• Authors:
    • Salazar,Osvaldo
    • Rojas,Claudia
    • Avendano,Fernando
    • Realini,Piero
    • Najera,Francisco
    • Tapia,Yasna
  • Source: Web Of Knowledge
  • Volume: 102
  • Issue: 3
  • Year: 2015
  • Summary: Vegetated buffer strips (BS) can help prevent nitrogen (N) losses from fields by subsurface lateral flow, thus protecting water resources. The purpose of this study was to determine if narrow BS would effectively remove dissolved inorganic N from subsurface lateral flow. Nitrate-N (NO3-N) and ammonia-N (NH3-N) concentrations in subsurface lateral flow were measured at 1 m depth in a BS system consisting of five treatments: G: strip of grass (Fescue arundinacea); GS: strip of grass and line of native shrubs (Fuchsia magellanica); GST1: strip of grass, line of shrubs and line of native trees 1 (Luma chequen); GST2: strip of grass, line of shrubs and line of native trees 2 (Drimys winteri); and C: bare soil as control. Water samples for the NO3-N and NH3-N measurements were collected between June 2012 and August 2014 in observation wells located at the inlet (input) and outlet (output) of each treatment. The analyses showed that vegetated BS had NO3-N removal efficiency ranging from 33 to 67 % (mean 52 %), with the G treatment showing the best performance in reducing NO3-N concentrations in subsurface lateral flow. The BS treatments were not effective in reducing NH3-N concentrations. The results suggested that N uptake by grass is the main process associated with the NO3-N retention capacity of vegetated BS.
  • Authors:
    • Thiel,B.
    • Smukler,S. M.
    • Krzic,M.
    • Gergel,S.
    • Terpsma,C.
  • Source: Journal of Soil and Water Conservation
  • Volume: 70
  • Issue: 4
  • Year: 2015
  • Summary: Hedgerows (also known as field margins, shelterbelts, or windbreaks) have the potential to help mitigate greenhouse gas emissions from agricultural activities through carbon (C) sequestration in the woody biomass of trees and shrubs as well as in the soil. A first step to understanding the sequestration potential is to quantify the biomass C and soil C storage. In the Fraser Valley of British Columbia, Canada, a hedgerow stewardship program incentivizes farmers to plant hedgerows to create habitat for biodiversity conservation and to improve ecosystem services such as climate change mitigation. This study evaluated the efficacy of hedgerows to store C in woody biomass and soil relative to remnant. hedgerows (RH) and neighboring production fields with annual crops. We measured soil C (equivalent soil mass) and soil aggregate stability in both hedgerows and production fields, while biomass C and species diversity were calculated for the trees and shrubs in the two hedgerow types. There was no significant difference in the biomass C in the two hedgerow types; despite Age differences with planted hedgerows (PH) having a mean total above- and belowground biomass of 76 +/- 32 t C ha(-1) (33.8 +/- 14.2 tn C ac(-1)) and RH 124 +/- 21 t C ha(-1) (55.3 +/- 9.3 tn C ac(-1)). Aggregate stability was similar in both hedgerow types, and was significantly greater than neighboring production fields. Woody vegetation biodiversity was significantly greater in PH than RH for richness, Shannon, and Simpson measures. Planted hedgerows stored significantly greater soil C than RH to 1.2 t m(-2) (1.1 tn yd(-2)) standard soil mass with values being 175.9 +/- 13.2 t C ha(-1) (78.4 +/- 5.8 tn C ac(-1)) and 132.7 +/- 7.3 t C ha(-1) (5.9.1 +/- 3.2 tn C ac(-1)) respectively. Soil C in PH was 40% greater than that of their neighboring production fields. Soil C was significantly correlated with the Shannon and Simpson diversity of the hedgerow shrubs and trees indicating that planting hedgerows, with improved woody vegetation biodiversity, may have a positive effect on their greenhouse gas mitigation potential on farmland.
  • Authors:
    • Uzoma,K. C.
    • Smith,W.
    • Grant,B.
    • Desjardins,R. L.
    • Gao XiaoPeng
    • Hanis,K.
    • Tenuta,M.
    • Goglio,P.
    • Li,C. S.
  • Source: Agriculture, Ecosystems and Environment
  • Volume: 206
  • Year: 2015
  • Summary: Biogeochemical models are useful tools for integrating the effects of agricultural management on GHG emissions; however, their development is often hampered by the incomplete temporal and spatial representation of measurements. Adding to the problem is that a full complement of ancillary measurements necessary to understand and validate the soil processes responsible for GHG emissions is often not available. This study presents a rare case where continuous N 2O emissions, measured over seven years using a flux gradient technique, along with a robust set of ancillary measurements were used to assess the ability of the DNDC model for estimating N 2O emissions under varying crop-management regimes. The analysis revealed that the model estimated soil water content more precisely in the normal and wet years (ARE 3.4%) than during the dry years (ARE 11.5%). This was attributed to the model's inability to characterize episodic preferential flow through clay cracks. Soil mineral N across differing management regimes (ARE 2%) proved to be well estimated by DNDC. The model captured the relative differences in N 2O emissions between the annual (measured: 35.5 kg N 2O-N ha -1, modeled: 30.1 kg N 2O-N ha -1) and annual-perennial (measured: 26.6 kg N 2O-N ha -1, modeled: 21.2 kg N 2O-N ha -1) cropping systems over the 7 year period but overestimated emissions from alfalfa production and underestimated emissions after spring applied anhydrous ammonia. Model predictions compared well with the measured total N 2O emissions (ARE -11%) while Tier II comparison to measurements (ARE -75%) helped to illustrate the strengths of a mechanistic approach in characterizing the site specific drivers responsible for N 2O emissions. Overall this study demonstrated the benefits of having near continuous GHG flux measurements coupled with detailed ancillary measurements towards identifying soil process interactions responsible for regulating GHG emissions.
  • Authors:
    • Vanhie,M.
    • Deen,W.
    • Bohner,H.
    • Hooker,D. C.
  • Source: Agronomy Journal
  • Volume: 107
  • Issue: 5
  • Year: 2015
  • Summary: Many soybean [ Glycine max (Merr.)] growers in northern climates are reverting back to some tillage based on perceptions that increasing corn residues interfere with no-till (NT) soybean performance. Field trials were established in southern Ontario, Canada, to investigate the impact of corn residues on soybean among seven tillage strategies (NT, stalk chop, vertical tillage (VT) twice in the fall, fall and spring VT, fall disc plus spring cultivate, fall disc plus fall cultivate, and fall plowed plus spring cultivate), three corn residue removal treatments (none, intermediate, and nearly complete), and two planters (row-unit and drill). Overall, soybean yields were not different between NT and plowed systems, despite delayed development, and cooler/wetter seedbeds where corn residue was not removed. Shallow tillage after corn harvest did not increase yields from NT alone. Removal of corn residue did not increase soybean yields when averaged across tillage systems. However, NT yield was lowered by 0.36 Mg ha -1 when corn stalks were chopped in the fall, but only in the drill-planted treatments. This result was significant since many farmers have purchased corn combine heads that chop stalks in an attempt to manage residue. Soybean planted with a row-unit planter yielded 0.13 Mg ha -1 higher compared to a drill when averaged across tillage-residue treatments; differences between planters were higher when contending with high amounts of corn residue or an uneven soil surface at planting. Our results show that shallow tillage and/or physically removing corn residue did not improve soybean yield compared to NT alone.
  • Authors:
    • Verheijen,L. M.
    • Aerts,R.
    • Brovkin,V.
    • Cavender-Bares,J.
    • Cornelissen,J. H. C.
    • Kattge,J.
    • Bodegom,P. M. van
  • Source: Global Change Biology
  • Volume: 21
  • Issue: 8
  • Year: 2015
  • Summary: Earth system models demonstrate large uncertainty in projected changes in terrestrial carbon budgets. The lack of inclusion of adaptive responses of vegetation communities to the environment has been suggested to hamper the ability of modeled vegetation to adequately respond to environmental change. In this study, variation in functional responses of vegetation has been added to an earth system model (ESM) based on ecological principles. The restriction of viable mean trait values of vegetation communities by the environment, called 'habitat filtering', is an important ecological assembly rule and allows for determination of global scale trait-environment relationships. These relationships were applied to model trait variation for different plant functional types (PFTs). For three leaf traits (specific leaf area, maximum carboxylation rate at 25°C, and maximum electron transport rate at 25°C), relationships with multiple environmental drivers, such as precipitation, temperature, radiation, and CO 2, were determined for the PFTs within the Max Planck Institute ESM. With these relationships, spatiotemporal variation in these formerly fixed traits in PFTs was modeled in global change projections (IPCC RCP8.5 scenario). Inclusion of this environment-driven trait variation resulted in a strong reduction of the global carbon sink by at least 33% (2.1 Pg C yr -1) from the 2nd quarter of the 21st century onward compared to the default model with fixed traits. In addition, the mid- and high latitudes became a stronger carbon sink and the tropics a stronger carbon source, caused by trait-induced differences in productivity and relative respirational costs. These results point toward a reduction of the global carbon sink when including a more realistic representation of functional vegetation responses, implying more carbon will stay airborne, which could fuel further climate change.
  • Authors:
    • Dale,Larry L.
    • Karali,Nihan
    • Millstein,Dev
    • Carnall,Mike
    • Vicua,Sebastian
    • Borchers,Nicolas
    • Bustos,Eduardo
    • O'Hagan,Joe
    • Purkey,David
    • Heaps,Charles
    • Sieber,Jack
    • Collins,William D.
    • Sohn,Michael D.
  • Source: Climatic Change
  • Volume: 132
  • Issue: 2
  • Year: 2015
  • Summary: This paper is among the first to report on the full integration of basin-scale models that include projections of the demand and supply of water and energy for residential, commercial, industrial, and agricultural sector users. We link two widely used regional planning models that allow one to study the impact of rising climate variability on water and electricity use in Sacramento, California. Historic data combined with the current energy and water system configuration was used to assess the implications of changes in temperature and precipitation. Climate simulations suggest that electricity imports to the region would increase during hot dry spells, when regional power production is most constrained. In particular, regional imports of electricity would increase over 35 % in hot dry years, assuming a 4 A degrees C increase in average temperature and a 25 % decrease in average precipitation.
  • Authors:
    • Evans,Jason M.
    • Calabria,Jon
    • Borisova,Tatiana
    • Boellstorf,Diane E.
    • Sochacka,Nicki
    • Smolen,Michael D.
    • Mahler,Robert L.
    • Risse,L. Mark
  • Source: Climatic Change
  • Volume: 132
  • Issue: 2
  • Year: 2015
  • Summary: A growing body of research indicates that opinions about long-term climate change and other natural resource issues can be significantly affected by current weather conditions (e.g., outside air temperature) and other highly contingent environmental cues. Although increased severity and frequency of droughts is regarded as a likely consequence of anthropogenic climate change, little previous research has attempted to relate the experience of drought with public attitudes about water supply or water-related climate change issues. For this study, a large set (n = 3,163) of public survey data collected across nine states of the southern United States was spatio-temporally linked with records of short-term (similar to 12 weeks) and long-term (similar to 5 years) drought condition at the level of each respondent's zip code. Multivariate ordinal logistic regression models that included numerous other independent variables (environmental ideology, age, gender, education, community size, residency duration, and local annual precipitation) indicated highly significant interactions with long-term drought condition, but showed no significant effect from short-term drought condition. Conversely, attitudes about water-related climate change showed highly significant interactions with short-term drought, with weaker to no effects from long-term drought. While the finding of significant effects from short-term drought condition on opinions about future drought is broadly consistent with previous public opinion research on climate change, the finding of water supply attitudes being more responsive to longer term drought condition is, to our knowledge, a novel result. This study more generally demonstrates the methodological feasibility and applied importance of accounting for local drought condition when public opinion information is used to evaluate outreach programs for water conservation and climate change.
  • Authors:
    • Gong,Daozhi
    • Hao,Weiping
    • Mei,Xurong
    • Gao,Xiang
    • Liu,Qi
    • Caylor,Kelly
  • Source: PLoS ONE
  • Volume: 10
  • Issue: 8
  • Year: 2015
  • Summary: Effects of agricultural practices on ecosystem carbon storage have acquired widespread concern due to its alleviation of rising atmospheric CO2 concentrations. Recently, combining of furrow-ridge with plastic film mulching in spring maize ecosystem was widely applied to boost crop water productivity in the semiarid regions of China. However, there is still limited information about the potentials for increased ecosystem carbon storage of this tillage method. The objective of this study was to quantify and contrast net carbon dioxide exchange, biomass accumulation and carbon budgets of maize (Zea maize L.) fields under the traditional non-mulching with flat tillage (CK) and partial plastic film mulching with furrow-ridge tillage (MFR) on the China Loess Plateau. Half-hourly net ecosystem CO2 exchange (NEE) of both treatments were synchronously measured with two eddy covariance systems during the growing seasons of 2011 through 2013. At same time green leaf area index (GLAI) and biomass were also measured biweekly. Compared with CK, the warmer and wetter (+1.3 degrees C and +4.3%) top soil at MFR accelerated the rates of biomass accumulation, promoted greater green leaf area and thus shortened the growing seasons by an average value of 10.4 days for three years. MFR stimulated assimilation more than respiration during whole growing season, resulting in a higher carbon sequestration in terms of NEE of -79 gC/m(2) than CK. However, after considering carbon in harvested grain (or aboveground biomass), there is a slight higher carbon sink (or a stronger carbon source) in MFR due to its greater difference of aboveground biomass than that of grain between both treatments. These results demonstrate that partial plastic film mulched furrow-ridge tillage with aboveground biomass exclusive of grain returned to the soil is an effective way to enhance simultaneously carbon sequestration and grain yield of maize in the semiarid regions.
  • Authors:
    • Hao,Xiying
  • Source: Geomicrobiology Journal
  • Volume: 32
  • Issue: 7
  • Year: 2015
  • Summary: This study investigated CO2 and N2O emissions from soil receiving long-term cattle feedlot manure applications under rainfed and irrigated conditions in semi-arid southern Alberta, Canada. Soil available N and CO2 and N2O fluxes were measured after fall crop harvesting and prior to next spring's seeding from plots that had received 0 and 60 t ha(-1)yr(-1) cattle feedlot manure application with (Mi0 and Mi60) or without irrigation (Mr0 and Mr60) for 27years. Both CO2 and N2O fluxes varied considerably over the 7-month nongrowing season. Cumulative CO2 emissions from manured treatments (Mr60 at 2.20 t ha(-1) and Mi60 at 2.36 t ha(-1)) were 2.6times values from nonmanured treatments (Mr0 at 0.83 t ha(-1) and Mi0 at 0.92 t ha(-1)). Similarly, cumulative N2O emission from manured treatments (Mr60 at 4.54kg ha(-1) and Mi60 at 5.34kg ha(-1)) were 8-12times values from nonmanured treatments (Mr0 at 0.40kg ha(-1) and Mi0 at 0.70kg ha(-1)). Growing season irrigation had no effect on CO2 and N2O emission over the nongrowing season.
  • Authors:
    • Hauptvogl, M.
    • Prcik, M.
    • Kotrla, M.
    • Jurekova, Z.
    • Paukova, Z.
  • Source: Science Journal
  • Volume: 12
  • Issue: 1
  • Year: 2015
  • Summary: The energy-efficient low-carbon EU economy (known as the 20-20-20) sets fundamental objectives in reducing greenhouse gas emissions (20%), increasing the share of renewable energy sources (20%) and saving primary energy consumption (20%). The objectives are incorporated in the National Renewable Energy Action Plans (NREAPs). Slovakia has to increase the share of renewable energy sources (RES) by 14% in its energy mix by 2020. Currently, the most widely used RES are water and solar energy, biomass and biogas. Our country has suitable ecological conditions for growing the so called energy crops in lowland and upland areas. So far, however, there is a lack of science-based information on the potential production of biomass in different soil-ecological and climatic conditions of the Slovak Republic. Our experimental research is focused on quantification of biomass production of various willow (genus Salix), poplar (genus Populus) and silvergrass ( Miscanthus sinensis) varieties grown in ecological conditions of southern Slovakia. We evaluated the biomass production of the studied crops. The results were evaluated in terms of the EU call (2013): to obtain more energy while reducing inputs and negative environmental impacts.