• Authors:
    • Thibeault, J. M.
    • Seth, A.
  • Source: CLIMATIC CHANGE
  • Volume: 127
  • Issue: 2
  • Year: 2014
  • Summary: Climate extremes indices are evaluated for the northeast United States and adjacent Canada (Northeast) using gridded observations and twenty-three CMIP5 coupled models. Previous results have demonstrated observed increases in warm and wet extremes and decreases in cold extremes, consistent with changes expected in a warming world. Here, a significant shift is found in the distribution of observed total annual precipitation over 1981-2010. In addition, significant positive trends are seen in all observed wet precipitation indices over 1951-2010. For the Northeast region, CMIP5 models project significant shifts in the distributions of most temperature and precipitation indices by 2041-2070. By the late century, the coldest (driest) future extremes are projected to be warmer (wetter) than the warmest (wettest) extremes at present. The multimodel interquartile range compares well with observations, providing a measure of confidence in the projections in this region. Spatial analysis suggests that the largest increases in heavy precipitation extremes are projected for northern, coastal, and mountainous areas. Results suggest that the projected increase in total annual precipitation is strongly influenced by increases in winter wet extremes. The largest decreases in cold extremes are projected for northern and interior portions of the Northeast, while the largest increases in summer warm extremes are projected for densely populated southern, central, and coastal areas. This study provides a regional analysis and verification of the latest generation of CMIP global models specifically for the Northeast, useful to stakeholders focused on understanding and adapting to climate change and its impacts in the region.
  • Authors:
    • Ansley, R. J.
    • Park, S.
    • Wang, T.
    • Amosson, S. H.
  • Source: BIOENERGY RESEARCH
  • Volume: 7
  • Issue: 4
  • Year: 2014
  • Summary: The US Environmental Protection Agency (EPA) implemented the revised Renewable Fuel Standard (RFS2) in 2010, which mandates that a minimum of 16 billion gallons of cellulosic biofuel be produced by 2022. Woody plants growing on native rangelands in the Southern Great Plains (SGP) region of the USA, such as honey mesquite and juniper species, may have potential as bioenergy feedstock, but there are concerns regarding variability in biomass density distribution and high harvest and transport costs. The objective of this study was to evaluate economic and greenhouse gas (GHG) performances of honey mesquite relative to irrigated and dryland sweet sorghum and dryland switchgrass bioenergy feedstock as delivered to the farm gate. Four efficiency criteria such as biomass production cost, energy cost, GHG offset, and GHG use were calculated. Our results suggest that mesquite lagged slightly behind switchgrass when biomass and energy efficiency are considered. However, mesquite appears superior to the other feedstocks in two categories-GHG offset efficiency and GHG use efficiency once land use change (LUC) effects are accounted for. Mesquite as a bioenergy feedstock in the SGP has greater potential if additional benefits such as increased grass production for livestock production and reduction in herbicide costs for mesquite control-both of which would occur as a result of mesquite harvesting-are considered. Mesquite production values on a per-land area basis are lower than the other feedstocks observed in this comparison and therefore could not supplant those feedstocks entirely, but mesquite appears to be suitable as a complementary feedstock to contribute to total biomass feedstock demand.
  • Authors:
    • Wuest, S. B.
    • Williams, J. D.
    • Long, D. S.
  • Source: JOURNAL OF SOIL AND WATER CONSERVATION
  • Volume: 69
  • Issue: 6
  • Year: 2014
  • Summary: The winter wheat (Triticum aestivum L.)/summer fallow rotation typically practiced in the intermediate precipitation zone (300 to 450 mm [12 to 18 in]) of the inland Pacific Northwest has proven to be economically stable for producers in this region. However, multiple tillage operations are used to control weeds and retain seed-zone soil moisture, which disturbs the soil and makes it prone to substantial erosion. Alternatives to this conventional disturbance tillage (DT) system include either no-tillage (NT) or minimum tillage (MT) in combination with increasing cropping intensity. The objective of this study was to compare runoff, soil erosion, crop residue, and yield productivity resulting from NT, and DT, or MT. Small collectors and flumes were used to quantify runoff and soil erosion from small drainages and slopes in three different experiments near Pendleton, Oregon. The first experiment included two neighboring drainages:one farmed using DT with a two-year crop rotation over eight years (2001 to 2008) and the other NT with a four-year crop rotation (2001 to 2008). The second experiment comprised a hillslope planted to different crops using NT over eight years (1998 to 2005) and MT over three years (2006 to 2008). The third experiment was situated in a shallow draw in which NT and MT with a four-year (2004 to 2008) crop rotation was compared. Runoff measured in flumes was substantially influenced by tillage method in the order of DT > NT in a ratio of 10:1 at the first site. At the second site, NT produced no runoff compared to 1.6 mm y(-1) (0.06 in yr(-1)) from MT. Soil erosion was found to be DT > NT in a ratio of 5:1 at the first site and 2:1 for the second site. For small collectors the differences were significant:runoff was DT > NT in a ratio of 47:1 for the first site, and MT > NT in a ratio of 2:1 for the third site. Winter wheat yields did not differ significantly among NT, DT, and MT. Broader acceptance of NT cropping systems in the intermediate precipitation zone of this region would substantially decrease soil losses from farm fields and improve downstream water quality.
  • Authors:
    • Ajanovic, A.
    • Haas, R.
  • Source: APPLIED ENERGY
  • Volume: 135
  • Year: 2014
  • Summary: In the early 2000s high expectations existed regarding the potential contribution of biofuels to the reduction of greenhouse gas emissions and substitution of fossil fuels in transport. In recent years sobering judgments prevailed. The major barriers for a further expansion of biofuels are their high costs (compared to fossil fuels), moderate ecological performances, limited feedstocks for biofuel production and their competition with food production. The objective of this paper is to investigate the market prospects of biofuels up to the year 2030. It focuses on the three currently most important regions for biofuels production and use: the US, EU and Brazil which in 2010 accounted together for almost three-quarters of global biofuel supply. Our method of approach is based on a dynamic economic framework considering the major cost components of biofuels and corresponding technological learning with respect to capital costs. Moreover, for the analysis of the competitiveness of biofuels with fossil fuels also taxes are considered. The most important result is that under existing tax policies biofuels are cost-effective today and also for the next decades in the regions investigated. However, their potentials are restricted especially due to limited crops areas, and their environmental performance is currently rather modest. The major final conclusions are: (i) To reveal the real future market value of biofuels, a CO 2 based tax system should be implemented for all types of fuels providing a neutral environmental incentive for competition between all types of fossil and renewable fuels; (ii) Moreover, the research and development for all types of biofuels, but especially for second generation biofuels, has to be intensified.
  • Authors:
    • Fennessy, M. S.
    • Marton, J. M.
    • Craft, C. B.
  • Source: RESTORATION ECOLOGY
  • Volume: 22
  • Issue: 1
  • Year: 2014
  • Summary: We compared potential denitrification and phosphorus (P) sorption in restored depressional wetlands, restored riparian buffers, and natural riparian buffers of central Ohio to determine to what extent systems restored under the U.S. Department of Agriculture's Wetland Reserve Program (WRP) and Conservation Reserve Program (CRP) provide water quality improvement benefits, and to determine which practice is more effective at nutrient retention. We also measured soil nutrient pools (organic C, N, and P) to evaluate the potential for long-term C sequestration and nutrient accumulation. Depressional wetland soils sorbed twice as much P as riparian soils, but had significantly lower denitrification rates. Phosphorus sorption and denitrification were similar between the restored and natural riparian buffers, although all Natural Resources Conservation Service (NRCS) practices had higher denitrification than agricultural soils. Pools of organic C (2570-3320 g/m 2), total N (216-243 g/m 2), and total P (60-71 g/m 2) were comparable among all three NRCS practices but were greater than nearby agricultural fields and less than natural wetlands in the region. Overall, restored wetlands and restored and natural riparian buffers provide ecosystem services to the landscape that were lost during the conversion to agriculture, but the delivery of services differs among conservation practices, with greater N removal by riparian buffers and greater P removal by wetlands, attributed to differences in landscape position and mineral soil composition. At the landscape, and even global level, wetland and riparian restoration in agricultural landscapes will reintroduce multiple ecosystem services (e.g. C sequestration, water quality improvement, and others) and should be considered in management plans.
  • Authors:
    • Burmester, C. H.
    • Balkcom, K. S.
  • Source: Agronomy Journal
  • Volume: 107
  • Issue: 2
  • Year: 2014
  • Summary: Alabama wheat ( Triticum aestivum L.) farmers are changing management practices, which include using higher N fertilizer rates and planting wheat with no-tillage or other conservation tillage systems to maximize yields. Experiments were conducted to (i) determine the level of tillage necessary to optimize wheat yields across different regions of Alabama and (ii) determine if N requirements change across tillage systems and regions in Alabama at four locations resulting in 9 site-year comparisons. Each experiment consisted of a split-plot design with tillage as the main plot and 12 N fertilizer treatments as subplots, replicated four times to compare Zadoks' Growth Stage (GS)-30 tiller densities, tiller N concentrations, tiller biomass, GS-31 wheat biomass, biomass N concentration, wheat yields, and grain crude protein. Nitrogen treatments consisted of different rates across fall, GS-30, and GS-31 application times. Tillage systems had no effect on tiller density, tiller N concentration, or tiller biomass, but fall N increased tiller density 15% and tiller biomass 34% across Coastal Plain locations. Non-inversion tillage increased wheat yields 13% on Coastal Plain soils compared to conventional tillage. Fall N increased wheat yields 10%, and N applied at GS-30 improved yields 18% compared to delaying application until GS-31, indicating application of fall N and applying total N by GS-30 was imperative for successful wheat production on Coastal Plain soils. Neither tillage system nor N applications affected wheat production extensively across the Limestone Valley. Non-inversion tillage or no-tillage with current recommended N practices can be successfully used in Alabama wheat production.
  • Authors:
    • Mahanta, S. K.
    • Ghosh, P. K.
  • Source: Invited Article
  • Volume: 35
  • Issue: 2
  • Year: 2014
  • Summary: Globally soils contain around twice the amount of carbon in the atmosphere and thrice in vegetation. Therefore, soil is both 'a source and a sink' for greenhouse gases and balance between the functions is very delicate. The gases move continuously from one pool to another maintaining balance in different pools of the ecosystem. Appropriate management of soil offers to the potential to provide solutions for each of the challenges related to food security and climate change. The estimated carbon sequestration potential of world soils lies between 0.4 to 1.2 Gt per year which includes 0.01-0.30 Gt per year from grasslands. Carbon sequestration can be enhanced in grasslands through grazing management, sowing favorable forage species, fertilizer application and irrigation, restoration of degraded grasslands etc. However, there are certain limitations that hinder in adopting the practices for enhancing carbon sequestration in grasslands. The limitations include continuous degradation of grasslands, changing climate, paucity of information on carbon stock of grasslands from developing countries, disagreement on systems for documenting carbon stock changes over a period of time, hindrance in policy implementations etc.
  • Authors:
    • Mengel, D. B.
    • Hettiarachchi, G. M.
    • Khatiwada, R.
    • Fei, M.
  • Source: Journal
  • Volume: 179
  • Issue: 3
  • Year: 2014
  • Summary: Crop yields are limited primarily by unavailability of nutrients in agricultural soil. Adoption of reduced-tillage and no-tillage systems leads to stratification of nutrients in surface soil, so management of phosphorus (P) in these systems is a major issue. The objective of this research was to understand the influence of placement (broadcast vs. deep-placed P) and fertilizer source (granular vs. liquid P) on the reaction products of P under greenhouse conditions using soil columns. Phosphorus was added at a rate of 75 kg/ha to two soils: an acid soil from Manhattan, KS, and a slightly acid to neutral soil from Ottawa, KS. At 5 weeks after P application, soil pH, resin-extractable P, and speciation of P in soils were determined at different distances from the point of fertilizer application. Scanning electron microscope with energy-dispersive X-ray analysis and synchrotron-based X-ray absorption near-edge structure spectroscopy were used to understand P speciation. Results for P fertilizer sources and placement with respect to resin-extractable P showed no clear differences between the treatments except for granular broadcast and granular deep-placed treatments in the Ottawa soil. Reaction products formed after application of P in two soils showed some clear differences. The X-ray absorption near-edge structure speciation revealed that Fe-P-like forms dominated in the acidic soil, whereas adsorbed and Fe and Ca-P-like forms dominated in the neutral to slightly acid soil. No clear trends in reaction products were detected with respect to P source or the P placement method. Furthermore, scanning electron microscope with energy-dispersive X-ray analysis of incubated fertilizer granules extracted from soils at 5 weeks showed enrichment of Al, Fe, and Ca in the zones of remaining P in incubated granules, indirectly indicating that these cations enter and or remaining in the granules and begin to react with P before the granules dissolve completely.
  • Authors:
    • Amichev,Beyhan Y.
    • Hangs,Ryan D.
    • Konecsni,Sheala M.
    • Stadnyk,Christine N.
    • Volk,Timothy A.
    • Belanger,Nicolas
    • Vujanovic,Vladimir
    • Schoenau,Jeff J.
    • Moukoumi,Judicael
    • Van Rees,Ken C. J.
  • Source: Soil Science Society of America Journal
  • Volume: 78
  • Issue: 1
  • Year: 2014
  • Summary: Willow (Salix spp.) short-rotation coppice (SRC) systems are becoming an attractive practice because they are a sustainable system fulfilling multiple ecological objectives with significant environmental benefits. A sustainable supply of bioenergy feedstock can be produced by willow on marginal land using well-adapted or tolerant cultivars. Across Canada and the northern United States, there are millions of hectares of available degraded land that have the potential for willow SRC biomass production, with a C sequestration potential capable of offsetting appreciable amounts of anthropogenic greenhouse gas emissions. A fundamental question concerning sustainable SRC willow yields was whether long-term soil productivity is maintained within a multi-rotation SRC system, given the rapid growth rate and associated nutrient exports offsite when harvesting the willow biomass after repeated short rotations. Based on early results from the first willow SRC rotation, it was found that willow systems have relatively low nutrient demands, with minimal nutrient outputs other than in the harvested biomass. Our overall aim was to summarize the literature and present findings and data from ongoing research trials across Canada and the northern United States examining willow SRC system establishment and viability. The research areas of interest are the crop production of willow SRC systems, above-and belowground biomass dynamics and the C budget, comprehensive soil-willow system nutrient budgets, and soil nutrient amendments (via fertilization) in willow SRC systems. Areas of existing research gaps were also identified for the Canadian context.
  • Authors:
    • Fisher,S.
    • Karunanithi,A.
  • Source: Proceedings of the 9th International Conference on Life Cycle Assessment in the Agri-Food Sector
  • Year: 2014
  • Summary: Local policy makers typically do not have useful, quantitative metrics to compare environmental costs and benefits of urban vegetable production versus the large-scale commercial production in the typical grocery store supply chain. While urban agriculture has been championed as a way to address social issues such as food access and nutrition, we know relatively little about net environmental benefits, if any. The study combines a comparative life cycle assessment of vegetables with effects of direct and indirect land use change resulting from the urban vegetable production. This paper presents a methodology and selected results of scenarios of land use change due to urban vegetable production address resource use, greenhouse gas emissions, employment, and soil organic carbon. Surprisingly, urban vegetable production is not categorically favorable for each metric; several key parameters can shift the balance in favor or out of favor for either growing format, and these parameters are distinctly bottom-up.