• Authors:
    • Verhoeven, E.
    • Six, J.
  • Source: Agriculture Ecosystems and Environment
  • Volume: 191
  • Year: 2014
  • Summary: Biochar amendment to soil has been proposed as a mechanism to mitigate climate change through an array of mechanisms; one being the mitigation of soil nitrous oxide (N 2O) emissions. Yet the extent and mechanisms through which this may be achieved in temperate agroecosystems is uncertain. We used a pine chip biochar produced at a moderate temperature (550°C, PC biochar) and a walnut shell biochar produced at a higher temperature (900°C, WS biochar). Biochar was applied at 10 Mg ha -1 to a working commercial wine grape system in North-Central California. The effects of biochar were assessed over two years at two distinct functional locations: the berm and row, which differed in N application and irrigation. N 2O emissions and ancillary soil properties (NH 4+, NO 3, water filled pore space (WFPS), and pH) were closely monitored following management and precipitation events. Soil bulk density, cover crop yield and soil C and N were measured annually to address longer term changes in cropping system and soil properties. In the PC biochar treatment, annual cumulative N 2O emissions were significantly higher than the control treatment each year ( p<0.05); 4.141.14 kg N 2O-N ha -1 yr -1 versus 2.000.66 kg N 2O-N ha -1 yr -1 in year one, and 4.240.74 kg N 2O-N ha -1 yr -1 versus 1.600.28 kg N 2O-N ha -1 yr -1 in year two. Emissions of N 2O in the WS biochar treatment were also higher than the control each year, but differences were not significant. The effect of biochar on N 2O emissions was more pronounced in the row location where annual emissions were significantly higher than the control in one and both years for the WS and PC biochars, respectively ( p<0.05). In the PC biochar treatment, we observed increased N 2O emissions at both functional locations, however increases were more pronounced in the row location where they were in part attributable to increased cover crop N inputs. Differences between treatments in NH 4+, NO 3- and WFPS were mostly not significant. The WS biochar significantly raised soil pH relative to the control ( p<0.05), however in the berm location only, and increased soil pH in this treatment did not correspond to changes in N 2O emissions. Since neither biochar amendment reduced N 2O emissions, our results demonstrate the need to evaluate N 2O emissions at a cropping system scale (e.g. encompassing changes in N inputs and cycling) and in systems where nitrification processes may dominate emissions.
  • Authors:
    • Horwath, W. R.
    • Burger, M.
    • Suddick, E.
    • Garland, G. M.
    • Six, J.
  • Source: AGRICULTURE ECOSYSTEMS & ENVIRONMENT
  • Volume: 195
  • Year: 2014
  • Summary: It is well known that agricultural production contributes to global warming through the release of greenhouse gases CO2, N2O, and CH4, the most potent of which is N2O. However, most N2O emission studies focus on intensively managed, annual cropping systems. Few have documented greenhouse gas production in perennial crops, which often have substantially different agricultural management practices and growth patterns compared to annual crops. Hence, the objectives of this study were to (1) quantify seasonal and annual direct N2O emissions from a Mediterranean vineyard and (2) determine how conventional management practices such as irrigation, fertigation, cover cropping and tillage affect the magnitude and duration of N2O emissions. This study took place in a wine grape vineyard (Vitis vinifera)in Arbuckle, CA over a two-year period using closed-flux chamber measurements. Annual emissions totaled 3.92 kg N2O-N ha(-1) the first year, when a leguminous cover crop was planted in the alleys, while emissions in the second year when the alleys were fallow showed a 7-fold reduction, reaching only 0.56 kg N2O-N ha(-1). During the growing season of both years, fertigation events in the crop rows produced slightly increased emissions, ranging from 11 to 23 g N2O-N ha(-1) day(-1) and lasting less than one week, compared to the low background values of 0.5 g N2O-N ha(-1) day(-1). The largest fluxes occurred during the dormant season in response to the first precipitation event of the year, especially in the alleys. Nitrous oxide emissions following precipitation events in the second year, when the alleys were fallow, did not follow the same pattern, indicating the significant influence of cover crop-derived N (and C), when coupled with precipitation events, on annual N2O emissions. The results of this study indicate that the effects of individual management practices such as cover cropping may not be seen immediately, but instead act in sequence with other events when conditions are favorable for N2O production. Hence, when determining specific management practices to employ, it is important to recognize the interaction between management, climatic events, and time as important drivers in total N2O production.
  • Authors:
    • Moreno, J. L.
    • Chocano, C.
    • Hernandez, T.
    • Garcia, C.
  • Source: AGRICULTURE ECOSYSTEMS & ENVIRONMENT
  • Volume: 196
  • Year: 2014
  • Summary: The feasibility of using combined organic and inorganic fertilizers as an alternative to conventional inorganic fertilization was tested for tomato crops. To do this, two different composts (compost from a mixture of cow manure+alperujo+olive prunings and compost from sheep and goat manure) were added to an agricultural soil either, alone or along with inorganic fertilization, for tomato cultivation in greenhouse conditions. Conventional inorganic fertilization was used as reference. When used alone, the organic fertilizers led to lower N concentrations in leaves and fruits than the conventional inorganic fertilization. The combined use of compost and inorganic fertilizer, however, produced higher yields and better fruit quality than soils that underwent the respective inorganic treatment when used alone. In addition, soils with combined fertilization showed higher values of microbial biomass C, basal respiration and dehydrogenase activity than the respective inorganic treatment. The conjunctive use of compost and inorganic fertilizer made it possible to reduce inorganic fertilization by about 40% while obtaining similar fruit quality and amounts in addition to improving soil characteristics.
  • Authors:
    • de Cortazar-Atauri,I. G.
    • Huard, F.
    • Bourgeois, G.
    • Caubel, J.
    • Launay, M.
    • Bancal, M. O.
    • Brisson, N.
  • Source: AGRICULTURE ECOSYSTEMS & ENVIRONMENT
  • Volume: 197
  • Year: 2014
  • Summary: Since weather has a major influence on the occurrence and development of crop diseases, valuable insight toward future agricultural planning emerges with assessment tools to evaluate fungal disease pressure and crop regional suitability under projected future climatic conditions. The aim of this study was to develop two climatic indicators, the average infection efficiency (AIE) and the number of infection days (NID), to quantify the potential effects of weather on the intensity and occurrence of pathogen infection. First, a simple and continuous infection function accounting for daily temperature and leaf wetness duration variations was implemented. The function was then parameterized from published data sets for five major contrasting fungal diseases affecting crops in Northern France: phoma of oilseed rape, late blight of potato, downy mildew of grape, leaf rust of wheat and net blotch of barley. Finally, AIE and NID were calculated for the recent past (1970-2000) and the future A1B climate scenario (2070-2100). An overall decrease in the risk of infection was shown for potato late blight and downy mildew of grapevine for all months during the period when the host plant is susceptible to infection. There were greater differences for the other three diseases, depending on the balance between warmer temperatures and lower humidity. The future climate would result in a later onset of disease and higher infection pressure in late autumn. In spring, for brown rust of wheat and net blotch of barley, the climatic risk for infection is expected to occur earlier but would result in lower infection pressure in May. These findings highlighted the need to use an infra-annual (monthly or seasonally) scale to achieve a relevant analysis of the impact of climate change on the infection risk. The described indicators can easily be adapted to other pathogens and may be useful for agricultural planning at the regional scale and in the medium term, when decision support tools are required to anticipate future trends and the associated risks of crop diseases.
  • Authors:
    • Esmaeili, A.
    • Kumar, L.
    • Shabani, F.
  • Source: AGRICULTURE ECOSYSTEMS & ENVIRONMENT
  • Volume: 197
  • Year: 2014
  • Summary: The levels of inaccuracy in projections of global climate model outputs can be reduced by identification of the correlations between the output results of a number of models, which include common assumptions. Some of the invasive pathogen of Fusarium oxysporum f. spp. pose risks to a number of cash crops such as banana, tomato, palm and garlic while some have a symbiotic relation varying from pathogenic to commensal (null effect), up to beneficial effect. Limitation of occurrence records of many single species such as F. oxysporum f. sp. cubense, F. oxysporum f. sp. albedinis, F. oxysporum f. sp. lycopersici and F. oxysporum f. sp. vasinfectum necessitated this study to model the future distribution of F. oxysporum f. spp. rather than individual species. The future distribution of F. oxysporum f. spp. was modeled by CSIRO-Mk3.0 (CS) and MIROC-H (MR) GCMs, and the results were correlated to identify areas suitable for F. oxysporum f. spp. growth for North Africa, Middle Eastern and European countries for the years 2050 and 2100. The projections established that a number of countries will become highly conducive to this fungus, while others are projected to produce marginal levels of conduciveness by 2050 and 2100. We also demonstrate that refining CLIMEX outputs with a combination of a number of alternative GCMs results ensures that modeled projections become more robust, rather than producing purely hypothetical findings.
  • Authors:
    • Kamgar-Haghighi, A. A.
    • Shekafandeh, A.
    • Assar, P.
  • Source: International Journal of Agriculture and Biosciences
  • Volume: 3
  • Issue: 6
  • Year: 2014
  • Summary: Water stress induced by consecutive years of drought constitutes a major constraint for citric culture in Fars province in Iran. The aim of this study was rapid and accurate screening of citrus seedling rootstocks (grown under greenhouse conditions) in terms of drought tolerance and ability to recovery, using chlorophyll fluorescence technique combined with measuring the leaf gas exchange parameters. Eight month-old seedlings of Mexican lime, sour orange, Volkameriana and Rangpur lime plants were submitted to a cycle of drought for 14 days/rewatering for 3 days and control plants were maintained in an optimal soil water condition during the whole experimental period. At the end of stress and recovery periods, measurements were made using fully developed leaves. According to F v/F m ratio index, treated Volkameriana plants had no significant photoinhibitory damage to PS II. Rewatered Mexican lime and Rangpur lime plants had ability to fully recover the significantly reduced fluorescence index, but in sour oranges, full recovery did not happened. Also, our results indicated that the rate of net photosynthesis ( A), transpiration ( E) and stomatal conductance ( gs) significantly reduced under drought stress, only Volkameriana and Mexican lime plants fully recovered from stress. Increased Ci in concomitant with stomata closure means a reduction in CO 2 photoassimilation and is a symptom of photoinhibition (in addition to decreased F v/F m ratio, maximum quantum yield of PS II). So, it seemed that at the end of drought period, except for Volkameriana, stomatal limitation combined with PS II photodestruction were responsible to significant reductions in net photosynthesis in treated plants. In other words, in stressed Volkameriana plants only stomatal closure caused the reduction in photosynthesis. Also it was demonstrated that in rewatered sour orange and Rangpur lime plants damage imposed to PS II and lack of recovery in stomatal conductance were major obstructions in photosynthesis recovery, respectively. Finally, it was concluded that Volkameriana seedlings were more tolerant and had better recovery ability and Mexican lime plants had profound ability to recover from imposed negative effects of water stress, too.
  • Authors:
    • Ridhima Gupta
  • Source: Climate Change Economics
  • Volume: 5
  • Issue: 4
  • Year: 2014
  • Summary: Biomass burning in South Asia is a significant contributor to global emissions of black carbon, the second most important greenhouse agent after carbon dioxide. Emissions from domestic fires are the largest contributor to biomass burning but may be costly to mitigate. Open-field burning is the second-largest contributor to black carbon in South Asia. This study uses primary field data to identify the determinants of emissions from open-field burning of crop residue with the aim of analyzing possibilities for its regulation. The effectiveness of a new seeding machine that lets farmers plant their crops without having to burn the residue from the previous crop is assessed. A comparison of the new machine with conventional practice shows that the new technology decreases field preparation costs but does not significantly impact crop yield and profits. The use of plot-level data with farmer fixed effects enables reliable identification of the impacts of the technology. Given the considerable adverse effects on mortality and health of pollution from burning, these results imply that this source of black carbon can be mitigated at zero private cost and negative social cost. Since farmers have no strong private incentive to adopt the new technology, extension, and subsidies to accelerate adoption would be a high net-benefit policy.
  • Authors:
    • Peter,C.
    • Fiore,A.
    • Nendel,C.
    • Xiloyannis,C.
  • Year: 2014
  • Summary: In this paper, we discuss different methods to calculate greenhouse gas field emissions from fertilization and soil carbon changes to be integrated into Carbon Footprint (CFP) of food and biomass products. At regional level, the simple Tier 1 approach proposed in the IPCC (2006a) AFOLU guidelines is often insufficient to account for emission variability which depends on soil type, climate or crop management. However, the extensive data collection required by Tier 2 and 3 approaches is usually considered too complex and time consuming to be practicable in Life Cycle Assessment. We present four case studies to compare Tier 1 with medium-effort Tier 2 and 3 methodologies. Relevant differences were found: for annual crops, a higher Tier approach seems more appropriate to calculate fertilizer-induced field emissions, while for perennial crops the impact on CFP was negligible. To calculate emissions related to soil carbon change higher Tiers are always more appropriate.
  • Authors:
    • Torres,C. M.
    • Anton,A.
    • Castells,F.
  • Source: Proceedings of the 9th International Conference on Life Cycle Assessment in the Agri-Food Sector (LCA Food 2014)
  • Year: 2014
  • Summary: Certain complexities in the agricultural production differentiate this sector from the conventional industrial processes. The main feature to take into account is that the resources consumption and production is subjected to high variability in soil, rainfall and latitude. We show here an environmental tool developed in close cooperation with farmers in order to achieve applicability and comprehensibility. The procedure relies on the data retrieved from parcel management monitoring of different crops, mostly allocated in Catalonia and Ebro river watershed region (NE Spain). A set of comprehensive but also simple reports are provided, including material and energy balances, agronomic efficiencies and water and carbon footprints. The calculations also cover impacts due to infrastructure, including the estimation of materials in the use of greenhouses. Besides, a simple algorithm for reporting uncertainty using an approximation method of error propagation was added using the input uncertainties as defined by their data pedigree.
  • Authors:
    • Goge,Fabien
    • Gomez,Cecile
    • Jolivet,Claudy
    • Joffre,Richard
  • Source: Geoderma
  • Volume: 213
  • Year: 2014
  • Summary: Numerous studies on the prediction of soil properties from visible and near-infrared spectroscopy, based on large libraries at county scale or small size soil libraries at local scales have been reported in literature. However, difficulties appear when large libraries are used to estimate the soil properties of a small area. The aim of this paper was to compare various strategies to predict soil properties of local samples using a French national database. Models were built: i) from the national database alone and ii) from the national database spiked with subsets of the local database. Two regression methods were tested: partial least square [PLS] and a local regression method (fast Fourier transform local weighted [FFT-LW]). No general rule was obtained in this study as the best strategy differed according to the property under study. It seems that when strong spectral features are related to the characteristic under study (as for CaCO3 content), the addition of local samples did not bring a decisive advantage over calibration based on a wide national database. There are three important and encouraging points of this work to emphasize: i) the evidence of the added value brought by the national library for the prediction of some soil properties over a local area, ii) the pertinence of spiking with local samples to the global database to reach accurate predictions, and iii) the interest of the FFT-LW non-linear method. As we examined only one local site with peculiar land-use and geologic characteristics, further researches are needed to elucidate the way in which these results depend on intrinsic properties of the local site samples and on the relationship between spectral features and considered soil properties. (C) 2013 Elsevier B.V. All rights reserved.