• 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:
    • Pessim de Oliveira, A.
    • Pereira, M.
    • Cunha dos Anjos, L.
    • Zuchello, F.
    • Chaves Soares, P.
  • Source: Agriculture Sciences
  • Volume: 31
  • Issue: 5
  • Year: 2015
  • Summary: Histosols are a natural reservoir of C in the soil, and their drainage followed by other farming practices leads to subsidence and soil organic matter transformations. The objective of this study was to evaluate the influence of use and management of Histosols, by means of: characterizing chemical and physical properties, and the content of SOM and humic fractions; and quantifying C and N stocks. In addition, to obtain preliminary data on greenhouse gas emissions (CO2, N2O) in Histosol areas with different agricultural practices. Three areas were selected with similar soil and environment, two in Macae municipality, under pasture, and with bean annual crop rotation, and the third in Santa Cruz, Rio de Janeiro city, cultivated with cassava (Manihot esculenta). The attributes evaluated were: physical - bulk density (BD), particle density (Dp), organic matter density (OMD), mineral matter (MM), mineral residue (MR), aggregate stability; and chemical - pH, exchangeable cations, soil organic matter (SOM), carbon in the humin (HUM-C), humic acid (HAF-C) and fulvic acid (FAF-C) fractions; stocks of C and N; and flux of CO2 and N2O. In general, the area cultivated with cassava had the highest values for exchangeable cations, as a result of fertilizer and soil management practices. The cassava site showed the highest values of BD and Dp; total volume of pores; MM, MR and OMD and higher degree of transformation of SOM; indicating higher alteration of Histosols properties under this usage. In all sites, the C levels indicated dominance of humin fraction. The SOM and C and N stocks were highest in the pasture, indicating preservation of organic matter, with values from 115.92 to 99.35Mg ha(-1) of C e 8.35 to 4.45 Mg ha(-1) for N. The values of CO2-C flux were within the range proposed by the IPCC, where the highest emission was 0.09 Mg CO2 ha(-1) day(-1) in the pasture site. The values of N2O-N flux were lower than proposed by the IPCC, with the highest value (270 g N2O-N m(-2) day(-1)) in the area under beans (crop rotation). In general, the multivariate analyses discriminated the sites and the pasture was the usage that least affected the Histosols properties.
  • 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:
    • Cisz, M.
    • Galdos, M.
    • Hilbert, J.
    • Rod, K.
    • Ferreira, A.
    • Leite, L.
    • Kaczmarek, D.
    • Chimner, R.
    • Resh, S.
    • Asbjornsen, H.
    • Scott, D.
    • Titus, B.
    • Gollany, H.
  • Source: Environmental Management
  • Volume: 56
  • Issue: 6
  • Year: 2015
  • Summary: Rapid expansion in biomass production for biofuels and bioenergy in the Americas is increasing demand on the ecosystem resources required to sustain soil and site productivity. We review the current state of knowledge and highlight gaps in research on biogeochemical processes and ecosystem sustainability related to biomass production. Biomass production systems incrementally remove greater quantities of organic matter, which in turn affects soil organic matter and associated carbon and nutrient storage (and hence long-term soil productivity) and off-site impacts. While these consequences have been extensively studied for some crops and sites, the ongoing and impending impacts of biomass removal require management strategies for ensuring that soil properties and functions are sustained for all combinations of crops, soils, sites, climates, and management systems, and that impacts of biomass management (including off-site impacts) are environmentally acceptable. In a changing global environment, knowledge of cumulative impacts will also become increasingly important. Long-term experiments are essential for key crops, soils, and management systems because short-term results do not necessarily reflect long-term impacts, although improved modeling capability may help to predict these impacts. Identification and validation of soil sustainability indicators for both site prescriptions and spatial applications would better inform commercial and policy decisions. In an increasingly inter-related but constrained global context, researchers should engage across inter-disciplinary, inter-agency, and international lines to better ensure the long-term soil productivity across a range of scales, from site to landscape.
  • Authors:
    • Pitombo, L.M.
    • Carmo, J.B.
    • Maria, I.C.
    • Andrade, C.A.
  • Source: Scientia Agricola
  • Volume: 72
  • Issue: 2
  • Year: 2015
  • Summary: The large volume of sewage sludge (SS) generated with high carbon (C) and nutrient content suggests that its agricultural use may represent an important alternative to soil carbon sequestration and provides a potential substitute for synthetic fertilizers. However, emissions of CH 4 and N 2O could neutralize benefits with increases in soil C or saving fertilizer production because these gases have a Global Warming Potential (GWP) 25 and 298 times greater than CO 2, respectively. Thus, this study aimed to determine C and N content as well as greenhouse gases (GHG) fluxes from soils historically amended with SS. Sewage sludge was applied between 2001 and 2007, and maize ( Zea mays L.) was sowed in every year between 2001 and 2009. We evaluated three treatments: Control (mineral fertilizer), 1SS (recommended rate) and 2SS (double rate). Carbon stocks (0-40 cm) were 58.8, 72.5 and 83.1 Mg ha -1 in the Control, 1SS and 2SS, respectively, whereas N stocks after two years without SS treatment were 4.8, 5.8, and 6.8 Mg ha -1, respectively. Soil CO 2 flux was highly responsive to soil temperature in SS treatments, and soil water content greatly impacted gas flux in the Control. Soil N 2O flux increased under the residual effects of SS, but in 1SS, the flux was similar to that found in moist tropical forests. Soil remained as a CH 4 sink. Large stores of carbon following historical SS application indicate that its use could be used as a method for carbon sequestration, even under tropical conditions.
  • Authors:
    • Santos, L.
    • Coelho, N. S.
    • Corral, T.
    • La Rovere, E. L.
    • Russell, J.
    • Cesano, D.
    • Burney, J.
  • Source: CLIMATIC CHANGE
  • Volume: 126
  • Issue: 1-2
  • Year: 2014
  • Summary: Climate models agree that semi-arid regions around the world are likely to experience increased rainfall variability and longer droughts in the coming decades. In regions dependent on agriculture, such changes threaten to aggravate existing food insecurity and economic underdevelopment, and to push migration to urban areas. In the Brazilian semi-arid region, the Sertao, farmers' vulnerability to climate-past, present, and future-stems from several factors, including low yielding production practices and reliance on scarce and seasonally variable water resources. Using interpolated local climate data, we show that, since 1962, in the Bacia do Jacuipe-one of the poorest regions in the Sertao of Bahia state-average temperatures have increased similar to 2 degrees C and rainfall has decreased similar to 350 mm. Over the same time period, average milk productivity-the main rural economic activity in the county-has fallen while in Brazil and in Bahia as a whole milk productivity has increased dramatically. This paper teases apart the drivers of climate vulnerability of the Bacia do Jacuipe in relation to the rest of Bahia. We then present the results of a suite of pilot projects by Adapta Sertao, a coalition of organizations working to improve the adaptive capacity of farmers living in the semi-arid region. By testing a number of different technologies and arrangements at the farm level, Adapta Sertao has shown that interventions focused on balanced animal diets and efficient irrigation systems can help reduce (but not eliminate) the dependence of production systems from climate. They are thus viable adaptation strategies that should be tested at a larger scale, with implications for semi-arid regions worldwide.
  • Authors:
    • Hartman, D. C.
    • Briedis, C.
    • Lal, R.
    • Tivet, F.
    • De Moraes Sá, J. C.
    • dos Santos, J. Z.
    • dos Santos, J. B.
  • Source: Soil & Tillage Research
  • Volume: 136
  • Year: 2014
  • Summary: No-till (NT) cropping systems have been widely promoted in many regions as an important tool to enhance soil quality and improve agronomic productivity. However, knowledge of their long-term effects on soil organic carbon (SOC) stocks and functional SOC fractions linking soil resilience capacity and crop yield is still limited. The aims of this study were to: (i) assess the long-term (16 years) effects of tillage systems (i.e., conventional - CT, minimum - MT, no-till with chisel - NTch, and continuous no-till cropping systems - CNT) on SOC in bulk soil and functional C fractions isolated by chemical (hot water extractable organic C - HWEOC, permanganate oxidizable C - POXC) and physical methods (light organic C - LOC, particulate organic C - POC, mineral-associated organic C - MAOC) of a subtropical Oxisol to 40cm depth; (ii) evaluate the soil resilience restoration effectiveness of tillage systems, and (iii) assess the relationship between the SOC stock enhancement and crop yield. The crop rotation comprised a 3-year cropping sequence involving two crops per year with soybean (Glycine max, L. Merril) and maize (Zea mays L.) in the summer alternating with winter crops. In 2005, the soil under CNT contained 25.8, 20.9, and 5.3Mgha-1 more SOC (P<0.006) than those under CT, MT, and NTch in 0-40cm layer, representing recovery rates of 1.61, 1.31, and 0.33Mg Cha-1yr-1, respectively. The relative C conversion ratio of 0.398 at CNT was more efficient in converting biomass-C input into sequestered soil C than NTch (0.349), MT (0.136), and CT (0.069). The soil under CNT in 0-10cm depth contained ~1.9 times more HWEOC and POXC than those under CT (P<0.05), and concentrations of LOC and POC physical fractions of SOC were significantly higher throughout the year under CNT. Considering CT as the disturbance baseline, the resilience index (RI) increased in the order of MT (0.10)<NTch (0.43)<CNT (0.54). Grain yield was positively affected by increase in SOC stock, and an increase of 1Mg Cha-1 in 0-20cm depth resulted in an increase in yield equal to ~11 and 26kg grainha-1 of soybean (R2=0.97, P=0.03) and wheat (R2=0.96, P=0.03), respectively. The data presented emphasizes the role of labile fractions in the overall SOC accumulation processes in soils managed under CNT and their positive impacts on the soil resilience restoration and on agronomic productivity. © 2013 Elsevier B.V.
  • Authors:
    • Balarezo Giarola, N.
    • Tormena, C.
    • Ball, B.
    • da Silva, A.
    • Locks Guimaraes, R.
  • Source: Scientia Agricola
  • Volume: 71
  • Issue: 2
  • Year: 2014
  • Summary: No-tillage in Brazil is an efficient agricultural system that improves crop productivity whilst controlling erosion caused to the soil by degradation. However, there is some concern regarding soil compaction. Our objective was to determine whether the function of soil structure in sustaining crop growth was dependent on row and interrow positions in long-term no-tillage. We took soil samples from a field in a commercial farm under long-term no-tillage since 1979 on a clayey Oxisol in Southern Brazil. We assessed soil physical quality using the revised Peerlkamp technique and measured bulk density, air-filled porosity and air permeability of intact soil cores. Samples were incubated to assess in vitro N2O and CO2 production. The soil physical and structural properties showed consistent differences between interrow and row positions, where the properties measured were more favorable. The revised Peerlkamp technique proved as efficient as quantitative parameters in discriminating treatment differences. Overall, soil physical conditions in the interrow were less favourable than in the row. Pore continuity did not vary as regards position. This may explain why row position did not influence in vitro N2O and CO2 production. Soil physical quality under no-tillage system is enhanced, at least in the short term, by superficial disturbances in the row as a result of the action of the coulters of the no-tillage seeder.
  • 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.