• Authors:
    • Solaiman,Zakaria M.
    • Anawar,Hossain M.
  • Source: Pedosphere
  • Volume: 25
  • Issue: 5
  • Year: 2015
  • Summary: Biochar addition to soil is currently being considered as a means to sequester carbon while simultaneously improving soil health, soil fertility and agronomic benefits. The focus of this special issue is on current research on the effects of biochar application to soil for overcoming diverse soil constraints and recommending further research relating to biochar application to soil. The biochar research has progressed considerably with important key findings on agronomic benefits, carbon sequestration, greenhouse gas emissions, soil acidity, soil fertility, soil health, soil salinity, etc., but more research is required before definitive recommendations can be made to end-users regarding the effects of biochar application across a range of soils, climates and land management practices.
  • Authors:
    • Wu,Shuang-Ye
  • Source: Web Of Knowledge
  • Volume: 132
  • Issue: 4
  • Year: 2015
  • Summary: Using the US collection from the Global Historical Climatology Network Daily (GHCN-D) precipitation data for the contiguous United States (CONUS), this study examines the changing characteristics of precipitation during 1951-2013. In addition to mean precipitation, all precipitation events are divided into three categories: light, moderate, and heavy based on percentile thresholds. The historical trends are established for precipitation total, frequency and intensity, as well as for total and frequency of different intensity categories. Results show that from 1951 to 2013, mean precipitation increased at 1.66 % per decade, a higher rate than previous estimates. About one third of the increase is attributed to frequency change, whereas the other two thirds are attributed to an intensity increase. There was a slight decrease in light precipitation, a small increase in moderate precipitation, and much higher increase for heavy precipitation. Spatially, eastern and northern parts of the CONUS experienced higher rates of increase, whereas western regions experienced less increase. A statistically significant positive correlation exists between mean precipitation and precipitation change, suggesting the wet regions experienced more precipitation increase than dry regions. Seasonally, precipitation increased most for the fall, less in other seasons. Particularly, there were significant decreasing trends in summer precipitation for many parts of western and central CONUS. Regional frequency analysis is used to examine the change in extreme precipitation events with return intervals longer than a year. Results show that extreme precipitation events increased for most of the CONUS with the exception of the west region. These changes were a result of both a shift in the mean state and the shape of the precipitation data distribution.
  • Authors:
    • Beach,R. H.
    • Cai,Y.
    • Thomson,A.
    • Zhang,X.
    • Jones,R.
    • McCarl,B. A.
    • Crimmins,A.
    • Martinich,J.
    • Cole,J.
    • Ohrel,S.
    • Deangelo,B.
    • McFarland,J.
    • Strzepek,K.
    • Boehlert,B.
  • Source: Environmental Research Letters
  • Volume: 10
  • Issue: 9
  • Year: 2015
  • Summary: Increasing atmospheric carbon dioxide levels, higher temperatures, altered precipitation patterns, and other climate change impacts have already begun to affect US agriculture and forestry, with impacts expected to become more substantial in the future. There have been numerous studies of climate change impacts on agriculture or forestry, but relatively little research examining the long-term net impacts of a stabilization scenario relative to a case with unabated climate change. We provide an analysis of the potential benefits of global climate change mitigation for US agriculture and forestry through 2100, accounting for landowner decisions regarding land use, crop mix, and management practices. The analytic approach involves a combination of climate models, a crop process model (EPIC), a dynamic vegetation model used for forests (MC1), and an economic model of the US forestry and agricultural sector (FASOM-GHG). We find substantial impacts on productivity, commodity markets, and consumer and producer welfare for the stabilization scenario relative to unabated climate change, though the magnitude and direction of impacts vary across regions and commodities. Although there is variability in welfare impacts across climate simulations, we find positive net benefits from stabilization in all cases, with cumulative impacts ranging from $32.7 billion to $54.5 billion over the period 2015-2100. Our estimates contribute to the literature on potential benefits of GHG mitigation and can help inform policy decisions weighing alternative mitigation and adaptation actions. © 2015 IOP Publishing Ltd.
  • Authors:
    • Blanco-Canqui,H.
    • Shaver,T. M.
    • Lindquist,J. L.
    • Shapiro,C. A.
    • Elmore,R. W.
    • Francis,C. A.
    • Hergert,G. W.
  • Source: Agronomy Journal
  • Volume: 107
  • Issue: 6
  • Year: 2015
  • Summary: Cover crops (CCs) can provide multiple soil, agricultural production, and environmental benefits. However, a better understanding of such potential ecosystem services is needed. We summarized the current state of knowledge of CC effects on soil C stocks, soil erosion, physical properties, soil water, nutrients, microbial properties, weed control, crop yields, expanded uses, and economics and highlighted research needs. Our review indicates that CCs are multifunctional. Cover crops increase soil organic C stocks (0.1-1 Mg ha -1 yr -1) with the magnitude depending on biomass amount, years in CCs, and initial soil C level. Runoff loss can decrease by up to 80% and sediment loss from 40 to 96% with CCs. Wind erosion potential also decreases with CCs, but studies are few. Cover crops alleviate soil compaction, improve soil structural and hydraulic properties, moderate soil temperature, improve microbial properties, recycle nutrients, and suppress weeds. Cover crops increase or have no effect on crop yields but reduce yields in water-limited regions by reducing available water for the subsequent crops. The few available studies indicate that grazing and haying of CCs do not adversely affect soil and crop production, which suggests that CC biomass removal for livestock or biofuel production can be another benefit from CCs. Overall, CCs provide numerous ecosystem services (i.e., soil, crop-livestock systems, and environment), although the magnitude of benefits is highly site specific. More research data are needed on the (i) multi-functionality of CCs for different climates and management scenarios and (ii) short- and long-term economic return from CCs.
  • Authors:
    • Gao,H.
    • Shao,M.
  • Source: Soil and Tillage Research
  • Volume: 153
  • Year: 2015
  • Summary: Accurate simulation of the effects of temperature on soil water movement processes is lacking in the study of hydrothermal interactions in soil systems. Previous research has proposed some likely mechanisms (e.g., surface tension-viscous flow) to explain soil hydraulic properties in relation to temperature, but little research has focused on the temperature dependence of soil particles (e.g., thermal expansion). Using simulation analyses and experimental data, the effect of temperature on soil hydraulic properties was explored focusing on the thermal effect of water surficial properties and soil particle characteristics. Two temperature coefficients, λ, representing the thermal effect of water surficial properties and c, representing the thermal effect of soil particle characteristics are introduced into soil hydraulics formulae to represent temperature dependence. Results show that temperature-dependent changes in water surficial properties including kinematics viscosity, surface tension and water density effects on soil hydraulic properties. Changes in temperature also affect soil particles, soil porosity and the interactive surface between liquid and solid, especially in heavy loam with high clay content. Expected soil hydraulic properties were calculated at three temperatures in two soil types and then compared to corresponding experimental results. Comparison of predicted and experimental soil hydraulic properties revealed overall similarities with a few exceptions. This study represents an initial simulation study of the effects of temperature on soil hydraulic properties. © 2015.
  • Authors:
    • Lin, E.
    • Ju. H.
    • Wheeler, T.
    • Li, Y.
    • Wang, H.
    • Lam, S.
    • Hao, X.
    • Han, X.
  • Source: Article
  • Volume: 209
  • Year: 2015
  • Summary: Fossil fuel combustion and deforestation have resulted in a rapid increase in atmospheric [CO 2] since the 1950's, and it will reach about 550 mol mol -1 in 2050. Field experiments were conducted at the Free-air CO 2 Enrichment facility in Beijing, China. Winter wheat was grown to maturity under elevated [CO 2] (55017 mol mol -1) and ambient [CO 2] (41516 mol mol -1), with high nitrogen (N) supply (HN, 170 kg N ha -1) and low nitrogen supply (LN, 100 kg N ha -1) for three growing seasons from 2007 to 2010. Elevated [CO 2] increased wheat grain yield by 11.4% across the three years. [CO 2]-induced yield enhancements were 10.8% and 11.9% under low N and high N supply, respectively. Nitrogen accumulation under elevated [CO 2] was increased by 12.9% and 9.2% at the half-way anthesis and ripening stage across three years, respectively. Winter wheat had higher nitrogen demand under elevated [CO 2] than ambient [CO 2], and grain yield had a stronger correlation with plant N uptake after anthesis than before anthesis at high [CO 2]. Our results suggest that regulating on the N application rate and time, is likely important for sustainable grain production under future CO 2 climate.
  • Authors:
    • Haudenshield, J. S.
    • Bowen, C. R.
    • Hartman, G. L.
    • Fox, C. M.
    • Cary, T. R.
    • Diers, B. W.
  • Source: Agronomy Journal
  • Volume: 107
  • Issue: 6
  • Year: 2015
  • Summary: Diseases and pests of soybean [ Glycine max (L.) Merr.] often reduce soybean yields. Targeted breeding that incorporates known genes for resistance and non-targeted breeding that eliminates susceptible plants in breeding populations reduces the impact of soybean pathogens and pests. Maturity group (MG) III soybean cultivars released from 1923 through 2008 were grown in three field environments to determine if disease and insect ratings were associated with year of cultivar release. Disease and pest ratings were evaluated on 40 soybean cultivars at one location (Urbana, IL) planted in two rotation treatments in 2010 and on 59 cultivars in two locations (Urbana and Arthur) in 2011. During the season, foliar disease symptoms and insect foliar feeding damage were recorded. At harvest maturity, stem diseases were assessed. In at least one environment, foliar incidence reached 100% for bacterial diseases, brown spot ( Septoria glycines Hemmi), and insect foliar feeding damage and 100% incidence for anthracnose [ Colletotrichum truncatum (Schwein.) Andrus & W.D. Moore], Cercospora stem blight ( Cercospora kikuchii T. Matsumoto & Tomoy.), and charcoal rot [ Macrophomina phaseolina (Tassi) Goid.] on stems for all cultivars. For the nine different disease and pest severity assessments in 2010, seven had a significant ( P<0.05) negative correlation to year of cultivar release indicating that cultivars more recently released had lower severity ratings than cultivars with older release dates. This study demonstrated that incidence and severity of diseases were less pronounced on more newly-released soybean cultivars, showing that decades of breeding has resulted in increased disease resistance in modern soybean cultivars.
  • Authors:
    • Baer, S. G.
    • Bello, N. M.
    • Knapp, M.
    • Morgan, T. J.
    • Bryant, J.
    • DeLaCruz, A.
    • Tetreault, H.
    • Olsen, J. T.
    • Johnson, L. C.
    • Maricle, B. R.
  • Source: Original Article
  • Volume: 8
  • Issue: 7
  • Year: 2015
  • Summary: Identifying suitable genetic stock for restoration often employs a best guess' approach. Without adaptive variation studies, restoration may be misguided. We test the extent to which climate in central US grasslands exerts selection pressure on a foundation grass big bluestem (Andropogon gerardii), widely used in restorations, and resulting in local adaptation. We seeded three regional ecotypes of A.gerardii in reciprocal transplant garden communities across 1150km precipitation gradient. We measured ecological responses over several timescales (instantaneous gas exchange, medium-term chlorophyll absorbance, and long-term responses of establishment and cover) in response to climate and biotic factors and tested if ecotypes could expand range. The ecotype from the driest region exhibited greatest cover under low rainfall, suggesting local adaptation under abiotic stress. Unexpectedly, no evidence for cover differences between ecotypes exists at mesic sites where establishment and cover of all ecotypes were low, perhaps due to strong biotic pressures. Expression of adaptive differences is strongly environment specific. Given observed adaptive variation, the most conservative restoration strategy would be to plant the local ecotype, especially in drier locations. With superior performance of the most xeric ecotype under dry conditions and predicted drought, this ecotype may migrate eastward, naturally or with assistance in restorations.
  • Authors:
    • Maxted, N.
    • Kang, D.
    • Wei, W.
    • Ford-Lloyd,B.
    • Chen, B.
    • Qin, H.
    • Kell, S.
  • Source: Science Article
  • Volume: 209
  • Year: 2015
  • Summary: The potentially devastating impacts of climate change on crop production and food security are now widely acknowledged. An important component of efforts to mitigate these impacts is the production of new varieties of crops which will be able to thrive in more extreme and changeable environmental conditions. There is therefore an urgent need to find new sources of genetic diversity for crop improvement. Wild plant species closely related to crops (crop wild relatives) contain vital sources of such genes, yet these resources themselves are threatened by the effects of climate change, as well as by a range of other human-induced pressures and socio-economic changes. The flora of China comprises more than 20,000 native higher plant species, a proportion of which have known or potential value as gene donors for crop improvement. However, until now, the full range of these valuable crop wild relative species had not been identified. In this paper we present a methodology for creating a checklist of, and prioritizing China's crop wild relatives, and reveal that 871 native species are related to crops that are of particularly high socio-economic importance in China-including rice, wheat, soybean, potato, sweet potato, millet and yam-crops which are also of notably high value for food and economic security in other parts of the world. Within this list we have identified species that are in particular need of conservation assessment based on their relative Red List status and potential for use in crop improvement programs. Endemic species that have particularly high economic value potential in China and that are under severe threat of genetic erosion and thus in need of urgent conservation action include wild relatives of tea ( Camellia fangchengensis S. Yun Liang et Y.C. Zhong and C. grandibracteata H.T. Chang et F.L. Yu), apple ( e.g., Malus honanensis Rehder, M. ombrophila Hand.-Mazz. and M. toringoides (Rehder) Hughes), and pear ( Pyrus pseudopashia T.T. Yu). We provide recommendations for developing a systematic and comprehensive national CWR conservation strategy for China, highlighting the challenges and requirements of taking the strategy forward to the implementation phase.
  • Authors:
    • Shimoda, S.
    • Hayashi, K.
    • Koga, N.
  • Source: Journal
  • Volume: 62
  • Issue: 1
  • Year: 2015
  • Summary: In the context of sustainable soil-quality management and mitigating global warming, the impacts of incorporating raw or field-burned adzuki bean (Vigna angularis (Willd.) Ohwi & Ohashi) and wheat (Triticum aestivum L.) straw residues on carbon dioxide (CO2) and nitrous oxide (N2O) emission rates from soil were assessed in an Andosol field in northern Japan. Losses of carbon (C) and nitrogen (N) in residue biomass during field burning were much greater from adzuki bean residue (98.6% of C and 98.1% of N) than from wheat straw (85.3% and 75.3%, respectively). Although we noted considerable inputs of carbon (499 ± 119 kg C ha–1) and nitrogen (5.97 ± 0.76 kg N ha–1) from burned wheat straw into the soil, neither CO2 nor N2O emission rates from soil (over 210 d) increased significantly after the incorporation of field-burned wheat straw. Thus, the field-burned wheat straw contained organic carbon fractions that were more resistant to decomposition in soil in comparison with the unburned wheat straw. Our results and previously reported rates of CO2, methane (CH4) and N2O emission during wheat straw burning showed that CO2-equivalent greenhouse gas emissions under raw residue incorporation were similar to or slightly higher than those under burned residue incorporation when emission rates were assessed during residue burning and after subsequent soil incorporation. © 2015 Japanese Society of Soil Science and Plant Nutrition