• Authors:
    • Banger,Kamaljit
    • Tian,Hanqin
    • Tao,Bo
    • Ren,Wei
    • Pan,Shufen
    • Dangal,Shree
    • Yang,Jia
  • Source: Climatic Change
  • Volume: 132
  • Issue: 4
  • Year: 2015
  • Summary: India is very important but relatively unexplored region in terms of carbon studies, where significant environmental changes have occurred in the 20th century that can alter terrestrial net primary productivity (NPP). Here, we used a process-based, Dynamic Land Ecosystem Model (DLEM), driven by land cover and land use change (LCLUC), climate change, elevated atmospheric CO2 concentration, atmospheric nitrogen deposition (NDEP), and tropospheric ozone (O-3) pollution to estimate terrestrial NPP in India during 1901-2010. Over the country, terrestrial NPP showed significant inter-annual variations ranging 1.2 Pg C year(-1) to 1.7 Pg C year(-1) during the 1901-2010. Overall, multiple environmental changes have increased terrestrial NPP by 0.23 Pg C year(-1). Elevated atmospheric CO2 concentration has increased NPP by 0.29 Pg C; however climate change has offset a portion of terrestrial NPP (0.11 Pg C) during this study period. On an average, terrestrial NPP reduced by 0.12 Pg C year(-1) in drought years; when precipitation was 100 mm year(-1) lower than long term average, suggesting that terrestrial carbon cycle in India is strongly linked to climate change. LCLUC, including land conversions and cropland management practices, increased terrestrial NPP by 0.043 Pg C year(-1) over the country. Tropospheric O-3 pollution reduced terrestrial NPP by 0.06 Pg C year(-1) and the decrease was comparatively higher in croplands than other biomes after the 1980s. Our results have shown that climate change and tropospheric O-3 pollution may partially offset terrestrial NPP increase caused by elevated CO2 concentration, LCLUC, and NDEP over India.
  • Authors:
    • Kambauwa,Gertrude
    • Mlamba,James
    • Delgado,Jorge A.
    • Kabambe,Vernon
  • Source: Journal of Soil and Water Conservation
  • Volume: 70
  • Issue: 5
  • Year: 2015
  • Authors:
    • Ashworth,A. J.
    • West,C. P.
    • Allen,F. L.
    • Keyser,P. D.
    • Weiss,S. A.
    • Tyler,D. D.
    • Taylor,A. M.
    • Warwick,K. L.
    • Beamer,K. P.
  • Source: Agronomy Journal
  • Volume: 107
  • Issue: 6
  • Year: 2015
  • Summary: Biological N 2 fixation (BNF) via legume intercrops can provide an alternative to inorganic N fertilizer and thereby minimize the economic and environmental costs of bioenergy feedstock and forage production. The objectives of this study were to (i) verify switchgrass ( Panicum virgatum L.) as a non-N 2-fixing reference plant for distinguishing between soil- and atmosphere-derived N; (ii) determine BNF levels via the 15N enrichment method for one cool-season legume (red clover [ Trifolium pratense L.]) and three warm-season legumes ([partridge pea] [ Chamaecrista fasciculate Michx.], sunn hemp [ Crotalaria juncea L.], and pigeonpea [ Cajanus cajan (L.) Millsp.]) when intercropped into switchgrass and a near relative, guineagrass ( Panicum maximum L.); and (iii) evaluate the validity of the N-difference method by comparing it against the 15N enrichment technique in humid temperate and semiarid tropical climates. The results revealed little difference in the N assimilation rates of legume and non-N 2-fixing reference plants, suggesting that switchgrass is an appropriate reference species. Annual fixation for red clover was greatest, followed by partridge pea, and lastly sunn hemp in temperate systems (87, 84, and 35 kg ha -1, respectively), all of which tended to supply greater amounts of N in subsequent seasons. Considerably greater BNF occurred in tropical intercrop systems (exceeding 240 kg ha -1). Consequently, the BNF of selected legumes approximates or exceeds recommended N fertilizer rates (67 kg N ha -1) in both humid temperate and semiarid tropical pasture and feedstock systems. The N-difference method did not provide estimates for BNF that were comparable to 15N-enrichment-derived values ( P>0.05).
  • Authors:
    • Nhung, N.
  • Source: Journal
  • Volume: 20
  • Issue: 6
  • Year: 2015
  • Summary: Enhancing carbon sequestration is crucial to mitigate rising global levels of greenhouse gases, and for developing countries, carbon sequestration may also provide economic benefits via international carbon trading schemes. This study aimed to determine the optimal management strategy for tropical planted forests when timber and carbon sequestration are valued. The survey data were collected from 291 household foresters, who were growing Eucalyptus urophylla and Acacia mangium in Yen Bai Province, Vietnam. The regression exercise suggests that financial status was negatively correlated with forest management practices, and ethnicity and financial status were correlated with carbon sequestration management. The survey results suggest that the mean rotation age employed by household foresters is five years. However, the optimization modelling suggests that the optimal rotation age for maximizing net present value is greater than nine years. The differences between current practices and optimal practices therefore favour a role for government policy interventions.
  • Authors:
    • Okoth, S. A.
    • Wachira, P. M.
    • Matiru, V. N.
    • Muthuri, C. W.
    • Jefwa, J. M.
    • Nyaga, J.
  • Source: Article
  • Volume: 103
  • Issue: 2
  • Year: 2015
  • Summary: Several interrelated and site-specific agronomic factors ranging from agroecological conditions to systems management practices have been shown to variably affect arbuscular mycorrhizal fungi (AMF) diversity in the soil. Also, there have been various attempts in the past to evaluate the potential of AMF field inoculation but a majority focussed on the use of exotic strains, disregarding the potential of the existing naturally occurring strains. In an attempt to address these problems, our study aimed to develop 'best-bet practice' based on soil fertility amendment practice (SFAP) that encourages occurrence and diversity of AMF in the soil. Control treatment (no application) was compared with three (3) SFAP used singly or in combination with AMF or two other soil nutrients enhancing organisms (Bacillus and Trichoderma) which included the following: (1) Mavuno (macro- and micronutrients and secondary nutrients) fertilizer, (2) calcium ammonium nitrate (CAN) plus triple super phosphate (TSP) and (3) cattle manure. Maize (Zea mays L.) and common bean (Phaseoli vulgaris L.) were planted at on-station and on-farm plots for two consecutive cropping seasons with the experiment replicated in two benchmark sites of Embu and Taita-Taveta Districts. Embu site recorded a lower soil pH and also very low phosphorus levels compared to Taita site. The number of AMF spores per kg of soil was very low, ranging from 30 to 100, at Embu in the first season and application of SFAP resulted in no significant difference. However, in the second season, use of Trichoderma + CAN plus TSP was shown to significantly stimulate AMF species in the soil, with a 250 % increase in species density compared to use of Bacillus + Manure. At Taita, after the first cropping season, significant change in spore density was only recorded from AMF applied singly with a 66.1 % increase in spore density compared to Control treatment. In comparison, after the second cropping season, use of AMF applied singly, AMF + CAN plus TSP and AMF + Manure increased spore density by 135.4, 109.6 and 100 % respectively compared to Control treatment. Use of AMF applied singly increased species density in the soil by 100 and 81.1 % compared to CAN plus TSP and Trichoderma treatments respectively after first season at Taita site: while after the second cropping season, application of AMF + CAN plus TSP, AMF + Manure and AMF + Mavuno increased AMF species density in the soil by 60.3, 51.5 and 55.9 % respectively compared to Control treatment. These findings provide evidence that it is possible to increase the number of AMF spores in the soil through inoculation with native species and also possibly stimulate dormant species through other SFAP treatments.
  • Authors:
    • Rathmann, R.
    • Soria, R.
    • Portugal-Pereira, J.
    • Schaeffer, R.
    • Szklo, A.
  • Source: Article
  • Volume: 81
  • Year: 2015
  • Summary: This study aims to quantify the environmentally sustainable and economically feasible potentials of agricultural and agro-industrial residues to generate electricity via direct combustion in centralised power plants in Brazil. Further, the energy savings and greenhouse gas (GHG) reduction potential of replacing natural gas-based electricity by bioenergy have been assessed. To this end, a methodology has been developed based on an integrated evaluation, incorporating statistical and geographical information system (GIS)-based analysis, and a life-cycle-assessment approach. Results reveal that the environmentally sustainable generation potential is nearly 141 TWh/year, mainly concentrated in the South, Southeast, and Midwest regions of the country. Sugarcane, soybean and maize crop residues are the major feedstocks for available bioenergy. On the other hand, the economic potential is far lower, accounting to 39 TWh/year. The total GHG mitigation is nearly 18 million tonne CO 2e and could reach 64 million tonne CO 2e yearly, if the technical potential is considered. The gap between technical and economic potentials implies that constraints to bioenergy are not related to a lack of resources, but rather associated to economic, logistical, regulatory and political barriers.
  • Authors:
    • Davies, C.
    • Oliveira, D.
    • Cerri, C.
    • Franco, A.
    • Cherubin, M.
    • Cerri, C.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 211
  • Year: 2015
  • Summary: Land use change (LUC) in Brazil for sugarcane ethanol production has raised concerns about its potential environmental impacts. Soil quality is a key indicator to infer about the environmental sustainability of Brazilian ethanol production. Our objective was to quantify the effects of the most common LUC sequence associated with sugarcane expansion ( i.e., native vegetation to pasture to sugarcane) on chemical attributes in tropical soils. Soil sampling was carried out in three study sites located in central-southern Brazil, primary sugarcane region of production and expansion of the world. Overall, long-term conversions from natural ecosystems to extensive pasturelands decreases available P, S, Ca, Mg and B contents. In addition, the LUC leads to soil acidification and decreases of CEC pH7, indicating that pasturelands have poor soil chemical quality. The LUC from pasture to sugarcane increases soil nutrient levels and reduces the soil acidity due to inputs of lime and fertilizers. Despite that, increments of available P and base saturation are necessary to achieve ideal soil chemical conditions to sugarcane growth. Overall, our findings suggest that sugarcane expansion in Brazil replacing pasturelands will promotes improvements on soil chemical quality. Nevertheless, sugarcane expansion can be associated with management strategies to increase soil organic matter and improve the soil fertility, reducing the environmental and economic costs associated with ethanol production in Brazil.
  • Authors:
    • Gomes, T.
    • Lins, S.
    • Mardegan, S.
    • Do Carmo, J.
    • Filoso, S.
    • Martinelli, L.
  • Source: Renewable and Sustainable Energy Reviews
  • Volume: 52
  • Year: 2015
  • Summary: The potential for sugarcane ethanol from Brazil to mitigate GHG emissions is undeniable, but the way that ethanol is produced during the agricultural and industrial phases will ultimately determine its benefits to society. In this paper, we evaluate the environmental impacts of sugarcane agriculture and ethanol production in Brazil as management practices continue to change and production expands to new frontiers. We focused our evaluation on the impacts on water, atmosphere, and soils, including how the application of organic and inorganic fertilizers and the accumulation of crop residue in the field affect emissions of greenhouse gases (GHG). We also addressed the impacts of land use changes on threatened biomes and discussed some of the present obstacles regarding conservation and restoration efforts. We concluded that, since a similar assessment was put forth in 2008, our knowledge about the environmental impacts of sugarcane ethanol in Brazil has advanced with regard to soil degradation, nitrogen dynamics, and soil carbon stocks. However, more information is still needed about the impacts of the increasing use of pesticides, herbicides, and fertilizers in sugarcane agriculture, especially on water resources. Furthermore, without a better understanding about how landscape fragmentation affects the biodiversity of terrestrial and aquatic tropical ecosystems and the services they provide, policies created to protect and restore them may be ineffective. On the other hand, the use of presently available scientific information to end unsustainable farming and the implementation of conservation strategies proposed by the Brazilian Forest Code could be a first step to guarantee that ethanol is produced more sustainably in Brazil. © 2015 Elsevier Ltd.
  • Authors:
    • Olalde-Portugal, V.
    • Luna-Guido, M.
    • Hernandez-Valdez, E.
    • Manuel Ruiz-Valdiviezo, V.
    • del Rosario Cardenas-Aquino, M.
    • Aguilar-Chavez, A.
    • Diaz-Rojas, M.
    • Dendooven, L.
  • Source: Applied Soil Ecology
  • Volume: 73
  • Year: 2014
  • Summary: Agriculture is an important source of greenhouse gases (GHG), mostly carbon dioxide (CO2), nitrous oxide (N2O) and methane (CH4). Application of charcoal to agricultural soils is known to reduce GHG emissions while application of fertilizer or wastewater sludge increases them. Therefore, the objective of this work was to study the effect of charcoal application on GHG emissions from soil planted with wheat (Triticum aestivum L.) and amended with wastewater sludge or urea, or left unamended. Wheat fertilized with urea or wastewater sludge, at a rate of 150 kg N ha(-1), was cultivated in soil amended with or without 2% (w/w) charcoal, a biochar used mostly for heating, in a greenhouse. Emission of CO2, CH4 and N2O, soil characteristics and plant development were monitored. Charcoal had no significant effect on the emission of CO2, CH4 and N2O in wastewater sludge or urea-amended soil. The wheat development and yields, and soil pH and electrolytic conductivity were also not affected by charcoal application. It was found that charcoal did not affect the emissions of the monitored GHG, wheat or soil characteristics. (C) 2013 Elsevier B.V. All rights reserved.
  • Authors:
    • Perluss, P.
    • Drouvot, H.
    • Drouvot, C.
  • Source: International Journal of Sustainable Development
  • Volume: 17
  • Issue: 1
  • Year: 2014
  • Summary: With the objective to offer contributions to resolve ecological, social and economic problems in Amazonia, Brazil's sustainable production of palm oil legislation has the specific goal of mobilising public administrations, private business, social aid agencies and family farmers with the following overall objectives: create employment and increase income by means of palm cultivation; reforest degraded lands in the Amazon (Margulis, 2004); contribute to carbon storage with the goal of reducing greenhouse gases; and induce family farmers to participate in the programme and thus favour their social inclusion. The study is based on information from documentary research undertaken to identify and a series of regionally-based interviews. Our research reveals that the national programme has mobilised a range of stakeholders (governments, firms, universities and NGOs) and small farmers' associations.