• Authors:
    • Barbera, V.
    • Poma, I.
    • Gristina, L.
    • Novara, A.
    • Egli, M.
  • Source: Land Degradation & Development
  • Volume: 23
  • Issue: 1
  • Year: 2012
  • Summary: A calcareous and clayey xeric Chromic Haploxerept of a long-term experimental site in Sicily (Italy) was sampled (0-15 cm depth) under different land use management and cropping systems (CSs) to study their effect on soil aggregate stability and organic carbon (SOC). The experimental site had three tillage managements (no till [NT], dual-layer [DL] and conventional tillage [CT]) and two CSs (durum wheat monocropping [W] and durum wheat/faba bean rotation [WB]). The annually sequestered SOC with W was 2.75-times higher than with WB. SOC concentrations were also higher. Both NT and CT management systems were the most effective in SOC sequestration whereas with DL system no C was sequestered. The differences in SOC concentrations between NT and CT were surprisingly small. Cumulative C input of all cropping and tillage systems and the annually sequestered SOC indicated that a steady state occurred at a sequestration rate of 7.4 Mg C ha -1 y -1. Independent of the CSs, most of the SOC was stored in the silt and clay fraction. This fraction had a high N content which is typical for organic matter interacting with minerals. Macroaggregates (>250 m) and large microaggregates (75-250 m) were influenced by the treatments whereas the finest fractions were not. DL reduced the SOC in macroaggregates while NT and CT gave rise to higher SOC contents. In Mediterranean areas with Vertisols, agricultural strategies aimed at increasing the SOC contents should probably consider enhancing the proportion of coarser soil fractions so that, in the short-term, organic C can be accumulated.
  • Authors:
    • Reyneri, A.
  • Source: Informatore Agrario
  • Volume: 68
  • Issue: 17
  • Year: 2012
  • Authors:
    • Jones, J.
    • Porter, C.
    • Orsini, R.
    • Seddaiu, G.
    • Roggero, P.
    • Sanctis, G.
  • Source: European Journal of Agronomy
  • Volume: 40
  • Year: 2012
  • Summary: The differential impact on soil organic carbon (SOC) of applying no tillage (NT) compared to conventional tillage (CT, i.e. mouldboard ploughing), along with three rates of nitrogen (N) fertilizer application (0, 90 and 180 kg ha -1 y -1), was studied under rain-fed Mediterranean conditions in a long-term experiment based on a durum wheat-maize rotation, in which crop residues were left on the soil (NT) or incorporated (CT). Observed SOC content following 8 and 12 years of continuous treatment application was significantly higher in the top 10 cm of the soil under NT than CT, but it was similar in the 10-40 cm layer. NT grain yields for both maize and durum wheat were below those attained under CT (on average 32% and 14% lower respectively) at a given rate of N fertilizer application. Soil, climate and crop data over 5 years were used to calibrate DSSAT model in order to simulate the impact of the different management practices over a 50-year period. Good agreement was obtained between observed and simulated values for crops grain yield, above-ground biomass and observed SOC values. Results from the simulations showed that under NT the weeds growing during the intercrop fallow period made a significant contribution to the observed SOC increase. When the contribution of the weed fallow was considered, NT significantly increased SOC in the top 40 cm of the soil at an average rate of 0.43, 0.31 and 0.03 t ha -1 per year, respectively for 180, 90 and 0 kg N ha -1 year -1, within the simulated 50 years. Under CT, a significant SOC increase was simulated under N180 and a significant decrease when no fertilizer was supplied.
  • Authors:
    • Zegada-Lizarazu, W.
    • Zatta, A.
    • Barbanti, L.
    • Monti, A.
  • Source: Global Change Biology Bioenergy
  • Volume: 4
  • Issue: 4
  • Year: 2012
  • Summary: The contribution of switchgrass (Panicum virgatum L.), a perennial C4 grass, in reducing greenhouse gas (GHG) emissions was reviewed under three main areas; the impact on carbon dioxide (CO2), nitrous oxide (N2O), and methane emissions (CH4), whilst also taking into account the effects of land conversion to switchgrass. Switchgrass is able to enhance biomass accumulation in a wide range of environmental conditions, which is the premise for considerable carbon assimilation and storage in the belowground organs. The progress in some areas of crop husbandry (e.g., tillage and fertilization) has fostered benefits for carbon storage, while restraining GHG emissions. As root biomass is the main indicator of soil carbon sequestration, switchgrass's dense and deep rooting is a relevant advantage, although uncertainty still exists about the crop's belowground biomass accumulation. In agreement with this, most LCA studies addressing CO2 emissions report significant benefits from switchgrass cultivation and processing. Beside CO2, switchgrass performed better than most other biomass crops also in terms of N2O emission. In the case of CH4 emission, it may be argued that switchgrass should act as a moderate sink, i.e., contributing to mitigate CH4 atmospheric concentration, but a substantial lack of information indicates the need for specific research on the topic. Land conversion to switchgrass is the latest issue which needs to be addressed in LCA studies: not surprisingly, the net CO2 abatement appears remarkable if switchgrass is grown in former arable lands, although it is slightly negative to positive if switchgrass replaces permanent grassland. In conclusion, switchgrass could significantly contribute to mitigate GHG emissions, although areas of uncertainty still exist in the assessment of soil carbon storage, N2O and CH4 emissions, and the effects of converting lands to switchgrass. Further improvements must, therefore, be achieved to strengthen the crop's remarkable sustainability.
  • Authors:
    • Cichelli, A.
    • Raggi, A.
    • Pattara, C.
  • Source: Environmental Management
  • Volume: 49
  • Issue: 6
  • Year: 2012
  • Summary: Global warming represents one of the most critical internationally perceived environmental issues. The growing, and increasingly global, wine sector is one of the industries which is under increasing pressure to adopt approaches for environmental assessment and reporting of product-related greenhouse gas emissions. The International Organization for Vine and Wine has recently recognized the need to develop a standard and objective methodology and a related tool for calculating carbon footprint (CF). This study applied this tool to a wine previously analyzed using the life cycle assessment (LCA) methodology. The objective was to test the tool as regards both its potential and possible limitations, and thus to assess its suitability as a standard tool. Despite the tool's user-friendliness, a number of limitations were noted including the lack of accurate baseline data, a partial system boundary and the impossibility of dealing with the multi-functionality issue. When the CF and LCA results are compared in absolute terms, large discrepancies become obvious due to a number of different assumptions, as well as the modeling framework adopted. Nonetheless, in relative terms the results seem to be quite consistent. However, a critical limitation of the CF methodology was its focus on a single issue, which can lead to burden shifting. In conclusion, the study confirmed the need for both further improvement and adaptation to additional contexts and further studies to validate the use of this tool in different companies.
  • Authors:
    • Grignani, C.
    • Sacco, D.
    • Monaco, S.
    • Zavattaro, L.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 147
  • Year: 2012
  • Summary: Maize (Zea mays, L) is not only the main crop in the intensively cultivated Po Plain (Northern Italy), but also the one that produces the largest N Surplus. This study is based on experimental data from the Tetto Frati long-term trial (Turin, NW Italy) to demonstrate that the impact on soil and water quality of high-yielding, maize-based cropping systems can be reduced through proper management. Nitrogen use efficiency and loss indicators were calculated and compared among various management options: (i) maize monoculture at high N fertilizer rates for grain production (most widespread management), (ii) entire plant (with straw) harvest, (iii) double-cropping system with a winter crop, (iv) maize-grass ley rotation, and (v) change in fertilizer type. The entire maize plant removal reduced N leaching by 10-20%; however, carbon sequestration was also reduced. A maize-Italian ryegrass double cropping system improved the efficiency of organic fertilizers, and reduced leaching by 25-40% relative to monoculture. A rotation with grass ley reduced N impact only when fertilized with urea, and not when organic fertilizers were used. Urea, slurry, and farmyard manure were equally utilized by the crop; if distributed and incorporated just before sowing, both organic fertilizers built up the soil organic matter content and reduced N leaching by 20-50% with respect to urea. This study has shown that farmers in NW Italy have several opportunities to continue cultivate maize thus accomplishing agri-environmental legislation.
  • Authors:
    • Saia, S.
    • Frenda, A. S.
    • Miceli, G. di
    • Giambalvo, D.
    • Ruisi, P.
    • Amato, G.
  • Source: Agronomy Journal
  • Volume: 104
  • Issue: 5
  • Year: 2012
  • Summary: The no-tillage (NT) technique represents a valuable alternative to conventional tillage (CT) for many crops, but little research has evaluated the effects of its use on the performance of grain legumes, particularly in Mediterranean regions. The present study assessed the effects of NT compared with CT on the grain yield and N 2 fixation of chickpea ( Cicer arietinum L.), faba bean ( Vicia faba L. variety minor), pea ( Pisum sativum L.), and lentil ( Lens culinaris Medik.). The experiment was performed under rainfed conditions during four growing seasons. Nitrogen fixation was estimated using the 15N isotope dilution technique. The response of the four species to the tillage system varied significantly by year. The grain yield was significantly higher under NT than under CT only for pea and chickpea, but the differences between the two tillage techniques were consistent only when rainfall was very scarce. The percentage of N fixed differed by species in the order faba bean > chickpea > pea > lentil. The effects of tillage on the N 2 fixation process varied significantly by species and year. Nitrogen balance was positive for faba bean and lentil and negative for chickpea and pea, with no differences by tillage. The results indicate that in cereal-dominated Mediterranean agro-ecosystems NT can be a valuable option for producing grain legumes, as it can improve productivity, particularly under conditions of deficient soil moisture.
  • Authors:
    • Chidthaisong, A.
    • Lu, Y.
    • Yuan, Q.
    • Klose, M.
    • Conrad, R.
  • Source: Soil Biology and Biochemistry
  • Volume: 49
  • Issue: June
  • Year: 2012
  • Summary: Straw amendment is a common practice for improving the fertility of rice field soils, but it also enhances production of the greenhouse gas methane. To quantify carbon flux partitioning and priming effects due to straw amendment, we measured delta C-13 in CH4 and CH4 precursors produced in anoxic slurries of soil from Italy, China and Thailand after addition of straw from either rice (C3 plant) or maize plants (C4 plant), which have different delta C-13 signatures. The delta C-13 values of the CH4, acetate and CO2 produced were similar when expressed as the difference to the delta C-13 value of the straw applied. These results indicated that the C-13-isotopic fractionation involved in methanogenic decomposition was similar for rice straw and maize straw. However, measurement of CH4 produced in soil without or with straw showed that isotopic fractionation during methanogenic degradation of straw was smaller than during degradation of soil organic matter. Isotopic fractionation during hydrogenotrophic methanogenesis, measured in the presence of methyl fluoride, with straw was also smaller than with soil organic matter. The results show that C-13-isotopic analysis after application of rice straw and maize straw is a convenient approach for quantifying carbon flux partitioning during methanogenic degradation of straw and soil organic matter. In our experiments, straw degradation accounted for most of the CH4 production and caused a negative priming effect on the methanogenic degradation of soil organic matter. (c) 2012 Elsevier Ltd. All rights reserved.
  • Authors:
    • Zegada-Lizarazu, W.
    • Walter, K.
    • Valentine, J.
    • Djomo, S. Njakou
    • Monti, A.
    • Mander, U.
    • Lanigan, G. J.
    • Jones, M. B.
    • Hyvonen, N.
    • Freibauer, A.
    • Flessa, H.
    • Drewer, J.
    • Carter, M. S.
    • Skiba, U.
    • Hastings, A.
    • Osborne, B.
    • Don, A.
    • Zenone, T.
  • Source: GCB Bioenergy
  • Volume: 4
  • Issue: 4
  • Year: 2012
  • Summary: Bioenergy from crops is expected to make a considerable contribution to climate change mitigation. However, bioenergy is not necessarily carbon neutral because emissions of CO2, N2O and CH4 during crop production may reduce or completely counterbalance CO2 savings of the substituted fossil fuels. These greenhouse gases (GHGs) need to be included into the carbon footprint calculation of different bioenergy crops under a range of soil conditions and management practices. This review compiles existing knowledge on agronomic and environmental constraints and GHG balances of the major European bioenergy crops, although it focuses on dedicated perennial crops such as Miscanthus and short rotation coppice species. Such second-generation crops account for only 3% of the current European bioenergy production, but field data suggest they emit 40% to >99% less N2O than conventional annual crops. This is a result of lower fertilizer requirements as well as a higher N-use efficiency, due to effective N-recycling. Perennial energy crops have the potential to sequester additional carbon in soil biomass if established on former cropland (0.44 Mg soil C ha(-1) yr(-1) for poplar and willow and 0.66 Mg soil C ha(-1) yr(-1) for Miscanthus). However, there was no positive or even negative effects on the C balance if energy crops are established on former grassland. Increased bioenergy production may also result in direct and indirect land-use changes with potential high C losses when native vegetation is converted to annual crops. Although dedicated perennial energy crops have a high potential to improve the GHG balance of bioenergy production, several agronomic and economic constraints still have to be overcome.
  • Authors:
    • Mancinelli, R.
    • Radicetti, E.
    • Campiglia, E.
  • Source: Crop Protection
  • Volume: 33
  • Year: 2012
  • Summary: Organic mulches could be a part of a wide strategy of integrated weed management in vegetable production systems. A 2-year field experiment was carried out in Central Italy with the aim of assessing the effect of grass and legume mulches, coming from winter cover crops, combined with herbicide or mechanical hoeing on weed control, on weed community (density and aboveground biomass of each species), and yield of a pepper crop. Hairy vetch (Vicia villosa Roth), oat (Avena sativa L) and their mixture were sown in early autumn and suppressed in May. The cover crop aboveground biomass was cut and arranged in strips which were used as beds for pepper seedlings transplanted in paired rows. A conventional treatment kept bare during the cover crop growing season with two different levels of nitrogen fertilizer on pepper (0-100 kg ha(-1) of N) was also included. Three weed control treatments were applied between the paired pepper rows 30 days after transplanting: a weed free treatment, glyphosate or mechanical hoeing. Dry matter production at cover crop suppression ranged from 5.3 t ha(-1) in oat to 7.1 t ha(-1) in hairy vetch/oat mixture and the N accumulation ranged from 56 kg ha(-1) in oat to 179 kg ha(-1) in hairy vetch. Within the pepper paired rows, mulch treatments reduced weed density and biomass throughout the pepper cropping season. At harvest, weed density and aboveground biomass within the pepper paired rows ranged from 1.7 to 4.6 plants m(-2) and 28 and 133 gm(-2) of DM, respectively. Oat mulch had the highest weed suppression ability and the lowest species richness. Shannon's index and Shannon evenness. Between the pepper paired rows the mulch treatments had the highest species richness and the most diverse weed community in chemical compared to mechanical weed control. The densities of Portulaca oleracea L and Polygonum aviculare L. were the highest under chemical and mechanical control, respectively. The weeds did not hinder pepper production in hairy vetch and hairy vetch/oat mixture where the yield was similar to that obtained in a conventional weedfree system fertilized with 100 kg ha(-1) of N. Therefore the use of hairy vetch mulches in combination with reduced mechanical or chemical weed control could be a feasible strategy in order to control weeds and to produce high yields in a pepper crop. (C) 2011 Elsevier Ltd. All rights reserved.