an indicator of EONR as these other, more conventional tests. Because relative GNDVI can be obtained simultaneously with a sidedress N fertilizer application, the potential to accommodate within-field spatial and season-to-season temporal variability in N availability should improve N management decisions for corn production.
  • Authors:
    • Science Applications International Corporation
  • Source: Bus Fleet Upgrade Projects
  • Year: 2009
  • Summary: This paper discusses the key issues with developing a GHG offsets methodology for bus fleet upgrades, including options for setting a performance threshold for identifying those projects that should receive credit. A performance standard sets a threshold emissions level that is significantly better than the average emissions performance for a specified service. In this case, we expect the threshold to be set by reference to the emissions performance of bus fleets. If a project for improving fleet performance has emissions that are equal to or better than the threshold, then the project would be considered to exceed the "business-as-usual" (BAU) performance and would be eligible for registration of emission reduction credits.
  • Authors:
    • Science Applications International Corporation
  • Source: Development of Issues Papers for GHG Reduction Project Types
  • Year: 2009
  • Summary: This paper investigates the options for greenhouse gas emission reductions from the installation of new and retrofit high efficiency boilers. The types of boilers addressed are industrial boilers, commercial boilers, biomass boilers, cogeneration boilers and residential boilers. Each of these boiler types have unique technological characteristics and regulatory requirements that need to be addressed to determine if an appropriate performance standard can be developed. Some boiler types have additional issues associated with leakage – primarily biomass boilers. Residential boilers have similar regulatory and technology issues as the commercial boilers, but are widely distributed in the general population and GHG emission reduction ownership "rights" are an issue that must also be considered. This paper explores these issues and makes recommendations on if and how to proceed with GHG offset methodologies.
  • Authors:
    • Weischer, L.
    • Tan, X.
    • Heilmayr, R.
    • Seligsohn, D.
  • Year: 2009
  • Summary: from executive summary: "This report discusses the successes and challenges to effective regulation in China, outlining the major advances made in implementing effective energy efficiency programs in the past several years. These include targeted programs for both large and small enterprises, specific goals for government officials, and the development of energy statistics infrastructure. It also addresses U.S. competitiveness concerns in relation to the introduction of U.S. cap-and-trade policies, and specific opportunities for enhanced climate change cooperation between the two countries.