• Authors:
    • Garcia,G. A.
    • Dreccer,M. F.
    • Miralles,D. J.
    • Serrago,R. A.
  • Source: Global Change Biology
  • Volume: 21
  • Issue: 11
  • Year: 2015
  • Summary: Warm nights are a widespread predicted feature of climate change. This study investigated the impact of high night temperatures during the critical period for grain yield determination in wheat and barley crops under field conditions, assessing the effects on development, growth and partitioning crop-level processes driving grain number per unit area (GN). Experiments combined: (i) two contrasting radiation and temperature environments: late sowing in 2011 and early sowing in 2013, (ii) two well-adapted crops with similar phenology: bread wheat and two-row malting barley and (iii) two temperature regimes: ambient and high night temperatures. The night temperature increase (ca. 3.9°C in both crops and growing seasons) was achieved using purpose-built heating chambers placed on the crop at 19:000 hours and removed at 7:00 hours every day from the third detectable stem node to 10 days post-flowering. Across growing seasons and crops, the average minimum temperature during the critical period ranged from 11.2 to 17.2°C. Wheat and barley grain yield were similarly reduced under warm nights (ca. 7% °C -1), due to GN reductions (ca. 6% °C -1) linked to a lower number of spikes per m 2. An accelerated development under high night temperatures led to a shorter critical period duration, reducing solar radiation capture with negative consequences for biomass production, GN and therefore, grain yield. The information generated could be used as a starting point to design management and/or breeding strategies to improve crop adaptation facing climate change.
  • Authors:
    • Steffens, D.
    • Azam, F.
    • Koyro, H. W.
    • Haider, G.
    • Muller, C.
    • Kammann, C.
  • Source: Regular Article
  • Volume: 395
  • Issue: 1/2
  • Year: 2015
  • Summary: Aims: Biochar (BC) and humic acid product (HAP) soil amendments may improve plant performance under water-limited conditions. Our aim was to investigate if BC and HAP amendments, alone or in combination, will have positive and synergistic effects. Methods: A three-factorial fully randomized study was carried out in the greenhouse for 66 days, including the factors 'BC', 'HAP' and 'water regime'. Maize ( Zea mays var. 'Amadeo' DKC-3399) was grown in pots (6 kg sandy soil pot -1) amended with/without BC (0, 1.5 and 3%; w/ w) and with/without HAP (0 or an equivalent of 8 kg ha -1). Two water regimes, limited and frequent (H 2O limit , H 2O frequ ), were applied after day 28 following seedling establishment at 60% water holding capacity (WHC). In the H 2O limit treatment, the soil water content was allowed to drop until wilting symptoms became visible (25-30% WHC) while in H 2O frequ the WHC was brought to 60% of the maximum on a daily basis Results BC but not HAP, added alone or in combination with BC, significantly increased the biomass yield and the water and N use efficiency of plants at both water regimes. The BC-mediated relative increase in the yield was equal with both watering regimes, refuting initial hypotheses. BC had generally a stimulating effect on water relations and photosynthesis, it increased the relative water content and the leaf osmotic potential, decreased the stomatal resistance and stimulated the leaf gas exchange (transpiration). Both, BC and pure HAP addition, stimulated photosynthesis by increasing the electron transport rate (ETR) of photosystem II (PSII) and of the ratio between effective photochemical quantum yield to non-photochemical quenching (Y(II)/Y(NPQ)), revealing reduced heat dissipation. Conclusions: Biochar use in poor sandy soils can improve plant growth by improving soil-plant water relations and photosynthesis under both H 2O frequ and H 2O limit conditions. HAP loading, however, did not improve the effect of biochar or vice versa.
  • Authors:
    • Serret, M. D.
    • Garcia-Mina, J. M.
    • Zamarreno, A. M.
    • Garnica, M.
    • Aroca, R.
    • Jauregui, I.
    • Parry, M.
    • Irigoyen, J. J.
    • Aranjuelo, I.
  • Source: Article
  • Volume: 155
  • Issue: 3
  • Year: 2015
  • Summary: Although climate scenarios have predicted an increase in [CO 2] and temperature conditions, to date few experiments have focused on the interaction of [CO 2] and temperature effects in wheat development. Recent evidence suggests that photosynthetic acclimation is linked to the photorespiration and N assimilation inhibition of plants exposed to elevated CO 2. The main goal of this study was to analyze the effect of interacting [CO 2] and temperature on leaf photorespiration, C/N metabolism and N transport in wheat plants exposed to elevated [CO 2] and temperature conditions. For this purpose, wheat plants were exposed to elevated [CO 2] (400 vs 700 molmol -1) and temperature (ambient vs ambient+4°C) in CO 2 gradient greenhouses during the entire life cycle. Although at the agronomic level, elevated temperature had no effect on plant biomass, physiological analyses revealed that combined elevated [CO 2] and temperature negatively affected photosynthetic performance. The limited energy levels resulting from the reduced respiratory and photorespiration rates of such plants were apparently inadequate to sustain nitrate reductase activity. Inhibited N assimilation was associated with a strong reduction in amino acid content, conditioned leaf soluble protein content and constrained leaf N status. Therefore, the plant response to elevated [CO 2] and elevated temperature resulted in photosynthetic acclimation. The reduction in transpiration rates induced limitations in nutrient transport in leaves of plants exposed to elevated [CO 2] and temperature, led to mineral depletion and therefore contributed to the inhibition of photosynthetic activity.
  • Authors:
    • Fenner, R.
    • McMahon, R.
    • Kopec, G.
    • Richards, K.
    • Allwood, J.
    • Mourão, Z.
    • Konadu, D.
  • Source: Energy Policy
  • Volume: 86
  • Year: 2015
  • Summary: The UK's 2008 Climate Change Act sets a legally binding target for reducing territorial greenhouse gas emissions by 80% by 2050, relative to 1990 levels. Four pathways to achieve this target have been developed by the Department of Energy and Climate Change, with all pathways requiring increased us of bioenergy. A significant amount of this could be indigenously sourced from crops, but will increased domestic production of energy crops conflict with other agricultural priorities?To address this question, a coupled analysis of the UK energy system and land use has been developed. The two systems are connected by the production of bioenergy, and are projected forwards in time under the energy pathways, accounting for various constraints on land use for agriculture and ecosystem services. The results show different combinations of crop yield and compositions for the pathways lead to the appropriation of between 7% and 61% of UK's agricultural land for bioenergy production. This could result in competition for land for food production and other land uses, as well as indirect land use change in other countries due to an increase in bioenergy imports. Consequently, the potential role of bioenergy in achieving UK emissions reduction targets may face significant deployment challenges. © 2015 The Authors.
  • Authors:
    • Nayak, D.
    • Lu, Y.
    • Pan, G.
    • Newbold, J.
    • Cardenas, L.
    • Yan, X.
    • Moran, D.
    • Liu, J.
    • Wang, J.
    • Zhu, W.
    • Cheng, Y.
    • Koslowski, F.
    • Wang, W.
    • Cheng, K.
    • Saetnan, E.
    • Smith, P.
  • Source: Article
  • Volume: 209
  • Year: 2015
  • Summary: Agriculture accounts for approximately 11% of China's national greenhouse gas (GHG) emissions. Through adoption of region-specific best management practices, Chinese farmers can contribute to emission reduction while maintaining food security for its large population (>1300 Million). This paper presents the outcome of a bottom-up assessment to quantify technical potential of mitigation measures for Chinese agriculture using meta-analysis of data from 240 publications for cropland, 67 publications for grassland and 139 publications for livestock, and provides the reference scenario for the cost analysis of identified mitigation measures. Management options with greatest mitigation potential for rice, or rice-based cropping systems are conservation tillage, controlled irrigation; replacement of urea with ammonium sulphate, nitrogen (N) inhibitor application, reduced N fertilizer application, integrated rice-fish-duck farming and biochar application. A 15% reduction in current average synthetic N fertilizer application for rice in China i.e., 231 kg N ha -1, would result in 12% decrease in direct soil nitrous oxide (N 2O) emissions. Combined application of chemical and organic fertilizer, conservation tillage, biochar application and reduced N application are possible measures that can reduce overall GHG emissions from upland cropping systems. Conventional fertilizer inputs for greenhouse vegetables are more than 2-8 times the optimal crop nutrient demand. A 20-40% reduction in N fertilizer application to vegetable crops can reduce N 2O emissions by 32-121%, while not negatively impacting the yield. One of the most important mitigation measures for agricultural grasslands could be conversion of low yielding cropland, particularly on slopes, to shrub land or grassland, which is also a promising option to decrease soil erosion. In addition, grazing exclusion and reduced grazing intensity can increase SOC sequestration and decrease overall emissions while improving the largely degraded grasslands. For livestock production, where poor quality forage is commonly fed, improving grazing management and diet quality can reduce methane (CH 4) emissions by 11% and 5%, on average. Dietary supplements can reduce CH 4 emissions further, with lipids (15% reduction) and tannins or saponins (11% reduction) showing the greatest potential. We also suggest the most economically cost-effective mitigation measures, drawing on related work on the construction of marginal abatement cost curves for the sector.
  • Authors:
    • Hauschild, M. Z.
    • Jorgensen, R. B.
    • Ingvordsen, C., H.
    • Niero, M.
  • Source: Article
  • Volume: 107
  • Year: 2015
  • Summary: When Life Cycle Assessment (LCA) is used to provide insights on how to pursue future food demand, it faces the challenge to describe scenarios of the future in which the environmental impacts occur. In the case of future crop production, the effects of climate change should be considered. In this context, the objectives of this paper are two-fold: (i) to recommend an approach to deal with uncertainty in scenario analysis for LCA of crop production in a changed climate, when the goal of the study is to suggest strategies for adaptation of crop cultivation practices towards low environmental impacts, and (ii) to implement the suggested approach to spring barley cultivation in Denmark. First, the main implications of climate change for future crop cultivation are analyzed, and the factors which should be included when modeling the climate change effects on crops through LCA are introduced, namely climate, soil, water loss and production parameters. Secondly, the handling of these factors in the inventory modeling is discussed and finally implemented in the case study. Our approach follows a 3-step procedure consisting of: (1) definition of a baseline scenario at the Life Cycle Inventory (LCI) level for the selected crop and performance of Life Cycle Impact Assessment (LCIA) including normalization and contribution analysis, in order to identify the focus points in terms of impact categories, unit processes and substances; (2) identification of the main deviations from the baseline scenario for these key parameters in alternative future scenarios; (3) comparison of the different scenarios including quantification of the uncertainty at inventory level. The procedure presented was successfully implemented to assess the consequences of the changed climate on Danish spring barley cultivated under future climate conditions. The LCA results, obtained using mainly primary data from phytotron experiments mimicking a future Danish climate, emphasized that adaptation strategies should prioritize the development of resilient and stable cultivars, i.e. robust to the expected extremes of the future climate and offering a reasonable yield under different climatic conditions. (C) 2015 Elsevier Ltd. All rights reserved.
  • Authors:
    • Ju, X.
    • Norse, D.
  • Source: Article
  • Volume: 209
  • Year: 2015
  • Summary: China's successful achievement of food security in recent decades has resulted in serious damage to the environment upstream of the agricultural sector, on farm and downstream. The environmental costs of this damage are not only agro-ecosystem function and the long-term sustainability of food production, but also bio-physical including human health with impacts at all levels from the local to the global, and with economic loss estimates ranging from 7 to 10% of China's agricultural gross domestic product (GDP). This paper presents a systematic analysis of the causes and impacts of these environmental costs for China's cropping systems and crop-based livestock systems, and focuses on the nitrogen management. Since the 1980s most of the environmental costs have been related to the intensification of first grain production stimulated by high nitrogen fertilizer and irrigation subsidies, and then vegetable production and fruit trees, with the overuse and misuse of synthetic nitrogen fertilizer and manure being the dominant cause of eutrophication, soil acidification and high greenhouse gas emissions. However, during the last 10 years or so the expansion of intensive livestock production has become a serious cause of direct and indirect air and water pollution and is destined to be the main agricultural threat to China's environment in the long-term unless a holistic strategy for sustainable intensification is adopted for the next and future 5 Year Plans. This strategy should focus on improving nutrient management to limit nitrogen overuse, which is now the main cause of the economic losses from agriculture's damage to the environment.
  • Authors:
    • Stinner, P.
  • Source: Energy, Sustainability and Society
  • Volume: 5
  • Issue: 4
  • Year: 2015
  • Summary: Background: Energy crops are of considerable importance for biogas production, especially in Germany. The main energy crops for that purpose are corn silage, grass silage, whole crop grain silage and other non-legume crops. The reason for preferring these crops is their high yield, which not only results in high yields of biogas per hectare but also in a high mitigation of greenhouse gases in the course of replacing fossil energy. This article aims to show an additional effect exerted on energy yield and mitigation of greenhouse gases by the use of legume energy crops. The symbiotic nitrogen fixation (SNF) of legumes compensates inorganic N fertilizer in conventional farms, if the digestate is applied as a fertilizer to the non-legume cash crops. The production of chemical N fertilizer is very energy intensive and leads to emissions of greenhouse gases from fossil energy consumption and from nitrous oxide generation. So, the creation of an effective organic fertilizer with nitrogen from biological N 2 fixation is a further energy add-on effect to the reduction of greenhouse gas emissions. Methods: For this article, data with regard to the SNF of legumes obtained in field experiments at the research station at Gladbacherhof (University of Giessen) from 2002 to 2005 were re-calculated and compared with data concerning energy need and greenhouse gas emissions in the process of producing mineral nitrogen fertilizer. In addition to the possible methane yield of these substrates, the saving in energy and greenhouse gas emissions by substituting mineral fertilizers is shown. Results: As a result, the possible replacement of primary energy by SNF of clover grass leys is calculated to be approximately less than 6.4 MWh ha -1 a -1. This is a yield that is reached in addition to the methane production, i.e. a possible reduction of greenhouse gas emissions through SNF per hectare of clover grass leys of more than 2 t CO 2 equivalents ha -1 a -1 can be achieved. Conclusions: Based on these results, it can be recommended to evaluate energy crops in a more holistic way. For legumes, the effect of SNF needs to be included into the energy and greenhouse balance.
  • Authors:
    • Vogel, A.
    • Strecker, T.
    • Steinauer, K.
    • Richter, A.
    • Ramirez, N.
    • Pierce, S.
    • Rong, J.
    • HongYan, G.
    • FuXun, A.
    • Tilman, D.
    • Scheu, S.
    • Reich, P.
    • Power, S.
    • Roscher, C.
    • Niklaus, P.
    • Manning, P.
    • Milcu, A.
    • Thakur, M.
    • Eisenhauer, N.
  • Source: Global Change Biology
  • Volume: 21
  • Issue: 11
  • Year: 2015
  • Summary: Soil microbial biomass is a key determinant of carbon dynamics in the soil. Several studies have shown that soil microbial biomass significantly increases with plant species diversity, but it remains unclear whether plant species diversity can also stabilize soil microbial biomass in a changing environment. This question is particularly relevant as many global environmental change (GEC) factors, such as drought and nutrient enrichment, have been shown to reduce soil microbial biomass. Experiments with orthogonal manipulations of plant diversity and GEC factors can provide insights whether plant diversity can attenuate such detrimental effects on soil microbial biomass. Here, we present the analysis of 12 different studies with 14 unique orthogonal plant diversity * GEC manipulations in grasslands, where plant diversity and at least one GEC factor (elevated CO 2, nutrient enrichment, drought, earthworm presence, or warming) were manipulated. Our results show that higher plant diversity significantly enhances soil microbial biomass with the strongest effects in long-term field experiments. In contrast, GEC factors had inconsistent effects with only drought having a significant negative effect. Importantly, we report consistent non-significant effects for all 14 interactions between plant diversity and GEC factors, which indicates a limited potential of plant diversity to attenuate the effects of GEC factors on soil microbial biomass. We highlight that plant diversity is a major determinant of soil microbial biomass in experimental grasslands that can influence soil carbon dynamics irrespective of GEC.
  • Authors:
    • Davidson, B.
    • White, R.
  • Source: IOP Conference Series: Earth and Environmental Science
  • Volume: 25
  • Issue: 1
  • Year: 2015
  • Summary: Data for cropping and pastoral enterprises in south eastern Australia were used in a cost-effectiveness analysis to assess the feasibility of abating greenhouse gas (GHG) emissions through storing soil carbon (C) as soil organic matter under the Australian government's Carbon Farming Initiative. We used the C credit value for 2013-14 of $24.15 per tonne of CO2- equivalent (CO2-e) and a C storage rate of 0.5 tonne C/hectare/year for conversion of cropland to pasture. Given that a change of enterprise is driven primarily by farmer returns, we found that none of the changes were feasible at current prices, with the exception of wheat to cattle or sheep in an irrigated system, and dryland cotton to cattle or sheep. Given that our model scenario assumed the most favourable economic factors, it is unlikely that increased soil C storage through a change from cropping to pasture can make a significant contribution to abating Australia's CO2 emissions. However, of greater concern to society is the methane emissions from grazing cattle or sheep, which would negate any gain in soil C under pasture, except for a switch from dryland cropping to sheep. © Published under licence by IOP Publishing Ltd.