• Authors:
    • Moore,J. R.
    • Watt,M. S.
  • Source: Global Change Biology
  • Volume: 21
  • Issue: 8
  • Year: 2015
  • Summary: Wind is the major abiotic disturbance in New Zealand's planted forests, but little is known about how the risk of wind damage may be affected by future climate change. We linked a mechanistic wind damage model (ForestGALES) to an empirical growth model for radiata pine ( Pinus radiata D. Don) and a process-based growth model (CENW) to predict the risk of wind damage under different future emissions scenarios and assumptions about the future wind climate. The CENW model was used to estimate site productivity for constant CO 2 concentration at 1990 values and for assumed increases in CO 2 concentration from current values to those expected during 2040 and 2090 under the B1 (low), A1 B (mid-range) and A2 (high) emission scenarios. Stand development was modelled for different levels of site productivity, contrasting silvicultural regimes and sites across New Zealand. The risk of wind damage was predicted for each regime and emission scenario combination using the ForestGALES model. The sensitivity to changes in the intensity of the future wind climate was also examined. Results showed that increased tree growth rates under the different emissions scenarios had the greatest impact on the risk of wind damage. The increase in risk was greatest for stands growing at high stand density under the A2 emissions scenario with increased CO 2 concentration. The increased productivity under this scenario resulted in increased tree height, without a corresponding increase in diameter, leading to more slender trees that were predicted to be at greater risk from wind damage. The risk of wind damage was further increased by the modest increases in the extreme wind climate that are predicted to occur. These results have implications for the development of silvicultural regimes that are resilient to climate change and also indicate that future productivity gains may be offset by greater losses from disturbances.
  • Authors:
    • Nadeu,Elisabet
    • Gobin,Anne
    • Fiener,Peter
    • Van Wesemael,Bas
    • Van Oost,Kristof
  • Source: Global Change Biology
  • Volume: 21
  • Issue: 8
  • Year: 2015
  • Summary: Agricultural management has received increased attention over the last decades due to its central role in carbon (C) sequestration and greenhouse gas mitigation. Yet, regardless of the large body of literature on the effects of soil erosion by tillage and water on soil organic carbon (SOC) stocks in agricultural landscapes, the significance of soil redistribution for the overall C budget and the C sequestration potential of land management options remains poorly quantified. In this study, we explore the role of lateral SOC fluxes in regional scale modelling of SOC stocks under three different agricultural management practices in central Belgium: conventional tillage (CT), reduced tillage (RT) and reduced tillage with additional carbon input (RT+i). We assessed each management scenario twice: using a conventional approach that did not account for lateral fluxes and an alternative approach that included soil erosion-induced lateral SOC fluxes. The results show that accounting for lateral fluxes increased C sequestration rates by 2.7, 2.5 and 1.5gCm(-2)yr(-1) for CT, RT and RT+i, respectively, relative to the conventional approach. Soil redistribution also led to a reduction of SOC concentration in the plough layer and increased the spatial variability of SOC stocks, suggesting that C sequestration studies relying on changes in the plough layer may underestimate the soil's C sequestration potential due to the effects of soil erosion. Additionally, lateral C export from cropland was in the same of order of magnitude as C sequestration; hence, the fate of C exported from cropland into other land uses is crucial to determine the ultimate impact of management and erosion on the landscape C balance. Consequently, soil management strategies targeting C sequestration will be most effective when accompanied by measures that reduce soil erosion given that erosion loss can balance potential C uptake, particularly in sloping areas.
  • Authors:
    • Panettieri,M.
    • Berns,A. E.
    • Knicker,H.
    • Murillo,J. M.
    • Madejon,E.
  • Source: Soil & Tillage Research
  • Volume: 151
  • Year: 2015
  • Summary: An augment of soil organic matter (SOM) in agricultural lands is mandatory to improve soil quality and fertility and to limit greenhouse gases emissions. A better protection of SOM from degradation is seconded to its inclusion in aggregates and to the formation of organo-mineral interactions with the clay fraction within the soil matrix. Under Mediterranean conditions, conservation agriculture (CA) has been widely related with macro-aggregates formation, SOM protection, and to an improvement of soil fertility and crop yields. The objective of this work was to evaluate the biogeochemical properties of five aggregate-size fractions obtained by dry sieving of a Calcic Fluvisol of an experimental farm managed under three different tillages. Soil aggregates distribution, total organic carbon (TOC), labile carbon pools, and enzymatic activities were measured in 2 different periods of the same agricultural campaign. CPMAS 13C NMR analyses were also performed to elucidate the structure of preserved SOM. The results evidenced seasonal variability in aggregate distribution, labile carbon pools and dehydrogenase activity (DHA), whereas TOC, permanganate oxidizable carbon (POxC), and beta- glucosidase activity demonstrated to be reliable soil quality indices for soil fractions. The NMR analyses showed a better SOM preservation under conservation tillages, due to higher plant litter inputs and/or higher amount of necromass derived compounds if compared with traditional tillage. Particularly interesting are the results of the O 0.5-1 mm fraction, in which different trends were found for beta-Glu and several organic compound classes if compared with the other fractions. Possibly, in this fraction are concentrated most of the products from cellulose depolymerization stabilized by organo-mineral interactions.
  • Authors:
    • Steenwerth,K. L.
    • Strong,E. B.
    • Greenhut,R. F.
    • Williams,L.
    • Kendall,A.
  • Source: The International Journal of Life Cycle Assessment
  • Volume: 20
  • Issue: 9
  • Year: 2015
  • Summary: Purpose: This study assesses life cycle greenhouse gas (GHG) emissions, energy use, and freshwater use in wine grape production across common vineyard management scenarios in two representative growing regions (Napa and Lodi) of the US state of California. California hosts 90 % of US grape growing area, and demand for GHG emissions estimates of crops has increased due to consumer interest and policies such as California’s Global Warming Solutions Act. Methods: The study’s scope includes the annual cycle for wine grape production, beginning at raw material extraction for production of vineyard inputs and ending at delivery of wine grapes to the winery gate, and excludes capital infrastructure. Two hundred forty production scenarios were modeled based on data collected from land owners, vineyard managers, and third-party vineyard management companies. Thirty additional in-person interviews with growers throughout Napa and Lodi were also conducted to identify the diversity of farming practices, site characteristics, and yields (among other factors) across 90 vineyards. These vineyards represent a cross-section of the regional variability in soil, climate, and landscape used for wine grape production. Results and discussion: Energy use and global warming potential (GWP) per metric ton (t) across all 240 production scenarios range between 1669 and 8567 MJ and 87 and 548 kg CO2e. Twelve scenarios were selected for closer inspection to facilitate comparison of the two regions and grower practices. Comparison by region shows energy use, GWP, and water use for typical practices were more than twice as great in Napa (6529 MJ/t, 456 kg CO2e/t, and 265 m3 H2O/t) than Lodi (2759 MJ/t, 203 kg CO2e/t, and 141 m3 H2O/t), but approximately 16 % greater on a per hectare basis. Hand harvest (versus mechanical harvesting) and frost protection processes in Napa contributed to higher values per hectare, and lower yields in Napa account for the even larger difference per metric ton. Hand harvesting and lower yields reflect the higher value of Napa wine grapes. Conclusions: The findings underscore the regional distinctions in wine grape production, which include different management goals, soils, and climate. When vineyards are managed for lower yields, as they are in Napa, energy, water, and GWP will likely be higher on a per mass basis. Strategies to reduce emissions in these regions cannot rely on increasing yields (a common approach), and alternative strategies are required, for example developing high-value co-products. © 2015 Springer-Verlag Berlin Heidelberg
  • Authors:
    • Dang,Y. P.
    • Seymour,N. P.
    • Walker,S. R.
    • Bell,M. J.
    • Freebairn,D. M.
  • Source: Soil & Tillage Research
  • Volume: 152
  • Year: 2015
  • Summary: Development of no-tillage (NT) farming has revolutionized agricultural systems by allowing growers to manage greater areas of land with reduced energy, labour and machinery inputs to control erosion, improve soil health and reduce greenhouse gas emission. However, NT farming systems have resulted in a build-up of herbicide-resistant weeds, an increased incidence of soil- and stubble-borne diseases and enrichment of nutrients and carbon near the soil surface. Consequently, there is an increased interest in the use of an occasional tillage (termed strategic tillage, ST) to address such emerging constraints in otherwise-NT farming systems. Decisions around ST uses will depend upon the specific issues present on the individual field or farm, and profitability and effectiveness of available options for management. This paper explores some of the issues with the implementation of ST in NT farming systems. The impact of contrasting soil properties, the timing of the tillage and the prevailing climate exert a strong influence on the success of ST. Decisions around timing of tillage are very complex and depend on the interactions between soil water content and the purpose for which the ST is intended. The soil needs to be at the right water content before executing any tillage, while the objective of the ST will influence the frequency and type of tillage implement used. The use of ST in long-term NT systems will depend on factors associated with system costs and profitability, soil health and environmental impacts. For many farmers maintaining farm profitability is a priority, so economic considerations are likely to be a primary factor dictating adoption. However, impacts on soil health and environment, especially the risk of erosion and the loss of soil carbon, will also influence a grower's choice to adopt ST, as will the impact on soil moisture reserves in rainfed cropping systems. (C) 2015 Elsevier B.V. All rights reserved.
  • Authors:
    • Djomo,S. Njakou
    • Witters,N.
    • Van Dael,M.
    • Gabrielle,B.
    • Ceulemans,R.
  • Source: Applied Energy
  • Volume: 154
  • Year: 2015
  • Summary: Bioenergy (i.e., bioheat and bioelectricity) could simultaneously address energy insecurity and climate change. However, bioenergy's impact on climate change remains incomplete when land use changes (LUC), soil organic carbon (SOC) changes, and the auxiliary energy consumption are not accounted for in the life cycle. Using data collected from Belgian farmers, combined heat and power (CHP) operators, and a life cycle approach, we compared 40 bioenergy pathways to a fossil-fuel CHP system. Bioenergy required between 0.024 and 0.204 MJ (0.86 MJ(th) + 0.14 MJ(el))(-1), and the estimated energy ratio (energy output-to-input ratio) ranged from 5 to 42. SOC loss increased the greenhouse gas (GHG) emissions of residue based bioenergy. On average, the iLUC represented similar to 67% of the total GHG emissions of bioenergy from perennial energy crops. However, the net LUC (i.e., dLUC + iLUC) effects substantially reduced the GHG emissions incurred during all phases of bioenergy production from perennial crops, turning most pathways based on energy crops to GHG sinks. Relative to fossil-fuel based CHP all bioenergy pathways reduced GHG emissions by 8-114%. Fluidized bed technologies maximize the energy and the GHG benefits of all pathways. The size and the power-to-heat ratio for a given CHP influenced the energy and GHG performance of these bioenergy pathways. Even with the inclusion of LUC, perennial crops had better GHG performance than agricultural and forest residues. Perennial crops have a high potential in the multidimensional approach to increase energy security and to mitigate climate change. The full impacts of bioenergy from these perennial energy crops must, however, be assessed before they can be deployed on a large scale. (C) 2015 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.orgilicenses/by-nc-nd/4.0/).
  • 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.
  • Authors:
    • Lubbers,Ingrid M.
    • van Groenigen,Kees Jan
    • Brussaard,Lijbert
    • van Groenigen,Jan Willem
  • Source: Scientific Reports
  • Volume: 5
  • Year: 2015
  • Summary: Concerns about rising greenhouse gas (GHG) concentrations have spurred the promotion of no-tillage practices as a means to stimulate carbon storage and reduce CO2 emissions in agro-ecosystems. Recent research has ignited debate about the effect of earthworms on the GHG balance of soil. It is unclear how earthworms interact with soil management practices, making long-term predictions on their effect in agro-ecosystems problematic. Here we show, in a unique two-year experiment, that earthworm presence increases the combined cumulative emissions of CO2 and N2O from a simulated no-tillage (NT) system to the same level as a simulated conventional tillage (CT) system. We found no evidence for increased soil C storage in the presence of earthworms. Because NT agriculture stimulates earthworm presence, our results identify a possible biological pathway for the limited potential of no-tillage soils with respect to GHG mitigation.
  • Authors:
    • Mangalassery,S.
    • Sjoegersten,S.
    • Sparkes,D. L.
    • Mooney,S. J.
  • Source: The Journal of Agricultural Science
  • Volume: 153
  • Issue: 7
  • Year: 2015
  • Summary: The benefits of reduced and zero-tillage systems have been presented as reducing runoff, enhancing water retention and preventing soil erosion. There is also general agreement that the practice can conserve and enhance soil organic carbon (C) levels to some extent. However, their applicability in mitigating climate change has been debated extensively, especially when the whole profile of C in the soil is considered, along with a reported risk of enhanced nitrous oxide (N2O) emissions. The current paper presents a meta-analysis of existing literature to ascertain the climate change mitigation opportunities offered by minimizing tillage operations. Research suggests zero tillage is effective in sequestering C in both soil surface and sub-soil layers in tropical and temperate conditions. The C sequestration rate in tropical soils can be about five times higher than in temperate soils. In tropical soils, C accumulation is generally correlated with the duration of tillage. Reduced N2O emissions under long-term zero tillage have been reported in the literature but significant variability exists in the N2O flux information. Long-term, location-specific studies are needed urgently to determine the precise role of zero tillage in driving N2O fluxes. Considering the wide variety of crops utilized in zero-tillage studies, for example maize, barley, soybean and winter wheat, only soybean has been reported to show an increase in yield with zero tillage (77% over 10 years). In several cases yield reductions have been recorded e.g. c. 1-8% over 10 years under winter wheat and barley, respectively, suggesting zero tillage does not bring appreciable changes in yield but that the difference between the two approaches may be small. A key question that remains to be answered is: are any potential reductions in yield acceptable in the quest to mitigate climate change, given the importance of global food security?
  • Authors:
    • McCabe,Gregory J.
    • Wolock,David M.
  • Source: Climatic Change
  • Volume: 132
  • Issue: 2
  • Year: 2015
  • Summary: A monthly water-balance model is used with CRUTS3.1 gridded monthly precipitation and potential evapotranspiration (PET) data to examine changes in global water deficit (PET minus actual evapotranspiration) for the Northern Hemisphere (NH) for the years 1905 through 2009. Results show that NH deficit increased dramatically near the year 2000 during both the cool (October through March) and warm (April through September) seasons. The increase in water deficit near 2000 coincides with a substantial increase in NH temperature and PET. The most pronounced increases in deficit occurred for the latitudinal band from 0 to 40A degrees N. These results indicate that global warming has increased the water deficit in the NH and that the increase since 2000 is unprecedented for the 1905 through 2009 period. Additionally, coincident with the increase in deficit near 2000, mean NH runoff also increased due to increases in P. We explain the apparent contradiction of concurrent increases in deficit and increases in runoff.