• Authors:
    • Hanewinkel, M.
    • Yousefpour, R.
  • Source: Article
  • Volume: 130
  • Issue: 2
  • Year: 2015
  • Summary: Forestry professionals' perceptions of the risks and uncertainties associated with climate change were investigated in a questionnaire survey in south-west Germany. The respondents were employed in forestry in either public or private forests or working for state authorities. They were specifically asked about the related impacts of climate change on forest ecosystems, adaptive forest management and the potential of forestry to mitigate climate change. A factor analysis of the responses revealed significant variables explaining the major part of the variance and the key variable groups were identified in a canonical analysis. The majority of respondents (72 %) said they were under-informed, but most (83 %) view climate change as a reality, human-caused, and a significant risk. These forestry professionals were particularly concerned about extreme hazards, water scarcity, and changes in climatic zones. They generally said the potential of forestry to mitigate climate change is low, and saw few realistic measures like increased harvesting to substitute fossil fuels and energy-intensive materials for mitigation. Despite the uncertainty involved, adaptation strategies like using better-adapted tree species and provenances were mainly perceived as helpful, and tools such as spatially-explicit maps with recommendations for adapted species and indices of biotic and abiotic risks as important. The forestry professionals reported obtaining their information about climate change from advanced forestry training, the media, and scientific literature. The findings of the study are discussed in the light of the ongoing debate on climate change in Germany and recommendations made, including periodically checking and improving forestry professionals' knowledge about climate change.
  • Authors:
    • Lynch, J. P.
    • Zhan, A.
  • Source: Article
  • Volume: 66
  • Issue: 7
  • Year: 2015
  • Summary: Suboptimal nitrogen (N) availability is a primary constraint for crop production in developing countries, while in developed countries, intensive N fertilization is a primary economic, energy, and environmental cost for crop production. We tested the hypothesis that under low-N conditions, maize ( Zea mays) lines with few but long (FL) lateral roots would have greater axial root elongation, deeper rooting, and greater N acquisition than lines with many but short (MS) lateral roots. Maize recombinant inbred lines contrasting in lateral root number and length were grown with adequate and suboptimal N in greenhouse mesocosms and in the field in the USA and South Africa (SA). In low-N mesocosms, the FLphenotype had substantially reduced root respiration and greater rooting depth than the MS phenotype. In low-N fields in the USA and SA, the FLphenotype had greater rooting depth, shoot N content, leaf photosynthesis, and shoot biomass than the MS phenotype. The FLphenotype yielded 31.5% more than the MS phenotype under low N in the USA. Our results are consistent with the hypothesis that sparse but long lateral roots improve N capture from low-N soils. These results with maize probably pertain to other species. The FLlateral root phenotype merits consideration as a selection target for greater crop N efficiency.
  • Authors:
    • Qiu, W.
    • Beare, M. H.
    • Curtin, D.
    • Chantigny, M. H.
    • Curtin, D.
    • Beare, M. H.
    • Qiu, W.
    • Chantigny, M. H.
  • Source: Agronomyhttps://dl.sciencesocieties.org/publications/sssaj/articles/79/3/858 Journal
  • Volume: 79
  • Issue: 3
  • Year: 2015
  • Summary: Water-extractable organic matter has been shown to increase as temperature increases (from 20 to 80°C), with the rate of increase being soil dependent. We examined whether biodegradation during overnight soil-water extraction may influence the temperature response of extractable C and N. Dissolved organic N (DON) and C (DOC), and NH4-N were determined after 16 h of soil-water extraction at either 80 or 50°C (previous work in our laboratory suggested that biodegradation in soil-water suspensions peaks at ~50°C). For both DOC and DON, there were large differences among soils in their temperature responses (e.g., the increase in DON between 50 and 80°C ranged from 29 to 148 mg kg-1). More NH4-N was generated at 50 than at 80°C. Ammonium N produced at 50°C was largely attributable to mineralization (it was almost eliminated when microbial activity was suppressed by extracting with 2 mol L-1 KCI at 50°C). The small amounts of NH4-N found at 80°C were probably of abiotic origin (e.g., thermal degradation of soil organic N). Our results suggested that dissolved organic matter (DOM) was mineralized during the 50°C extraction. The release of DOM was thus underestimated at 50°C and, as a consequence, the temperature response of DOM between 50 and 80°C was overestimated (mineralization at 50°C accounted for most of the variability in the temperature response of DOM). We conclude that the temperature response of DOM can be affected by biodegradation during extraction and that an extraction at 80°C has the important merit that biodegradation during extraction should be negligible. © Soil Science Society of America, 5585 Guilford Rd., Madison Wl 53711 USA.
  • Authors:
    • Holland,R. A.
    • Eigenbrod,F.
    • Muggeridge,A.
    • Brown,G.
    • Clarke,D.
    • Taylor,G.
  • Source: Renewable and Sustainable Energy Reviews
  • Volume: 46
  • Year: 2015
  • Summary: The production of bioenergy from second generation (2G) feedstocks is being encouraged by legislation targeted at addressing a number of controversial issues including carbon emissions driven by land-use change and competition for crops used in food production. Here, we synthesise the implications of 2G feedstock production for a range of key ecosystem services beyond climate regulation. We consider feedstocks typical of temperate systems (Miscanthus; short-rotation coppice, short rotation forestry) and transitions from areas of forest, marginal land and first generation (1G) feedstock production. For transitions from 1G feedstocks, studies suggest significant benefits may arise for a number of ecosystem services, including hazard regulation, disease and pest control, water and soil quality. Although less evidence is available, the conversion of marginal land to 2G production will likely deliver benefits for some services while remaining broadly neutral for others. Conversion of forest to 2G production will likely reduce the provision of a range of services due to increased disturbance associated with shortening of the management cycle. Most importantly, further research is needed to broaden, and deepen, our understanding of the implications of transitions to 2G feedstocks on ecosystem services, providing empirical evidence for policy development, particularly for commercial deployment where landscape scale effects may emerge. A programme of research that mixes both the natural and social sciences based on an ecosystem service framework, and occurs concurrently with large scale commercial deployment of 2G feedstocks, would address this gap, providing evidence on the effectiveness of policies to promote production of 2G feedstocks on a wide range of ecosystem services. (C) 2015 Elsevier Ltd. All rights reserved.
  • Authors:
    • Mangalassery,S.
    • Mooney,S. J.
    • Sparkes,D. L.
    • Fraser,W. T.
    • Sjoegersten,S.
  • Source: European Journal of Soil Biology
  • Volume: 68
  • Issue: 1
  • Year: 2015
  • Summary: Zero tillage management of agricultural soils has potential for enhancing soil carbon (C) storage and reducing greenhouse gas emissions. However, the mechanisms which control carbon (C) sequestration in soil in response to zero tillage are not well understood. The aim of this study was to investigate the links between zero tillage practices and the functioning of the soil microbial community with regards to C cycling, testing the hypothesis that zero tillage enhances biological functioning in soil with positive implications for C sequestration. Specifically, we determined microbial respiration rates, enzyme activities, carbon source utilization and the functional chemistry of the soil organic matter in temperate well drained soils that had been zero tilled for seven years against annually tilled soils. Zero tilled soils contained 9% more soil C, 30% higher microbial biomass C than tilled soil and an increased presence of aromatic functional groups indicating greater preservation of recalcitrant C. Greater CO2 emission and higher respirational quotients were observed from tilled soils compared to zero tilled soils while microbial biomass was 30% greater in zero tilled soils indicating a more efficient functioning of the microbial community under zero tillage practice. Furthermore, microbial enzyme activities of dehydrogenase, cellulase, xylanase, beta-glucosidase, phenol oxidase and peroxidase were higher in zero tilled soils. Considering zero tillage enhanced both microbial functioning and C storage in soil, we suggest that it offers significant promise to improve soil health and support mitigation measures against climate change. (C) 2015 Elsevier Masson SAS. All rights reserved.
  • Authors:
    • Nowak,B.
    • Nesme,T.
    • David,C.
    • Pellerin,S.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 204
  • Year: 2015
  • Summary: Many authors have focused on the contribution of inner farm nutrient recycling to closed nutrient cycles, but little is known about the contribution of exchanges among farms to nutrient cycling. By using a network approach, we assessed the structure of farm mass flows networks and their consequences for nitrogen (N), phosphorus (P) and potassium (K) recycling in organic farming at the local scale. Organic farming was considered as a prototype of farming systems that aims at better closing nutrient cycles. Inflows and outflows were collected for two cropping years on 63 organic farms. The farms were located in three French agricultural districts with areas ranging from 520 to 1021 km 2 and differentiated by their degree of specialization (specialized in crop production, animal production, or mixed). Local nutrient recycling was assessed at the district scale through: (i) the local supply, defined as the ratio of the amount of nutrients from exchanges among farms plus the amount of nitrogen from atmospheric sources, to the sum of inputs to organic farms; and (ii) the cycling index, defined as the fraction of nutrients flowing at least twice through the same farms. Results showed that exchanges among farms were mainly short-distance exchanges (<50 km on average) and contributed up to 70% of farm nutrient inflow. Mass flows among farms were two to four times greater in the mixed district than in specialized districts. As a consequence, both the local supply and the cycling index were greater in the mixed district than in the specialized districts. However, even if the local supply was generally high (85%, 52% and 54% for N, P and K inflows in the mixed district, respectively), the cycling index remained low (5%, 20% and 10% for N, P and K in the mixed district), indicating that most flows among farms were one-way and not actual nutrient recycling. This study contributes to the understanding of the magnitude, conditions and factors of nutrient recycling in agriculture at the local scale.
  • Authors:
    • Antille,D. L.
    • Chamen,W. C. T.
    • Tullberg,J. N.
    • Lal,R.
  • Source: Transactions of the ASABE
  • Volume: 58
  • Issue: 3
  • Year: 2015
  • Summary: The drive toward adoption of conservation agriculture to reduce costs and increase production sustainably causes concern due to the potentially negative effects of increased soil compaction. Soil compaction reduces aeration, water infiltration, and saturated hydraulic conductivity and increases the risk of waterlogging. Controlled traffic farming (CTF) is a system in which: (1) all machinery has the same or modular working and track width so that field traffic can be confined to the least possible area of permanent traffic lanes, (2) all machinery is capable of precise guidance along those permanent traffic lanes, and (3) the layout of the permanent traffic lanes is designed to optimize surface drainage and logistics. Without CTF, varying equipment operating and track widths translate into random traffic patterns, which can cover up to 85% of the cultivated field area each time a crop is produced. Nitrous oxide (N2O) is the greatest contributor to agriculture's greenhouse gas (GHG) emissions from cropping, and research suggests that its production increases significantly under conditions of high (>60%) water-filled porosity when nitrate (mainly from fertilizer N) and carbon (usually from crop residues) are available. Self-amelioration of soils affected by compaction occurs slowly from the surface downward; however, the rate of amelioration decreases with increase in depth. Consequently, all soils in non-CTF systems in mechanized agriculture are prone to some degree of compaction, which compromises water infiltration, increases the frequency and duration of waterlogged conditions, reduces gaseous exchange between soil and the atmosphere, inhibits root penetration and exploitation of nutrients and water in the subsoil, and enhances N2O emissions. Adoption of CTF increases soil porosity in the range of 5% to 70%, water infiltration by a factor of 4, and saturated hydraulic conductivity by a factor of 2. The greater cropping opportunity and enhanced crop growth for given fertilizer and rainfall inputs offered by CTF, coupled with no-tillage, provide potential for enhanced soil carbon sequestration. Reduced need and intensity of tillage, where compaction is avoided, also helps protect soil organic matter in stable aggregates, which may otherwise be exposed and oxidized. There is both circumstantial and direct evidence to suggest that improved soil structural conditions and aeration offered by CTF can reduce N2O emissions by 20% to 50% compared with non-CTF. It is not compaction per se that increases the risk of N2O emissions but rather the increased risk of waterlogging and increase in water-filled pore space. There may be an elevated risk of GHG emissions from the relatively small area of permanent traffic lanes (typically <20% of total cultivated area) if these are not managed appropriately. Quantification of the benefits of compaction avoidance in terms of GHG emissions may be possible through the use of well-developed models.
  • Authors:
    • Cayambe,J.
    • Iglesias,A.
    • de Jalón,S. G.
    • Chuquillanqui,C.
    • Riga,P.
  • Source: ITEA
  • Volume: 111
  • Issue: 2
  • Year: 2015
  • Summary: The temperature rise of the planet associated with anthropogenic greenhouse gas emissions promotes interest for strategies to mitigate them. Since agriculture is a sector responsible for nearly a fifth of global emissions, it is necessary to identify measures to be applied, what is their mitigation potential and the estimated cost of implementing each measure. Our study addresses these questions by comparing the production of potato in two distinct production systems and with actual field data. In a first step, this paper calculates in a modern agricultural system the carbon footprint of mechanization and energy use for irrigation (located in Spain) and in less productive systems that integrate less technologies (located in Peru) . The results show that in the case studies in both countries the nitrogen cycle represents the primary source of greenhouse gas emissions, followed by energy fuel for irrigation and mechanization. Subsequently this study evaluates economically the mitigation actions through Marginal Abatement Cost Curves. These results demonstrate that the management of nitrogen fertilizer is the best alternative to reduce the carbon footprint because of their greater potential to reduce greenhouse gas emissions and their lower equivalent mitigation costs. Finally, the study provides a methodological framework that can be easily applied to other crops. © 2015, Asociacion Interprofesional para el Desarrollo Agrario. All rights reserved.
  • Authors:
    • Louw,E. L.
    • Hoffman,E. W.
    • Theron,K. I.
    • Midgley,S. J. E.
  • Source: South African Journal of Botany
  • Volume: 99
  • Year: 2015
  • Summary: Rising temperatures associated with global climate change may alter the physiology and phenology of Protea species and cultivars. Protea species are assumed to be well adapted to warm summers characteristic of their natural Mediterranean-type habitat, but their plasticity in responding to higher growth temperatures is not known. Using infrared lamps, a greenhouse-based temperature gradient was constructed, with temperatures ranging from ambient to ambient + 3.1°C. Potted plants of Protea 'Pink Ice' ( P. compacta R. Br * P. susannae Phill.) were grown at five positions along this gradient for 12 months under irrigation. Simultaneously, a field verification experiment in a nearby commercial 'Pink Ice' orchard was conducted under ambient temperature and ambient + 2.9°C. Increased sclerophylly (leaf dry weight per unit area) with increasing temperature indicated leaf structural changes. While leaf area based gas exchange (net CO 2 assimilation rate, stomatal conductance and dark respiration rate) did not differ across the temperature gradient, leaf weight based CO 2 assimilation rate and dark respiration rate decreased significantly towards the upper end of the temperature range. The optimum temperature for net CO 2 assimilation rate (T opt) showed seasonal adjustments, but increased in response to experimental warming only in the field experiment. Significant temperature elevation resulted in an earlier onset of spring bud break, but warming extended inflorescence initiation from the spring flush to the summer flush, leading to delayed flowering. Aboveground biomass allocation shifted from inflorescences to leaves and to a lesser degree to stems, with elevated temperatures, whereas root growth was stimulated in the middle of the warming range. The results of this study suggest that elevated temperature may prolong the vegetative growth period in some Protea cultivars where water is not limiting, at the expense of flower production. This could have significant economic and marketing consequences for commercial cut flower production systems. The findings are also of significance to ecologists studying the responses of Proteaceae to climate change.
  • Authors:
    • Martinez-Luscher,J.
    • Morales,F.
    • Sanchez-Diaz,M.
    • Delrot,S.
    • Aguirreolea,J.
    • Gomes,E.
    • Pascual,I.
  • Source: Plant Science
  • Volume: 236
  • Year: 2015
  • Summary: The increase in grape berry ripening rates associated to climate change is a growing concern for wine makers as it rises the alcohol content of the wine. The present work studied the combined effects of elevated CO 2, temperature and UV-B radiation on leaf physiology and berry ripening rates. Three doses of UV-B: 0, 5.98, 9.66 kJ m -2 d -1, and two CO 2-temperature regimes: ambient CO 2-24/14°C (day/night) (current situation) and 700 ppm CO 2-28/18°C (climate change) were imposed to grapevine fruit-bearing cuttings from fruit set to maturity under greenhouse-controlled conditions. Photosynthetic performance was always higher under climate change conditions. High levels of UV-B radiation down regulated carbon fixation rates. A transient recovery took place at veraison, through the accumulation of flavonols and the increase of antioxidant enzyme activities. Interacting effects between UV-B and CO 2-temperature regimes were observed for the lipid peroxidation, which suggests that UV-B may contribute to palliate the signs of oxidative damage induced under elevated CO 2-temperature. Photosynthetic and ripening rates were correlated. Thereby, the hastening effect of climate change conditions on ripening, associated to higher rates of carbon fixation, was attenuated by UV-B radiation.