• Authors:
    • Oliveira, E. B. de
    • Moraes, A. de
    • Pelissari, A.
    • Reis, E. F. dos
    • Ruaro, L.
  • Source: Pesquisa Agropecuária Brasileira
  • Volume: 47
  • Issue: 4
  • Year: 2012
  • Summary: The objective of this work was to assess the effect of soil management systems and winter cover crops on the number of propagules of Fusarium spp. in soil, the incidence of sudden death syndrome (SDS), and the productivity of the soybean cultivars CD 206 and FT Fenix. Two experiments were carried out in the 2006/2007 and 2007/2008 crop years. The experimental design was a randomized complete block in a split-split plot arrangement, with three replicates. Two soil tillage systems were evaluated: no-tillage and plowed soil at a depth of 25 cm. The soil covers used were: black oat, with two planting densities; black oat+vetch; ryegrass; and fallow. The incidence of the disease in the 2006/2007 crop year in the cultivar FT Fenix was lower than in CD 206. In the 2007/2008 crop, there was no significant difference. There was an increase in productivity, of 125 kg ha -1, in the plowed treatment, when compared to no-tillage. The cover with black oat+vetch showed a higher number of propagules of Fusarium spp. in soil in the 2006/2007 crop year. However, in the second year, this difference was not observed. The soil management systems and winter cover crops used do not influence the incidence of SDS in soybean cultivars or the number of Fusarium spp. propagules in soil. The plowed system provides an increase in soybean yield in the second year of management.
  • Authors:
    • Marins, A. C. de
    • Souza, S. N. M. de
    • Santos, R. F.
    • Veloso, G.
    • Secco, D.
    • Rosa, H. A.
    • Borsoi, A.
  • Source: Food, Agriculture and Environment (JFAE)
  • Volume: 10
  • Issue: 2 part 3
  • Year: 2012
  • Summary: Certain soil physical characteristics such as resistance to penetration (Rs) and bulk density (Ds) are extremely important, and are also indicators of the soil structural quality. This paper aims at evaluating the use of four cover crop species in the reduction of density and soil resistance to penetration in areas where a no-till farming system is applied. The so-called "regenerator" species, which act in soil structure, were considered treatments, and consisted of four species: showy rattlebox ( Crotalaria spectabilis), moha grass ( Setaria italica), pigeon pea ( Cajanus cajan), sorghum ( Sorghum bicolor), and yet the control (an area without crops). Soil bulk density evaluations were carried out according to the methodology recommended by EMBRAPA, in the following depths: 0.0-0.1, 0.1-0.2 and 0.2-0.3 m. Sampling was carried out with five replications for the crop row and five for the spacing between each crop row, in each experimental unit (5 m * 5 m), up to 0.40 m in depth. An experimental design was 5*4*2 factorial, meaning 5 treatments, 4 depths and 2 sampling conditions. The species studied, especially the pigeon pea and the sorghum, showed a great potential to improve soil structural state, for they showed figures to Ds and Rs that were lower than the ones from the area without crops.
  • Authors:
    • Pereira Nóbrega, L. H.
    • dos Santos, D.
    • Gonçalves Junior, A. C.
    • de Souza, E. G.
    • Tavares-Silva, C. A.
  • Source: Food, Agriculture and Environment (JFAE)
  • Volume: 10
  • Issue: 1
  • Year: 2012
  • Summary: No-tillage system is an alternative agricultural management to protect soil; however, the cover crops association is required in crop rotation or succession, allowing an amount of nutrients supply and organic matter to soil through mineralization of plant residues. Thus, this trial aimed at evaluating the effects of crops succession on soybean yield and on chemical properties of soil: calcium, magnesium and aluminium saturation (m%). The trial was carried out in Cafelandia (PR) city, in a typical eutrophic red latosol, from June 2008 to March 2010. The experimental design was completely randomized with five treatments: black oat; consortium 1 (turnip and black oat); consortium 2 (turnip, black oat and common vetch), wheat and fallow, with six replications in a 2 ha area, in four periods during two agricultural harvests, in order to record chemical analyses of soil in a depth from 0 to 0.2 m. The cover crops management was with roll-knife, while wheat was harvested with an automotive combine. Soybean was sown in summer and its yield was determined for each treatment. Winter cover crops influenced on Mg concentration in soil when evaluated after soybean harvest in 2010, so that, black oat and the second consortium were the main responsible for such increase, although, the treatments showed no effect on soybean yield during the 2009/2010 harvest.
  • Authors:
    • Weirich Neto, P. H.
    • Lopes, A. R. C.
  • Source: Engenharia Agrícola
  • Volume: 32
  • Issue: 2
  • Year: 2012
  • Summary: The seeding process was the operation that suffered the most changes in no-tillage system due the cover crop soil and new particle soil arrangement. The objective of this study was to verify the effects of loads applied to the wheels and adjustments of sowing depth on seedling emergence of corn in no-tillage system. The experimental design was completely randomized with a factorial arrangement 5*4, with five loads applied to the wheels and four theoretical sowing depth adjustments. The real sowing depth increased in the lower theoretical depth and decreased in the higher theoretical depth, due to the compaction loads. Regarding the time of emergence, loads applied had not influence at the greater depths. Emergence time decreased with the load increase in the lower depths. Thus, the adjustment of the compactor wheels can influence in the corn seeding process.
  • Authors:
    • Fernandes, R. B. A.
    • Duarte, E. M. G.
    • Cardoso, I. M.
    • Brussaard, L.
    • Goede, R. G. M. de
    • Souza, H. N. de
    • Gomes, L. C.
    • Pulleman, M. M.
  • Source: Agriculture Ecosystems and Environment
  • Volume: 146
  • Issue: 1
  • Year: 2012
  • Summary: Sustainable production and biodiversity conservation can be mutually supportive in providing multiple ecosystem services to farmers and society. This study aimed to determine the contribution of agroforestry systems, as tested by family farmers in the Brazilian Rainforest region since 1993, to tree biodiversity and evaluated farmers' criteria for tree species selection. In addition, long-term effects on microclimatic temperature conditions for coffee production and chemical and biological soil characteristics at the field scale were compared to full-sun coffee systems. A floristic inventory of 8 agroforests and 4 reference forest sites identified 231 tree species in total. Seventy-eight percent of the tree species found in agroforests were native. The variation in species composition among agroforests contributed to a greater gamma-diversity than alpha-diversity. Monthly average maximum temperatures were approximately 6°C higher in full-sun coffee than in agroforests and forests. Total soil organic C, N mineralization and soil microbial activity were higher in forests than in coffee systems, whereas the chemical and biological soil quality in agroforests did not differ significantly from full-sun coffee after 13 years. Given its contribution to the conservation of biodiversity and its capacity to adapt coffee production to future climate change, coffee agroforestry offers a promising strategy for the area.
  • Authors:
    • Tavares Filho, J.
    • Hungria, M.
    • Machado, W.
    • Telles, T. S.
    • Souza, R. A.
    • Guimaraes, M. de F.
  • Source: Agriculture Ecosystems and Environment
  • Volume: 155
  • Year: 2012
  • Summary: Soil microbial biomass represents an important and strategic reservoir of plant nutrients that can be quickly altered due to different soil and crop managements. In this context, the aim of this study was to evaluate the influence of sugarcane harvesting systems, with or without burning, on the chemical and biological properties of the soil. The experiment was conducted on a dystrophic red latosol (Oxisol) soil in 2008, in a commercial area of a sugarcane factory in the municipality of Paraguacu Paulista, Sao Paulo state, Brazil. The treatments included areas previously burned, areas with mechanical harvesting and no burning and native forest. Soil samples were collected immediately after the sugarcane harvest from the treatments at a depth of 0-20 cm. The parameters evaluated were: microbial biomass C and N (MB-C and MB-N), total organic C (TOC), recalcitrant C (R-C), labile-C (L-C), total nitrogen (TN), pH, exchangeable cations (Ca 2++Mg 2+ and K +), exchangeable (Al 3+) and potential (H ++Al 3+) acidity, and P available in the soil. Soil chemical fertility under the sugarcane without burning was better than under sugarcane with burn. The TOC values for native forest and for the harvesting without burn were higher than those under the sugarcane with burn (148% and 54%, respectively). This superiority was also confirmed for TN, L-C and R-C. An even more significant difference was found under natural forest and sugarcane without burn for MB-C, which was 222% higher under native forest and 102% higher under sugarcane without burn than the value under sugarcane with burn, confirming that MB-C could be a reliable indicator of soil quality for monitoring soils under different sugarcane harvesting systems.
  • Authors:
    • Amorim, R. S. S.
    • Mund, E. E.
    • Couto, E. G.
    • Wantzen, K. M.
    • Siqueira, A.
    • Tielborger, K.
    • Seifan, M.
  • Source: Agriculture Ecosystems and Environment
  • Volume: 151
  • Year: 2012
  • Summary: For climate mitigation it is important to identify and protect landscape units that have disproportionally large carbon storage (CS). Here we report on CS of the upper 30 and 60 cm of soil in transects of vegetation types in stream valleys in the Brazilian Cerrado savanna, including Pasture, nearly native Cerrado vegetation, Vereda wetlands, and Gallery Forests. We chose three areas with varying types of human impacts in each of which three degraded and reference transects were compared. For the 60 cm CS in undisturbed sites, maximum and average values per area were highest for Gallery Forest (360.0 and 206.5 Mg C ha -1) and Vereda wetland (201.9 and 142.4 Mg C ha -1), while those of Cerrado (57.7 and 52.7) and Pasture (62.3 and 52.7 Mg C ha -1) were considerably lower. Variation between the three areas was high. In an area degraded by cattle trampling, losses in the upper 60 cm compared to reference sites were highest in the carbon-rich vegetation types Vereda (72%) and Gallery Forest (71%) and lower in the carbon-poorer Pasture (33%) and Cerrado (7%). In areas degraded by fire or by erosion, results were less conclusive. Our data appeal to an improved conservation of riparian ecosystems of the Cerrado biome.
  • Authors:
    • De Figueiredo, E. B.
    • La Scala Junior, N.
    • Panosso, A. R.
  • Source: Brazilian Journal of Biology
  • Volume: 72
  • Issue: 3
  • Year: 2012
  • Summary: Agricultural areas deal with enormous CO2 intake fluxes offering an opportunity for greenhouse effect mitigation. In this work we studied the potential of soil carbon sequestration due to the management conversion in major agricultural activities in Brazil. Data from several studies indicate that in soybean/maize, and related rotation systems, a significant soil carbon sequestration was observed over the year of conversion from conventional to no-till practices, with a mean rate of 0.41 Mg C ha(-1) year(-1). The same effect was observed in sugarcane fields, but with a much higher accumulation of carbon in soil stocks, when sugarcane fields are converted from burned to mechanised based harvest, where large amounts of sugarcane residues remain on the soil surface (1.8 Mg C ha(-1) year(-1)). The higher sequestration potential of sugarcane crops, when compared to the others, has a direct relation to the primary production of this crop. Nevertheless, much of this mitigation potential of soil carbon accumulation in sugarcane fields is lost once areas are reformed, or intensive tillage is applied. Pasture lands have shown soil carbon depletion once natural areas are converted to livestock use, while integration of those areas with agriculture use has shown an improvement in soil carbon stocks. Those works have shown that the main crop systems of Brazil have a huge mitigation potential, especially in soil carbon form, being an opportunity for future mitigation strategies.
  • Authors:
    • de Barros Viana Hissa, L.
    • Soares-Filho, B. S.
    • Costa, M. H.
    • Leite, C. C.
  • Source: Global Biogeochemical Cycles
  • Volume: 26
  • Issue: 2
  • Year: 2012
  • Summary: The evaluation of impacts of land use change is in general limited by the knowledge of past land use conditions. Most publications on the field present only a vague description of the earlier patterns of land use, which is usually insufficient for more comprehensive studies. Here we present the first spatially explicit reconstruction of historical land use patterns in Brazil, including both croplands and pasturelands, for the period between 1940 and 1995. This reconstruction was obtained by merging satellite imagery with census data, and provides a 5' x 5' yearly data set of land use for three different categories (cropland, natural pastureland and planted pastureland) for Brazil. The results show that important land use changes occurred in Brazil. Natural pasture dominated in the 1950s and 1960s, but since the beginning of 1970s it has been gradually replaced by planted pasture, especially in southeast and center west of Brazil. The croplands began its expansion in the 1960s reaching extensive areas in almost all states in 1980. Carbon emissions from historical land use changes were calculated by superimposing a composite biomass map on grids of a weighted average of the fractions of the vegetation types and the replacement land uses. Net emissions from land use changes between 1940 and 1995 totaled 17.2 +/- 9.0 Pg-C (90% confidence range), averaging 0.31 +/- 0.16 Pg-C yr(-1), but reaching up to 0.47 +/- 0.25 Pg-C yr(-1) during the 1960s and through 1986-1995. Despite international concerns about Amazon deforestation emissions, 72% of Brazil's carbon emissions during the period actually came from deforestation in the Atlantic Forest and Cerrado biomes. Brazil's carbon emissions from land use change are about 11 times larger than its emissions from fossil fuel burning, although only about 18.1% of the native biomass has been lost due to agricultural expansion, which is similar to the global mean (17.7%).
  • Authors:
    • Mauli, M. M.
    • Machado Coelho, S. R.
    • Pereira Nobrega, L. H.
    • de Lima, G. P.
    • Rosa, D. M.
  • Source: Journal of Food Agriculture and Environment (JFAE)
  • Volume: 10
  • Issue: 2
  • Year: 2012
  • Summary: It is known that cover crops can influence on seed quality, as well as on yield cropping. This trial analyzed possible allelopathic interferences of black oat (Avena strigosa Schreb.) remains and a consortium of black oat, forage turnip (Raphanus sativus L.) and vetch (Vicia sativa L.) on cropped seeds quality and soybean yield according to different intervals between the drying of some cover crops with Glyphosate 480 (3 L had) herbicide and seeding with BRS 232 cultivar. Plots of 5.0 m x 2.5 m were established, plus 1 m of edge between each of them. The cover crop was sown in August, 2006, with 0.15 m of width among rows: the parcels were dried in intervals of one, ten, twenty and thirty days before the soybean seedling. Four treatments were arranged for black oat cover, four for consortium and one control for each cover, all randomized, with five replications. The soybean was seeded in November, 2006, with 0.45 m width among seeding rows. Data as yield, adjusted to 13% of moisture content on cropped seeds; seedling rate; weight of 100 seeds; moisture content and seeds vigor were recorded by the accelerated aging test. All the tests were submitted to an experimental design, with subdivided plots (split plot), completely randomized; the averages were also compared using Scott-Knott test at 5% of probability. The data showed a possible allelopathic interference of cover crops on soybean seed quality. The greatest weight of 100 seeds was obtained when soybean was sown under black oat cover compared to the consortium. On the other hand, when it was sown under consortium, it showed the best vigor, evaluated by the accelerated aging test. The yield did not differ between both covers. The intervals between drying and sowing interfered on weight of 100 seeds and soybean yield. The interval between drying and sowing of one day had a positive effect on weight of 100 seeds, but soybean yield decreased. Hence, it is not well recommended to sow soybean next to the drying management of a cover crop.