19862015
  • Authors:
    • Valentine, T. A.
    • Hawes, C.
    • Squire, G. R.
    • Young, M. W.
  • Source: AGRICULTURE ECOSYSTEMS & ENVIRONMENT
  • Volume: 202
  • Year: 2015
  • Summary: Efforts to maintain or increase food production in developed agriculture would be compromised if current high-intensity production was degrading supporting ecosystem services, such as the ability of soil to function. The link between cropping intensity, defined by pesticide and fertiliser applications, and soil biophysical status was examined at 70 sites in a high-yielding region of the UK, in which cropping sequences covering a wide range of intensity had diverged from a common low-intensity origin in the 1970s. Two sequences of still low or moderate intensity based on spring cereals or a low frequency of winter cereals formed comparators for three high intensity sequences based on winter wheat and potato which together were associated with adverse effects of -30% on soil carbon content in the upper soil layer ( P<0.001), -11% on soil water holding capacity ( P<0.01) and +15% on soil bulk density ( P<0.001). Negative effects were also found in some high intensity sequences on soil macroporosity and penetrometer resistance. Even in this high-yielding region, therefore, current forms of intensification are associated with adverse trends in soil condition that may be detrimental to future production. The effects of these trends in soil condition on agricultural output now need to be quantified, and the economic burden accounted for, if fields reduce their capacity to yield or need reparation to keep them productive.
  • Authors:
    • Lal,Rattan
  • Source: Journal of Soil and Water Conservation
  • Volume: 70
  • Issue: 3
  • Year: 2015
  • Authors:
    • Migliorati,M. de A.
    • Bell,M.
    • Grace,P. R.
    • Scheer,C.
    • Rowlings,D. W.
    • Liu Shen
  • Source: Agriculture, Ecosystems and Environment
  • Volume: 204
  • Issue: 1
  • Year: 2015
  • Summary: Alternative sources of N are required to bolster subtropical cereal production without increasing N 2O emissions from these agro-ecosystems. The reintroduction of legumes in cereal cropping systems is a possible strategy to reduce synthetic N inputs but elevated N 2O losses have sometimes been observed after the incorporation of legume residues. However, the magnitude of these losses is highly dependent on local conditions and very little data are available for subtropical regions. The aim of this study was to assess whether, under subtropical conditions, the N mineralised from legume residues can substantially decrease the synthetic N input required by the subsequent cereal crop and reduce overall N 2O emissions during the cereal cropping phase. Using a fully automated measuring system, N 2O emissions were monitored in a cereal crop (sorghum) following a legume pasture and compared to the same crop in rotation with a grass pasture. Each crop rotation included a nil and a fertilised treatment to assess the N availability of the residues. The incorporation of legumes provided enough readily available N to effectively support crop development but the low labile C left by these residues is likely to have limited denitrification and therefore N 2O emissions. As a result, N 2O emissions intensities (kg N 2O-N yield -1 ha -1) were considerably lower in the legume histories than in the grass. Overall, these findings indicate that the C supplied by the crop residue can be more important than the soil NO 3- content in stimulating denitrification and that introducing a legume pasture in a subtropical cereal cropping system is a sustainable practice from both environmental and agronomic perspectives.
  • Authors:
    • Ingrao,Carlo
    • Rana,Roberto
    • Tricase,Caterina
    • Lombardi,Mariarosaria
  • Source: Applied Energy
  • Volume: 149
  • Year: 2015
  • Summary: Over the last few years, agro-biogas has been receiving great attention since it enables replacement of natural gas, thereby representing a tool which reduces greenhouse gas emissions and other environmental impacts. In this context, this paper is aimed at the application of the Carbon Footprint (CF) to an agro-biogas supply chain (SC) in Southern Italy, according to ISO/TS 14067:2013, so as to calculate the related 100-year Global Warming Potential (GWP(100)). The topic was addressed because agro-biogas SCs, though being acknowledged worldwide as sustainable ways to produce both electricity and heat, can be source of GHG emissions and therefore environmental assessments and improvements are needed. Additionally, the performed literature review highlighted deficiencies in PCF assessments, so this study could contribute to enriching the international knowledge on the environmental burdens associated with agro-biogas SCs. The analysis was conducted using a life-cycle approach, thus including in the assessment: functional unit choice, system border definition and inventory analysis development. The primary data needed was provided by a farm located in the province of Foggia (Apulia region in Southern Italy), already equipped with anaerobic digestion and cogeneration plant for biogas production and utilisation. Results from this study are in agreement with those found by some of the most relevant studies in the sector. Indeed, it was possible to observe that GWP100 was almost entirely due to cropland farming and, in particular, to the production of ammonium nitrate in the amount required for fertilisation. Furthermore, environmental credits were observed thanks to: carbon sequestration enabled by no-tillage practice; and avoided production of chemical fertiliser thanks to 50% organic farming. Based upon the results obtained, a sensitivity analysis was carried out, thus highlighting reduced environmental impacts if ammonium nitrate was replaced with urea. Finally, thanks to this study, all the target stakeholders will learn more about the input/output flows involved in the system analysed, the related environmental impacts and the improvements needed to reduce them. In this way, it could be possible to compare the analysed agro-biogas SC with others of equal functionality, and so to enable considerations to be made on the resulting similarities and differences in terms of methodological approach, inventory flows and environmental impact. (C) 2015 Elsevier Ltd. All rights
  • Authors:
    • Karki,S.
    • Elsgaard,L.
    • Kandel,T. P.
    • Lærke,P. E.
  • 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-Ceq ha(-1) from SB and RCG, respectively (mean ± standard error, n = 3). Annual CH4 emissions were negligible (<0.006 Mg CO2-Ceq ha(-1)), and N2O emissions contributed only 4-13 % of the full GHG balance (0.5 and 0.3 Mg CO2-Ceq 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:
    • Monteleone,M.
    • Garofalo,P.
    • Cammerino,A. R. B.
    • Libutti,A.
  • Source: Italian Journal of Agronomy
  • Volume: 10
  • Issue: 2
  • Year: 2015
  • Summary: Climate change mitigation is the most important driving force for bioenergy development. Consequently, the environmental design of bioenergy value chains should address the actual savings of both primary energy demand and greenhouse gases (GHG) emissions. According to the EU Renewable Energy Directive (2009/28/EC), no direct impacts and no GHG emissions should be attributed to crop residues (like cereal straws) when they are removed from agricultural land for the purpose of bioenergy utilisation. The carbon neutral assumption applied to crop residues is, however, a rough simplification. Crop residues, indeed, should not be viewed simply as a waste to be disposed, because they play a critical role in sustaining soil organic matter and therefore have an inherent C-capturing value. Moreover, considering straws as an energy feedstock, its status of co-product is clearly recognised and its availability could be obtained according to different cropping systems, corresponding to different primary energy costs and GHG emissions. This paper highlights some hidden features in the assessment of agricultural energy and carbon balance, still very difficult to be detected and accounted for. Although they are frequently disregarded, these features (such as long term dynamic trend of soil organic carbon and annual nitrous oxide emissions from the soil) should be carefully considered in assembling the energy and emission balance. By using a crop simulation model, the long-term soil organic matter and annual N2O soil emissions were estimated. Consequently, a comprehensive energy and GHG balance was determined in accordance with the life cycle assessment methodology. Contrasting methods of straw management and wheat cultivation were compared: straw retention vs removal from the soil; conventional vs conservation tillage; wheat cropping system as a single-crop or in rotation. The resulting carbon footprint of straws has different magnitudes with respect to the several experimental conditions. By selecting the best agricultural practices, energy from straw can be optimally coupled with grain productions, without detrimental effects on soil fertility. An improved and specifically tailored cropping system is designed to obtain an optimal trade-off. © M. Monteleone et al., 2015.
  • 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:
    • Brady,M. V.
    • Hedlund,K.
    • Rong-Gang Cong
    • Hemerik,L.
    • Hotes,S.
    • Machado,S.
    • Mattsson,L.
    • Schulz,E.
    • Thomsen,I. K.
  • Source: Agronomy Journal
  • Volume: 107
  • Issue: 5
  • Year: 2015
  • Summary: Soil biodiversity through its delivery of ecosystem functions and attendant supporting ecosystem services - benefits soil organisms generate for farmers - underpins agricultural production. Yet lack of practical methods to value the long-term effects of current farming practices results, inevitably, in short-sighted management decisions. We present a method for valuing changes in supporting soil ecosystem services and associated soil natural capital - the value of the stock of soil organisms - in agriculture, based on resultant changes in future farm income streams. We assume that a relative change in soil organic C (SOC) concentration is correlated with changes in soil biodiversity and the generation of supporting ecosystem services. To quantify the effects of changes in supporting services on agricultural productivity, we fitted production functions to data from long-term field experiments in Europe and the United States. The different agricultural treatments at each site resulted in significant changes in SOC concentrations with time. Declines in associated services are shown to reduce both maximum yield and fertilizer-use efficiency in the future. The average depreciation of soil natural capital, for a 1% relative reduction in SOC concentration, was 144 Euro ha -1 (SD 47 Euro ha -1) when discounting future values to their current value at 3%; the variation was explained by site-specific factors and the current SOC concentration. Moreover, the results show that soil ecosystem services cannot be fully replaced by purchased inputs; they are imperfect substitutes. We anticipate that our results will both encourage and make it possible to include the value of soil natural capital in decisions.
  • Authors:
    • Buckley,Cathal
    • Wall,David P.
    • Moran,Brian
    • Murphy,Paul N. C.
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 102
  • Issue: 3
  • Year: 2015
  • Summary: This study uses a national farm survey which is part of the European Union (EU) Farm Accountancy Data Network (FADN) to develop environmental sustainability indicators in the use of nitrogen (N) and phosphorus (P) across a range of farm systems in the Republic of Ireland. Farm level micro data were used to calculate all inputs and outputs of N and P that cross the farm gate and to derive balances (kg ha(-1)) and overall use efficiencies across 827 farms in 2012. The sample is populated weighted to represents 71,480 farms nationally. Results indicated an average N balance of 71.0 kg ha(-1) and use efficiency of 36.7 % across the nationally representative sample. Nitrogen balances were between two and four times higher across specialist dairy farms compared to livestock rearing and specialist tillage systems. Nitrogen use efficiency was generally lowest across milk producing systems compared to livestock rearing and tillage systems. Phosphorus balance and use efficiency averaged 4.7 kg ha(-1) and 79.6 % respectively across the sample. Specialist tillage and dairying farms had higher average P balances compared to other livestock based systems. The approach developed in this analysis will form the benchmark for temporal analysis across these indicators for future nutrient balance and efficiency trends and could assist other members of the EU FADN to develop similar nationally representative indicators.
  • Authors:
    • Hao,B.
    • Xue,Q.
    • Marek,T. H.
    • Jessup,K. E.
    • Becker,J.
    • Hou,X.
    • Xu,W.
    • Bynum,E. D.
    • Bean,B. W.
    • Colaizzi,P. D.
    • Howell,T. A.
  • Source: Agronomy Journal
  • Volume: 107
  • Issue: 5
  • Year: 2015
  • Summary: Drought is an important factor limiting corn ( Zea mays L.) yields in the Texas High Plains, and adoption of drought-tolerant (DT) hybrids could be a management tool under water shortage. We conducted a 3-yr field study to investigate yield, evapotranspiration (ET), and water use efficiency (WUE) in DT hybrids. One conventional (33D49) and 4 DT hybrids (P1151HR, P1324HR, P1498HR, and P1564HR) were grown at three water regimes (I 100, I 75, and I 50, referring to 100, 75, and 50% ET requirement) and three planting densities (PD) (5.9, 7.4, and 8.4 plants m -2). Yield (13.56 Mg ha -1) and ET (719 mm) were the greatest at I 100 but WUE (2.1 kg m -3) was the greatest at I 75. Although DT hybrids did not always have greater yield and WUE than 33D49 at I 100, hybrids P1151HR and P1564HR consistently had greater yield and WUE than 33D49 at I 75 and I 50. Compared to 33D49, P1151HR and P1564HR had 8.6 to 12.1% and 19.1% greater yield at I 75 and I 50, respectively. Correspondingly, WUE was 9.8 to 11.7% and 20.0% greater at I 75 and I 50, respectively. Greater PD resulted in greater yield and WUE at I 100 and I 75 but PD did not affect yield and WUE at I 50. Yield and WUE in greater PD (8.4 plants m -2) were 6.3 to 8.3% greater than those in smaller PD (5.9 plants m -2). The results of this study demonstrated that proper selection of DT hybrids can increase corn yield and WUE under water-limited conditions.