• Authors:
    • Priesack, E.
    • Palosuo, T.
    • Osborne, T. M.
    • Olesen, J. E.
    • O'Leary, G.
    • Nendel, C.
    • Kumar, S. Naresh
    • Mueller, C.
    • Kersebaum, K. C.
    • Izaurralde, R. C.
    • Ingwersen, J.
    • Hunt, L. A.
    • Hooker, J.
    • Heng, L.
    • Grant, R.
    • Goldberg, R.
    • Gayler, S.
    • Doltra, J.
    • Challinor, A. J.
    • Biernath, C.
    • Bertuzzi, P.
    • Angulo, C.
    • Aggarwal, P. K.
    • Martre, P.
    • Basso, B.
    • Brisson, N.
    • Cammarano, D.
    • Rotter, R. P.
    • Thorburn, P. J.
    • Boote, K. J.
    • Ruane, A. C.
    • Hatfield, J. L.
    • Jones, J. W.
    • Rosenzweig, C.
    • Ewert, F.
    • Asseng, S.
    • Ripoche, D.
    • Semenov, M. A.
    • Shcherbak, I.
    • Steduto, P.
    • Stoeckle, C.
    • Stratonovitch, P.
    • Streck, T.
    • Supit, I.
    • Tao, F.
    • Travasso, M.
    • Waha, K.
    • Wallach, D.
    • White, J. W.
    • Williams, J. R.
    • Wolf, J.
  • Source: Nature Climate Change
  • Volume: 3
  • Issue: 9
  • Year: 2013
  • Summary: Projections of climate change impacts on crop yields are inherently uncertain(1). Uncertainty is often quantified when projecting future greenhouse gas emissions and their influence on climate(2). However, multi-model uncertainty analysis of crop responses to climate change is rare because systematic and objective comparisons among process-based crop simulation models(1,3) are difficult(4). Here we present the largest standardized model intercomparison for climate change impacts so far. We found that individual crop models are able to simulate measured wheat grain yields accurately under a range of environments, particularly if the input information is sufficient. However, simulated climate change impacts vary across models owing to differences in model structures and parameter values. A greater proportion of the uncertainty in climate change impact projections was due to variations among crop models than to variations among downscaled general circulation models. Uncertainties in simulated impacts increased with CO2 concentrations and associated warming. These impact uncertainties can be reduced by improving temperature and CO2 relationships in models and better quantified through use of multi-model ensembles. Less uncertainty in describing how climate change may affect agricultural productivity will aid adaptation strategy development and policy making.
  • Authors:
    • Lonergan, V. E.
    • Andersson, K. O.
    • Rawson, A.
    • Murphy, B. M.
    • Simmons, A. T.
    • Badgery, W. B.
    • van de Ven, R.
  • Source: Soil Research
  • Volume: 51
  • Issue: 7-8
  • Year: 2013
  • Summary: The potential to change agricultural land use to increase soil carbon stocks has been proposed as a mechanism to offset greenhouse gas emissions. To estimate the potential carbon storage in the soil from regional surveys it is important to understand the influence of environmental variables (climate, soil type, and landscape) before land management can be assessed. A survey was done of 354 sites to determine soil organic carbon stock (SOC stock; Mg C/ha) across the Lachlan and Macquarie catchments of New South Wales, Australia. The influences of climate, soil physical and chemical properties, landscape position, and 10 years of land management information were assessed. The environmental variables described most of the regional variation compared with management. The strongest influence on SOC stock at 0-10cm was from climatic variables, particularly 30-year average annual rainfall. At a soil depth of 20-30cm, the proportion of silica (SiO2) determined by mid-infrared spectra (Si-MIR) had a negative relationship with SOC stock, and sand and clay measured by particle size analysis also showed strong relationships at sites where measured. Of the difference in SOC stock explained by land use, cropping had lower soil carbon than pasture in rotation or permanent pasture at 0-10cm. This relationship was consistent across a rainfall gradient, but once soil carbon was standardized per mm of average annual rainfall, there was a greater difference between cropping and permanent pasture with increasing Si-MIR in soils. Land use is also regulated by climate, topography, and soil type, and the effect on SOC stock is better assessed in smaller land-management units to remove some variability due to climate and soil.
  • Authors:
    • Lloveras, J.
    • Santiveri, F.
    • Biau, A.
  • Source: Agronomy Journal
  • Volume: 105
  • Issue: 5
  • Year: 2013
  • Summary: The incorporation of crop stover into the soil improves soil fertility and crop productivity by increasing C sequestration and reducing the emission of greenhouse gases among other parameters. Interactions between crop stover management and N fertilization could help to improve C sequestration while increasing productivity. The objective of this study was to evaluate the impact of incorporating or removing corn (Zea mays L.) stover, in combination with different N fertilization rates (0, 100, 200, and 300 kg N ha(-1)), on corn production, soil organic carbon (SOC), and soil mineral nitrogen (SMN) in high production areas. We performed two field experiments (Exp. 1 and 2) for 3 yr under sprinkler irrigation. Over the duration of the experiment (short-term period), stover management did not affect corn production or SMN levels, while high average grain yields were achieved (16-20 Mg ha(-1)) when N was applied. After 3 yr, removing the stover reduced SOC levels by approximately 0.82 and 1.06 g C m(-2) (0-30-cm depth) in 2012 in Exp. 1 and 2, respectively. The amounts of corn stover incorporated were higher than 16 Mg ha(-1) yr(-1) of dry matter. Our data suggest that returning stover to the soil has a positive short-term impact on soil quality without grain yield penalties. Although selling the stover provides a short-term economic advantage, continuous stover removal may cause significant soil degradation in the future.
  • Authors:
    • Masters, B.
    • Crimp, S.
    • Thorburn, P. J.
    • Biggs, J. S.
    • Attard, S. J.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 180
  • Year: 2013
  • Summary: Nitrogen (N) lost from cropping is one of the major threats to the health of the Great Barrier Reef (GBR) in northern Australia, and there are government initiatives to change farming practices and reduce N losses from farms. Sugarcane is the dominant crop in most catchments draining into the GBR lagoon, especially those of the Mackay Whitsunday region (8400 km(2)) where sugarcane represents >99% of cropping in the catchments, and is grown with large applications of N fertiliser. As farmers and farming systems adapt to a future requiring lower environmental impact, the question arises whether climate change may influence the effectiveness of these changes, an issue rarely considered in past water quality studies. To address this question we used the APSIM farming-systems model to investigate the complex interactions between a factorial of five proposed sugarcane management systems, three soil types, three sub-regional climatic locations and four climate change projections (weak, moderate and strong, with historical climate as a 'control'). These projections, developed from general circulation models and greenhouse gas emission scenarios, estimated that median annual rainfall would be reduced by up to 19%, and maximum and minimum temperatures increased by up to 0.5 degrees C and 0.6 degrees C, respectively. Management practices, such as tillage, fallow management and N inputs, were grouped into five systems according to the perceived benefits to water quality. For example; Management System A grouped together zero tillage, soybean rotation crops, reduced N inputs and controlled traffic practices. While at the other end of the scale, System E included many severe tillage operations, bare fallows, high N inputs and conventional row spacing; practices that are still used in some areas. Importantly, this study parameterised controlled traffic systems, which is considered an important component of 'best' management in the GBR catchment, but for which water quality benefits have yet to be widely quantified. The study predicted that the improvement in farm management needed to meet water quality improvement goals will not be greatly affected by climate change. However, without any interventions, the frequency of years with very high N losses, and hence extreme ecological risk, was predicted to increase by up to 10-15%. Compared with traditional practices, improved management systems were predicted to reduce N losses by up to 66% during these years. The results support continued adoption of improved management systems to achieve proposed water quality targets in both the current and a range of potential future climates. However, there are important uncertainties about the effects of elevated atmospheric CO2 concentration on plant assimilation rates and the characterisation of extreme climate events that deserve further study.
  • Authors:
    • Yilmaz, G.
    • Bilgili, A. V.
    • Ikinci, A.
  • Source: Turkish Journal of Agriculture & Forestry
  • Volume: 37
  • Issue: 6
  • Year: 2013
  • Summary: Broad interest in reducing greenhouse gas emissions requires a better understanding of controls on carbon dioxide (CO2) release under different agricultural management practices. The objective of this study was to investigate and model seasonal variation of soil CO2 emissions from an apple orchard field (Malus domestica L. 'Starkrimson'). Soil CO2 emissions from an apple orchard managed with common practices were measured weekly over a 3-year period (May 2008 to May 2011) from both under the crowns of trees (CO2-UC) and between rows (CO2-BR) using a soda lime technique and were modeled using available environmental data. The study area is located in the Harran Plain of southeastern Turkey and has a semiarid climate. The weekly soil CO2 emissions ranged from 87.8 to 1428 kg week(-1) ha(-1), from 74.6 to 835 kg week(-1) ha(-1), and from 88.6 to 1087 kg week(-1) ha(-1) for CO2-UC, CO2-BR, and the average of both (CO2-AVG), respectively, and showed a pronounced seasonal pattern with the lowest emissions in winter (January and February) and the highest emissions during the growing season (April to December). Relative to 2008 emissions, 2009 CO2 emissions increased by approximately 75%, and 2010 emissions increased by approximately 88%. Comparison of 3 models (multiple linear regression, principal component regression, and multivariate adaptive regression splines) showed that multivariate adaptive regression splines provided the best performance in modeling soil CO2 emissions, explaining overall variation of 64%, 56%, 76%, and 53% in CO2-AVG for the first, second, third, and all three 3 periods, respectively. In conclusion, overall findings showed that soil CO2 emissions could be modeled by available environmental data such as air and soil temperature.
  • Authors:
    • Bonari, E.
    • Massai, R.
    • Remorini, D.
    • Galli, M.
    • Di Bene, C.
    • Bosco, S.
  • Source: The International Journal of Life Cycle Assessment
  • Volume: 18
  • Issue: 5
  • Year: 2013
  • Summary: Concerns about global warming led to the calculation of the carbon footprint (CF) left by human activities. The agricultural sector is a significant source of greenhouse gas (GHG) emissions, though cropland soils can also act as sinks. So far, most LCA studies on agricultural products have not considered changes in soil organic matter (SOM). This paper aimed to: (1) integrate the H,nin-Dupuis SOM model into the CF study and (2) outline the impacts of different vineyard soil management scenarios on the overall CF. A representative wine chain in the Maremma Rural District, Tuscany (Italy), made up of a cooperative winery and nine of its associated farms, was selected to investigate the production of a non-aged, high-quality red wine. The system boundary was established from vineyard planting to waste management after use. The functional unit (FU) chosen for this study was a 0.75-L bottle of wine, and all data refer to the year 2009. The SOM balance, based on H,nin-Dupuis' equation, was integrated and run using GaBi4 software. A sensitivity analysis was performed, and four scenarios were developed to assess the impact of vineyard soil management types with decreasing levels of organic matter inputs. SOM accounting reduced the overall CF of one wine bottle from 0.663 to 0.531 kg CO2-eq/FU. The vineyard planting sub-phase produced a loss of SOM while, in the pre-production and production sub-phases, the loss/accumulation of SOM was related to the soil management practices. On average, soil management in the production sub-phase led to a net accumulation of SOM, and the overall vineyard phase was a sink of CO2. Residue incorporation and grassing were identified as the main factors affecting changes in SOM in vineyard soils. Our results showed that incorporating SOM accounting into the wine chain's CF analysis changed the vineyard phase from a GHG source to a modest net GHG sink. These results highlighted the need to include soil C dynamics in the CF of the agricultural product. Here, the SOM balance method proposed was sensitive to changes in management practices and was site specific. Moreover, we were also able to define a minimum data set for SOM accounting. The EU recognises soil carbon sequestration as one of the major European strategies for mitigation. However, specific measures have yet to be included in the CAP 2020. It would be desirable to include soil in the new ISO 14067-Carbon Footprint of Products.
  • Authors:
    • Ahmad, W.
    • Biswas, W. K.
    • Engelbrecht, D.
  • Source: Journal of Cleaner Production
  • Volume: 57
  • Year: 2013
  • Summary: The International Panel on Climate Change (IPCC) predicts an increase of 0.2 degrees C per decade for the next two decades in global temperatures and a rise of between 1.5 and 4.5 degrees C by the year 2100. Related to the increase in world temperatures is the increase in Greenhouse Gases (GHGs) which are primarily made up of carbon dioxide (CO2), nitrous oxide (N2O), methane (CH4) and fluorinated gases. In 2004, the GHGs from agriculture contributed 14% of the overall global GHGs made up mainly of methane (CH4) and nitrous oxide (N2O) emissions. In Australia, the dominant source of CH4 and N2O emissions for the year ending June 2012 was found to be from the agricultural sector. With the recent introduction of the Clean Energy Act 2011, the agricultural sector of Australia is expected to develop appropriate GHG mitigation strategies to maintain and improve its competitiveness in the green commodity market. This paper proposes the use of Integrated Spatial Technologies (IST) framework by linking Life Cycle Assessment (LCA), Remote Sensing (RS) and Geographical Information Systems (GIS). The IST approach also integrates and highlights the use of Cleaner Production (CP) strategies for the formulation and application of cost-effective GHG mitigation options for grain production in Western Australia (WA). In this study, the IST framework was tested using data from an existing study (the baseline study) and two mitigation options. The analysis results revealed production and use of fertiliser as the "hotspot", and for mitigation purposes was replaced with pig manure in option I, whereas option 2 emphasised crop rotation system/s.
  • Authors:
    • Elanchezhian, R.
    • Chhabra, V.
    • Biswas, S.
    • Haris, A. V. A.
    • Bhatt, B. P.
  • Source: CURRENT SCIENCE
  • Volume: 104
  • Issue: 2
  • Year: 2013
  • Summary: Accumulation of greenhouse gases (GHGs) in the atmosphere has exposed us to the potential warming and its adverse effects on agriculture. The present study deals with the impact of climate change on winter wheat and maize using the Infocrop model. Simulation studies were performed for different time-periods using HADCM3 factors at four centres located in three different agroecological zones, with prevalent management practices. The results showed that under changed climate, wheat yield decreased whereas the yield of winter maize increased due to warmer winters and enhanced CO2 compared to baseline. Duration of both the crops has decreased owing to the higher temperatures during the growing period. The increase in yield of winter maize points to the suitability of the region for its cultivation in future. Further, increase in maize cultivation in locations with poor wheat yield could well be considered as an adaptation option.
  • Authors:
    • Ferro, C. A. T.
    • Challinor, A. J.
    • Fricker, T. E.
    • Hawkins, E.
    • Osborne,T. M.
    • Ho, C. K.
  • Source: Global Change Biology
  • Volume: 19
  • Issue: 3
  • Year: 2013
  • Summary: Improved crop yield forecasts could enable more effective adaptation to climate variability and change. Here, we explore how to combine historical observations of crop yields and weather with climate model simulations to produce crop yield projections for decision relevant timescales. Firstly, the effects on historical crop yields of improved technology, precipitation and daily maximum temperatures are modelled empirically, accounting for a nonlinear technology trend and interactions between temperature and precipitation, and applied specifically for a case study of maize in France. The relative importance of precipitation variability for maize yields in France has decreased significantly since the 1960s, likely due to increased irrigation. In addition, heat stress is found to be as important for yield as precipitation since around 2000. A significant reduction in maize yield is found for each day with a maximum temperature above 32°C, in broad agreement with previous estimates. The recent increase in such hot days has likely contributed to the observed yield stagnation. Furthermore, a general method for producing near-term crop yield projections, based on climate model simulations, is developed and utilized. We use projections of future daily maximum temperatures to assess the likely change in yields due to variations in climate. Importantly, we calibrate the climate model projections using observed data to ensure both reliable temperature mean and daily variability characteristics, and demonstrate that these methods work using retrospective predictions. We conclude that, to offset the projected increased daily maximum temperatures over France, improved technology will need to increase base level yields by 12% to be confident about maintaining current levels of yield for the period 2016-2035; the current rate of yield technology increase is not sufficient to meet this target.
  • Authors:
    • Parras-Alcantara, L.
    • Lozano-Garcia, B.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 165
  • Year: 2013
  • Summary: Olive grove soils in semi-arid Mediterranean areas are very poor in organic matter and are exposed to progressive degradation processes. Therefore, additions of the olive mill by-products as organic amendments can improve soil quality and hence mitigate the negative environmental and agronomic limitations of these soils. A field study was conducted to assess the short-term effects of two oil mill by-products [olive leaves and alperujo (a two-phase olive mill waste)] and determine soil organic carbon (SOC), total nitrogen (TN), the C:N ratio, and their stratification across the soil profile, in an area under Mediterranean conditions. The experimental design consisted on three large plots each spanning a 100 m * 100 m area covered with unirrigated olive trees of the Picual variety less than 30 years old under conventional tillage (CT) in the province of Jaen (southern Spain). One of the plots (CT) was used as control plot and the other two were treated with alperujo (CTa) and olive leaves (CTol), respectively. Soil properties were assessed three years after the by-products were applied. Supplying the soil with the by-products increased C and N stocks. Thus, the SOC stock was 75.4 Mg ha -1 in CT, 91.5 Mg ha -1 in CTa and 136.3 Mg ha -1 in CTol; and the TN stock 12.1, 13.9 and 16.1 Mg ha -1 in CT, CTa and CTol, respectively. SOC, TN and the C:N ratio in the surface horizon were higher in the treated plots (viz. 18.5 g C kg -1, 1.4 g N kg -1 and 13.2:1 in CTa, and 84.1 g C kg -1, 5.7 g N kg -1 and 14.7:1 in CTol) than in the control plot (8.9 g C kg -1, 0.9 g N kg -1 and 9.8:1, respectively). In addition, application of the by-products improved soil quality (the stratification ratio, SR, for SOC was greater than 2). Oil mill by-products such as olive leaves and alperujo are thus potentially useful as soil amendments since they are effective sources of organic matter and nitrogen, improve soil quality and alleviate the environmental and agronomic limitations of Mediterranean agricultural soils, even those under using CT. In addition, the by-products can be recycled on site.