• Authors:
    • Stuth, J. W.
    • Blaisdell, R.
    • Salley, S. W.
    • Angerer, J.
    • Brown, J.
  • Source: Rangeland Ecology & Management
  • Volume: 63
  • Issue: 1
  • Year: 2010
  • Summary: Rangelands make an important contribution to carbon dynamics of terrestrial ecosystems. We used a readily accessible interface (COMET VR) to a simulation model (CENTURY) to predict changes in soil carbon in response to management changes commonly associated with conservation programs. We also used a subroutine of the model to calculate an estimate of uncertainty of the model output based on the similarity between climate, soil, and management history inputs and those used previously to parameterize the model for common land use (cropland to perennial grassland) and management (stocking rate reductions and legume addition) changes to test the validity of the approach across the southwestern United States. The conversion of small grain cropland to perennial cover was simulated acceptably (<20% uncertainty) by the model for soil, climate, and management history attributes representative of 32% of land area currently in small grain production, while the simulation of small grain cropland to perennial cover + legumes was acceptable on 73% of current small grain production area. The model performed poorly on and and semiarid rangelands for both management (reduced stocking) and restoration (legume addition) practices. Only 66% of land area currently used as rangeland had climate, soil, and management attributes that resulted in acceptable uncertainty. Based on our results, it will be difficult to credibly predict changes to soil carbon resulting from common land use and management practices, both at fine and coarse scales. To overcome these limitations, we propose an integrated system of spatially explicit direct measurement of soil carbon at locations with well-documented management histories and climatic records to better parameterize the model for rangeland applications. Further, because the drivers of soil carbon fluxes on rangelands are dominated by climate rather than management, the interface should be redesigned to simulate soil carbon changes based on ecological state rather than practice application.
  • Authors:
    • Carbon Disclosure Project
  • Year: 2010
  • Summary: CDP drew on data submitted through the CDP annual information request from S&P 100 companies. Of the 100 companies, only 51 companies submitted sufficient data, to analyze the current absolute emissions trends within reported scopes 1 & 2 5 emissions in the years 2007-2009, showing the need for more detailed reporting year on year. From the data received from 51 companies, we then analyzed the annual percentage reduction or increase represented by reported emissions data and compared this to both the average annual emissions reductions required to meet President Obama's commitment of a 17% reduction by 2020 and to the IPCC recommendations of an absolute reduction in emissions of 80-95% by 2050. * CDP has calculated that the average annual reduction rate required to reach the US 2020 target is 1.05% per annum.
  • Authors:
    • Sohngen, B.
    • Choi, S. W.
  • Source: Climatic Change
  • Volume: 99
  • Issue: 1-2
  • Year: 2010
  • Summary: This study investigates the cost of soil carbon sequestration in the Midwest US. The model addresses several missing components in earlier analyses: the link between the residue level choice and carbon payments, crop rotations, carbon loss when shifting from conservation to conventional tillage and the spatial pattern of carbon sequestration across different soil types. The results suggest that for $100 per metric ton of carbon, 1.5 million metric tons of carbon could be sequestered per year on the 19.9 million hectares of cropland in the study region. These estimates suggest less carbon potential than existing studies because the opportunity costs associated with conservation tillage are fairly high. Annual carbon rental payments are found to be more efficient, as expected, but for smaller programs, per hectare rental payments are not substantially more costly.
  • Authors:
    • Pedersen, P.
    • Janssen, M. R.
    • Nafziger, E. D.
    • Coulter, J. A.
  • Source: Agronomy Journal
  • Volume: 102
  • Issue: 1
  • Year: 2010
  • Summary: Transgenic Bt corn hybrids with resistance to corn rootworm or European corn borer can have greater tolerance to water and nutrient stress, and thus may have higher optimum plant densities. Experiments were conducted following soybean over nine site-years in Illinois to determine whether the response to plant density for corn grain yield and net return to seed cost differ among near-isoline hybrids with no insect resistance, Bt resistance to CRW, or Bt resistance to CRW plus ECB. Similar experiments were conducted over three site-years in Iowa following both soybean and corn for near-isoline hybrids with Bt resistance to ECB or ECB plus CRW. Larval CRW injury was low in Iowa and stalk lodging was minimal in all experiments. Across site-years in Illinois and in both crop sequences in Iowa, grain yield and net return to seed cost were not af ected by hybrid. Net return to seed cost within $2.50 ha-1 of the maximum occurred with densities of 76,300 to >98,600 plants following soybean in Illinois, 87,100 to 93,400 plants following soybean in Iowa, and 87,400 to 95,700 plants following corn in Iowa. Yields within these optimum plant densities were 15.9, 16.1, and 15.4 Mg ha-1, respectively. When CRW and ECB are managed or are at low levels, optimum plant density is similar between hybrids with or without resistance to these pests.
  • Authors:
    • McCarl, B. A.
    • Adams, D. M.
    • Latta, G.
    • Alig, R.
  • Source: Forest Policy and Economics
  • Volume: 12
  • Issue: 1
  • Year: 2010
  • Summary: The forest sector can contribute to atmospheric greenhouse gas reduction, while also providing other environmental, economic, and social benefiĀts. Policy tools for climate change mitigation include carbon-related payment programs as well as laws and programs to impede the loss of agricultural and forest lands to development. Policy makers will base their expectations of the effectiveness of these strategies to some degree on anticipated land use impacts. We examine a number of scenarios about carbon prices, urban development rates, and potential future land transfers between forestry and agriculture to provide information about the potential effectiveness of policies to address climate change in the U.S. Because large areas of land can move between forestry and agricultural uses, we used the Forest and Agriculture Sector Optimization Model-Greenhouse Gases model to examine responses between sectors as part of GHG policy analysis. The model projects changes in land uses,has full carbon accounting for both forestry and agriculture, and can examine a broad range of adaptation and climate change mitigation options. Modeling results suggest that receipt of carbon-related payments by landowners in forestry and agriculture can have substantial impacts on future land use patterns, levels of terrestrial carbon sequestration, forest resource conditions, agricultural production trends, and bioenergy production.
  • Authors:
    • Halvorson, A. D.
    • Archer, D. W.
  • Source: Soil Science Society of America Journal
  • Volume: 74
  • Issue: 2
  • Year: 2010
  • Summary: Recent soil and crop management technologies have potential for mitigating greenhouse gas emissions; however, these management strategies must be profitable if they are to be adopted by producers. The economic feasibility of reducing net greenhouse gas emissions in irrigated cropping systems was evaluated for 5 yr on a Fort Collins clay loam soil (a fine-loamy, mixed, superactive, mesic Aridic Haplustalf). Cropping systems included conventional tillage continuous corn (Zea mays L.) (CT-CC), no-till continuous corn (NT-CC), and no-till corn-bean (NT-CB) including 1 yr soybean [Glycine max (L.) Merr.] and 1 yr dry bean (Phaseolus vulgaris L.). The study included six N fertilization rates ranging from 0 to 246 kg ha-1. Results showed highest average net returns for NT-CB, exceeding net returns for NT-CC and CT-CC by US$182 and US$228 ha-1, respectively, at economically optimum N fertilizer rates. Net global warming potential (GWP) generally increased with increasing N fertilizer rate with the exception of NT-CC, where net GWP initially declined and then increased at higher N rates. Combining economic and net GWP measurements showed that producers have an economic incentive to switch from CT-CC to NT-CB, increasing annual average net returns by US$228 ha-1 while reducing annual net GWP by 929 kg CO2 equivalents ha-1. The greatest GWP reductions (1463 kg CO2 equivalents ha-1) could be achieved by switching from CT-CC to NT-CC while also increasing net returns, but the presence of a more profitable NT-CB alternative means NT-CC is unlikely to be chosen without additional economic incentives.
  • Authors:
    • Daigneault, A.
    • Beach, R. H.
    • Latta, G.
    • Adams, D. M.
    • Alig, R. J.
    • Rose, S. K.
    • Murray, B. C.
    • McCarl, B. A.
    • Baker, J. S.
  • Source: Mitigation Beyond the Cap: A Series of Brief on Expanding Climate Mitigation Opportunities
  • Year: 2010
  • Summary: Concerns about expected increases in energy and other agricultural input costs have led some to oppose greenhouse gas cap-and-trade legislative proposals. However, these policies could result in significant revenue for U.S. agriculture, which is a potential source of low-carbon bioenergy and low-cost abatement alternatives to fossil fuel emission reductions (i.e., offsets) through terrestrial sequestration, afforestation, and reductions in nitrous oxide and methane emissions. It is important to simultaneously model these factors in order to properly assess the net impacts for U.S. agriculture. Existing studies of the impacts of low-carbon policies on the agricultural sector have generally not accounted for changes in production practices, demand responses, or commodity and offset revenues. In this study, we estimate the U.S. net farm income implications of moving to a low-carbon economy. We find higher input costs, higher output prices, modest consumer response, increased bioenergy supply, and offset income opportunities. On net, we find that the U.S. agricultural sector would benefit from a U.S. climate policy.
  • Authors:
    • Daigneault, A.
    • Beach, R.
    • Latta, G.
    • Adams, D. M.
    • Alig, R. J.
    • Rose, S. K.
    • Murray, B. C.
    • McCarl, B. A.
    • Baker, J. S.
  • Source: Policy Issues
  • Volume: PI7
  • Year: 2010
  • Summary: Concerns about expected increases in energy and other agricultural input costs have led some to oppose greenhouse gas cap-and-trade legislative proposals. However, these policies could result in significant revenue for U.S. agriculture, which is a potential source of low-carbon bioenergy and low-cost abatement alternatives to fossil fuel emission reductions (i.e., offsets) through terrestrial sequestration, afforestation, and reductions in nitrous oxide and methane emissions. It is important to simultaneously model these factors in order to properly assess the net impacts for U.S. agriculture. Existing studies of the impacts of low-carbon policies on the agricultural sector have generally not accounted for changes in production practices, demand responses, or commodity and offset revenues. In this study, we estimate the U.S. net farm income implications of moving to a low-carbon economy. We find higher input costs, higher output prices, modest consumer response, increased bioenergy supply, and offset income opportunities. On net, we find that the U.S. agricultural sector would benefit from a U.S. climate policy.
  • Authors:
    • Blanco-Canqui, H.
  • Source: Agronomy Journal
  • Volume: 102
  • Issue: 2
  • Year: 2010
  • Summary: Interest in producing cellulosic ethanol from renewable energy sources is growing. Potential energy crops include row crops such as corn (Zea mays L.), perennial warm-season grasses (WSGs), and short-rotation woody crops (SRWCs). However, impacts of growing dedicated energy crops as biofuel on soil and environment have not been well documented. This article reviews the (i) impacts of growing WSGs and SRWCs on soil properties, soil organic carbon (SOC) sequestration, and water quality, and (ii) performance of energy crops in marginal lands. Literature shows that excessive (>= 50%) crop residue removal adversely impacts sod and environmental quality as well as crop yields. Growing WSGs and SRWCs can be potential alternatives to crop residue removal as biofuel. Warm-season grasses and SRWCs can improve soil properties, reduce soil erosion, and sequester SOC. Crop residue removal reduces SOC concentration by 1 to 3 Mg ha(-1) yr(-1) in the top 10 cm, whereas growing WSGs and SRWCs increase SOC concentration while providing biofuel feedstocks. The WSGs can store SOC between 0 and 3 Mg C ha(-1) yr(-1) in the top 5 cm of soil, while the SRWCs can store between 0 and 1.6 Mg ha(-1) yr(-1) of SOC in the top 100 cm. The WSGs and SRWCs have more beneficial effects on soil and environment when grown in marginal lands than when grown in croplands or natural forests. Indeed, they can grow in nutrient-depleted, compacted, poorly drained, acid, and eroded soils. Development of sustainable systems of WSGs and SRWCs in marginal lands is a high priority.
  • Authors:
    • Sun, Y.
    • Dowd, S.
    • Acosta-Martinez, V.
    • Wester, D.
    • Allen, V.
  • Source: Applied Soil Ecology
  • Volume: 45
  • Issue: 1
  • Year: 2010
  • Summary: Bacterial tag-encoded FLX amplicon pyrosequencing of the 16S rDNA gene was used to evaluate bacterial diversity of a clay loam soil (fine, mixed, thermic Torrertic Paleustolls) after 10 years under an integrated livestock (beef)-cotton ( Gossypium hirsutum L.) production system compared to continuous cotton in a semiarid region. In the integrated system, cattle alternatively grazed a perennial warm-season grass [ Bothriochloa bladhii (Retz) S.T. Blake] paddock and small grains grown in two paddocks of a wheat ( Triticum aestivum L.)-fallow-rye ( Secale cereal L.)-cotton rotation. Areas excluded from grazing in the integrated system were also evaluated. Maximum observed number of unique sequences operational taxonomic units (OTU) at 3% dissimilarity level (roughly corresponding to the species level) corresponded to 1200 and 1100 at 0-5 and 5-15 cm depths, respectively. Predominant phyla (up to 65% of abundance) at 0-5 and 5-15 cm in this soil were Proteobacteria, Actinobacteria and Gemmatimonadetes. Proteobacteria were predominant in soil under all components of the integrated livestock-cotton system compared to continuous cotton whereas Bacteroidetes were predominant under continuous cotton. Firmicutes (i.e., Clostridia) and Chlorofexi (i.e., Thermomicrobia) were more abundant in soil under fallow periods of the rotation compared to under cotton (Rye- Cotton-Wheat-Fallow or continuous cotton) or grass (i.e., pasture). The lowest OTUs were detected in soil under fallow periods of the rotation (Wheat- Fallow-Rye-Cotton) compared to the other treatments. Grazing effects were significant for Actinobacteria, Proteobacteria and Chlorofexi. Compared to the continuous cotton system, this study revealed significant changes in bacterial phyla distribution under integrated livestock-cotton systems for a semiarid soil after 10 years. Positive correlations were found between certain bacteria ( Proteobacteria, Firmicutes, Chloroflexi, Verrucomicrobiae and Fibrobacteres) and the activities of alkaline phosphatase and beta-glucosidase or beta-glucosaminidase.