• Authors:
    • Jani,Arun D.
    • Grossman,Julie M.
    • Smyth,Thomas J.
    • Hu,Shuijin
  • Source: Plant and Soil
  • Volume: 393
  • Issue: 1-2
  • Year: 2015
  • Summary: Legume cover crops are primarily grown for their contribution to soil N pools, but the effect that this added N has on cover crop root decomposition and N release is poorly understood. Our primary objective was to determine the effect that soil N and root diameter size have on root decomposition and N release. We determined coarse (> 1-mm diameter) and fine (< 1-mm diameter) root distribution for crimson clover (Trifolium incarnatum) and hairy vetch (Vicia villosa Roth) using greenhouse-grown plants, and followed with a 12-week incubation in which coarse and fine roots from both species were incubated under natural and elevated (200 kg ha(-1)) soil N levels. Crimson clover and hairy vetch consisted primarily of fine roots (a parts per thousand yen79 %), which decomposed and released N faster than coarse roots. Soil N addition had a small positive effect on root decomposition, but an inconsistent effect on root N release. There was a net increase in soil inorganic N for all treatments after 12 weeks. These results improved our understanding of decomposition and N release from crimson clover and hairy vetch roots, and are valuable to farmers seeking to better manage soil C and N pools.
  • Authors:
    • Jarvie,H. P.
    • Sharpley,A. N.
    • Flaten,D.
    • Kleinman,P. J. A.
    • Jenkins,A.
    • Simmons,T.
  • Source: Journal of Environmental Quality
  • Volume: 44
  • Issue: 4
  • Year: 2015
  • Summary: We make the case that phosphorus (P) is inextricably linked to an increasingly fragile, interconnected, and interdependent nexus of water, energy, and food security and should be managed accordingly. Although there are many other drivers that influence water, energy, and food security, P plays a unique and under-recognized role within the nexus. The P paradox derives from fundamental challenges in meeting water, energy, and food security for a growing global population. We face simultaneous dilemmas of overcoming scarcity of P to sustain terrestrial food and biofuel production and addressing overabundance of P entering aquatic systems, which impairs water quality and aquatic ecosystems and threatens water security. Historical success in redistributing rock phosphate as fertilizer to enable modern feed and food production systems is a grand societal achievement in overcoming inequality. However, using the United States as the main example, we demonstrate how successes in redistribution of P and reorganization of farming systems have broken local P cycles and have inadvertently created instability that threatens resilience within the nexus. Furthermore, recent expansion of the biofuels sector is placing further pressure on P distribution and availability. Despite these challenges, opportunities exist to intensify and expand food and biofuel production through recycling and better management of land and water resources. Ultimately, a strategic approach to sustainable P management can help address the P paradox, minimize tradeoffs, and catalyze synergies to improve resilience among components of the water, energy, and food security nexus.
  • Authors:
    • Landauer,Mia
    • Juhola,Sirkku
    • Soderholm,Maria
  • Source: Climatic Change
  • Volume: 131
  • Issue: 4
  • Year: 2015
  • Summary: Based on a systematic literature review method that consists of a bibliometric and a content analysis, we examine the current state of research on climate change adaptation and mitigation inter-relationships. Although systematic literature reviews have been applied in other research fields such as health sciences, there are only a few examples in social and environmental sciences. First, we investigate in which research fields the inter-relationships between adaptation and mitigation have been studied and how they have been conceptualised. Second, we analyse what kinds of synergies, trade-offs or conflicts between adaptation and mitigation policies and practices can be identified particularly in urban studies. Third, based on selected urban studies, we examine how inter-relationships between the two policy objectives or practical measures have been studied, in which context, and what is the main outcome of these studies. We also present what suggestions there are for solving conflicts, and how synergies can be enhanced in urban areas. The results indicate that there is value in examining the two together since urban areas are balancing between adaptation and mitigation and have to negotiate trade-offs at different scales.
  • Authors:
    • Liu,Xinsheng
    • Vedlitz,Arnold
    • Stoutenborough,James W.
    • Robinson,Scott
  • Source: Climatic Change
  • Volume: 131
  • Issue: 4
  • Year: 2015
  • Summary: Among many potential causes for policymakers' contention over whether there is a largely unified scientific agreement on global warming and climate change (GWCC), one possible factor, according to the information deficit theory, is that the scientists who testified in congressional hearings might be substantially divided in their views and positions associated with GWCC. To clarify this, we perform content analysis of 1350 testimonies from congressional GWCC hearings over a period of 39 years from 1969 to 2007 and use the data derived from this content analysis to provide an overview of scientist witnesses' stances on GWCC. The key findings include: (1) among the scientists' testimonies with an expressed view on whether GWCC is real, a vast majority (86 %) indicates that it is happening; (2) among the scientists' testimonies with an identified stance on whether GWCC is anthropogenic, a great majority of them (78 %) indicates that GWCC is caused, at least to some degree, by human activity; (3) even under Republican controlled congresses, there is still a supermajority (75 %) - among the scientists' testimonies with an expressed position on GWCC existence or GWCC cause - that believes that GWCC is real and that GWCC is anthropogenic; (4) most scientists' testimonies (95 %) endorse pro-action policy to combat GWCC; and (5) the percentages of scientists' views and positions are consistent across different types of scientist testimony groups. Our findings suggest that the scientific information transmitted to Congress is not substantially different from the general agreement in the climate science community.
  • Authors:
    • Machado,S.
    • Pritchett,L.
    • Petrie,S.
  • Source: Agronomy Journal
  • Volume: 107
  • Issue: 5
  • Year: 2015
  • Summary: Winter wheat ( Triticum aestivum L.)-summer fallow (WW-SF) using conventional tillage (CT), the predominant cropping system in eastern Oregon, has increased soil erosion and depleted soil organic carbon (SOC). This research evaluates no-tillage (NT) systems designed to reduce these negative impacts on soil. In this long-term experiment (2004-2010), WW-SF using CT was compared with annual winter wheat (WW-WW), annual spring wheat (SW-SW), annual spring barley ( Hordeum vulgare L.) (SB-SB), winter wheat-chemical fallow (WW-CF), winter wheat-winter pea ( Pisum sativum L.) (WW-WP), and winter wheat-spring barley-chemical fallow rotation (WW-SB-CF), using NT. Measurements included, phenology, plant population, grain yield and yield components, residues, SOC, soil moisture, and precipitation. Water-use efficiency (WUE) was derived from precipitation and yield data. Under annual cropping, WW-WP and SB-SB produced higher yields than WW-WW and SW-SW. Grain yields in rotations with fallow (WW-SF, WW-CF, and WW-SB-CF) were not significantly different. On an annual basis, SB-SB and WW-WP produced the highest and lowest yields, respectively. The WUEs of fallow rotations, SB-SB, and SW-SW, were not different but were higher than WUEs of WW-WP and WW-WW. Residue cover and SOC were highest under annual cropping systems and lowest following peas in WW-WP and SF in WW-SF. We conclude that rotations with fallow using NT (WW-CF and WW-SB-CF) can replace the traditional WW-SF system without yield penalty.
  • Authors:
    • Morrison,Geoffrey M.
    • Yeh,Sonia
    • Eggert,Anthony R.
    • Yang,Christopher
    • Nelson,James H.
    • Greenblatt,Jeffery B.
    • Isaac,Raphael
    • Jacobson,Mark Z.
    • Johnston,Josiah
    • Kammen,Daniel M.
    • Mileva,Ana
    • Moore,Jack
    • Roland-Holst,David
    • Wei,Max
    • Weyant,John P.
    • Williams,James H.
    • Williams,Ray
    • Zapata,Christina B.
  • Source: Climatic Change
  • Volume: 131
  • Issue: 4
  • Year: 2015
  • Summary: Jurisdictions throughout the world are contemplating greenhouse gas (GHG) mitigation strategies that will enable meeting long-term GHG targets. Many jurisdictions are now focusing on the 2020-2050 timeframe. We conduct an inter-model comparison of nine California statewide energy models with GHG mitigation scenarios to 2050 to better understand common insights across models, ranges of intermediate GHG targets (i.e., for 2030), necessary technology deployment rates, and future modeling needs for the state. The models are diverse in their representation of the California economy: across scenarios with deep reductions in GHGs, annual statewide GHG emissions are 8-46 % lower than 1990 levels by 2030 and 59-84 % lower by 2050 (not including the Wind-Water-Solar model); the largest cumulative reductions occur in scenarios that favor early mitigation; non-hydroelectric renewables account for 30-58 % of electricity generated for the state in 2030 and 30-89 % by 2050 (not including the Wind-Water-Solar model) ; the transportation sector is decarbonized using a mix of energy efficiency gains and alternative-fueled vehicles; and bioenergy is directed almost exclusively towards the transportation sector, accounting for a maximum of 40 % of transportation energy by 2050. Models suggest that without new policies, emissions from non-energy sectors and from high-global-warming-potential gases may alone exceed California's 2050 GHG goal. Finally, future modeling efforts should focus on the: economic impacts and logistical feasibility of given scenarios, interactive effects between two or more climate policies, role of uncertainty in the state's long-term energy planning, and identification of pathways that achieve the dual goals of criteria pollutant and GHG emission reduction.
  • Authors:
    • Nash,R.
    • Motavalli,P.
    • Nelson,K.
    • Kremer,R.
  • Source: Journal of Soil and Water Conservation
  • Volume: 70
  • Issue: 4
  • Year: 2015
  • Summary: Gaseous nitrogen (N) loss from denitrification and ammonia (NH3) volatilization from poorly drained soils in corn (Zea mays L.) production can be significant, diminish production, and lead farmers to apply a high rate of N. Nitrous oxide (N2O), a greenhouse gas that is emitted during denitrification, has a high global warming potential that contributes to climate change. Reducing gaseous N loss from poorly drained soils through drainage and N management in corn production is essential to minimizing the environmental impact and maintaining high yields. The objective of the study Was to determine how subsurface tile drainage and applications of polymer-coated urea (PCU) affect soil N2O emissions and N fertilizer-induced NH3 volatilization loss from a claypan soil. Drainage water management treatments consisted of conventional subsurface tile drainage, managed subsurface tile drainage, and no-drainage in combination with N fertilizer source (noncoated urea [NCU] and PCU). Subsurface drainage treatments did not significantly (p <= 0.05) affect cumulative soil N2O emissions and NH3 volatilization loss compared to no-drainage. Averaged over 2010 to 2013, cumulative soil N2O emissions from PCU was 2% of applied N, and NCU was 4% of applied N. Yield-scaled soil N2O emissions were reduced 53% with PCU compared to NCU. The percentage fertilizer loss from NH3 volatilization was significantly (p <= 0.05) reduced from 2.8% with NCU to 0.8% with PCU. These results suggest that use of PCU may assist in reducing cumulative losses of N2O and NH3 from poorly drained claypan soils, but drainage systems operating under this study's environmental conditions did not affect gaseous N losses.
  • Authors:
    • Northupl,B. K.
    • Rao,S. C.
  • Source: Crop Economics, Production & Management
  • Volume: 107
  • Issue: 5
  • Year: 2015
  • Summary: Continuous winter wheat ( Triticum aestivum L. em Thell.) is the foundation for most US Southern Great Plains (SGP) agriculture. Inorganic N fertilizers are important to wheat production, but increasing N prices have caused producers to reconsider growing legumes during summer fallow for green N. This study was conducted during 2008 to 2012 to determine the potential for using lablab [ Lablab purpureus (L.) Sweet cv. Rio Verde] to support wheat under conventional and no-till management compared with soybean [ Glycine max (L.) Merr. cv. Laredo] and three inorganic fertilizer treatments (none, 40, and 80 kg N ha -1). Legume seeds were inoculated and sown after wheat harvest each year, grown from June to August, and terminated in early September. Wheat was then sown with or without preplant tillage and grown to maturity. Grain yield, N concentration, and N accumulated in grain were analyzed to define N treatment, tillage system, and year effects. The amount and distribution of precipitation during 2008 to 2012 varied from 53 to 92% and 63 to 160% of the long-term averages for wheat (688 mm) and legume (162 mm) phases. Tillage effects were nonsignificant ( P<0.76), but N treatment * year interactions were significant for grain yield, N concentration, and N accumulated in grain ( P<0.01). The legumes resulted in some single-year increases in grain yield, but the overall yield response was inconsistent. The legume treatments reduced N concentration in wheat grain compared with the unfertilized control. These results show that neither legume was an effective short-term (≤4-yr) N source for systems of continuous wheat production in the SGP.
  • Authors:
    • Sainju,U. M.
    • Allen,B. A.
    • Caesar-Tonthat,T.
    • Lenssen,A. W.
  • Volume: 107
  • Issue: 5
  • Year: 2015
  • Summary: Little is known about the long-term management impact on soil C and N contents in the northern Great Plains. We evaluated the 30-yr effect of tillage and cropping sequence combination on dryland crop biomass yield and soil bulk density, soil organic carbon (SOC), soil inorganic carbon (SIC), soil total nitrogen (STN), NH 4-N, and NO 3-N contents at the 0- to 120-cm depth in a Dooley sandy loam (fine loamy, mixed, frigid Typic Argiboroll) in eastern Montana. Treatments were no-till continuous spring wheat ( Triticum aestivum L.) (NTCW), spring till continuous spring wheat (STCW), fall and spring till continuous spring wheat (FSTCW), fall and spring till spring wheat-barley ( Hordeum vulgare L., 1984-1999) followed by spring wheat-pea ( Pisum sativum L., 2000-2013) (FSTW-B/P), and spring till spring wheat-fallow (STW-F, traditional system). Mean annualized crop biomass returned to the soil was 23 to 30% greater in NTCW, STCW, FSTCW, and FSTW-B/P than STW-F. At 0 to 7.5 cm, bulk density was 13 to 21% greater in STW-F, but SOC, SIC, and STN were 12 to 98% greater in STCW than other treatments. Ammonium-N and NO 3-N contents were 25 to 74% greater in FSTCW than other treatments. At other depths, SOC, SIC, STN, NH 4-N and NO 3-N contents varied among treatments. Reduced tillage with increased crop residue returned to the soil increased soil C and N storage in NTCW and STCW, but increased tillage intensity increased mineral N content in FSTCW compared with STW-F. Improved management practices, such as NTCW and STCW, may be adopted to improve dryland soil C and N stocks.
  • Authors:
    • Schlegel,A. J.
    • Assefa,Y.
    • Bond,H. D.
    • Wetter,S. M.
    • Stone,L. R.
  • Source: Web Of Knowledge
  • Volume: 107
  • Issue: 5
  • Year: 2015
  • Summary: Cattle ( Bos taurus) manure and swine ( Sus scrofa) effluent are applied to cropland to recycle nutrients, build soil quality, and increase crop productivity. The objective of this study was to determine the long-term effects of land application of cattle manure and swine effluent using the Kansas Nutrient Utilization Plan on crop yield, yield components, and crop nutrient uptake. The study was conducted for 10 yr (1999 through 2008) near Tribune, KS. There were 10 treatments: three levels of cattle manure and swine effluent (P, N, and 2N), three levels of N fertilizer (N 1=56, N 2=112, and N 3=168 kg N ha -1), and an untreated control. Corn ( Zea mays L.) grain and stover yields, yield components, and water use were measured. In all but 2 yr, all treatments significantly increased grain yield compared with the control and the lowest inorganic N rate. Mean corn grain yield over the years from the Cattle N and P, Swine N and P, and inorganic N 2 and N 3 treatments were about 2*, 1.8*, and 1.9* greater than the untreated control, respectively. Grain nutrient content and water productivity were consistently higher for the cattle manure treatments and the inorganic N 2 and N 3 treatments. However, grain yield and nutrient uptake did not differ among rates of cattle manure and swine effluent application. We concluded that using the lower application rate based on either N or P from the Kansas Nutrient Utilization Plan was sufficient to achieve optimal crop yield and water productivity.