• Authors:
    • Wollenberg, L.
    • Agrawal, A.
    • Newton, P.
  • Source: Global Environmental Change
  • Volume: 23
  • Issue: 6
  • Year: 2013
  • Summary: The rapid expansion of the production of agricultural commodities such as beef, cocoa, palm oil, rubber and soybean is associated with high rates of deforestation in tropical forest landscapes. Many state, civil society and market sector actors are engaged in developing and implementing innovative interventions that aim to enhance the sustainability of commodity supply chains by affecting where and how agricultural production occurs, particularly in relation to forests. These interventions - in the form of novel or moderated institutions and policies, incentives, or information and technology - can influence producers directly or achieve their impacts indirectly by influencing consumer, retailer and processor decisions. However, the evidence base for assessing the impacts of these interventions in reducing the negative impacts of commodity agriculture production in tropical forest landscapes remains limited, and there has been little comparative analysis across commodities, cases, and countries. Further, there is little consensus of the governance mechanisms and institutional arrangements that best support such interventions. We develop a framework for analyzing commodity supply chain interventions by different actors across multiple contexts. The framework can be used to comparatively analyze interventions and their impacts on commodity production with respect to the spatial and temporal scales over which they operate, the groups of supply chain actors they affect, and the combinations of mechanisms upon which they depend. We find that the roles of actors in influencing agricultural production depends on their position and influence within the supply chain; that complementary institutions, incentives and information are often combined; and that multi-stakeholder collaborations between different groups of actors are common. We discuss how the framework can be used to characterize different interventions using a common language and structure, to aid planning and analysis of interventions, and to facilitate the evaluation of interventions with respect to their structure and outcomes. Studying the collective experience of multiple interventions across commodities and spatial contexts is necessary to generate more systematic understandings of the impacts of commodity supply chain interventions in forest-agriculture landscapes.
  • Authors:
    • Oikawa,S.
    • Okada,M.
    • Hikosaka,K.
  • Source: Plant and Soil
  • Volume: 373
  • Issue: 1-2
  • Year: 2013
  • Summary: The effects of elevated CO2 on leaf area index (LAI) vary among studies. We hypothesized that the interactive effects of CO2 and nitrogen on leaf area loss have important roles in LAI regulation. We studied the leaf area production and loss using nodulating soybean and its non-nodulating isogenic line in CO2-controlled greenhouse systems. Leaf area production increased with elevated CO2 levels in the nodulating soybean stand and to a lesser extent in the non-nodulating line. Elevated CO2 levels accelerated leaf area loss only in nodulating plants. Consequently, both plants exhibited a similar stimulation of peak LAI with CO2 elevation. The accelerated leaf loss in nodulating plants may have been caused by newly produced leaves shading the lower leaves. The nodulating plants acquired N throughout the growth phase, whereas non-nodulating plants did not acquire N after flowering due to the depletion of soil N. N retranslocation to new organs and subsequent leaf loss were faster in non-nodulating plants compared with nodulating plants, irrespective of the CO2 levels. LAI regulation in soybean involved various factors, such as light availability within the canopy, N acquisition and N demands in new organs. These effects varied among the growth stages and CO2 levels.
  • Authors:
    • Ouyang, W.
    • Qi, S.
    • Hao, F.
    • Wang, X.
    • Shan, Y.
    • Chen, S.
  • Source: Ecological Modelling
  • Volume: 252
  • Year: 2013
  • Summary: Agricultural activity is a primary factor contributing to global warming. In higher latitude freeze zone, agricultural activities pose a more serious threat to global warming than other zones. The crop management practices of various land use types have direct impacts on soil organic carbon (SOC) and global warming potential (GWP). Crop variations and cultivation practices are two important factors affecting carbon sequestration and the exchange of greenhouse gases between soils and the atmosphere. This exchange has special characteristics in the freeze zone. In this paper, the impact of crop patterns and cultivation management (i.e., residue return rate, manure amendment, and chemical N fertiliser application) on SOC and GWP in an agricultural freeze zone was analysed. The Denitrification-Decomposition (DNDC) model was employed to predict the long-term dynamics of nitrous oxide (N2O), carbon dioxide (CO2) and methane (CH4) for diyland and paddy rice systems. The CO2-equivalent index was used to express the GWP response of N2O, CH4 and CO2. The simulated results indicated that the manure amendment and N fertiliser application can improve the SOC, increase crop production and enhance the GWP. The cultivation of returning residue to the soil is the win-win solution for SOC conservation and GWP control. It was found that paddy rice was preferable to dryland for sequestering atmospheric CO2 and mitigating global warming. This analysis also indicated that the DNDC model is a valid tool for predicting the consequences of SOC and GWP changes in cropland agroecosystems in the freeze zone. (C) 2012 Elsevier B.V. All rights reserved.
  • Authors:
    • Kuzyakov, Y.
    • Zhu, B.
    • Pausch, J.
    • Cheng, W.
  • Source: Soil Biology & Biochemistry
  • Volume: 57
  • Year: 2013
  • Summary: Living roots and their hizodeposits can stimulate microbial activity and soil organic matter (SOM) decomposition up to several folds. This so-called rhizosphere priming effect (RPE) varies widely among plant species possibly due to species-specific differences in the quality and quantity of rhizodeposits and other root functions. However, whether the RPE is influenced by plant inter-species interactions remains largely unexplored, even though these interactions can fundamentally shape plant functions such as carbon allocation and nutrient uptake. In a 60-day greenhouse experiment, we continuously labeled monocultures and mixtures of sunflower, soybean and wheat with C-13-depleted CO2 and partitioned total CO2 efflux released from soil at two stages of plant development for SOM- and root-derived CO2. The RPE was calculated as the difference in SOM-derived CO2 between the planted and the unplanted soil, and was compared among the monocultures and mixtures. We found that the RPE was positive under all plants, ranging from 43% to 136% increase above the unplanted control. There were no significant differences in RPE at the vegetative stage. At the flowering stage however, the RPE in the soybean-wheat mixture was significantly higher than those in the sunflower monoculture, the sunflower-wheat mixture, and the sunflower-soybean mixture. These results indicated that the influence of plant inter-specific interactions on the RPE is case-specific and phenology-dependent. To evaluate the intensity of inter-specific effects on priming, we calculated an expected RPE for the mixtures based on the RPE of the monocultures weighted by their root biomass and compared it to the measured RPE under mixtures. At flowering, the measured RPE was significantly lower for the sunflower wheat mixture than what can be expected from their monocultures, suggesting that RPE was significantly reduced by the inter-species effects of sunflower and wheat. In summary, our results clearly demonstrated that inter-species interactions can significantly modify rhizosphere priming on SOM decomposition. (C) 2012 Elsevier Ltd. All rights reserved.
  • Authors:
    • Zebarth, B.
    • Laganiere, J.
    • Angers, D. A.
    • Rochette, P.
    • Chantigny, M. H.
    • Pelster, D. E.
    • Goyer, C.
  • Source: Canadian Journal of Soil Science
  • Volume: 93
  • Issue: 4
  • Year: 2013
  • Summary: Freeze-thaw (FT) cycles stimulate soil nitrogen (N) and carbon (C) mineralization, which may induce nitrous oxide (N2O) emissions. We examined how soybean (Glycine max L.) and corn (Zea mays L.) residue incorporation affect N2O emissions from high C content (35 g kg(-1)) silty clay and low C content (19 g kg(-1)) sandy loam soils over eight 10-d FT cycles, as a function of three temperature treatments [constant at +1 degrees C (unfrozen control), +1 to -3 degrees C (moderate FT), or +1 to -7 degrees C (extreme FT)]. In unamended soils, N2O emissions were stimulated by FT, and were the highest with extreme FT. This was attributed to the increased NO3 availability measured under FT. Application of mature crop residues (C:N ratios of 75 for soybean and 130 for corn) caused rapid N immobilization, attenuating FT-induced N2O emissions in the silty clay. In the sandy loam, residue addition also induced immobilization of soil mineral N. However, N2O emissions under moderate FT were higher with than without crop residues, likely because N2O production in this low-C sandy loam was stimulated by C addition in the early phase of incubation. We conclude that FT-induced N2O emissions could be reduced through incorporation of mature crop residues and the subsequent immobilization of mineral N, especially in C-rich soils.
  • Authors:
    • Halberg, N.
    • Hermansen, J E.
    • Knudsen, M T.
    • Petersen, B M.
  • Source: Journal of Cleaner Production
  • Volume: 52
  • Year: 2013
  • Summary: Globally, soil carbon sequestration is expected to hold a major potential to mitigate agricultural greenhouse gas emissions. However, the majority of life cycle assessments (LCA) of agricultural products have not included possible changes in soil carbon sequestration. In the present study, a method to estimate carbon sequestration to be included in LCA is suggested and applied to two examples where the inclusion of carbon sequestration is especially relevant: 1) Bioenergy: removal of straw from a Danish soil for energy purposes and 2) Organic versus conventional farming: comparative study of soybean production in China. The suggested approach considers the time of the soil CO2 emissions for the LCA by including the Bern Carbon Cycle Model. Time perspectives of 20,100 and 200 years are used and a soil depth of 0-100 cm is considered. The application of the suggested method showed that the results were comparable to the IPCC 2006 tier I approach in a time perspective of 20 year, where after the suggested methodology showed a continued soil carbon change toward a new steady state. The suggested method estimated a carbon sequestration for the first example when storing straw in the soil instead of using it for bioenergy of 54, 97 and 213 kg C t(-1) straw C in a 200, 100 and 20 years perspective, respectively. For the conversion from conventional to organic soybean production, a difference of 32, 60 or 143 kg soil C ha(-1) yr(-1) in a 200,100 or 20 years perspective, respectively was found. The study indicated that soil carbon changes included in an LCA can constitute a major contribution to the total greenhouse gas emissions per crop unit for plant products. The suggested approach takes into account the temporal aspects of soil carbon changes by combining the degradation and emissions of CO2 from the soil and the following decline in the atmosphere. Furthermore, the results from the present study highlights that the choice of the time perspective has a huge impact on the results used for the LCA. For comparability with the calculation of the global warming potential in LCA, it is suggested to use a time perspective of 100 years when using the suggested approach for soil carbon changes in LCA. (C) 2013 Elsevier Ltd. All rights reserved.
  • Authors:
    • Rotz, C. A.
    • Mauzerall, D. L.
    • Kanter, D.
    • Gehl, R. J.
    • Bruulsema, T. W.
    • Robertson, G. P.
    • Williams, C. O.
  • Source: Biogeochemistry
  • Volume: 114
  • Issue: 1-3
  • Year: 2013
  • Summary: Agriculture in the United States (US) cycles large quantities of nitrogen (N) to produce food, fuel, and fiber and is a major source of excess reactive nitrogen (Nr) in the environment. Nitrogen lost from cropping systems and animal operations moves to waterways, groundwater, and the atmosphere. Changes in climate and climate variability may further affect the ability of agricultural systems to conserve N. The N that escapes affects climate directly through the emissions of nitrous oxide (N2O), and indirectly through the loss of nitrate (NO3 (-)), nitrogen oxides (NO (x) ) and ammonia to downstream and downwind ecosystems that then emit some of the N received as N2O and NO (x) . Emissions of NO (x) lead to the formation of tropospheric ozone, a greenhouse gas that can also harm crops directly. There are many opportunities to mitigate the impact of agricultural N on climate and the impact of climate on agricultural N. Some are available today; many need further research; and all await effective incentives to become adopted. Research needs can be grouped into four major categories: (1) an improved understanding of agricultural N cycle responses to changing climate; (2) a systems-level understanding of important crop and animal systems sufficient to identify key interactions and feedbacks; (3) the further development and testing of quantitative models capable of predicting N-climate interactions with confidence across a wide variety of crop-soil-climate combinations; and (4) socioecological research to better understand the incentives necessary to achieve meaningful deployment of realistic solutions.
  • Authors:
    • Moraes, O. L. L. de
    • Fontana, D. C.
    • Rodrigues, C. P.
    • Roberti, D. R.
  • Source: Revista Brasileira de Meteorologia
  • Volume: 28
  • Issue: 1
  • Year: 2013
  • Summary: The increasing on the greenhouse gases (GHG) emissions is today one of the main environmental problems, which can significantly affect human activities and land ecosystems. One of the main GHG is CO 2, which has been emitted indiscriminately due to the current lifestyle, as well as the intensification of agricultural activities. In this context, the objective of this investigation was to study the relationship between the spectral behavior of soybean during the crop cycle, using NDVI (Normalized Difference Vegetation Index), and the CO 2 fluxes, calculated by the eddy covariance method, generating information and methodology to investigate the carbon exchange in a soybean crop area in the State of Rio Grande do Sul, during the 2008/2009 soybean crop. For this, Landsat images 5 (TM), the phenological information and collected data from micrometeorological station throughout the development cycle of soybean were used. The results showed that the temporal pattern of CO 2 flux during the day was cyclical, showing negative values (capture) during daytime and positive values (liberation) at night. The global solar radiation determines the magnitude of the trapping of CO 2 by soybean, but the flow is modulated by the phenological stage of the crop. The photosynthetic activity of soybean plants is higher during the vegetative stage, coinciding to the higher incidence of solar radiation and the greater photosynthetic apparatus. The NDVI, obtained from Landsat images, is an indicator of the evolution of soybean biomass during the cycle. NDVI and negative CO 2 flow (capture) are correlated during the day. Therefore, remote sensing techniques show potentiality in generating of useful information on CO 2 exchange between the surface and atmosphere.
  • Authors:
    • Robertson, G.
    • Ruan, L.
  • Source: Global Change Biology
  • Volume: 19
  • Issue: 8
  • Year: 2013
  • Summary: Around 4.4 millionha of land in USDA Conservation Reserve Program (CRP) contracts will expire between 2013 and 2018 and some will likely return to crop production. No-till (NT) management offers the potential to reduce the global warming costs of CO2, CH4, and N2O emissions during CRP conversion, but to date there have been no CRP conversion tillage comparisons. In 2009, we converted portions of three 9-21ha CRP fields in Michigan to conventional tillage (CT) or NT soybean production and reserved a fourth field for reference. Both CO2 and N2O fluxes increased following herbicide application in all converted fields, but in the CT treatment substantial and immediate N2O and CO2 fluxes occurred after tillage. For the initial 201-day conversion period, average daily N2O fluxes (g N2O-Nha(-1)d(-1)) were significantly different in the order: CT (47.5 +/- 6.31, n=6)>> NT (16.7 +/- 2.45, n=6)>> reference (2.51 +/- 0.73, n=4). Similarly, soil CO2 fluxes in CT were 1.2 times those in NT and 3.1 times those in the unconverted CRP reference field. All treatments were minor sinks for CH4 (-0.69 +/- 0.42 to -1.86 +/- 0.37g CH4-Cha(-1)d(-1)) with no significant differences among treatments. The positive global warming impact (GWI) of converted soybean fields under both CT (11.5 Mg CO(2)eha(-1)) and NT (2.87 Mg CO(2)eha(-1)) was in contrast to the negative GWI of the unconverted reference field (-3.5 Mg CO(2)eha(-1)) with on-going greenhouse gas (GHG) mitigation. N2O contributed 39.3% and 55.0% of the GWI under CT and NT systems with the remainder contributed by CO2 (60.7% and 45.0%, respectively). Including foregone mitigation, we conclude that NT management can reduce GHG costs by 60% compared to CT during initial CRP conversion.
  • Authors:
    • Salokhe, V. M.
    • Taewichit, C.
    • Soni, P.
  • Source: Agricultural Systems
  • Volume: 116
  • Year: 2013
  • Summary: Farm mechanization has been progressively increasing in Thailand for the past decades. Consumption and abuse of energy intensive inputs, machinery and agro-chemicals is increasingly propagated into agricultural production systems. Effects of energy intensive input utilization and farm technologies are directly associated especially with farm economic and atmospheric issues. This warrants the need of energy input-output analyses coupled with its environmental dimension. This paper presents the energy input-output analyses of different agricultural activities and fresh pond-culture (polyculture), for which data were collected from 46 rainfed integrated agricultural production systems (IAPSs) of 281 farm plots surveyed. Total energy consumption including non-renewable energy input (NREI), direct and indirect energy input, and system efficiency are calculated and compared for different crops. Resource-wise energy input utilization and energy consumed by farm operations are also discussed for different crops. Further, this study simultaneously relates energy consumption in agricultural production systems associated with their corresponding greenhouse gases (GHGs) emission - presented in terms of total carbon dioxide equivalent (CO(2)e). Results reveal noticeable variations in energy consumption and CO(2)e emissions from various agricultural production activities. The study reveals that the maximum energy consumer is cassava (32.4 GJ ha(-1)). Major energy input consumption for all productions are indicated by fossil fuel (diesel oil) as fresh pond-culture depended on fish feed. Transplanted rice provides the highest CO(2)e emission (1112 kg CO(2)e ha(-1)) among crops, in which more than 50% is contributed by methane (CH4).