Embrapa Agrobiologia


Embrapa Agrobiologia

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Isernhagen I.,Embrapa Agrossilvipastoril | Moraes L.F.D.,Embrapa Agrobiologia | Engel V.L.,São Paulo State University
Restoration Ecology | Year: 2017

As ecological restoration is gaining importance worldwide, researchers, practitioners, and interested people are beginning to self-organize, in order to exchange knowledge and experiences in this growing area. Latin America has recently shown some examples, and the Brazilian Network for Ecological Restoration (REBRE) is one of them. Working on a nonhierarchical basis, its members, some of whom are important actors in the proposing and implementing of public policies, are able to freely express their doubts and share experiences, thereby contributing to legislative improvements, developing relevant restoration initiatives, and adopting novel approaches and paradigms. Through its three main communication platforms (website, Google Groups, and Facebook), REBRE has reached more than 2,300 members, and although a more equitable distribution through Brazilian regions should still be reached, it is gradually becoming stronger and more representative. In this scenario, REBRE will act with its branch organization, SOBRE (Brazilian Society for Ecological Restoration), to host the next Society for Ecological Restoration Conference, to be held in Brazil, in 2017, exchanging relevant experiences and welcoming restorationists from all over the world. © 2017 Society for Ecological Restoration

Fernandes M.F.,Embrapa Tabuleiros Costeiros | Chaer G.M.,Embrapa Agrobiologia
Plant and Soil | Year: 2012

Aims: Over a 2 year period, we compared the soil biological functioning (SBF) of Cerrado physiognomies ranging from grassland-savannic to forest formations, sampling in the middle of the dry and rainy seasons. Methods: Soil samples were collected at two depths (0 to 5 cm and 5 to 20 cm) under the following physiognomies: Campo Sujo, Cerrado Ralo, Cerrado sensu stricto, Cerradão and Mata de Galeria. The SBF was represented by the simultaneous analyses of microbial biomass carbon, soil basal respiration and the activity of enzymes linked to the C, P and S cycles (β-glucosidase, acid phosphatase and arylsulfatase, respectively). Results: The results demonstrated that Cerrado physiognomies are a major determinant of SBF patterns. The forest-like physiognomies (Mata de Galeria and Cerradão) presented the highest biomass and activity compared to the grassland (Campo Sujo) and savanna physiognomies (Cerrado Ralo and Cerrado sensu stricto). These differences were more evident in the topsoil layer (0 to 5 cm), and the seasonal effect on the SBF of the Mata de Galeria and Cerradão was more pronounced than on the other physiognomies. Conclusions: These results provide a benchmark for evaluating changes in SBF and related processes in Cerrado areas due to shifts toward agriculture and cattle production. © 2012 Springer Science+Business Media B.V.

De Carvalho F.,Federal University of Minas Gerais | de Souza F.A.,Embrapa Milho e Sorgo Nucleo de Biologia Aplicada | Carrenho R.,State University of Maringá | Moreira F.M.D.S.,Federal University of Lavras | And 2 more authors.
Applied Soil Ecology | Year: 2012

The high diversity in rupestrian field vegetation has been attributed to the mosaic of environments formed by several soil classes, rugged relief and microclimatic variation. Although advances in the knowledge of some biological areas in rupestrian fields have been made, little is known about the relevance of soil microorganisms and their relationships with the vegetation. Symbiosis with arbuscular mycorrhizal fungi (AMF) is one of the most studied interactions between microorganisms and plants, because they are ubiquitous and contribute to the sustainability of ecosystems. This study aimed to investigate the occurrence and diversity of AMF species and to evaluate their relationship with soil physicochemical attributes and plant diversity in different habitats of the rupestrian fields from the Cadeia do Espinhaço, Serra do Cipó, Brazil. These rupestrian fields were delimited into five distinct habitats: rock outcrop, quartz gravel fields, sandy bogs, peat bogs and the Cerrado. Forty-nine AMF species were identified as belonging to nine families and twelve genera. Among them, Acaulospora colossica and Pacispora dominikii were found for the first time in Brazil. The results of this study suggest that the diversity of AMF is related to the heterogeneity of habitats and that the soil texture (coarse sand, gravel and silt) is better related to the structure of these fungi communities than to the soil chemical attributes. Plant species richness was related to AMF richness only in the quartz gravel field, rocky outcrop, and sandy bog habitats. Considering these habitats constitute one of the most menaced ecosystems on the planet, our survey provides information to improve knowledge about rupestrian field biodiversity, thus supporting policy actions for its conservation and preservation. © 2011 Elsevier B.V.

da Silva R.F.,State University of Mato Grosso do Sul | de Fatima Guimaraes M.,State University Londrina | de Aquino A.M.,Embrapa Agrobiologia | Mercante F.M.,Embrapa Agropecuaria Oeste
Pesquisa Agropecuaria Brasileira | Year: 2011

The objective of this work was to evaluate the effects of the integrated crop-livestock system on the morphological, physical and biological properties of soil. The experiment was carried out in Dourados, Mato Grosso do Sul State, Brazil, in a typic Hapludox soil. The following systems were sampled: grain crop under conventional soil tillage system, integrated crop-livestock system under no-tillage, continuous Urochloa decumbens (Syn. Brachiaria decumbens) pasture and natural system. In each system, a trench was opened in order to detect morphological changes caused by different management, using the cultural profile method. Assessments of soil macroinvertebrates were done according to the method Tropical Soil Biology and Fertility. Undisturbed soil samples were also used to assess the physical attributes of soil (soil density, total porosity, macro and microporosity). Among the cultivated systems, better soil structure was observed in the integrated crop-livestock system, in the layers 0.0.1 and m. The systems under crop-livestock and pasture continuously cultivated favored a more biologically active soil environment, among the other agricultural systems. The visualization of soil attributes showed that crop-livestock integration is a promising strategy to develop sustainable production systems and that the period of two years of management is considered suitable for crop-pasture rotation.

Ferreira D.A.,Federal University of Goais | Carneiro M.A.C.,UFG | Saggin Jr. O.J.,Embrapa Agrobiologia
Revista Brasileira de Ciencia do Solo | Year: 2012

The alterations in the communities of arbuscular mycorrhizal fungi (AMF) induced by changes in land use and different agricultural uses are still insufficiently studied, particularly in the Cerrado biome. This study evaluated how human interference by management and land use change affect the AMF density and diversity in a Cerrado Oxisol. The study evaluated five areas: Riparian Forest (MC), Riparian Forest Edge (BM), Pasture (Past), no-till monoculture (PD) and Riparian Deforested Area (AD). In each area, 20 plots of 250 m2 were marked. Within each plot, 10 subsamples were randomly collected to form a composite soil sample. The density and diversity of AMF spores, by morphological characteristics, were determined for each composite sample. In the PD and AD areas, the density of recovered spores and mycorrhizal colonization were lower than in the other areas due to the low density of living plants. The AMF families with highest abundance in the study areas were Acaulosporaceae, Glomeraceae and Gigasporaceae, the first two dominant in the areas with leass anthropogenic influence MC and BM. The most frequent AMF species were Acaulospora scrobiculata, Glomus macrocarpum and Acaulospora tuberculata, of which the first two appeared in all areas and the third was absent only in PD. These species have great capacity to adapt to changing environments. The occurrence of the species Acaulospora rehmii, Acaulospora sp.3, Glomus etunicatum, Glomus tortuosum, Glomus sp.1, Gigaspora sp.2 and Scutellospora heterogama was low, and were recovered in only one of the study areas. The area with highest density and species occurrence was Past with 414 spores (individuals) and 11 AMF species. The highest and lowest Shannon diversity (H') index were calculated for Past and BM, respectively. Principal component analysis indicated the formation of three groups, the first with MC and BM, the second with PD and AD and the third with only Past. It was concluded that land use changes modify the AMF community, which may increase spore density and diversity, as in the case of Pasture, or reduced, in the case of deforestation.

de Morais R.F.,Federal Rural University of Rio de Janeiro | Boddey R.M.,Embrapa Agrobiologia | Urquiaga S.,Embrapa Agrobiologia | Jantalia C.P.,Embrapa Agrobiologia | Alves B.J.R.,Embrapa Agrobiologia
Soil Biology and Biochemistry | Year: 2013

Promising renewable fuels such as elephant grass in Brazil are under critical examination with reference to greenhouse gases (GHGs) produced during the production phase, especially with regard to the impact of nitrous oxide (N2O) emissions. The objective of this field study was to examine the impact of N fertilization on biomass yield, plant N accumulation, emissions of N2O and ammonia (NH3) volatilization grown on an Acrisol typical of large regions of the Atlantic coast of Brazil over a period of 618 days, covering three growth cycles of elephant grass with three harvests. The tillage required for planting the crop produced emissions of N2O totalling 726g N2O-Nha-1, representing approximately 0.6% of the mineralized N as estimated from the soil CO2 emission. Reduction in tillage operations prior to planting would reduce N2O emissions and preserve soil C stocks. There was only a small response of biomass production to additions of urea fertilizer which may be related to the high loss of fertilizer N. Fertilizer induced N2O emissions were 173, 410 and 705g N2O-Nha-1 for each growth cycle, respectively, equivalent to a mean emission factor (EF) of 0.51% with a confidence interval of 0.35-0.73%, almost half of the IPCC default EF of 1.0%. Ammonia volatilization losses were high, amounting to a mean of 49% of applied urea N, which is fivefold the IPCC default value (10%) and may indicate that indirect N2O emissions are currently underestimated. © 2013 Elsevier Ltd.

Estrada G.A.,Federal Rural University of Rio de Janeiro | Baldani V.L.D.,Embrapa Agrobiologia | de Oliveira D.M.,Federal Rural University of Rio de Janeiro | Urquiaga S.,Embrapa Agrobiologia | Baldani J.I.,Embrapa Agrobiologia
Plant and Soil | Year: 2013

Background and Aims: Plant growth-promoting bacteria, mainly diazotrophs and phosphate solubilizers, can reduce the use of chemical fertilizers for rice crops. Here, diazotrophic bacteria isolated from rice were screened for their ability to solubilize inorganic P (Pi) in vitro and in association with rice plants cultivated in pots. Methods: Forty-nine isolates were tested for the ability to solubilize Pi on NBRIP and GL agar plate media and seven selected strains were further evaluated in NBRIP liquid medium. Three of these strains were inoculated in rice plants grown in soil pots containing 15N-labeled fertilizer and two sources of P: tricalcium phosphate (TCP) or simple superphosphate (SSP). The dry matter, yield, N, P, and the 15N content accumulated in plant tissues were measured at 135 days after planting. Results: Seven strains belonging to the genera Herbaspirillum and Burkholderia formed a halo of solubilized Pi on agar plates. The Burkholderia strains showed peak soluble P (around 200 mg P L-1) on the fifth day when grown in NBRIP liquid medium for 14 days. Inoculation of Herbaspirillum strains (H18, ZA15) and a Burkholderia vietaminensis strain (AR114) increased rice grain yield from 33 to 47 % with TCP and 18 to 44 % with TSS, respectively. The bacterial inoculation led to enhanced N-use efficiency of the 15N-labeled fertilizer. Conclusion: These results suggest that the selection and use of P-solubilizing diazotrophic bacteria are a good strategy to promote P solubilization and/or N use efficiency in rice plants. © 2012 Springer Science+Business Media Dordrecht.

dos Reis Martins M.,Embrapa Agrobiologia | Angers D.A.,Agriculture and Agri Food Canada
Geoderma | Year: 2015

Sequestration of atmospheric carbon (C) and erosion prevention are two ecosystem services that can be provided by plants through their impact on soil aggregation and organic matter. We propose a conceptual model aimed at generalizing the effect of plant material decomposition on C sequestration and soil water-stable macroaggregation (WSMA). We characterized plant material mineralization using a first order exponential plus linear equation in which parameter b describes the mineralization rate of the labile C pool, followed by a low mineralization rate of the non-labile C pool (parameter k). We propose that there are two selected types of plant materials that have differential positive effects on soil organic C (SOC) or soil WSMA: type-. B and type-. K plant materials. During decomposition in soil, type-. B plant materials present a high b parameter followed by low k and have a positive effect on SOC, whereas type-. K plant materials show an inverse mineralization pattern and favor longevity of soil WSMA. In our field and laboratory experiments, the model for type-. B plant material was pigeon pea [. Cajanus cajan (L.) Millsp.] which was characterized by high lignin and N contents, and the model for type-. K plant material was mature corn (. Zea mays L.) residue which contained high levels of pentoses, the main component of hemicellulose. According to this model, type-. B plants would be adequate in strategies aiming primarily at soil C sequestration, while type-. K would be more appropriate in reducing a soil's susceptibility to physical degradation. Cropping or reclamation systems involving both plant types would contribute to both ecosystem services. © 2014.

Jensen E.S.,Swedish University of Agricultural Sciences | Peoples M.B.,CSIRO | Boddey R.M.,Embrapa Agrobiologia | Gresshoff P.M.,Embrapa Agrobiologia | And 3 more authors.
Agronomy for Sustainable Development | Year: 2012

Humans are currently confronted by many global challenges. These include achieving food security for a rapidly expanding population, lowering the risk of climate change by reducing the net release of greenhouse gases into the atmosphere due to human activity, and meeting the increasing demand for energy in the face of dwindling reserves of fossil energy and uncertainties about future reliability of supply. Legumes deliver several important services to societies. They provide important sources of oil, fiber, and protein-rich food and feed while supplying nitrogen (N) to agro-ecosystems via their unique ability to fix atmospheric N2 in symbiosis with the soil bacteria rhizobia, increasing soil carbon content, and stimulating the productivity of the crops that follow. However, the role of legumes has rarely been considered in the context of their potential to contribute to the mitigation of climate change by reducing fossil fuel use or by providing feedstock for the emerging biobased economies where fossil sources of energy and industrial raw materials are replaced in part by sustainable and renewable biomass resources. The aim of this review was to collate the current knowledge regarding the capacity of legumes to (1) lower the emissions of the key greenhouse gases carbon dioxide (CO2) and nitrous oxide (N2O) compared to N-fertilized systems, (2) reduce the fossil energy used in the production of food and forage, (3) contribute to the sequestration of carbon (C) in soils, and (4) provide a viable source of biomass for the generation of biofuels and other materials in future biorefinery concepts. We estimated that globally between 350 and 500 Tg CO2 could be emitted as a result of the 33 to 46 Tg N that is biologically fixed by agricultural legumes each year. This compares to around 300 Tg CO2 released annually from the manufacture of 100 Tg fertilizer N. The main difference is that the CO2 respired from the nodulated roots of N2-fixing legumes originated from photosynthesis and will not represent a net contribution to atmospheric concentrations of CO2, whereas the CO2 generated during the synthesis of N fertilizer was derived from fossil fuels. Experimental measures of total N2O fluxes from legumes and N-fertilized systems were found to vary enormously (0.03-7.09 and 0.09-18.16 kg N2O-N ha?1, respectively). This reflected the data being collated from a diverse range of studies using different rates of N inputs, as well as the large number of climatic, soil, and management variables known to influence denitrification and the portion of the total N lost as N2O. Averages across 71 site-years of data, soils under legumes emitted a total of 1.29 kg N2O-N ha?1 during a growing season. This compared to a mean of 3.22 kg N2O-N ha?1 from 67 site-years of N-fertilized crops and pastures, and 1.20 kg N2O-N ha?1 from 33 site-years of data collected from unplanted soils or unfertilized nonlegumes. It was concluded that there was little evidence that biological N2 fixation substantially contributed to total N2O emissions, and that losses of N2O from legume soil were generally lower than N-fertilized systems, especially when commercial rates of N fertilizer were applied. Elevated rates of N2O losses can occur following the termination of legume-based pastures, or where legumes had been green-or brown-manured and there was a rapid build-up of high concentrations of nitrate in soil. Legume crops and legume-based pastures use 35% to 60% less fossil energy than N-fertilized cereals or grasslands, and the inclusion of legumes in cropping sequences reduced the average annual energy usage over a rotation by 12% to 34%. The reduced energy use was primarily due to the removal of the need to apply N fertilizer and the subsequently lower N fertilizer requirements for crops grown following legumes. Life cycle energy balances of legume-based rotations were also assisted by a lower use of agrichemicals for crop protection as diversification of cropping sequences reduce the incidence of cereal pathogens and pests and assisted weed control, although it was noted that differences in fossil energy use between legumes and Nfertilized systems were greatly diminished if energy use was expressed per unit of biomass or grain produced. For a change in land use to result in a net increase C sequestration in soil, the inputs of C remaining in plant residues need to exceed the CO2 respired by soil microbes during the decomposition of plant residues or soil organic C, and the C lost through wind or water erosion. The net N-balance of the system was a key driver of changes in soil C stocks in many environments, and data collected from pasture, cropping, and agroforestry systems all indicated that legumes played a pivotal role in providing the additional organic N required to encourage the accumulation of soil C at rates greater than can be achieved by cereals or grasses even when they were supplied with N fertilizer. Legumes contain a range of compounds, which could be refined to produce raw industrial materials currently manufactured from petroleum-based sources, pharmaceuticals, surfactants, or food additives as valuable by-products if legume biomass was to be used to generate biodiesel, bioethanol, biojet A1 fuel, or biogas. The attraction of using leguminous material feedstock is that they do not need the inputs of N fertilizer that would otherwise be necessary to support the production of high grain yields or large amounts of plant biomass since it is the high fossil energy use in the synthesis, transport, and application of N fertilizers that often negates much of the net C benefits of many other bioenergy sources. The use of legume biomass for biorefineries needs careful thought as there will be significant trade-offs with the current role of legumes in contributing to the organic fertility of soils. Agricultural systems will require novel management and plant breeding solutions to provide the range of options that will be required to mitigate climate change. Given their array of ecosystem services and their ability to reduce greenhouse gas emissions, lower the use of fossil energy, accelerate rates of C sequestration in soil, and provide a valuable source of feedstock for biorefineries, legumes should be considered as important components in the development of future agroecosystems. © INRA and Springer-Verlag, France 2011.

Alves B.J.R.,Embrapa Agrobiologia | Smith K.A.,University of Edinburgh | Flores R.A.,Federal Rural University of Rio de Janeiro | Cardoso A.S.,Federal Rural University of Rio de Janeiro | And 4 more authors.
Soil Biology and Biochemistry | Year: 2012

Soil N 2O fluxes are frequently assessed by the use of static chambers with a single daily sampling. In this study, two experiments were conducted in two contrasting climatic locations, one in Edinburgh, UK, and the other at Seropédica, Rio de Janeiro State, Brazil. Soil N 2O fluxes were monitored every 6h for 30 days during the summer in Edinburgh by the use of an automatic chamber system, and every 3h for 5 days at Seropédica, using a manually-sampled static chamber. Air and soil temperatures were also measured at the same time as the N 2O fluxes. The principal driver of N 2O flux within any diurnal period was found to be soil temperature. Regression analysis showed that, for both places, the evenings (21:00-22:00h) and mornings (09:00-10:00h), were the times that the flux best represented the daily mean. The ability to work in daylight make the morning period the preferred one. © 2011 Elsevier Ltd.

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