• Authors:
    • Robertson, G. P.
    • Grace, P. R.
    • Bohm, S.
    • McSwiney, C. P.
  • Source: Journal of Natural Resources and Life Sciences Education
  • Volume: 39
  • Year: 2010
  • Summary: Opportunities for farmers to participate in greenhouse gas (GHG) credit markets require that growers, students, extension educators, offset aggregators, and other stakeholders understand the impact of agricultural practices on GHG emissions. The Farming Systems Greenhouse Gas Emissions Calculator, a web-based tool linked to the SOCRATES soil carbon process model, provides a simple introduction to the concepts and magnitudes of gas emissions associated with crop management. Users choose a county of interest on an introductory screen and are taken to the input/output window, where they choose crops, yields, tillage practices, or nitrogen fertilizer rates. Default values are provided based on convention and county averages. Outputs include major contributors of greenhouse gases in field crops: soil carbon change, nitrous oxide (N2O) emission, fuel use, and fertilizer. We contrast conventional tillage and no-till in a corn-soybean-wheat (Zea mays L.-Glycine max (L.) Merr.-Triticum aestivum L.) rotation and compare continuous corn fertilized at 101 and 134 kg N ha-1 yr-1. In corn years, N2O was the dominant GHG, due to high fertilizer requirements for corn. No-till management reduced greenhouse gas emissions by 50% due to net soil carbon storage. Continuous corn fertilized at 101 kg N ha-1 yr-1 emitted 1.25 Mg CO2 equivalents ha-1 yr-1 compared with 1.42 Mg CO2 equivalents ha-1 yr-1 at 134 kg N ha-1 yr-1, providing a 12% GHG savings. The calculator demonstrates how cropping systems and management choices affect greenhouse gas emissions in field crops.
  • Authors:
    • Yagi, K.
    • Nakajima, Y.
    • Sawamoto, T.
    • Nishimura, S.
    • Minamikawa, K.
  • Source: Global Change Biology
  • Volume: 16
  • Issue: 2
  • Year: 2010
  • Summary: Abstract: Indirect emission of nitrous oxide (N2O), associated with nitrogen (N) leaching and runoff from agricultural lands is a major source of atmospheric N2O. Recent studies have shown that carbon dioxide (CO2) and methane (CH4) are also emitted via these pathways. We measured the concentrations of three dissolved greenhouse gases (GHGs) in the subsurface drainage from field lysimeter that had a shallow groundwater table. Above-ground fluxes of CH4 and N2O were monitored using an automated closed-chamber system. The annual total emissions of dissolved and aboveground GHGs were compared among three cropping systems; paddy rice, soybean and wheat, and upland rice. The annual drainage in the paddy rice, the soybean and wheat, and the upland rice plots was 1435, 782, and 1010mmyr -1, respectively. Dissolved CO2 emissions were highest in the paddy rice plots, and were equivalent to 1.05-1.16% of the carbon storage in the topsoil. Dissolved CH4 emissions were also higher in the paddy rice plots, but were only 0.03-0.05% of the aboveground emissions. Dissolved N2O emissions were highest in the upland rice plots, where leached N was greatest due to small crop biomass. In the soybean and wheat plots, large crop biomass, due to double cropping, decreased the drainage volume, and thus decreased dissolved GHG emissions. Dissolved N2O emissions from both the soybean and wheat plots and the upland rice plots were equivalent to 50.3-67.3% of the aboveground emissions. The results indicate that crop type and rotation are important factors in determining dissolved GHG emissions in the drainage from a crop field.
  • Authors:
    • Six, J.
    • Lee, J.
    • Temple, S. R.
    • Rolston, D. E.
    • Mitchell, J.
    • Kaffka, S. R.
    • Wolf, A.
    • De Gryze, S.
  • Source: Ecological Applications
  • Volume: 20
  • Issue: 7
  • Year: 2010
  • Summary: Despite the importance of agriculture in California's Central Valley, the potential of alternative management practices to reduce soil greenhouse gas (GHG) emissions has been poorly studied in California. This study aims at (1) calibrating and validating DAYCENT, an ecosystem model, for conventional and alternative cropping systems in California's Central Valley, (2) estimating CO2, N2O and CH4 soil fluxes from these systems, and (3) quantifying the uncertainty around model predictions induced by variability in the input data. The alternative practices considered were cover cropping, organic practices, and conservation tillage. These practices were compared with conventional agricultural management. The crops considered were beans, corn, cotton, safflower, sunflower, tomato, and wheat. Four field sites for which at least five years of measured data were available, were used to calibrate and validate the DAYCENT model. The model was able to predict 86% to 94% of the measured variation in crop yields and 69% to 87% of the measured variation in soil organic carbon (SOC) contents. A Monte-Carlo analysis showed that the predicted variability of SOC contents, crop yields and N2O fluxes was generally smaller than the measured variability of these parameters, in particular for N2O fluxes. Conservation tillage had the smallest potential to reduce GHG emissions among the alternative practices evaluated, with a significant reduction of the net soil GHG fluxes in two of the three sites of 336 ± 47 (mean ± standard error) and 550 ± 123 kg CO2-eq ha-1 yr-1. Cover cropping had a larger potential, with net soil GHG flux reductions of 752 ± 10, 1072 ± 272 and 2201 ± 82 kg CO2-eq ha-1 yr-1. Organic practices had the greatest potential for soil GHG flux reduction, with 4577 ± 272 kg CO2-eq ha-1 yr-1. Annual differences in weather or management conditions contributed more to the variance in annual GHG emissions than soil variability did. We concluded that the DAYCENT model was successful at predicting GHG emissions of different alternative management systems in California, but that a sound error analysis must accompany the predictions to understand the risks and potentials of GHG mitigation through adoption of alternative practices.
  • Authors:
    • Ogle, S.
    • Del Grosso, S.
    • Delgado, J.
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 86
  • Issue: 3
  • Year: 2010
  • Summary: It is difficult to quantify nitrogen (N) losses from agricultural systems; however, we can use 15N isotopic techniques to conduct site-specific studies to increase our knowledge about N management and fate. Our manuscript analyzes two reviews of selected 15N isotopic studies conducted to monitor N fate. The mechanistic foci of these studies include crop residue exchange and N fate in farming systems. Analysis of the data presented in these studies supports the claim that the average N losses are greater from inorganic N fertilizer inputs than organic crop residue N inputs. Additionally we conducted unique DAYCENT simulations of the effects of crop residue on nitrous oxide (N2O-N) emissions and nitrate (NO3-N) leaching. The simulation evaluations support the crop residue 15N exchange studies and show lower leaching and N2O-N emissions from crop residue sources when compared to N fertilizer. The 15N data suggest that the N in the crop residue pool must be recycled, and that this is a slower and more protected pool when compared to the readily available fertilizer. The results suggest that the Intergovernmental Panel on Climate Change (IPCC) methodology should be reevaluated to determine whether the direct and indirect N2O-N emission coefficients need to be lowered to reflect fewer N2O-N emissions from high C/N crop residue N inputs. The data suggest that accounting for nutrient cycling has implications for public policy associated with the United Nations Framework Convention on Climate Change (UNFCCC) and mitigation of N2O-N emissions from agricultural soils. Additional crop residue exchange studies, field N2O-N and NO3-N leaching and support model evaluations are needed across different worldwide agroecosystems.
  • Authors:
    • ERS,USDA
  • Volume: 2012
  • Year: 2010
  • Authors:
    • Jackson, W.
    • Cox, T. S.
    • Cox, C. M.
    • Buckler, E. S.
    • Brummer, E. C.
    • Ibrahim, A. M. H.
    • Hulke, B. S.
    • Murray, S. C.
    • Jones, S. S.
    • Ploschuk, E.
    • Paterson, A. H.
    • Hu, F.
    • Culman, S. W.
    • Crews, T. E.
    • Xu, Y.
    • Wyse, D. L.
    • Wade, L. J.
    • Van Tassel, D. L.
    • Tao, D.
    • Snapp, S.
    • Sacks, E. J.
    • Borevitz, J.
    • Bell, L. W.
    • Reganold, J. P.
    • Glover, J. D.
    • Holland, J.
    • Gill, B. S.
    • Eriksson, D.
    • DeHaan, L. R.
  • Source: Science
  • Volume: 328
  • Issue: 5986
  • Year: 2010
  • Summary: Despite doubling of yields of major grain crops since the 1950s, more than one in seven people suffer from malnutrition. Global population is growing; demand for food, especially meat, is increasing; much land most suitable for annual crops is already in use; and production of nonfood goods (e.g., biofuels) increasingly competes with food production for land. The best lands have soils at low or moderate risk of degradation under annual grain production but make up only 12.6% of global land area (16.5 million km2). Supporting more than 50% of world population is another 43.7 million km2 of marginal lands (33.5% of global land area), at high risk of degradation under annual grain production but otherwise capable of producing crops. Global food security depends on annual grains—cereals, oilseeds, and legumes—planted on almost 70% of croplands, which combined supply a similar portion of human calories. Annual grain production, though, often compromises essential ecosystem services, pushing some beyond sustainable boundaries. To ensure food and ecosystem security, farmers need more options to produce grains under different, generally less favorable circumstances than those under which increases in food security were achieved this past century. Development of perennial versions of important grain crops could expand options.
  • Authors:
    • Kohei, U.
    • Ebel, R.
    • Horowitz, J.
  • Source: Economic Information Bulletin
  • Volume: 70
  • Year: 2010
  • Summary: Most U.S. farmers prepare their soil for seeding and weed and pest control through tillage-plowing operations that disturb the soil. Tillage practices affect soil carbon, water pollution, and farmers' energy and pesticide use, and therefore data on tillage can be valuable for understanding the practice's role in reaching climate and other environmental goals. In order to help policymakers and other interested parties better understand U.S. tillage practices and, especially, those practices' potential contribution to climate-change efforts, ERS researchers compiled data from the Agricultural Resource Management Survey and the National Resources Inventory-Conservation Effects Assessment Project's Cropland Survey. The data show that approximately 35.5 percent of U.S. cropland planted to eight major crops, or 88 million acres, had no tillage operations in 2009.
  • Authors:
    • Singh, A.
    • Kumar, R.
    • Pathak, H.
    • Jain, N.
    • Sasmal, S.
    • Bhatia, A.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 136
  • Issue: 3
  • Year: 2010
  • Summary: No-till farming in wheat is being practiced in the rice-wheat system of the Indo-Gangetic plains of south Asia for resource conservation. No-tillage leads to mitigation of carbon dioxide emission, but may emit more nitrous oxide (N2O) as compared to conventional tillage reducing mitigation benefit. The aim of this study was assessment of N2O emission in wheat grown under conventional and no-tillage and its mitigation using two new nitrification inhibitors, viz. S-benzylisothiouronium butanoate (SBT-butanoate) and S-benzylisothiouronium furoate (SBT-furoate). Cumulative emission of N2O-N was higher under no-tillage by 12.2% with urea fertilization and from 4.1 to 4.8% for the inhibitor treatments as compared to the conventional tillage. In no-tillage total emission of N2O-N reduced from 0.43% of applied N with urea to 0.29% of applied N with SBT-furoate treatment. The N2O-N emissions in SBT-butanoate treatment were at par with the standard dicyandiamide (DCD) inhibitor treatment. Water-filled pore space (WFPS) was higher on most days under no-tillage, with the largest emissions (>1000 mu g N2O-N m(-2) day(-1)) coming with nitrification of ammonium-N present in soil below 60% WFPS. Carbon efficiency ratio was highest (48.1) from SBT-furoate treatment under conventional tillage. The nitrification inhibitors used in the study increased yield of wheat, reduced global warming potential by 8.9-19.5% over urea treatment and may be used to mitigate N2O emission.
  • Authors:
    • Horvath, G. V.
    • Sass, L.
    • Majer, P.
    • Lelley, T.
    • Feherne, J. E.
    • Szenasi, M.
    • Mihaly, R.
    • Lantos, C.
    • Cseuz, L.
    • Pauk, J.
    • Vass, I.
    • Dudits, D.
  • Source: Tagung der Vereinigung der Pflanzenzüchter und Saatgutkau fleute Österreichs
  • Year: 2010
  • Summary: Breeding for drought tolerance is becoming a more and more important challenge in case of crop plants, notably in wheat in Europe, not only in the Mediterranean area, but in central Europe too. The breeding process includes the characterization of the basic breeding material in regard to performance under well-watered and drought stressed conditions. For our experiments we set up a mobile automatic rain shelter (MARS) system in the breeding nursery and a complex stress diagnostic system (CSDS) in greenhouse tests of the Cereal Research Non-Profit Limited Company, where we could analyze the responses of different wheat materials to drought stress. Wheat plants were grown under ideal water regime in parallel experiments using sprinkler irrigation and shadowing by MARS. In greenhouse the tested wheat materials were grown under optimal (watering to 60% of the 100% soil water capacity) and suboptimal stress (watering to 20%) conditions. The effect of water withholding on plant growing was registered by a digital imaging system in CSDS and traditional way under MARS. After harvesting, plant heights, spike lengths, grain numbers, total grain weights and other agronomical parameters were measured and values of well-watered and stressed plants were compared.
  • Authors:
    • Pepo, P.
  • Source: CEREAL RESEARCH COMMUNICATIONS
  • Volume: 59
  • Issue: Supplement
  • Year: 2010
  • Summary: The interactions of ecological conditions, genotypes and agrotechnical elements determine the yield quantity, quality and stability in cereal (wheat, maize) production. The applied input-level can modify the adaptive capacity of crop models to ecological conditions and resilience of agro-ecosystems. The effects of agrotechnical elements (crop rotation, fertilization, irrigation, crop protection, plant density) were studied in the long-term experiment on chernozem soil. Our scientific results proved that the high yields and good yield-stability were obtained in the input-intensive crop models, so these models had better adaptive capacity and resilience. Maize had lower ecological adaptive ability than winter wheat. The optimalization of agrotechnical elements reduces the harmful climatic effects so we can increase the resilience of cereals agro-ecosystems. The yields of wheat varied between 2 and 7 t ha -1 in extensive and 8 and 10 t ha -1 in intensive crop models and the yields of maize ranged between 2 and 11 t ha -1 and 10 and 15 t ha -1, respectively.