• Authors:
    • Henriksen, C. B.
    • Braun, M.
    • Bluwstein, J.
  • Source: AGROECOLOGY AND SUSTAINABLE FOOD SYSTEMS
  • Volume: 39
  • Issue: 5
  • Year: 2015
  • Summary: GHG emissions of an extensively managed Danish organic farm were estimated upstream and on-farm. The results were compared to Danish national levels based on land area and output. Overall, the farm emitted 2.12 t CO 2eq ha -1 yr -1. Excluding land use, land use change, and forestry (LULUCF) related emissions, the combined GHG emissions from energy- and agriculture-based activities at the case farm were 47% lower (per unit area) and 12% higher (per unit output), than GHG emissions from Danish agriculture. With current livestock density (0.64 LU ha -1) and crop production area, the case study farm would supply at average 1,466 kcal per inhabitant per day in Denmark, if the farm was scaled up to Danish national level. With a reduction of livestock density to 0.36 LU ha -1 and proportional cropland area expansion for food production ( ceteris paribus), the case study farm could supply around 4,940 kcal person -1 day -1, matching Danish national levels (including Danish net food export surplus of 41.5%). Simultaneously, the case study farm would have a better GHG balance per unit area and unit output in food, compared to the rest of Denmark. Hence, the case study farm system could serve as an alternative model for Danish agriculture under a sustainable extensification scenario with lower GHG emissions, while maintaining sufficient output for human consumption.
  • Authors:
    • Sorensen, P.
    • Petersen, S. O.
    • Li, X. X.
    • Olesen, J. E.
  • Source: AGRICULTURE ECOSYSTEMS & ENVIRONMENT
  • Volume: 199
  • Year: 2015
  • Summary: Legume-based catch crops (LBCCs) may act as an important source of nitrogen (N) in organic crop rotations because of biological N fixation. However, the potential risk of high nitrous oxide (N 2O) emissions needs to be taken into account when including LBCCs in crop rotations. Here, we report the results from a one-year field experiment, which investigated N availability and N 2O emissions as affected by three LBCCs, i.e., red clover (CL), red clover-ryegrass mixture (GC) and winter vetch (WV), two non-LBCCs, i.e., perennial ryegrass (GR) and fodder radish (FR), and a control (CO) without catch crops. The effect of two catch crop management strategies was also tested: autumn harvest of the catch crop versus incorporation of whole-crop residues by spring ploughing. LBCCs accumulated 59-67 kg N ha -1 in their tops, significantly more than those of the non-LBCC, 32-40 kg N ha -1. Macro-roots accounted for >33% of total N in the catch crops. In accordance with this, LBCCs enhanced the performance of the succeeding unfertilised spring barley, thus obtaining a grain yield of 3.3-4.5 Mg ha -1 compared to 2.6-3.3 Mg ha -1 grain yield from non-LBCC and the fallow control treatments. Autumn harvest of catch crops, especially LBCCs, tended to reduce crop yield. The annual N 2O emissions were comparable across treatments except for fodder radish, which had the highest N 2O emission, and also the highest average yield-scaled N 2O emission, at 499 g N 2O-N Mg -1 grain. Although the sampling strategy employed in this study introduces uncertainty about the spatial and temporal variability, differences in seasonal emission patterns among catch crops were captured and harvest of catch crops in late autumn induced significantly higher emissions during winter, but lower emissions after residue incorporation in spring. In comparison with non-LBCC, LBCCs have the potential to partly replace the effect of manure application in organic cropping systems with greater crop production and less environmental footprint with respect to N 2O emissions. However, harvest of the catch crops may reduce crop yield unless the harvested N is recycled as fertiliser to the crops in the rotation.
  • Authors:
    • Fan,T. -T
    • Wang,Y. -J
    • Li,C. -B
    • Zhou,D. -M
    • Friedman,S. P.
  • Source: Soil Science Society of America Journal
  • Volume: 79
  • Issue: 3
  • Year: 2015
  • Summary: Wien effect measurements were used to study the effect of organic matter on the interactions between divalent cations and soil clay particles of two black soil samples containing organic matter (OM) at 54.4 and 12.3 g kg-1 in the top (0-20-cm) and bottom (100-120-cm) horizons, respectively, and a sample of OM-free black soil, all saturated with Cd2+, Cu2+, Pb2+, and with Ca2+ as a reference cation. The weak-field electrical conductivities of suspensions of the top and bottom horizons and OM-free black soil samples were 0.021 to 0.033, 0.011 to 0.021, and 0.0065 to 0.0082 mS cm-1, respectively. The mean free binding energies of the cations in the same soil sample suspensions were 5.5 to 7.3, 7.3 to 9.3, and 9.6 to 10 kJ mol-1, respectively. The mean free adsorption energies of all cations increased with field strength and were in the order OM-free > bottom horizon > top horizon. At field strengths >100 kV cm-1, in the top-horizon soil, the adsorption energies of Ca were 0.21 to 0.72 kJ mol-1, those of Cd and Cu were similar to one another at 0.01 to 0.25 kJ mol-1, and those of Pb were close to zero, while in the bottom horizon soil, the adsorption energies of the various cations were in descending order: Ca > Cd > Pb > Cu, and in the OM-free soil the order of the adsorption energies of the various cations were Cd ˜ Cu ˜ Ca > Pb. The humus basically increased the negative electrokinetic potentials of the clay-size-fraction particles of the three black soil samples saturated with Ca, Cd, Cu, or Pb. © Soil Science Society of America, 5585 Guilford Rd., Madison Wl 53711 USA.
  • Authors:
    • Salahvarzi, Y.
    • Goldani, M.
    • Tehranifar, A.
    • Shour, M.
    • Kamali, M.
  • Source: Journal of Science
  • Volume: 5
  • Issue: 20
  • Year: 2015
  • Summary: High carbon dioxide (CO2) concentration in atmosphere has direct effects on plants activities. In order to investigate the effect of increased CO2 concentration from 380 to 700 and 1050 mg/L on some chemical and physiological characteristics of Amaranthus tricolor under three salinity treatments (0, 150, and 300 mM NaCl), an experiment was conducted in Research Greenhouse of Ferdowsi University of Mashhad, Iran. The results showed that interaction of salinity and CO2 in traits such as total dry weight, electrolyte leakage, relative water content and Na+uptake was significant at 1% probability level. However, interaction of CO2 and salt stress in plant traits such as proline and total carbohydrates did not show any significant difference (p<0.01). The highest relative water content was measured in 700 mg/L CO2 treatment, when the plants were irrigated with distilled water (no salinity stress). Application of 700 and 1050 mg/L CO2 treatments, at the highest salinity level, reduced electrolyte leakage by 26 and 19 percent, respectively, as compared to CO2 control treatment.
  • Authors:
    • Margenot,A. J.
    • Calderón,F. J.
    • Bowles,T. M.
    • Parikh,S. J.
    • Jackson,L. E.
  • Source: Soil Science Society of America Journal
  • Volume: 79
  • Issue: 3
  • Year: 2015
  • Summary: The objectives of this study were to examine soil organic matter (SOM) functional group composition and its relationship to labile SOM fractions with diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). We analyzed soils from 13 organically managed tomato (Solatium lycopersicum) fields in northern California for labile organic C, N, and P fractions and by DRIFTS for bands representing organic functional groups, including aliphatic C-H (2924, 2850, 1470, 1405, 1390 cm-1), aromatic C=C (1650 cm-1) and C-H (920, 840 cm-1), polysaccharide and phenol C-O (1270, 1110, 1080 cm-1), and amine and amide N-H (3400, 1575 cm-1). Significant differences in relative band intensities occurred among the 13 organic tomato fields, in particular a relative increase in absorbance of bands representing aliphatic C-H positively associated with soil organic carbon (SOC), as well as permanganate-oxidizable carbon (POXC), extractable organic carbon (EOC) and nitrogen (EON), and potentially mineralizable N (PMN). In comparison, organic P fractions like sodium bicarbonate extractable (NaHCO3-P0) and sodium hydroxide extractable organic P (NaOH-P0) were poorly associated with SOC and functional groups represented by bands, including aliphatic C-H. This could reflect limitations of DRIFTS, but is consistent with hypotheses of greater decoupling of C and P vs. C and N in soils. This study implicates relative differences in organic functional groups with differences in SOC and labile SOM fractions, and in agreement with previous studies, identifies absorbance of infrared bands representing aliphatic C-H functional groups in these systems as a potential indicator of SOM transformations related to changes in its labile fractions. © Soil Science Society of America, 5585 Guilford Rd., Madison Wl 53711 USA.
  • Authors:
    • Montemurro,Francesco
    • Tittarelli,Fabio
    • Lopedota,Ornella
    • Verrastro,Vincenzo
    • Diacono,Mariangela
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 102
  • Issue: 2
  • Year: 2015
  • Summary: In organic farming, soil application of processed agro-industrial by-products could sustain soil fertility for vegetables, which have short cropping cycles. Therefore, the objectives of this 2-year research on organic spinach crop were to assess the productive performance of different experimental fertilizers, the effects on soil fertility, and investigate the dynamics of some soil properties and the N balance. Two types of olive pomace mixtures, with a different initial C/N ratio, were composted and both stopped at the active phase (A1 and B1) and processed until maturation (A2 and B2). Also an anaerobic digestate (DA), and the B2 applied as amendment (B2A) were studied. The four composts, DA, and B2A were compared with a commercial organic fertilizer (Org), and a control (N0). The Org resulted as not sustainable in maintaining soil fertility in the long-term, mainly due to reduction in the soil of total organic carbon by 32 %, compared to the average of the other treatments. Conversely, choosing stage of maturity and adequate C/N of starting mixtures was among the best practices for compost use in spinach crop. The great content of nutrients (N and K higher by 102 and 86 % than Org, respectively), and N surplus (1431 kg ha(-1)) in the B2A plots would suggest that they could accumulate after subsequent soil applications, with the risk of losses in the environment. The DA appeared to be the most suitable fertilizer to get a favorable trade-off among yield, quality and N-use efficiency, when applied according to best agronomic practices.
  • Authors:
    • Niero,Monia
    • Ingvordsen,Cathrine H.
    • Peltonen-Sainio,Pirjo
    • Jalli,Marja
    • Lyngkjaer,Michael F.
    • Hauschild,Michael Z.
    • Jorgensen,Rikke B.
  • Source: Agricultural Systems
  • Volume: 136
  • Year: 2015
  • Summary: The paper has two main objectives: (i) to assess the eco-efficiency of spring barley cultivation for malting in Denmark in a future changed climate (700 ppm [CO2] and +5 degrees C) through Life Cycle Assessment (LCA) and (ii) to compare alternative future cultivation scenarios, both excluding and including earlier sowing and cultivar selection as measures of adaptation to a changed climate. A baseline scenario describing the current spring barley cultivation in Denmark was defined, and the expected main deviations were identified (differences in pesticide treatment index, modifications in nitrate leaching and change in crop yield). The main input data originate from experiments, where spring barley cultivars were cultivated in a climate phytotron under controlled and manipulated treatments. Effects of changed climate on both crop productivity and crop quality were represented, as well as impacts of predicted extreme events, simulated through a long heat-wave. LCA results showed that the changed climatic conditions will likely increase the negative impacts on the environment from Danish spring barley cultivation, since all environmental impact categories experienced increased impact for all investigated scenarios, except under the very optimistic assumption that the pace of yield improvement by breeding in the future will be the same as it was in the last decades. The main driver of the increased environmental impact was identified as the reduction in crop yield. Therefore, potential adaptation strategies should mainly focus on maintaining or improving crop productivity. The LCA also showed that selection of proper cultivars for future climate conditions including the challenge from extreme events is one of the most effective ways to reduce future environmental impacts of spring barley. Finally, if yield measurements are based on relative protein content, the negative effects of the future climate seem to be reduced. (C) 2015 Elsevier Ltd. 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:
    • Buller,L. S.
    • Bergier,I.
    • Ortega,E.
    • Moraes,A.
    • Bayma-Silva,G.
    • Zanetti,M. R.
  • Source: Agricultural Systems
  • Volume: 137
  • Year: 2015
  • Summary: Greenhouse gas emissions and climate change has been partially attributed to agricultural expansion by deforestation, while the pressure to assure food, fiber and energy for the future generations leads to the intensification of agricultural systems. The transition to more efficient systems is actually considered an important strategy to reduce deforestation and to spare land for other uses, including the recovery of environmental services and ecohydrological processes in the drainage basin such as carbon sink and water regulation. The Brazilian Federal Program for Low Carbon Agriculture (ABC Program) intends to reduce carbon emissions by stimulating technological processes that neutralize emissions or enhance the sinking of greenhouse gases. A pilot farm has been established to assess an intensive animal-plant farming system that incorporates anaerobic digestion for biogas, power generation and organic fertilizer production. Emergy Synthesis was chosen as a methodological tool to assess and to diagnosis the farm system design. The modified emergy assessment including externalities (greenhouse gas emissions) improves the understanding of integrated crop-livestock systems efficiency in internal recycling of nutrients and power conversion. The adoption of manure treatment in intensified agricultural systems can effectively contribute to enhance environmental and economic performances.
  • Authors:
    • Möller,K.
  • Source: Agronomy for Sustainable Development
  • Volume: 35
  • Issue: 3
  • Year: 2015
  • Summary: Sustainability in agriculture means the inclusion of several aspects, as sustainable agriculture systems must not compromise not only their ability to satisfy future needs by undermining soil fertility and the natural resource base but also sustainable agriculture has had to address a range of other issues including energy use, efficient use, and recycling of nutrients, the effects on adjacent ecosystems including the effects on water bodies and climate change. Organic manures are an important factor to keep the soil fertility level of soils. However, their management is often related to large emissions. In this context, anaerobic digestion is—similarly to composting—a treatment option for stabilization of biogenic wastes leading to a residual product called digestates, enabling the sanitation and the recycling and use as fertilizer. It is also a means to obtain energy from wastes as well as from dedicated energy crops. Therefore, anaerobic digestion potentially addresses several aspects of agricultural sustainability. This review discusses the current state of knowledge on the effects of anaerobic digestion on organic compounds in digestates and the most important processes influencing N emissions in the field, as well as the possible long-term effects on soil microbial biomass and soil fertility. The main findings are that (1) the direct effects of anaerobic digestion on long-term sustainability in terms of soil fertility and environmental impact at the field level are of minor relevance. (2) The most relevant effects of anaerobic digestion on soil fertility as well as on N emissions will be expected from indirect effects related to cropping system changes such as changes in crop rotation, crop acreage, cover cropping, and total amounts of organic manures including digestates. Furthermore, (3) the remaining organic fraction after anaerobic digestion is much more recalcitrant than the input feedstocks leading to a stabilization of the organic matter and a lower organic matter degradation rate after field application, enabling a similar reproduction of the soil organic matter as obtained by direct application of the feedstock or by composting of the feedstock. (4) Regarding emissions, the main direct effect of anaerobic digestion on a farm level is the influence on gaseous emissions during manure or digestate treatment and handling, whereas the direct effects of anaerobic digestion on a field level on emissions (NH3− and N2O− emissions, NO3- leaching) are negligible or at least ambiguous. (5) The main direct effects of anaerobic digestion on the field level are short-term effects on soil microbial activity and changes in the soil microbial community. Therefore, in terms of the effects on agricultural sustainability, potential cropping system-based changes induced by introduction of biogas plants are probably much more relevant for the overall performance and sustainability of the cropping system than the direct effects triggered by application of digestates in comparison to the undigested feedstocks. Furthermore, to get the full potential advances from implementation of biogas plants in terms of improvement of the nutrient use efficiency and reduction of greenhouse gas emissions, there is the need to introduce more sophisticated techniques to avoid counteracting effects by pollution swapping, e.g., by gas-tight closure of the digestate stores and direct soil incorporation of the field-applied digestates. © 2015, INRA and Springer-Verlag France.