• Authors:
    • Sawyer, J. E.
    • Miguez, F.
    • Barker, D. W.
    • Mitchell, D. C.
    • Iqbal, J.
    • Pantoja, J.
    • Castellano, M. J.
  • Source: Web Of Knowledge
  • Volume: 44
  • Issue: 3
  • Year: 2015
  • Summary: Little information exists on the potential for N fertilizer application to corn ( Zea mays L.) to affect N 2O emissions during subsequent unfertilized crops in a rotation. To determine if N fertilizer application to corn affects N 2O emissions during subsequent crops in rotation, we measured N 2O emissions for 3 yr (2011-2013) in an Iowa, corn-soybean [ Glycine max (L.) Merr.] rotation with three N fertilizer rates applied to corn (0 kg N ha -1, the recommended rate of 135 kg N ha -1, and a high rate of 225 kg N ha -1); soybean received no N fertilizer. We further investigated the potential for a winter cereal rye ( Secale cereale L.) cover crop to interact with N fertilizer rate to affect N 2O emissions from both crops. The cover crop did not consistently affect N 2O emissions. Across all years and irrespective of cover crop, N fertilizer application above the recommended rate resulted in a 16% increase in mean N 2O flux rate during the corn phase of the rotation. In 2 of the 3 yr, N fertilizer application to corn (0-225 kg N ha -1) did not affect mean N 2O flux rates from the subsequent unfertilized soybean crop. However, in 1 yr after a drought, mean N 2O flux rates from the soybean crops that received 135 and 225 kg N ha -1 N application in the corn year were 35 and 70% higher than those from the soybean crop that received no N application in the corn year. Our results are consistent with previous studies demonstrating that cover crop effects on N 2O emissions are not easily generalizable. When N fertilizer affects N 2O emissions during a subsequent unfertilized crop, it will be important to determine if total fertilizer-induced N 2O emissions are altered or only spread across a greater period of time.
  • Authors:
    • Gizaw, Mesgana
    • Gan, Thian Yew
    • Kuo, Chun-Chao
  • Source: Article
  • Volume: 130
  • Issue: 2
  • Year: 2015
  • Summary: Under the effect of climate change, warming likely means that there will be more water vapour in the atmosphere and extreme storms are expected to occur more frequently and with greater severity, resulting in municipal Intensity-Duration-Frequency (IDF) curves with higher intensities and shorter return periods. A regional climate model, MM5 (the Pennsylvania State University / National Center for Atmospheric Research numerical model), was set up in a one-way, three-domain nested framework to simulate future summer (May to August) precipitation of central Alberta. MM5 is forced with climate data of four Global Climate Models, CGCM3, ECHAM5, CCSM3, and MIROC3.2, for the baseline 1971-2000 and 2011-2100 based on the Special Report on Emissions Scenarios A2, A1B, and B1 of Intergovernmental Panel on Climate Change. Due to the bias of MM5's simulations, a quantile-quantile bias correction method and a regional frequency analysis is applied to derive projected grid-based IDF curves for central Alberta. In addition, future trends of air temperature and precipitable water, which affect storm pattern and intensity, are investigated. Future IDF curves show a wide range of increased intensities especially for storms of short durations (a parts per thousand currency sign1-h). Conversely, future IDF curves are expected to shift upward because of increased air temperature and precipitable water which are projected to be about 2.9 A degrees C and 29 % in average by 2071-2100, respectively. Our results imply that the impact of climate change could increase the future risk of flooding in central Alberta.
  • Authors:
    • Shirtliffe, S. J.
    • Banniza, S.
    • Syrovy, L. D.
  • Source: Agronomy Journal
  • Volume: 107
  • Issue: 1
  • Year: 2015
  • Summary: Field pea ( Pisum sativum L.) is an important organic crop due to its contribution to soil fertility and other rotational benefits. Leafed (wild-type) pea cultivars tend to be more weed suppressive, but their poor standing ability limits yield compared with semi-leafless cultivars. Growing mixtures of leafed and semi-leafless cultivars may improve weed suppression and yield compared with monocultures of the same cultivars by altering canopy morphology. To test this hypothesis, replicated field experiments were conducted under weedy, organic conditions in Saskatchewan, Canada, in 2011 and 2012. Mixtures of a leafed and semi-leafless cultivar, CDC Sonata and CDC Dakota, were sown in ratios of 0:100, 25:75, 50:50, 75:25, and 100:0 leafed to semi-leafless pea, at target seeding rates of 88 and 132 plants m -2. Mixtures that included 50% or more semi-leafless pea had similar lodging resistance and weed biomass suppression to the agronomically superior semi-leafless cultivar grown alone. The strong competitive ability of the semi-leafless cultivar was unexpected based on previous accounts. The combined yield of the two cultivars grown in a 75% semi-leafless mixture exceeded the seed and biomass yield of either single cultivar by at least 18 and 12%, respectively. Yield enhancement was attributed to the leafed cultivar, whose seed yield increased by more than two and a half times in this mixture relative to its monoculture. Results suggest that breeding of leafed cultivars specifically for mixture with semi-leafless pea may be a future source of yield gains in organic and low-input systems.
  • Authors:
    • Kankanen, H.
    • Lemola, R.
    • Valkama, E.
    • Turtola, E.
  • Source: Agronomy Journal
  • Volume: 203
  • Year: 2015
  • Summary: The growing of catch crops aims to prevent nutrient leaching in autumn after harvest and during the following winter, but due to competition, catch crops may also reduce yields of the main crop. We used meta-analysis to quantitatively review 35 studies conducted in Denmark, Sweden, Finland and Norway over the past four decades. These studies assessed the effect of both non-legume and legume catch crops undersown in spring cereals on nitrogen (N) leaching loss or its risk as estimated by the content of soil nitrate N(NO3--N) or its sum with ammonium N(NH4+-N) in late autumn. The meta-analysis also included the grain yield and N content of spring cereals. To identify sources of variation, we studied the effects of soil texture and management (ploughing time, the amount of N applied), as well as climatic (annual precipitation) and experimental conditions (duration of experiments, lysimeter vs. field experiments, the decade in which the experiment took place). Compared to control groups with no catch crops, non-legume catch crops, mainly ryegrass species, reduced N leaching loss by 50% on average, and soil nitrate N or inorganic N by 35% in autumn. Italian ryegrass depleted soil N more effectively (by 60%) than did perennial ryegrass or Westerwolds ryegrass (by 25%). In contrast, legumes (white and red clovers) did not diminish the risk for N leaching. Otherwise, the effect on N leaching and its risk were consistent across the studies conducted in different countries on clay and coarse-textured mineral soils with different ploughing times, N fertilization rates (<160 kg ha -1), and amounts of annual precipitation (480-1040 mm). Non-legume catch crops reduced grain yield by 3% with no changes in grain N content. In contrast, legumes and mixed catch crops increased both grain yield and grain N content by 6%. Therefore, in spring cereal production, non-legume catch crops represent a universal and effective method for reducing N leaching across the varieties of soils and weather conditions in the Nordic countries. Moreover, the trade-off between potential grain yield loss and environmental benefits seems tolerable and can be taken into account in environmental subsidy schemes.
  • Authors:
    • VandenBygaart, A. J.
    • Smith, W. N.
    • Campbell, C. A.
    • Grant, B. B.
    • Congreves, K. A.
    • Krobel, R.
    • Lemke, R. L.
    • Desjardins, R. L.
  • Source: Agronomy Journal
  • Volume: 107
  • Issue: 3
  • Year: 2015
  • Summary: Agricultural management practices which promote soil organic carbon (SOC) sequestration can contribute to the long-term productivity of soils, thus research must quantify and predict SOC dynamics in response to crop management. Using long-term (1967-2009) data from 10 cropping systems on a Brown Chernozem (Aridic Haploboroll) in the Canadian semiarid prairies at Swift Current, Saskatchewan, we assessed the effect of fertilizer, cropping frequency, and crop type on SOC dynamics in the 0- to 15-cm depth. Three models: Campbell, introductory carbon balance model (ICBM), and DayCent were evaluated, all of which produced fairly accurate predictions of SOC content and sequestration rates ( R2 of 0.64-0.82); however, DayCent had the highest correlation and lowest errors of prediction and was deemed superior. Residue inputs of 0.87 to 1.13 Mg C ha -1 yr -1 maintained the SOC level, and SOC content was directly related to factors which increased C inputs. The SOC content and sequestration rates were lowest for wheat ( Triticum aestivum L.)-based rotations which were frequently fallowed and included flax ( Linum usitatissimum L.), but highest for systems which were frequently cropped, well-fertilized, and included rye ( Secale cereale L.) or pulse crops in rotation. For systems with high C input, DayCent projected SOC gains of 12 Mg C ha -1 from 2009 to 2100, indicating that the soil at Swift Current had not reached maximum C capacity. This study was the first to rigorously test and demonstrate the strength of the DayCent for simulating SOC under different cropping systems on the Canadian prairies.
  • Authors:
    • Heimonen,Kaisa
    • Valtonen,Anu
    • Kontunen-Soppela,Sari
    • Keski-Saari,Sarita
    • Rousi,Matti
    • Oksanen,Elina
    • Roininen,Heikki
  • Source: Climatic Change
  • Volume: 131
  • Issue: 2
  • Year: 2015
  • Summary: Boreal forests might be challenged by increased herbivory pressure in the future due to global warming, since warming is predicted to increase the abundance of herbivorous insects and to lead to shifts in their distribution towards higher latitudes where they might face more palatable food sources. We studied the effect of the latitudinal translocation of silver birch (Betula pendula Roth) on herbivore damage to 26 micropropagated genotypes originating from six populations ranging from 60 to 67 degrees N in Finland in two growing seasons, 2011 and 2012. The genotypes were planted at three sites located in southern (60 degrees N), central (62 degrees N) and northern (67 degrees N) Finland. The genotypes translocated to lower latitudes from their latitudes of origin were experiencing higher intensity of herbivore damage compared to the genotypes translocated to higher latitudes in 2011, but not in 2012. All genotypes were experiencing herbivore damage by local herbivores of each study site. These results suggest that, as many herbivore species are predicted to shift their ranges towards higher latitudes, they can feed on novel host plant genotypes and may face more palatable food sources than at their present range. This suggests that future climate change will increase herbivore damage to young silver birch. Increased herbivory, in turn, might affect the growth of birch and therefore should be considered when making predictions about the boreal forest composition in the future.
  • Authors:
    • Du YuNeng
    • Huffman,T.
    • Daneshfar,B.
    • Green,M.
    • Feng Feng
    • Liu JianGui
    • Liu TingTing
    • Liu HuanJun
  • Source: Canadian Journal of Soil Science
  • Volume: 95
  • Issue: 3
  • Year: 2015
  • Summary: Canada's terrestrial ecostratification framework provides nested spatial units for organizing national data related to soils, landforms and land use. In the agricultural domain, the lack of national, uniform crop yield data on the ecostratification framework severely hinders our ability to evaluate the biophysical data with respect to economic and climatic conditions. We developed a national crop yield database at the regional (ecodistrict) level by aggregating individual records of an existing but very broad-level sample-derived yield database according to the ecostratification hierarchy. Issues related to the different sampling frameworks and the need for confidentiality of individual records were resolved in order to generate an ecostratified crop yield dataset at a reasonably detailed spatial scale. Sixty crops were first statistically arranged into 37 agronomically similar crop groups in order to increase class size, and these crop groups were aggregated into increasingly large spatial units until confidentiality was assured. The methodology maintained data quality and confidentiality while producing crop yield estimates at the ecodistrict level. Comparison to independent crop insurance data confirmed that the resulting crop yield data are valid where estimates were derived from data released at the level of an ecodistrict or an ecoregion, but not at the ecoprovince level. Our crop yield estimates offer a reasonably high level of spatial precision while remaining within standard confidentiality constraints.
  • Authors:
    • Mu, J.
    • Guo, J.
    • Zhao, J.
  • Source: Science Article
  • Volume: 207
  • Year: 2015
  • Summary: Understanding regional relationships between climate change and crop yield will help with making the strategic decisions for food security in China under climate change. In this study, the contributions of climate change to spring maize yield over the past three decades in Northeast China were decoupled based on the daily climate variables gathered from 68 meteorological stations and detailed observed data of spring maize from 55 agricultural meteorological experimental stations for the period 1978-2010 in Northeast China, analyzed with a linear statistical model. Then, the key climatic factors limiting the climate-induced yield of spring maize were identified. The agro-climatic similarity theory was applied. Finally, the relationships between the climatic variables and the climate-induced yield of spring maize were further explored by provinces. The results show that: from 1978 to 2010, the observed yields of spring maize in Northeast China increased markedly, with inter-annual fluctuations. Compared with the methods of moving average and harmonic average, Logistic regression optimally decoupled the climate-induced yield of spring maize. The key meteorological factors limiting the climate-induced yield were temperature, precipitation and sunshine, varying in the different regions. In Heilongjiang Province, the climate-induced yields of spring maize were mainly affected by maximum temperatures in August and precipitation in June. In Jilin Province, climate-induced yield was closely related to precipitation during daily the average temperature stably passing 10°C (≥10°C). In Liaoning Province, when the maximum temperature was high and the sunshine was abundant in June, the climate-induced yield of spring maize significantly increased. Finally, the regression models between climatic variables and climate-induced yield of spring maize in 11 representative zones in Northeast China also established geographical differences.
  • Authors:
    • Johansen,A.
    • Pommeresche,R.
    • Riley,H.
    • Loes,A. K.
  • Source: Nordic View to Sustainable Rural Development
  • Year: 2015
  • Summary: Anaerobic digestion of farmyard manures may help farmers to produce bioenergy instead of using fossil fuels, support cycling of nutrients and reduce greenhouse gas emission. However, compared to pristine slurry, digested slurry has a reduced content of organic carbon which may impact the soil biota negatively due to substrate shortage. Our knowledge on these processes and their influence on soil quality is scarce. Hence, a field experiment with two organic cropping systems (grass-clover ley and arable system; at two slurry-application levels) was established in 2011, to study how application of digestates affects crop yields, soil characteristics and soil biota (earthworms, springtails, microbiota). The grass-clover system showed comparable yield levels over 3 years when digested slurry was compared to untreated slurry. Digested slurries had no influence on soil nutrient concentrations or on soil organic matter levels over the first 2 years. Application of high levels of manure increased the mortality of both surface-dwelling and soil-living earthworms just after application, but the long-term effect of manure application seemed more positive, especially at low application levels. Springtails and microorganisms seemed only little affected by application of digested slurry.
  • Authors:
    • Soimakallio, S.
    • Koponen, K.
  • Source: The International Journal of Life Cycle Assessment
  • Volume: 20
  • Issue: 11
  • Year: 2015
  • Summary: As proposed by United Nations Environment Programme (UNEP)-Society for Environmental Toxicology and Chemistry (SETAC) Life Cycle Initiative (MilA i Canals et al., Int J Life Cycle Assess 18:1265-1277, 2007 and Koellner et al., Int J Life Cycle Assess 18:1188-1202, 2013), the impacts of land occupation should be studied in comparison to a baseline. Regardless of these guidelines, a land use baseline is often ignored in agro-bioenergy life cycle assessment (LCA) studies. This paper tests the appropriateness and significance of applying natural regeneration as a land use baseline for assessing the greenhouse gas (GHG) balances of agro-bioenergy in Finland. In the land use baseline applied, the land is assumed to be left to regenerate toward its natural state, which, in Finland, would most probably be some sort of forest. The foregone carbon stock of the natural regeneration baseline was estimated based on the literature. The GHG balances were studied by comparing the cumulative warming impacts of the dynamic biomass carbon cycle of the agro-bioenergy production system and the defined baseline over a given time horizon varying from 0 to 100 years. The significance of the results is illustrated by comparing them to other GHG emissions related to bioenergy. The results depend significantly on the agro-bioenergy yields and the carbon sequestration rate assumed in the natural regeneration baseline scenario. The GHG balances may be of the same magnitude as GHG emissions due to indirect land use changes resulting from market-mediated impacts, life cycle emissions of fossil fuels, and relative reduction in carbon stocks due to forest harvesting for bioenergy. Ignoring a dynamic land use baseline results in misleading conclusions on the GHG balances of land occupation, including agro-bioenergy, due to ignorance of foregone carbon sequestration. Thus, the interpretation of the results and conclusions provided in the vast number of agro-bioenergy LCA studies relying on biomass carbon neutrality should be reassessed. Besides bioenergy, the issue of land use baseline is relevant for any provision service function of land occupation. The foregone carbon sequestration is, however, highly uncertain and thus speculative.