• Authors:
    • Samarah, N. H.
    • Harb, A. M.
  • Source: Journal of Crop Improvement
  • Volume: 29
  • Issue: 1
  • Year: 2015
  • Summary: Drought is a major abiotic stress that restricts growth and productivity of many crops. The objectives of this study were to assess the morphological and physiological responses of barley plants at the vegetative stage to controlled severe drought, and to test the expression of drought-responsive genes (HvHsdr4, HvNCED2, HvDHN1, HvDHN9, and HvCBF3) in a time course of drought treatment. Barley plants of two genotypes (Rum and Yarmouk) were exposed to controlled severe drought (25% field capacity) in a greenhouse experiment. The two genotypes showed a similar and significant reduction in net photosynthetic rate and plant height. At the molecular level, a differential gene expression of drought-responsive genes was shown between the two genotypes. The results indicate that drought-responsive genes can be useful marker genes to study the differential response of barley genotypes to drought stress conditions.
  • Authors:
    • Lafond, J.
    • Paré, M. C.
    • Pageau, D.
  • Source: Soil and Tillage Research
  • Volume: 150
  • Year: 2015
  • Summary: In the northern agroecosystem of Saguenay-Lac-Saint-Jean, cash crops such as barley, canola, and field pea are gaining popularity over traditional perennial crops like alfalfa. However, very little information is available on the relatively long-term effect of different crop rotations and soil tillage practices on crop yields and soil quality parameters. This study was conducted at the Normandin Research Farm of Agriculture and Agri-Food Canada. Five rotation types [1: Canola-Barley-Barley-Pea (C-B-B-P); 2: Canola-Pea-Barley-Barley (C-P-B-B); 3: Canola-Barley-Pea-Barley (C-B-P-B); 4: Pea monoculture; and 5: Barley monoculture] and two soil tillage practices [1: Chisel plough (CP) and 2: Moldboard plough (MP)] were evaluated. Canola monoculture of was not included. The study began in 1999 on a former alfalfa field and ended in 2010 after three four-year rotation cycles. Barley monoculture decreased yields by 600kgha-1 in the last five years, whereas field pea monoculture decreased yields by about 1000kgha-1 in most years. Barley monoculture did not significantly reduce grain yields compared to C-B-B-P and C-P-B-B, highlighting the importance of alternate crops every year. Soil tillage (CP versus MP) did not significantly affect yields for all crops in most years; and when it did have an effect, it showed inconsistencies by either increasing or decreasing grain yields. Soil tillage also had insignificant impact regardless of the rotation type involved. Rotation type and soil tillage had insignificant effect on soil organic matter content, whereas CP increased nitrate and phosphorus content in the 0-20cm soil layer. Rotation type had insignificant impact on soil physical properties, whereas CP improved soil water conductivity by 0.03cmh-1 for C-B-B-P and barley monoculture. Compared to MP, CP improved soil macro-aggregate (2-6mm) stability to water as well as aggregate mean weight diameter by about 15% for most of the rotations.
  • Authors:
    • Filser, J.
    • Vincze, T.
    • Strandberg, B.
    • Cortet, J.
    • Sechi, V.
    • Larsen, T.
    • D'Annibale, A.
    • Audisio, P. A.
    • Krogh, P. H.
  • Source: Soil Biology and Biochemistry
  • Volume: 84
  • Year: 2015
  • Summary: We hypothesized that the combined effect of rising levels of atmospheric carbon dioxide (CO2) and increasing use of genetically modified (GM) crops in agriculture may affect soil food-webs. So we designed a study for the assessment of the effects of elevated CO2 (eCO2) concentrations and GM barley on a soil-mesofauna community employing a 2nd tier mesocosm test system. The GM barley, Hordeum vulgare cv. Golden Promise, had a modified content of amino acids and it was compared with three non-GM barley cultivated varieties including the isogenic line. Our mesocosm experiment was conducted in a greenhouse at ambient (aCO2) and eCO2 (+80ppm) levels and included a multispecies assemblage of Collembola, Acari and Enchytraeidae with either a GM or conventional spring barley varieties. To detect food-web changes we added dried maize leaves naturally enriched in d13C and d15N relative to the soil substrate. Soil, plants and animals were collected after five and eleven weeks. We found that the eCO2 concentration did not affect the plant biomass, but the predatory mite and two collembolan species showed significantly lower abundances at eCO2. The densities of three collembolan species (Folsomia fimetaria, Proisotoma minuta and juveniles of Mesaphorura macrochaeta) was significantly lower in the GM treatment compared to some of the non-GM varieties. F.fimetaria was less abundant in presence of GM barley compared to the cultivated barley variety "Netto" at both CO2 levels, while the density of P.minuta was significantly reduced with the GM barley compared to variety "Netto" at aCO2 and the isogenic variety at eCO2. Maize litter acted as a food source for the community, as it was revealed by d13C values in microarthropods. Microarthropod d13C decreased over time, which indicates a diet change of the species towards carbon derived from barley, due to maize litter decomposition. The industrially produced CO2 gas also had a role as an isotopic marker, as the different d13C values were reflected in the barley and in the collembolan species. GM barley did not affect d13C and d15N values of soil animals indicating that the overall trophic structure of the mesofauna community was not changed compared to the non-GM cultivated varieties. The mesocosm methodology integrating stable isotope analysis demonstrates the potential of the multi-species mesocosm as a tool to detect and track changes in the soil trophic interactions in response to environmental pressures, climate and novel agricultural crops.
  • Authors:
    • Laerke, P. E.
    • Kandel, T. P.
    • Elsgaard, L.
    • Karki, S.
  • Source: ENVIRONMENTAL MONITORING AND ASSESSMENT
  • Volume: 187
  • Issue: 3
  • Year: 2015
  • Summary: Empirical greenhouse gas (GHG) flux estimates from diverse peatlands are required in order to derive emission factors for managed peatlands. This study on a drained fen peatland quantified the annual GHG balance (Carbon dioxide (CO2), nitrous oxide (N2O), methane (CH4), and C exported in crop yield) from spring barley (SB) and reed canary grass (RCG) using static opaque chambers for GHG flux measurements and biomass yield for indirectly estimating gross primary production (GPP). Estimates of ecosystem respiration (ER) and GPP were compared with more advanced but costly and labor-intensive dynamic chamber studies. Annual GHG balance for the two cropping systems was 4.0 +/- 0.7 and 8.1 +/- 0.2 Mg CO2-C-eq ha(-1) from SB and RCG, respectively (mean +/- standard error, n= 3). Annual CH4 emissions were negligible (<0.006 Mg CO2-C-eq ha(-1)), and N2O emissions contributed only 4-13 % of the full GHG balance (0.5 and 0.3 Mg CO2-C-eq ha(-1) for SB and RCG, respectively). The statistical significance of low CH4 and N2O fluxes was evaluated by a simulation procedure which showed that most of CH4 fluxes were within the range that could arise from random variation associated with actual zero-flux situations. ER measured by static chamber and dynamic chamber methods was similar, particularly when using nonlinear regression techniques for flux calculations. A comparison of GPP derived from aboveground biomass and from measuring net ecosystem exchange (NEE) showed that GPP estimation from biomass might be useful, or serve as validation, for more advanced flux measurement methods. In conclusion, combining static opaque chambers for measuring ER of CO2 and CH4 and N2O fluxes with biomass yield for GPP estimation worked well in the drained fen peatland cropped to SB and RCG and presented a valid alternative to estimating the full GHG balance by dynamic chambers.
  • Authors:
    • Sorensen, P.
    • Petersen, S. O.
    • Li, X. X.
    • Olesen, J. E.
  • Source: AGRICULTURE ECOSYSTEMS & ENVIRONMENT
  • Volume: 199
  • Year: 2015
  • Summary: Legume-based catch crops (LBCCs) may act as an important source of nitrogen (N) in organic crop rotations because of biological N fixation. However, the potential risk of high nitrous oxide (N 2O) emissions needs to be taken into account when including LBCCs in crop rotations. Here, we report the results from a one-year field experiment, which investigated N availability and N 2O emissions as affected by three LBCCs, i.e., red clover (CL), red clover-ryegrass mixture (GC) and winter vetch (WV), two non-LBCCs, i.e., perennial ryegrass (GR) and fodder radish (FR), and a control (CO) without catch crops. The effect of two catch crop management strategies was also tested: autumn harvest of the catch crop versus incorporation of whole-crop residues by spring ploughing. LBCCs accumulated 59-67 kg N ha -1 in their tops, significantly more than those of the non-LBCC, 32-40 kg N ha -1. Macro-roots accounted for >33% of total N in the catch crops. In accordance with this, LBCCs enhanced the performance of the succeeding unfertilised spring barley, thus obtaining a grain yield of 3.3-4.5 Mg ha -1 compared to 2.6-3.3 Mg ha -1 grain yield from non-LBCC and the fallow control treatments. Autumn harvest of catch crops, especially LBCCs, tended to reduce crop yield. The annual N 2O emissions were comparable across treatments except for fodder radish, which had the highest N 2O emission, and also the highest average yield-scaled N 2O emission, at 499 g N 2O-N Mg -1 grain. Although the sampling strategy employed in this study introduces uncertainty about the spatial and temporal variability, differences in seasonal emission patterns among catch crops were captured and harvest of catch crops in late autumn induced significantly higher emissions during winter, but lower emissions after residue incorporation in spring. In comparison with non-LBCC, LBCCs have the potential to partly replace the effect of manure application in organic cropping systems with greater crop production and less environmental footprint with respect to N 2O emissions. However, harvest of the catch crops may reduce crop yield unless the harvested N is recycled as fertiliser to the crops in the rotation.
  • Authors:
    • Sheaffer, C. C.
    • Fernandez, A. L.
    • Wyse, D. L.
  • Source: Agronomy Journal
  • Volume: 107
  • Issue: 1
  • Year: 2015
  • Summary: Field pea ( Pisum sativum L.) and lentil ( Lens culinaris Medik.) have potential as grain-producing legumes in organic rotations, but their yield is limited by weed competition. Intercropping can control weeds and increase total grain productivity per land area compared to sole cropping. A field experiment was conducted to investigate the effect of intercropping on field pea and lentil yields. Intercrop treatments were spring wheat ( Triticum aestivum L.), oat ( Avena sativa L.), and radish ( Raphanus sativus L.), which were harvested for grain; and winter rye ( Secale cereale L.) and rapid-cycling brassica ( Brassica campestris L.), which were not harvested. Intercropped lentil yields and total (lentil plus intercrop) yields were lower than or equal to weeded and unweeded sole cropped lentils in 5 of 6 site-years. Intercropped pea yields and total (pea plus intercrop) yields were lower than or equal to weeded and unweeded sole cropped pea in all site-years. Unharvested intercrops showed variable effectiveness at suppressing weeds. In lentil, winter rye intercropping reduced weed biomass compared to the unweeded control in 4 site-years, and rapid-cycling brassica reduced weed biomass in 2 site-years. In pea, winter rye, and rapid-cycling brassica treatments reduced weed biomass in all site-years. However, reductions in weed biomass were not associated with increases in grain yield. Estimated net returns to intercropping were variable, but generally similar for sole crops and intercrops on average. We did not observe consistent agronomic or economic advantages to the use of intercrops with field pea and lentil in the Minnesota environments studied.
  • Authors:
    • Grosso, S. J.
    • Spatari, S.
    • Pourhashem, G.
    • Mitchell, J. G.
    • Adler, P. R.
    • Parton, W. J.
  • Source: Research Article
  • Volume: 25
  • Issue: 4
  • Year: 2015
  • Summary: Crop residues are potentially significant sources of feedstock for biofuel production in the United States. However, there are concerns with maintaining the environmental functions of these residues while also serving as a feedstock for biofuel production. Maintaining soil organic carbon (SOC) along with its functional benefits is considered a greater constraint than maintaining soil erosion losses to an acceptable level. We used the biogeochemical model DayCent to evaluate the effect of residue removal, corn stover, and wheat and barley straw in three diverse locations in the USA. We evaluated residue removal with and without N replacement, along with application of a high-lignin fermentation byproduct (HLFB), the residue by-product comprised of lignin and small quantities of nutrients from cellulosic ethanol production. SOC always decreased with residue harvest, but the decrease was greater in colder climates when expressed on a life cycle basis. The effect of residue harvest on soil N 2O emissions varied with N addition and climate. With N addition, N 2O emissions always increased, but the increase was greater in colder climates. Without N addition, N 2O emissions increased in Iowa, but decreased in Maryland and North Carolina with crop residue harvest. Although SOC was lower with residue harvest when HLFB was used for power production instead of being applied to land, the avoidance of fossil fuel emissions to the atmosphere by utilizing the cellulose and hemicellulose fractions of crop residue to produce ethanol (offsets) reduced the overall greenhouse gas (GHG) emissions because most of this residue carbon would normally be lost during microbial respiration. Losses of SOC and reduced N mineralization could both be mitigated with the application of HLFB to the land. Therefore, by returning the high-lignin fraction of crop residue to the land after production of ethanol at the biorefinery, soil carbon levels could be maintained along with the functional benefit of increased mineralized N, and more GHG emissions could be offset compared to leaving the crop residues on the land.
  • Authors:
    • Niero,Monia
    • Ingvordsen,Cathrine H.
    • Peltonen-Sainio,Pirjo
    • Jalli,Marja
    • Lyngkjaer,Michael F.
    • Hauschild,Michael Z.
    • Jorgensen,Rikke B.
  • Source: Agricultural Systems
  • Volume: 136
  • Year: 2015
  • Summary: The paper has two main objectives: (i) to assess the eco-efficiency of spring barley cultivation for malting in Denmark in a future changed climate (700 ppm [CO2] and +5 degrees C) through Life Cycle Assessment (LCA) and (ii) to compare alternative future cultivation scenarios, both excluding and including earlier sowing and cultivar selection as measures of adaptation to a changed climate. A baseline scenario describing the current spring barley cultivation in Denmark was defined, and the expected main deviations were identified (differences in pesticide treatment index, modifications in nitrate leaching and change in crop yield). The main input data originate from experiments, where spring barley cultivars were cultivated in a climate phytotron under controlled and manipulated treatments. Effects of changed climate on both crop productivity and crop quality were represented, as well as impacts of predicted extreme events, simulated through a long heat-wave. LCA results showed that the changed climatic conditions will likely increase the negative impacts on the environment from Danish spring barley cultivation, since all environmental impact categories experienced increased impact for all investigated scenarios, except under the very optimistic assumption that the pace of yield improvement by breeding in the future will be the same as it was in the last decades. The main driver of the increased environmental impact was identified as the reduction in crop yield. Therefore, potential adaptation strategies should mainly focus on maintaining or improving crop productivity. The LCA also showed that selection of proper cultivars for future climate conditions including the challenge from extreme events is one of the most effective ways to reduce future environmental impacts of spring barley. Finally, if yield measurements are based on relative protein content, the negative effects of the future climate seem to be reduced. (C) 2015 Elsevier Ltd. All rights reserved.
  • Authors:
    • Vary,Z.
    • Mullins,E.
    • McElwain,J. C.
    • Doohan,F. M.
  • Source: Global Change Biology
  • Volume: 21
  • Issue: 7
  • Year: 2015
  • Summary: Wheat diseases present a constant and evolving threat to food security. We have little understanding as to how increased atmospheric carbon dioxide levels will affect wheat diseases and thus the security of grain supply. Atmospheric CO 2 exceeded the 400 ppmv benchmark in 2013 and is predicted to double or even treble by the end of the century. This study investigated the impact of both pathogen and wheat acclimation to elevated CO 2 on the development of Fusarium head blight (FHB) and Septoria tritici blotch (STB) disease of wheat. Here, plants and pathogens were cultivated under either 390 or 780 ppmv CO 2 for a period (two wheat generations, multiple pathogen subcultures) prior to standard disease trials. Acclimation of pathogens and the wheat cultivar Remus to elevated CO 2 increased the severity of both STB and FHB diseases, relative to ambient conditions. The effect of CO 2 on disease development was greater for FHB than for STB. The highest FHB disease levels and associated yield losses were recorded for elevated CO 2-acclimated pathogen on elevated CO 2-acclimated wheat. When similar FHB experiments were conducted using the disease-resistant cultivar CM82036, pathogen acclimation significantly enhanced disease levels and yield loss under elevated CO 2 conditions, thereby indicating a reduction in the effectiveness of the defence pathways innate to this wheat cultivar. We conclude that acclimation to elevated CO 2 over the coming decades will have a significant influence on the outcome of plant-pathogen interactions and the durability of disease resistance.
  • Authors:
    • Bekele,A.
    • Roy,J. L.
    • Young,M. A.
  • Source: Canadian Journal of Soil Science
  • Volume: 95
  • Issue: 3
  • Year: 2015
  • Summary: Interest in the use of biochar as soil amendment has grown recently. However, studies evaluating its potential use for reclamation of disturbed agricultural lands are lacking. We studied the effects of amending clay, loam, and sand subsoil substrates with wood biochar pyrolized at 800°C, oxidized lignite (humalite), or labile organic mix (sawdust, wheat straw, and alfalfa; LOM) on soil organic carbon (C), microbial biomass, dry aggregated size distribution and penetration resistance in greenhouse. We also considered the co-application of LOM and biochar or humalite to the subsoil substrates as treatments where C from either biochar or humalite represented a stable form of C. The amount and composition of the mix of organic amendments was determined for each subsoil so that organic C levels of reconstructed topsoil would be equivalent to that of the corresponding native topsoil in the long term. Field pea ( Pisum sativum L.) and barley ( Hordeum vulgare L.) were grown in rotation in four sequential greenhouse studies. Results from soil analysis at the end of study II and study IV showed that subsoils amended with biochar or humalite had higher organic C than those with LOM only, regardless of soil type. Labile organic mix added alone or together with biochar or humalite to subsoil increased microbial biomass and decreased geometric mean diameter of the dry soil aggregates. The effects of biochar or humalite-only amendment on these soil properties were not significant relative to the unamended subsoil substrate. Simultaneous application of biochar or humalite with LOM can potentially be used for topsoil reconstruction and reclamation of disturbed agricultural lands, and to maintain soil quality in the long term. However, long-term field studies are required to ascertain the longevity of the desirable properties reported in this study and to assess effects associated with aging of biochar or humalite in the soil.