• 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:
    • Hunter, C.
    • Slee, B.
    • Feliciano, D.
    • Smith, P.
  • Source: Environmental Science & Policy
  • Volume: 25
  • Year: 2013
  • Summary: Challenging greenhouse gas (GHG) emission reduction targets were set in Scotland by the Climate Change (Scotland) Act in June 2009. The national objective is to reduce GHG emissions by 42% by 2020 and 80% by 2050 compared to 1990 levels. The GHG emission reduction targets apply both to the traded and non-traded sectors, thus including the rural land use sector. In North East Scotland, rural land uses cover the majority of the land area, with agriculture and forestry representing about 86% and sporting land about 10% of the total area. The objectives of this study were to provide guidance for the development of a regional GHG inventory to estimate methane (CH4), nitrous oxide (N2O) and carbon dioxide (CO2) emissions from rural land uses in North East of Scotland, to compare with that of the United Kingdom (UK), and discuss the advantages of regional GHG inventories for rural land uses. The study mainly followed the guidance of the IPCC (Intergovernmental Panel on Climate Change) Revised Guidelines for National Greenhouse Gas Inventories and adapts these to the region level. Data available for North East Scotland allowed an assessment of annual GHG emissions from livestock and grassland, cropland management and sporting land, as well as carbon sequestered by forests, between 1999 and 2010. Estimated GHG emissions of 1420 ktCO(2)e from livestock, grassland and cropland management obtained in this study for 2009 compare well with estimates for the same region from larger-scale inventories. The methodology described, including the steps undertaken for data collection, the shortcomings found and strategies to overcome these, could be applied to other UK or European regions.
  • Authors:
    • Emmerling, C.
    • Fries, J.
    • Froeba, N.
    • Felten, D.
  • Source: Renewable Energy
  • Volume: 55
  • Year: 2013
  • Summary: Biomass for bioenergy is an important option within global change mitigation policies. The present research focused on energy net production, net reduction of greenhouse gases (GHG) (considered as CO2-equivalents), and energy output:input ratio of the energy cropping systems 'rapeseed', 'maize', and 'Miscanthus'. The system-specific main products were biodiesel (rapeseed), electricity from biogas (maize), and Miscanthus chips (loose, chopped material); the related substituted fossil resources were diesel fuel (rapeseed), electricity from the German energy mix (maize), and heating oil (Miscanthus). However, research did not aim for a direct quantitative comparison of the crops. The study followed a case study approach with averaged data from commercial farms within an enclosed agricultural area (<5 km(2)) in Western Germany. Cultivation techniques were considered as communicated by farmers and operation managers; the diesel fuel consumption of agricultural machinery was modeled using an online-based calculator of the German Association for Technology and Structures in Agriculture (KTBL). Overall, rounded net energy production amounted to 66 GJ ha(-1) (rapeseed), 91 GJ ha(-1) (maize), and 254 GJ ha(-1) yr(-1) (Miscanthus); the related energy output:input ratios were 4.7 (rapeseed), 5.5 (maize), and 47.3 (Miscanthus), respectively. Compared to the respective fossil fuel-related energy supply, CO2-equivalent reduction potential ranged between 30 and 76% for electrical energy from maize biomass, 29 -82% for biodiesel from rapeseed, and 96-117% for Miscanthus chips, depending on whether or not the accruing by-products rapeseed cake, glycerin (rapeseed cropping system), and waste heat (maize) were considered. True 'CO2-neutrality' was only reached by the Miscanthus cropping system and was related to an additional credit from carbon sequestration in soil during the cultivation period; thus, this cropping system could be attributed to be a CO2-sink. The study indicated that bioenergy can be produced sustainably under commercial farming conditions in terms of a significantly reduced consumption of natural resources.
  • Authors:
    • Cao, Y.
    • Drake, B.
    • Elliott, J.
    • Firbank, L. G.
    • Gooday, R.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 173
  • Year: 2013
  • Summary: Several influential reports have suggested that one of the most appropriate responses to expected food shortages and ongoing environmental degradation is sustainable intensification, i.e. the increase of food production with at worst no increase in environmental harm, and ideally environmental benefit. Here we sought evidence of sustainable intensification among British farmers by selecting innovative arable, dairy, mixed and upland farms and analysing their own data on yields, inputs and land use and management for 2006 and 2011. The evidence was obtained by interview, and was interpreted in terms of the ecosystem services of food production (GJ ha(-1), where area took into account estimated area to grow any imported animal feeds), regulation of climate, air and water quality (modelled emissions of GHGs (CO(2)e ha(-1)), ammonia (kg ha(-1)) and nitrate loss (kg ha(-1))) and biodiversity (using an index based on the presence of habitats and management). Several farms have increased both food production and other ecosystem services over this time by increasing yields, using resources more efficiently and/or enhancing biodiversity, and sometimes by reducing livestock numbers and increasing cropping. The motivation has been to improve farm profitability through increasing food production, reducing input costs and accessing public payments through agri-environment schemes and generating renewable energy. Such sustainable intensification was not achieved by farmers who increased meat or milk yields. Sustainable intensification can be achieved when the correct drivers are in place to influence the actions of individual farmers. Also, it is possible to indicate sustainable intensification by using a small number of high-level indicators derived from data that farmers already hold, though such an approach may not capture the impacts of farmer innovative practices.
  • Authors:
    • Cerri, C. E. P.
    • Soares-Filho, B.
    • Galford, G. L.
  • Source: Philosophical Transactions of the Royal Society B, Biological Sciences
  • Volume: 368
  • Issue: 1619
  • Year: 2013
  • Summary: The Brazilian Amazon frontier shows how remarkable leadership can work towards increased agricultural productivity and environmental sustainability without new greenhouse gas emissions. This is due to initiatives among various stakeholders, including national and state government and agents, farmers, consumers, funding agencies and non-governmental organizations. Change has come both from bottom-up and top-down actions of these stakeholders, providing leadership, financing and monitoring to foster environmental sustainability and agricultural growth. Goals to reduce greenhouse gas emissions from land-cover and land-use change in Brazil are being achieved through a multi-tiered approach that includes policies to reduce deforestation and initiatives for forest restoration, as well as increased and diversified agricultural production, intensified ranching and innovations in agricultural management. Here, we address opportunities for the Brazilian Amazon in working towards low-carbon rural development and environmentally sustainable landscapes.
  • Authors:
    • Petersen,Soren O.
    • Schjonning,Per
    • Olesen,Jorgen E.
    • Christensen,Soren
    • Christensen,Bent T.
  • Source: Soil Science Society of America Journal
  • Volume: 77
  • Issue: 1
  • Year: 2013
  • Summary: In organic cropping systems, legumes, cover crops (CC), residue incorporation, and manure application are used to maintain soil fertility, but the contributions of these management practices to soil nitrogen (N) supply remain obscure. We examined potential sources of N for winter wheat (Triticum aestivum L.) in four experimental cropping systems established in 1997 on three soil types. Three of the four systems were under organic management. Topsoil N, depth of the A horizon, and cumulated inputs of N since 1997 were determined at plot level. Labile soil N pools [mineral N, potentially mineralizable N (PMN), microbial biomass N (MBN)] were monitored during two growth periods; at one site, biomass C/N ratios were also determined. Soil for labile N analysis was shielded from N inputs during spring application to isolate cumulated system effects. Potentially mineralizable N and MBN were correlated across all sites and rotations (r(2) = 0.72). The MBN corresponded to 46 to 85, 85 to 145, and 74 to 172 kg N ha(-1) at the three sites and differed significantly between cropping systems, but MBN could not explain differences in wheat grain N yields. Instead, a multiple linear regression model explained 76 and 82% of the variation in grain N yields in organic cropping systems in 2007 and 2008, showing significant effects of, respectively, topsoil N, depth of A horizon, cumulated inputs of N, and N applied to winter wheat in manure. Thus, soil properties and past and current management all contributed to winter wheat N supply.
  • Authors:
    • Karkee, M.
    • McNaull, R. P.
    • Birrell, S. J.
    • Steward, B. L.
  • Source: Transactions of the ASABE
  • Volume: 55
  • Issue: 1
  • Year: 2012
  • Summary: As the demand for biomass feedstocks grows, it is likely that agricultural residue will be removed in a way that compromises soil sustainability due to increased soil erosion, depletion of organic matter, and deterioration of soil physical characteristics. Since soil erosion from agricultural fields depends on several factors including soil type, field terrain, and cropping practices, the amount of biomass that can be removed while maintaining soil tilth varies substantially over space and time. The RUSLE2 soil erosion model, which takes into account these spatio-temporal variations, was used to estimate tolerable agricultural biomass removal rates at field scales for a single-pass crop grain and biomass harvesting system. Soil type, field topography, climate data, management practices, and conservation practices were stored in individual databases on a state or county basis. Geographic position of the field was used as a spatial key to access the databases to select site-specific information such as soil, topography, and management related parameters. These parameters along with actual grain yield were provided as inputs to the RUSLE2 model to calculate yearly soil loss per unit area of the field. An iterative technique was then used to determine site-specific tolerable biomass removal rates that keep the soil loss below the soil loss thresholds (T) of the field. The tolerable removal rates varied substantially with field terrain, crop management practices, and soil type. At a location in a field in Winnebago county, Iowa, with ~1% slope and conventional tillage practices, up to 98% of the 11 Mg ha -1 total above-ground biomass was available for collection with negligible soil loss. There was no biomass available to remove with conventional tillage practices on steep slopes, as in a field in Crawford county, Iowa, with a 12.6% slope. If no-till crop practices were adopted, up to 70% of the total above-ground biomass could be collected at the same location with 12.6% slope. In the case of a soybean-corn rotation with no-till practices, about 98% of total biomass was available for removal at the locations in the Winnebago field with low slopes, whereas 77% of total biomass was available at a location in the Crawford field with a 7.5% slope. Tolerable removal rates varied substantially over an agricultural field, which showed the importance of site-specific removal rate estimation. These removal rates can be useful in developing recommended rates for producers to use during a single-pass crop grain and biomass harvesting operation. However, this study only considered the soil erosion tolerance level in estimating biomass removal rates. Before providing the final recommendation to end users, further investigations will be necessary to study the potential effects of continuous biomass removal on organic matter content and other biophysical properties of the soil.
  • Authors:
    • Kennedy, T. F.
    • Connery, J.
  • Source: The Journal of Agricultural Science
  • Volume: 150
  • Issue: 2
  • Year: 2012
  • Summary: The control of barley yellow dwarf virus (BYDV) and its aphid vectors in minimum tillage (MT) and conventionally tilled (CT) winter barley by insecticide seed and foliar spray treatments was investigated in 2001, 2002 and 2003. Similar investigations were undertaken on winter wheat in 2004, 2005 and 2006. Aphids numbers in autumn and BYDV in spring on barley and wheat were significantly lower on MT relative to CT crops, in two of the six seasons. An insecticide spray at Zadoks growth stage (GS) 25 significantly reduced aphids and virus in both MT and CT crops in three of the six seasons of the study. An additional spray at GS 22 provided no benefit. Aphids were significantly fewer in three of the six seasons on crops grown from insecticide treated seeds, relative to untreated seeds. Both MT and CT barley sprayed at GS 25 had significantly fewer aphids than the seed treatment in one of the three seasons. Seed-treated MT and CT barley had significantly less BYDV than controls but significantly more than crops sprayed at GS 25. CT wheat grown from insecticide-treated seed had significantly less BYDV than controls. Overall, CT barley grown from insecticide-treated seed had 6-fold more BYDV than the sprayed crop, while untreated barley had 22-fold more than the spray treatment. In MT barley, the comparable values were 3- and 10-fold respectively. BYDV was almost exclusively the MAV strain. The grain yield for insecticide-sprayed CT barley was significantly greater in two of three seasons than that for untreated plots. In general, MT and CT barley receiving an insecticide spray had greater grain yield than barley grown from insecticide-treated seed, with differences being significant in one of three seasons. It is concluded that BYDV in MT and CT cereals is better controlled by applying a pyrethroid insecticide spray between GS 23 and 25, in autumn, than by treating the seed with a nitroguanidine-type insecticide. In MT crops, a single spray between GS 23 and 25 will give effective control of MAV-type BYDV.
  • Authors:
    • Ahuja, L. R.
    • Saseendran, S. A.
    • Green, T. R.
    • Ma, L. W.
    • Nielsen, D. C.
    • Walthall, C. L.
    • Ko, J. H.
  • Source: Climatic Change
  • Volume: 111
  • Issue: 2
  • Year: 2012
  • Summary: Agricultural systems models are essential tools to assess potential climate change (CC) impacts on crop production and help guide policy decisions. In this study, impacts of projected CC on dryland crop rotations of wheat-fallow (WF), wheat-corn-fallow (WCF), and wheat-corn-millet (WCM) in the U.S. Central Great Plains (Akron, Colorado) were simulated using the CERES V4.0 crop modules in RZWQM2. The CC scenarios for CO 2, temperature and precipitation were based on a synthesis of Intergovernmental Panel on Climate Change (IPCC 2007) projections for Colorado. The CC for years 2025, 2050, 2075, and 2100 (CC projection years) were super-imposed on measured baseline climate data for 15-17 years collected during the long-term WF and WCF (1992-2008), and WCM (1994-2008) experiments at the location to provide inter-annual variability. For all the CC projection years, a decline in simulated wheat yield and an increase in actual transpiration were observed, but compared to the baseline these changes were not significant ( p>0.05) in all cases but one. However, corn and proso millet yields in all rotations and projection years declined significantly ( p<0.05), which resulted in decreased transpiration. Overall, the projected negative effects of rising temperatures on crop production dominated over any positive impacts of atmospheric CO 2 increases in these dryland cropping systems. Simulated adaptation via changes in planting dates did not mitigate the yield losses of the crops significantly. However, the no-tillage maintained higher wheat yields than the conventional tillage in the WF rotation to year 2075. Possible effects of historical CO 2 increases during the past century (from 300 to 380 ppm) on crop yields were also simulated using 96 years of measured climate data (1912-2008) at the location. On average the CO 2 increase enhanced wheat yields by about 30%, and millet yields by about 17%, with no significant changes in corn yields.
  • Authors:
    • Weber, D.
    • Way, T. R.
    • Camargo, G. G.
    • Mirsky, S. B.
    • Ryan, M. R.
    • Curran, W. S.
    • Teasdale, J. R.
    • Maul, J.
    • Moyer, J.
    • Grantham, A. M.
    • Spargo, J. T.
  • Source: Renewable Agriculture and Food Systems
  • Volume: 27
  • Issue: 1
  • Year: 2012
  • Summary: Organic producers in the mid-Atlantic region of the USA are interested in reducing tillage, labor and time requirements for grain production. Cover crop-based, organic rotational no-till grain production is one approach to accomplish these goals. This approach is becoming more viable with advancements in a system for planting crops into cover crop residue flattened by a roller-crimper. However, inability to consistently control weeds, particularly perennial weeds, is a major constraint. Cover crop biomass can be increased by manipulating seeding rate, timing of planting and fertility to achieve levels (>8000 kg ha -1) necessary for suppressing summer annual weeds. However, while cover crops are multi-functional tools, when enhancing performance for a given function there are trade-off with other functions. While cover crop management is required for optimal system performance, integration into a crop rotation becomes a critical challenge to the overall success of the production system. Further, high levels of cover crop biomass can constrain crop establishment by reducing optimal seed placement, creating suitable habitat for seed- and seedling-feeding herbivores, and impeding placement of supplemental fertilizers. Multi-institutional and -disciplinary teams have been working in the mid-Atlantic region to address system constraints and management trade-off challenges. Here, we report on past and current research on cover crop-based organic rotational no-till grain production conducted in the mid-Atlantic region.