• Authors:
    • Johnson, K.
    • Yorgey, G. G.
    • Yoon, J. H.
    • Nelson, R.
    • Jiang, X. Y.
    • Choate, J. S.
    • Zhu, J.
    • Reyes, J.
    • Poinsatte, J.
    • Nergui,T.
    • Miller, C.
    • Mullis, T.
    • Malek, K.
    • Chandrasekharan, B.
    • Anderson, S.
    • Allen, E.
    • Yoder, J.
    • Perleberg, A. B.
    • Leung, L. R.
    • Leung, F. Y.
    • Guenther, A.
    • Chen, Y.
    • Kalyanaraman, A.
    • Tague, C. L.
    • Harrison, J. A.
    • Rajagopalan, K.
    • Vaughan, J. K.
    • Stoeckle, C. O.
    • Liu, M. L.
    • Lamb, B. K.
    • Kruger, C. E.
    • Evans, R. D.
    • Brady, M. P.
    • Chung, S. H.
    • Stephens, J. C.
    • Adam, J. C.
    • Chinnayakanahalli, K. J.
    • Hamlet, A. F.
    • Nijssen, B.
    • Walden, V.
  • Source: CLIMATIC CHANGE
  • Volume: 129
  • Issue: 3-4
  • Year: 2015
  • Summary: As managers of agricultural and natural resources are confronted with uncertainties in global change impacts, the complexities associated with the interconnected cycling of nitrogen, carbon, and water present daunting management challenges. Existing models provide detailed information on specific sub-systems (e.g., land, air, water, and economics). An increasing awareness of the unintended consequences of management decisions resulting from interconnectedness of these sub-systems, however, necessitates coupled regional earth system models (EaSMs). Decision makers' needs and priorities can be integrated into the model design and development processes to enhance decision-making relevance and "usability" of EaSMs. BioEarth is a research initiative currently under development with a focus on the U.S. Pacific Northwest region that explores the coupling of multiple stand-alone EaSMs to generate usable information for resource decision-making. Direct engagement between model developers and non-academic stakeholders involved in resource and environmental management decisions throughout the model development process is a critical component of this effort. BioEarth utilizes a bottom-up approach for its land surface model that preserves fine spatial-scale sensitivities and lateral hydrologic connectivity, which makes it unique among many regional EaSMs. This paper describes the BioEarth initiative and highlights opportunities and challenges associated with coupling multiple stand-alone models to generate usable information for agricultural and natural resource decision-making.
  • Authors:
    • Wang, D.
    • Tirado-Corbala, R.
    • Anderson, R. G.
    • Ayars, J. E.
  • Source: AGRICULTURE ECOSYSTEMS & ENVIRONMENT
  • Volume: 199
  • Year: 2015
  • Summary: Sugarcane has been a major agronomic crop in Hawaii with an unique, high-yield, two-year production system. However, parameters relevant to advanced, cellulosic biofuel production, such as net ecosystem productivity (NEP) and radiation use efficiency (RUE), have not been evaluated in Hawaii under commercial production. Recent demand potential has rekindled interest in Hawaiian grown biofuels; as such, there is a need to understand productivity under changing climate and agronomic practices. To this end, we established two eddy covariance towers in commercial sugarcane fields in Maui, Hawaii to evaluate the carbon balance and RUE of sugarcane under contrasting elevations and soil types. We combined the tower observations with biometric and satellite data to assess RUE in terms of net biomass accumulation and daily gross primary production. High, sustained net NEP was found in both fields (cumulative NEP 4.23-5.37*10 3 g C m -2 over the course of the measurement period). Biomass RUE was statistically similar for both fields (1.15-1.24 g above ground biomass per MJ intercepted solar irradiance). Carbon accumulated in both fields at nearly the same rate with differences in cumulative biomass due to differing crop cycle lengths; cumulative gross primary productivity and ecosystem respiration were higher in the lower elevation field. Contrary to previous studies in Hawaiian sugarcane, we did not see a large decrease in NEP or increase in ecosystem respiration in the 2nd year, which we attributed to suppressed decomposition of dead cane stalks and leaves due to drip irrigation and drought. Biomass RUE also showed little decline in the 2nd year. The results show that Hawaiian sugarcane has a higher productivity than sugarcane grown in other regions of the world and also suggests that a longer (>12 months) growing cycle may be optimal for biomass production.
  • Authors:
    • Terry, R. E.
    • Fernandez, F. G.
    • Coronel, E. G.
  • Source: JOURNAL OF ENVIRONMENTAL QUALITY
  • Volume: 44
  • Issue: 2
  • Year: 2015
  • Summary: The use of alternative N sources relative to conventional ones could mitigate soil-surface N 2O emissions. Our objective was to evaluate the effect of anhydrous ammonia (AA), urea, and polymer-coated urea (ESN) on N 2O emissions for continuous corn ( Zea mays L.) production. Corn received 110 kg N ha -1 in 2009 and 180 kg N ha -1 in 2010 and 2011. Soil N 2O fluxes were measured one to three times per week early in the growing season and less frequently later, using vented non-steady state closed chambers and a gas chromatograph. Regardless of N source, N 2O emissions were largest immediately after substantial (>20 mm) rains, dropping to background levels thereafter. Averaged across N sources, 2.85% of the applied N was lost as N 2O. Emission differences for treatments only occurred in 2010, the year with maximum N 2O production. In the 2010 growing season, cumulative emissions (in kg N 2O-N ha -1) were lowest for the check (2.21), followed by ESN (9.77), and ESN was lower than urea (14.07) and AA (16.89). Emissions in 2010 based on unit of corn yield produced followed a similar pattern, and N 2O emissions calculated as percent of applied N showed that AA losses were 1.9 times greater than ESN. Across years, relative to AA, ESN reduced N 2O emissions, emissions per unit of corn yield, and emissions per unit of N applied, whereas urea produced intermediate values. The study indicates that, under high N loss potential (wet and warm conditions), ESN could reduce N 2O emissions more that urea and AA.
  • Authors:
    • Es, H. M. van
    • Cassman, K. G.
    • Bouwman, L.
    • Grinsven, H. J. M. van
    • McCrackin, M. L.
    • Beusen, A. H. W.
  • Source: JOURNAL OF ENVIRONMENTAL QUALITY
  • Volume: 44
  • Issue: 2
  • Year: 2015
  • Summary: Historical trends and levels of nitrogen (N) budgets and emissions to air and water in the European Union and the United States are markedly different. Agro-environmental policy approaches also differ, with emphasis on voluntary or incentive-based schemes in the United States versus a more regulatory approach in the European Union. This paper explores the implications of these differences for attaining long-term policy targets for air and water quality. Nutrient surplus problems were more severe in the European Union than in the United States during the 1970s and 1980s. The EU Nitrates and National Emission Ceilings directives contributed to decreases in fertilizer use, N surplus, and ammonia (NH 3) emissions, whereas in the United States they stabilized, although NH 3 emissions are still increasing. These differences were analyzed using statistical data for 1900-2005 and the global IMAGE model. IMAGE could reproduce NH 3 emissions and soil N surpluses at different scales (European Union and United States, country and state) and N loads in the Rhine and Mississippi. The regulation-driven changes during the past 25 yr in the European Union have reduced public concerns and have brought agricultural N loads to the aquatic environment closer to US levels. Despite differences in agro-environmental policies and agricultural structure (more N-fixing soybean and more spatially separated feed and livestock production in the United States than in the European Union), current N use efficiency in US and EU crop production is similar. IMAGE projections for the IAASTD-baseline scenario indicate that N loading to the environment in 2050 will be similar to current levels. In the United States, environmental N loads will remain substantially smaller than in the European Union, whereas agricultural production in 2050 in the United States will increase by 30% relative to 2005, as compared with an increase of 8% in the European Union. However, in the United States, even rigorous mitigation with maximum recycling of manure N and a 25% reduction in fertilizer use will not achieve the policy target to halve the N export to the Gulf of Mexico.
  • Authors:
    • Holmes, K. J.
  • Source: CLIMATIC CHANGE
  • Volume: 129
  • Issue: 1-2
  • Year: 2015
  • Summary: The arid lands controversy beginning in the late 19th century provides a unique perspective on the role that large scale climate assessments play in the policy process. Initially the climate of the western arid lands divided scientists, policy makers, and the public between those that believed new conditions would require specialized policies and adaptations and those that argued conditions would not be severe. The consensus eventually emerged for a large-scale response, a consensus based on the seminal Report on the Arid Lands of the United States and later scientific assessments that coupled the physical and human dimensions of climatic change. This earlier debate demonstrates how climate assessments in the United States play out in policy deliberations with public opinion and climatological events to ultimately control the fate of responses.
  • Authors:
    • Hatfield, J. L.
    • Jarecki, M. K.
    • Barbour, W.
  • Source: JOURNAL OF ENVIRONMENTAL QUALITY
  • Volume: 44
  • Issue: 2
  • Year: 2015
  • Summary: The U.S. Corn Belt area has the capacity to generate high nitrous oxide (N 2O) emissions due to medium to high annual precipitation, medium- to heavy-textured soils rich in organic matter, and high nitrogen (N) application rates. The purpose of this work was to estimate N 2O emissions from cornfields in Iowa at the county level using the DeNitrification-DeComposition (DNDC) model and to compare the DNDC N 2O emission estimates with available results from field experiments. All data were acquired for 2007 to 2011. Weather Underground Network and the Iowa State University Iowa Soil Properties and Interpretation Database 7.3 were the data sources for DNDC inputs and for computing county soil parameters. The National Agriculture Statistic Service 5-yr averages for corn yield data were used to establish ex post fertilizer N input at the county level. The DNDC output suggested county-wide N 2O emissions in Iowa ranged from 2.2 kg N 2O-N ha -1 yr -1 in south-central to 4.6 to 4.7 kg N 2O-N ha -1 yr -1 in north-central and eastern Iowa counties. In northern districts, the average direct N 2O emissions were 3.2, 4.4, and 3.6 kg N 2O-N ha -1 yr -1 for west, central, and east, respectively. In central districts, average N 2O emissions were 3.5, 3.9, and 3.4 kg N 2O-N ha -1 yr -1 for west, central, and east, respectively. For southern districts, N 2O emissions were 3.5, 2.6, and 3.1 kg N 2O-N ha -1 yr -1 for west, central, and east, respectively. Direct N 2O emissions estimated by the DNDC model were 1.93% of N fertilizer input to corn fields in Iowa, with values ranging from 1.66% in the northwest cropping district to 2.25% in the north-central cropping district. These values are higher than the average 1% loss rate used in the IPCC Tier 1 approach.
  • Authors:
    • Sucre, E. B.
    • Strahm, B. D.
    • Seiler, J. R.
    • Shrestha, P.
    • Leggett, Z. H.
  • Source: Conference: 17th Biennial Southern Silvicultural Research Conference, Shreveport, Louisiana, USA, 5-7 March 2013. General Technical Report - Southern Research Station, USDA Forest Service Issue: SRS-203
  • Issue: SRS-203
  • Year: 2015
  • Authors:
    • Novak, J. M.
    • Cantrell, K. B.
    • Hunt, P. G.
    • Stone, K. C.
    • Sigua, G. C.
  • Source: AGRONOMY FOR SUSTAINABLE DEVELOPMENT
  • Volume: 35
  • Issue: 2
  • Year: 2015
  • Summary: Biochar is a black solid formed by pyrolysis of biomass such as crop residues. Biochar could be used for soil fertilization, carbon sequestration, and improvement of soil structure. Here, we tested the effect of sorghum biochars on winter wheat, with or without supplemental inorganic phosphorus, in a greenhouse. The application rate for sorghum residues and sorghum biochars based on a yield goal of 200 bushels ha(-1) was 13 Mg ha(-1). Inorganic phosphorus was added at the rate of 40 kg P ha(-1). Results show that addition of sorghum biochars increased the total biomass of winter wheat grown by about 31 % over the control plants. Addition of supplemental inorganic phosphorus did not increase the total biomass. Our findings suggest that the pyrolitic transformation of sorghum residues into sorghum biochars is a better strategy for both environmental and crop productivity improvement in the Coastal Plains region.
  • Authors:
    • Huntzinger, D. N.
    • Pan, S. F.
    • Ren, W.
    • Hayes, D. J.
    • Xu, X. F.
    • Lu, C. Q.
    • Chen, G. S.
    • Tian, H. Q.
    • Wofsy, S. C.
  • Source: CLIMATIC CHANGE
  • Volume: 129
  • Issue: 3-4
  • Year: 2015
  • Summary: The terrestrial ecosystems of North America have been identified as a sink of atmospheric CO2 though there is no consensus on the magnitude. However, the emissions of non-CO2 greenhouse gases (CH4 and N2O) may offset or even overturn the climate cooling effect induced by the CO2 sink. Using a coupled biogeochemical model, in this study, we have estimated the combined global warming potentials (GWP) of CO2, CH4 and N2O fluxes in North American terrestrial ecosystems and quantified the relative contributions of environmental factors to the GWP changes during 1979-2010. The uncertainty range for contemporary global warming potential has been quantified by synthesizing the existing estimates from inventory, forward modeling, and inverse modeling approaches. Our "best estimate" of net GWP for CO2, CH4 and N2O fluxes was -0.50 +/- 0.27 Pg CO2 eq/year (1 Pg = 10(15) g) in North American terrestrial ecosystems during 2001-2010. The emissions of CH4 and N2O from terrestrial ecosystems had offset about two thirds (73 %+/- 14 %) of the land CO2 sink in the North American continent, showing large differences across the three countries, with offset ratios of 57 % +/- 8 % in US, 83 % +/- 17 % in Canada and 329 % +/- 119 % in Mexico. Climate change and elevated tropospheric ozone concentration have contributed the most to GWP increase, while elevated atmospheric CO2 concentration have contributed the most to GWP reduction. Extreme drought events over certain periods could result in a positive GWP. By integrating the existing estimates, we have found a wide range of uncertainty for the combined GWP. From both climate change science and policy perspectives, it is necessary to integrate ground and satellite observations with models for a more accurate accounting of these three greenhouse gases in North America.
  • Authors:
    • Islam, K. R.
    • Mahmood, T.
    • Bangash, N.
    • Aziz, I.
  • Source: Pakistan Journal of Botany
  • Volume: 47
  • Issue: 1
  • Year: 2015
  • Summary: There is a global concern about progressive increase in the emission of greenhouse gases especially atmosphere CO2. An increasing awareness about environmental pollution by CO2 emission has led to recognition of the need to enhance soil C sequestration through sustainable agricultural management practices. Conservation management systems such as no-till (NT) with appropriate crop rotation have been reported to increase soil organic C content by creating less disturbed environment. The present study was conducted on Vanmeter farm of The Ohio State University South Centers at Piketon Ohio, USA to estimate the effect of different tillage practices with different cropping system on soil chemical properties. Tillage treatments were comprised of conventional tillage (CT) and No-till (NT). These treatments were applied under continuous corn (CC), corn-soybean (CS) and corn-soybean-wheat-cowpea (CSW) cropping system following randomized complete block design. No-till treatment showed significant increase in total C (30%), active C (10%), and passive salt extractable (18%) and microwave extractable C (8%) and total nitrogen (15%) compared to conventional tillage practices. Total nitrogen increased significantly 23 % in NT over time. Maximum effect of no-till was observed under corn-soybean-wheat-cowpea crop rotation. These findings illustrated that no-till practice could be useful for improving soil chemical properties.