• Authors:
    • Hosseini, S. M. B.
    • Jahansooz, M. R.
    • Heidari, H.
    • Chaichi, M. R.
  • Source: Annals of Biological Research
  • Volume: 3
  • Issue: 6
  • Year: 2012
  • Summary: The aim of the study was to determine the effect of alternate irrigation method and deficit irrigation on radiation use efficiency and forage quality of foxtail millet ( Setaria italica) under a double cropping system after barley ( Hordeum vulgar). Conventional furrow irrigation (M1) and alternate furrow irrigation (M2) methods and different deficit irrigation levels including 100, 85, 70 and 55% of crop water requirement (V1, V2, V3 and V4) were tested in a field experiment on the west of Tehran, Iran for 2 years (2008 and 2009). Results showed that alternate furrow irrigation with 85% of crop water requirement (M2V2) had the highest Absorption Ratio of Photosynthetically Active Radiation (PARAR) and Cumulative Absorption of Photosynthetically Active Radiation (PARCA) in 2008 (P
  • Authors:
    • O'Donovan, J. T.
    • Blackshaw, R. E.
    • Hao, X. Y.
    • Li. C. L.
    • Harker, K. N.
    • Clayton, G. W.
  • Source: Soil & Tillage Research
  • Volume: 118
  • Year: 2012
  • Summary: Environmentally Smart Nitrogen (ESN), a type of polymer-coated urea, synchronizes N release with crop demand to increase N use efficiency and potentially reduce N 2O emissions. This study investigated the effects of ESN and weed management on N 2O emissions from soil under a canola ( Brassica napus L.) no-till cropping system. The experiment was conducted from 2005 to 2008 at three sites: Lethbridge, Lacombe, and Beaverlodge, located in southern, central and northern Alberta, Canada. Treatments included a hybrid and an open-pollinated canola cultivar, with ESN and urea applied at 1 and 1.5 times (*) the recommended rate, and herbicide at 50 and 100% of registered in-crop application rates. Canola was grown in rotation with barley ( Hordeum vulgare L.) and both phases of crop rotation were present each year. The N 2O fluxes from soil were measured using vented static chambers at 2-week intervals during the growing season from 2006 to 2008. Except for a few occasions with higher fluxes from urea than ESN earlier in the growing season and higher fluxes from ESN than urea later on, N 2O fluxes were similar among all treatments for all three years and three sites. The N 2O fluxes also varied over the growing season, and peak flux occurred in response to rainfall events. Similarly, cumulative N 2O emissions, expressed as either per land area or per canola seed yield, over the three growing seasons were low (0.15-2.97 kg N ha -1 yr -1 or 0.05-1.19 g N kg -1 seed) for all treatments and sites, and unaffected by weed management or crop variety ( P>0.05). The N 2O emission across the three sites from ESN averaged 20% lower ( P=0.040) than from urea although the differences between fertilizer types or application rates were not significant ( P>0.05) at each site. Elevated N 2O emissions (72% higher; P=0.028) from 1.5 * ESN (0.83 kg N ha -1 yr -1 or 0.33 g N kg -1 seed) relative to 1 * ESN (0.26 kg N ha -1 yr -1 or 0.16 g N kg -1 seed) were only observed at Beaverlodge while emissions were similar ( P>0.05) at the other two sites. The higher N 2O emissions at 1.5 * ESN at Beaverlodge were due to excess N accumulation in soil caused by unfavourable weather conditions that reduced canola N uptake and yield. Our results suggest that ESN fertilizer could reduce N 2O emissions in Alberta, Canada, but reductions will depend on rainfall events and canola N utilization.
  • Authors:
    • Shen, X. J.
    • Zhang, J. P.
    • Zhang, J. Y.
    • Sun, J. S.
    • Liu, H.
  • Source: Ying Yong Sheng Tai Xue Bao
  • Volume: 23
  • Issue: 2
  • Year: 2012
  • Summary: To develop a suitable tillage mode and irrigation schedule of transplanted cotton following wheat harvest under sprinkler irrigation, a field experiment was conducted to study the effects of different tillage modes (conventional tillage and no-tillage) and different irrigation schedules (45 and 22.5 mm of irrigating water quota) on the water consumption, seed yield, water use efficiency, and fiber quality of cotton. Comparing with conventional tillage, no-tillage decreased the soil evaporation among cotton plants by 20.3%. Whether with conventional tillage or with no-tillage, deficit irrigation (22.5 mm of irrigating water quota) did not affect seed yield and fiber quality, while decreased the water consumption and improved the water use efficiency. No-tillage with 22.5 mm of irrigating water quota under sprinkler irrigation not only decreased the soil evaporation effectively, but also achieved water-saving, high quality and high yield of transplanted cotton following wheat harvest.
  • Authors:
    • Espadaler, X.
    • Ribes, J.
    • Ribes, E.
    • Piñol, J.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 158
  • Year: 2012
  • Summary: The Heteroptera assemblage of a citrus grove and how it was affected by ant-exclusion was examined during transformation from conventional to organic agriculture. The results showed that the Heteroptera assemblage changed dramatically over the eight years of the study: at first, it mainly consisted of herbivorous lygaeids and predatory anthocorids but became dominated by predatory mirids in 2008-2009. The predator/herbivore ratio increased steadily over the eight years of the study. Ants can form mutualistic relationships with heteropteran pests. However, exclusion of ants from canopies did not affect the Heteroptera assemblage at the beginning of the study, but had a profound effect later on. In particular, ant-exclusion increased the abundance of most predatory Heteroptera, except for the myrmecomorphic mirid Pilophorus perplexus, which was approximately five times more abundant in control than in ant-excluded trees; the analyses showed that the only mimicked ant species was Lasius grandis.
  • Authors:
    • Shi, H.
    • Luo, Y.
    • Xue, J.
    • Wu, D.
  • Source: Journal of Nanjing Forestry University (Natural Sciences Edition)
  • Volume: 36
  • Issue: 2
  • Year: 2012
  • Summary: By using in situ leaching device, a field experiment was conducted to study the nitrate leaching amount and density at 60 cm soil depth, nitrate accumulation in soil profile (0-80 cm) of poplar-wheat intercropping ecosystem. Four treatments were installed, no fertilization (N 0, 0 kg/hm 2) conventional fertilization (N 140, 140 kg/hm 2), reduced N application (N 70, 70 kg/hm 2), increased N application (N 210, 210 kg/hm 2). The results indicated a positive correlation between quantity of leachate water and precipitation, the poplar-wheat intercropping ecosystem can reduce the quantity of eluviate solution. The nitrate leaching loss increased according to the increasing N fertilization rate. In treatment spot N 210, the nitrate nitrogen loss from N fertilization at 60 cm soil depth was the greatest (13.89 kg/hm 2), it declined by 60.27% and 50.11% in poplar-wheat intercropping ecosystem away from the poplar row 0.5 m and 1.5 m, respectively. The nitrogen leaching and accumulation were significantly lower in poplar-wheat intercropping ecosystem, and variances of the distribution for soil nitrate nitrogen were significant.
  • Authors:
    • Healey, J.
    • Attarzadeh, N.
    • Soto, G.
    • Haggar, J.
    • Edwards-Jones, G.
    • Noponen, M.
  • Source: Agriculture Ecosystems & Environment
  • Volume: 151
  • Year: 2012
  • Summary: Coffee plays a key role in sustaining millions of livelihoods around the world. Understanding GHG emissions from coffee supply chains is important in evaluating options for climate change mitigation within the sector. We use data from two long-term coffee agroforestry experiments in Costa Rica and Nicaragua to calculate carbon footprints (CF) for coffee and identify emission hotspots within different management systems, levels of inputs and shade types. Management system and input level were the main cause of variation in CFs. Carbon footprints for 1 kg of fresh coffee cherries were between 0.26 and 0.67 kgCO(2)e for conventional and 0.12 and 0.52 kgCO(2)e for organic management systems. The main contributor to GHG emissions for all management systems was the inputs of organic and inorganic nitrogen. Nitrous oxide emissions from pruning inputs contributed between 7% and 42% of CFs. However, these estimates were strongly influenced by the choice of emission factor used in the calculations. Research is required to develop emission factors that account for different qualities and management of nitrogen inputs to enable effective calculation of the CF from different management strategies, and especially from the pruning and organic inputs managed in agroforestry systems. As such, effective climate change mitigation strategies can only be developed from site-specific studies which utilise accurate accounting and regional-specific emission factors. (c) 2012 Elsevier B.V. All rights reserved.
  • Authors:
    • Torbert, H.
    • Watts, D.
    • Way, T.
    • Mays, D.
    • Nyakatawa, E.
    • Smith, D.
  • Source: Journal of Sustainable Agriculture
  • Volume: 36
  • Issue: 8
  • Year: 2012
  • Summary: Soil management practices can alter the natural balance at the soil-plant-atmosphere ecosystem interface, which can significantly affect the environment. This study compared CO2 fluxes in conventional tillage (CT) and no-tillage (NT) corn (Zea mays L.) production systems receiving poultry litter (PL) and ammonium nitrate (AN) fertilizers on a Decatur silt loam soil in the Tennessee Valley region of North Alabama from Spring 2008 to Fall 2009. Soil CO2 flux in CT plots (9.5 kg CO2 ha(-1) day(-1)) was significantly greater than that in NT plots (4.9 kg CO2 ha(-1) day(-1) in summer. Soil CO2 fluxes were lowest in fall where CT plots had a mean soil CO2 emission of 0.8 kg CO2 ha(-1) day(-1), while plots under NT and grass fallow system were sinks of CO2 with fluxes -0.6 and -1.0 kg CO2 ha(-1) day(-1), respectively. Mean soil CO2 flux averaged over seasons in NT plots was 36% lower than that in CT plots. Grass fallow plots were net sinks of CO2 with a mean CO2 flux of -0.4 kg CO2 ha(-1) day(-1). Our study showed that application of PL or AN fertilizer in NT systems can significantly reduce soil CO2 emissions compared to CT systems in corn production.
  • Authors:
    • McKone, T. E.
    • Horvath, A.
    • Santero, N. J.
    • Masanet, E.
    • Lobscheid, A. B.
    • Strogen, B.
    • Mishra, U.
    • Nazaroff, W. W.
    • Scown, C. D.
  • Source: Environmental Research Letters
  • Volume: 7
  • Issue: 1
  • Year: 2012
  • Summary: The Energy Independence and Security Act of 2007 set an annual US national production goal of 39.7 billion 1 of cellulosic ethanol by 2020. This paper explores the possibility of meeting that target by growing and processing Miscanthus x giganteus. We define and assess six production scenarios in which active cropland and/or Conservation Reserve Program land are used to grow to Miscanthus. The crop and biorefinery locations are chosen with consideration of economic, land-use, water management and greenhouse gas (GHG) emissions reduction objectives. Using lifecycle assessment, the net GHG footprint of each scenario is evaluated, providing insight into the climate costs and benefits associated with each scenario's objectives. Assuming that indirect land-use change is successfully minimized or mitigated, the results suggest two major drivers for overall GHG impact of cellulosic ethanol from Miscanthus: (a) net soil carbon sequestration or emissions during Miscanthus cultivation and (b) GHG offset credits for electricity exported by biorefineries to the grid. Without these factors, the GHG intensity of bioethanol from Miscanthus is calculated to be 11-13 g CO2-equivalent per MJ of fuel, which is 80-90% lower than gasoline. Including soil carbon sequestration and the power-offset credit results in net GHG sequestration up to 26 g CO2-equivalent per MJ of fuel.
  • Authors:
    • Lence, S.
    • Livingston, M.
    • Greene, C.
    • Chase, C.
    • Delate, K.
    • Singerman, A.
    • Hart, C.
  • Source: Renewable Agriculture and Food Systems
  • Volume: 27
  • Issue: 4
  • Year: 2012
  • Summary: Emphasis on reducing emissions from the greenhouse gases (GHG), carbon dioxide (CO2), nitrous oxide (N2O) and methane (CH4) has increased in recent years in the USA, primarily for industry, transportation, energy and agricultural sectors. In this study, we utilized on-farm data collected by the USDA-National Agricultural Statistics Service (NASS) Agricultural Resource Management Survey (ARMS), secured under an agreement with the USDA-Economic Research Service (ERS) to analyze the profitability of organic and conventional soybean production, based on changes that 'green payments' in a cap-and-trade system would introduce in agricultural markets in the USA. In particular, the analysis focused on establishing whether organic producers would be better positioned to sequester carbon (C) and reap the benefits of the C-offset scheme compared to conventional producers, given the differences in costs, management practices and environmental benefits between organic and conventional production methods. We estimated several changes in profitability of soybean producers according to management practices, incentives for the generation of offset credits, and increase in energy input prices that a potential cap-and-trade system may introduce in future agricultural markets in the USA. Survey data suggested that even with lower yields, conventional producers could profit from converting to organic agriculture, given organic price premiums. In addition, taking into consideration both direct and indirect costs, average cost for conventional-till (CT) organic soybean production was approximately 9% lower than no-till (NT) conventional production. With a C market and payments for soil C sequestration through potential Clean Energy legislation, additional profit could be accrued by organic producers, because organic production would have 28% greater ton CO2 eq. acre(-1) yr(-1) sequestration than conventional NT. Thus, the environmental benefits from GHG reduction could incentivize increased conversion from conventional to organic production across the USA.
  • Authors:
    • Huggins, D.
    • Nelson, R.
    • Kemanian, A.
    • Higgins, S.
    • Stoeckle, C.
    • Marcos, J.
    • Collins, H.
  • Source: Journal of Soil and Water Conservation
  • Volume: 67
  • Issue: 5
  • Year: 2012
  • Summary: Conservation tillage is an agricultural strategy to mitigate atmospheric greenhouse gas (GHG) emissions. In eastern Washington, we evaluated the long-term effects of conventional tillage (CT), reduced tillage (RT) and no-tillage (NT) on soil organic carbon (SOC) storage and nitrous oxide (N2O) emissions at three dryland and one irrigated location using the cropping systems simulation model CropSyst. Conversion of CT to NT produced the largest relative increase in SOC storage (Delta SOC, average yearly change relative to CT) in the top 30 cm (11.8 in) of soil where Delta SOC ranged from 0.29 to 0.53 Mg CO(2)e ha(-1) y(-1) (CO(2)e is carbon dioxide [CO2] equivalent of SOC; 0.13 to 0.24 tn CO(2)e ac(-1) yr(-1)).The Delta SOC were less with lower annual precipitation, greater fallow frequency, and when changing from CT to RT. Overall, Delta SOC decreased from the first to the third decade after conversion from CT to NT or RT. Simulations of Delta SOC for the conversion of CT to NT based on a 0 to 15 cm (0 to 5.9 in) soil depth were greater than the Delta SOC based on a 0 to 30 cm depth, primarily due to differences among tillage regimes in the depth-distribution of carbon (C) inputs and the resultant SOC distribution with depth. Soil erosion rates under CT in the study region are high, posing deleterious effects on soil quality, productivity, and aquatic systems. However, an analysis that includes deposition, burial, and sedimentation on terrestrial and aquatic systems of eroded SOC indicates that the substantial erosion reduction obtained with RT and NT may result only in minor additional SOC oxidation as compared to CT Simulated N2O emissions, expressed as CO2 equivalent, were not very different under CT, RT, and NT However, N2O emissions were sufficiently high to offset gains in SOC from the conversion of CT to RT or NT.Thus, reducing tillage intensity can result in net C storage, but mitigation of GHG is limited unless it is coupled with nitrogen (N) fertilizer management to also reduce N2O emission.