19942015
  • Authors:
    • da Rocha, M. R.
    • Reinert, D. J.
    • Carneiro Amado, T. J.
    • Nicoloso, R. da S.
    • Foletto Eltz, F. L.
    • Lanzanova, M. E.
  • Source: Revista Brasileira de Ciência do Solo
  • Volume: 34
  • Issue: 4
  • Year: 2010
  • Summary: No-tillage associated to cover crops may maintain soil quality, improving or preserving favorable soil physical conditions for plant growth. This study assessed soil bulk density, porosity, penetration resistance, and water infiltration of a PALEUDALF, in the Experimental Area of the Soil Science Department of the Federal University of Santa Maria, in Santa Maria, RS, Brazil, in an experiment started in 1991, with the following crop successions and rotations: (1) Corn/Soybean - Jackbean - MFP; (2) Bare soil - SDES; (3) Corn/Soybean - Fallow - POU; (4) Corn / Soybean - Ryegrass + Vetch - AZEV; (5) Corn / Soybean - Mucuna - MUG; (7) Natural Grass - CNA; (6) Corn/Soybean - Oilseed radish - NFO. Soil bulk density was affected in the 0-0.10 in layer; values were highest in the SDES. Total soil porosity and soil macroporosity were closely correlated to a depth of 0.10 m. Major restriction to root penetration occurred in the surface layer (0-0.03 m) in the SDES treatment, and NFO had greatest values at 0.16-0.18 m depth. The water infiltration rate was lowest in SDES and CNA treatments in all evaluations, while in the others infiltration was constant and statistically equal. Constantly uncovered soil induces degradation in soil physical properties. The studied cropping systems confirmed significant benefits in soil density, porosity, resistance, and water infiltration rate under long term no-tillage.
  • Authors:
    • Portz, G.
    • Chagas, J. P.
    • Bagatini, T.
    • Cogo, Neroli P.
    • Portela, J. C.
  • Source: Revista Brasileira de Ciência do Solo
  • Volume: 34
  • Issue: 4
  • Year: 2010
  • Summary: Soil structure plays a prominent role in plant growth and erosion control, and consequently in food production and soil and water conservation. This research was developed with the objective of implementing and accompanying the restoration process of the structure of a degraded soil, by planting crop sequences under no-tillage (autumn-winter and spring-summer, grass and legume, in single and intercropped systems), and later verifying the relations with water and soil losses caused by rainfall erosion, under distinct surface physical conditions (untitled soil, with and without crust; freshly-tilled soil by chiseling and by chiseling followed by disking after one month, and crop residue covering 100, 18, and 0 %). The field study was developed under simulated rainfall, at the Agriculture Experimental Station of the Federal University of Rio Grande do Sul (EEA/UFRGS), in Rio Grande do Sul State, Brazil, from May 2004 to Decembe, 2007. The six erosion tests, in intervals of about a week, were performed from October to December, 2007. The soil used is an Ultisol, with a sandy clay loam texture in the surface layer and 0.115 in m(-1) average slope steepness, and an advanced degree of degradation. The rains were applied with a rotating-boom rainfall simulator, at a constant intensity of 64 mm h(-1), for 1-3 h. For this study, water and soil loss data were adjusted to a rainfall duration of 1.5 h. Properties of soil and plants were measured in the experimental plots and water erosion in the surface runoff The crop sequences and erosion tests influenced the results of the study significantly, with greater differences in the latter than in the former. The erosive process was more influenced by the external or soil surface than the internal or subsurface physical conditions. In general, all crop sequences were effective in restoring the soil structure in the experimental period. The sequence involving teosinte controlled the rainfall erosion process most effectively with regard to soil and water loss and the one involving corn+cowpea and pearl millet with regard to soil loss. The highest soil and water losses in the study were observed from the soil surface with no mobilization and little crop residue cover, regardless of the presence or type of crust, but especially when this latter was slightly cracked prior to rainfall application. The soil surface entirely covered by crop residue, be it untilled or freshly chiseled, controlled runoff effectively and impeded erosion completely. Soil and water losses from the freshly-disked soil surface chiseled a month earlier, although the soil was the most mobilized of all and bare, were practically zero, opposite to what was expected.
  • Authors:
    • Nepomuceno, A. L.
    • Oliveira, G. M. de
    • Neumaier, N.
    • Rakocevic, M.
    • Farias, J. R. B.
  • Source: Pesquisa Agropecuária Brasileira
  • Volume: 45
  • Issue: 7
  • Year: 2010
  • Summary: The objectives of this work were to determine the heliotropic movements of the upper trifoliates for two soybean cultivars, BR 16 and Embrapa 48, during a daily cycle, in three phenological stages and two water regimes, and to estimate the impact of irrigation and daily leaflet movements on agronomic characteristics and grain yield. Heliotropic movements were studied in three phenological stages: V4-V6, V7-V10, and R5 in irrigated and non-irrigated plots. For each stage, the leaflet elevation and azimuth were measured hourly. Under a low (V4-V6 stage) and mid (V7-V10 stage) leaf area index (LAI) the diaheliotropism was slightly more frequent and intensive in non-irrigated than in irrigated plants, only at early morning and late afternoon hours. At R5 stage (high LAI) the paraheliotropism of superior trifoliates was predominant and more intensive in non-irrigated plants. The heliotropic movements are correlated to carbon gain, but not to environment (light intensity or temperature), for measurements at 11 h. 'Embrapa 48' expresses greater paraheliotropism than 'BR 16' at high LAI, while 'BR 16' displays lower heliotropic plasticity under irrigation. In spite of significant heliotropic differences, genotype and water availability treatments did not influence the final grain yield.
  • Authors:
    • Sa, M. E. de
    • Lazarini, E.
    • Silva, J. B. da
    • Vieira, R. D.
  • Source: Revista Brasileira de Sementes
  • Volume: 32
  • Issue: 2
  • Year: 2010
  • Summary: During the maturation and harvest of soybean (Glycine max (L.) Merr.) seed the ideal climatic conditions include dryness and lower temperatures. Using winter-sown (July to September) soybean we verified the effects of irrigation on the physiological quality of soybean seeds during maturity using a factorial treatment design with three varieties (IAC-19, Conquista and IAC 8-2) and two irrigation interruption times (starting at stage R 7 and irrigating until 14 days after stage R 8). The samples were taken at stage R 7 and at 3 days, 7 days, 10 days, 14 days (stage R 8) and 28 days after starting stage R 7. We evaluated the percentage germination, vigor using accelerated aging and electric conductivity tests, and the percentage of spotted and imperfect seeds and found that irrigation after stage R 7 does not reduce seed quality but can improve the physiological potential of the seeds.
  • Authors:
    • Fontaneli, R. S.
    • Santos, H. P. dos
    • Spera, S. T.
    • Tomm, G. O.
  • Source: Acta Scientiarum. Agronomy
  • Volume: 32
  • Issue: 1
  • Year: 2010
  • Summary: Soil physical characteristics were evaluated, after eight years (1995 to 2003), on a typic Hapludox located in Coxilha, Rio Grande do Sul State, Brazil. Six crop production systems were evaluated: system I (wheat-soybean/black oat+common vetch pasture-corn); system II (wheat-soybean/black oat+common vetch+annual ryegrass pasture-corn); system III (wheat-soybean/black oat+common vetch pasture-pearl millet pasture); system IV (wheat-soybean/black oat+common vetch+annual ryegrass pasture-pearl millet pasture); system V (wheat-soybean, white oat-soybean/black oat+common vetch pasture-pearl millet pasture); and system VI (wheat-soybean/white oat-soybean/black oat+common vetch+annual ryegrass pasture-pearl millet pasture). Soil bulk density and resistance to penetration increased from deeper layer (10-15 cm) to top layer (0-5 cm). In the systems I, V and VI, total porosity decreased and soil bulk density resistance to penetration increased from the deeper layers to top layer surface, due to higher intensity of livestock activities. After eight years of use, the production systems under no-till, involving annual winter and summer pastures and crops, did not promoted soil degradation, in constraining levels, on soil physical attributes.
  • Authors:
    • Pires, C. S. S.
    • Medeiros, M. A. de
    • Gravina, C. S.
    • Langer, L. F.
    • Cavalcante, K. R.
    • Togni, P. H. B.
    • Fontes, E. M. G.
    • Sujii, E. R.
  • Source: Arquivos do Instituto Biologico Sao Paulo
  • Volume: 77
  • Issue: 4
  • Year: 2010
  • Summary: The adoption of cultural practices such as companion plants and the kind of irrigation system can benefit the community of natural enemies in the agroecosystem due to the increase of more favorable microhabitats available and as a source of alternative resources, mainly in periods of low precipitation. This study evaluated how the tomato+coriander intercrop and the kind of irrigation (drip and sprinkler) could benefit the community of natural enemies in the tomato agroecosystem. This work was carried out in the experimental field of Embrapa Hortalicas, Gama, DF, from September to November 2008. The tomatoes were planted in monoculture or with coriander (companion plant) and irrigated by drip and sprinkler irrigation (three replicates per treatment), forming two groups of experimental plots according to the kind of irrigation. The community of natural enemies was sampled by the direct observation of specimens on 20 tomatoes plants per plot and in the treatments. Coriander plants were shaken over a plastic tray for collection of insects. The abundance, richness and diversity of natural enemies were higher in tomato+coriander plots, regardless of the irrigation system. We observed more species of natural enemies in tomato monoculture plots when it was irrigated by sprinkler irrigation. However, the cultural practices adopted had a different effect on each species or group of species. Therefore, in periods of low precipitation, the tomato+coriander consortium associated with sprinkler irrigation can enhance the conservation of natural enemies in the organic tomato agroecosystem.
  • Authors:
    • Scopel, E.
    • Triomphe, B.
    • Tourdonnet, S. de
    • de Tourdonnet, S.
  • Source: Proceedings of a symposium on Innovation and Sustainable Development in Agriculture and Food, Montpellier, France, 28 June to 1st July 2010
  • Year: 2010
  • Summary: No-tillage techniques and conservation agriculture (CA), based on minimal soil disturbance, the maintenance of plant cover and a diversification of rotations and intercropping, are developing rapidly in both the North and South. The emergence of these techniques often involves an original process of innovation based on continuous and adaptive learning within innovative socio-technical networks, which overturn the traditionally linear process of innovation design and transfer. Changes in the functioning of the agrosystem associated with CA are likely to supply ecosystem services, but the difficult implementation of these techniques may decrease the performance of the agrosystem, in particular by increasing dependence on pesticides. The general objective of the PEPITES project is to generate knowledge concerning ecological processes, technical and social innovation processes and their interactions, for the evaluation and design of more sustainable technical and support systems. We are working towards this objective by constructing an interdisciplinary approach combining biophysical sciences, cropping system and production system agronomy and the sociology of innovation, in partnership with professionals in four study terrains: conventional field crops in France, organic farming in France and small-scale family farms in Brazil and Madagascar. After one year of operation, we present here the progress made towards answering the questions posed in this project, in terms of the positioning of research with respect to two key questions: first concerning the construction of an interdisciplinary approach in partnership to assist the innovation process and the generation of knowledge, and second the construction of an approach for comparing terrains in the North and South.
  • Authors:
    • Paula Junior, T. J. de
    • Vieira, R. F.
    • Teixeira, H.
  • Source: Informe Agropecuario Pages:
  • Volume: 31
  • Issue: 254
  • Year: 2010
  • Summary: Despite the growth of bean production, those from small farms still accounts for significant percentage of the total production. Most produced are from Minas Gerais. Maximizing efficiency and minimizing production costs are important factors to increase the profits of small producers. The use of technology and exploitation of natural resources should guide the actions of farmers. Planting dates, cultivars, row spacing and plant density, cropping systems, maize-bean intercropping, irrigation, weed control, pests and diseases as well as practical information technologies from research that aimed at increasing the income of the farmer with the cultivation of beans should be addressed.
  • Authors:
    • Rosolem, C. A.
    • Calonego, J. C.
  • Source: European Journal of Agronomy
  • Volume: 33
  • Issue: 3
  • Year: 2010
  • Summary: Compacted subsoil layers result in shallow root systems hindering the absorption of water and nutrients by plants. Disruption of soil compacted layers can be promoted by mechanical and/or biological methods, using plants with strong root systems. The immediate and medium term effects of mechanical chiseling and crop rotations on soybean root growth and yield were evaluated during four years in Brazil. Triticale (X Triticosecale Wittmack) and sunflower (Helianthus annuus L) were grown in the autumn-winter (April-August). In the next spring (September-October/early November), designated plots were chiseled down to 0.25 m or planted to millet (Pennisetum glaucum L), sorghum (Sorghum bicolor (L.) Moench) and sunn hemp (Crotalaria juncea L.), grown as cover crops, preceding soybean (Glycine max (L.) Merrill). Chiseling was done only in the first year, and these plots were left fallow during the spring (September-October/early November) for the rest of the experiment. Chiseling resulted in lower soil penetration resistance and higher soybean yields in the first year. However, in the following years soybean root growth in depth was increased under rotation with triticale and pearl millet due to the presence of biopores and a decrease in soil penetration resistance. Soybean yields tended to decrease over the years in plots that were chiseled when compared with plots under crop rotation. Chiseling can be replaced by crop rotations involving species with aggressive root systems in order to alleviate deleterious effects of soil compaction on soybean yields in tropical soils. This effect is gradual, thus crop rotation will be fully effective in remediating soil compaction in a 3- to 4-year term. (C) 2010 Elsevier B.V. All rights reserved.
  • Authors:
    • Nobrega, L. H. P.
    • Smanhotto, A.
    • Sampaio, S. C.
    • Caovilla, F. A.
    • Queiroz, M. M. F. de
    • Gomes, B. M.
  • Source: Revista Brasileira de Engenharia Agricola e Ambiental
  • Volume: 14
  • Issue: 7
  • Year: 2010
  • Summary: In this work the distribution was evaluated "in situ" of phosphorus (P), organic matter (MO), potassium (K), calcium (Ca), magnesium (Mg), cation exchange capacity (CEC), aluminum (Al), sum of bases (S), base saturation (V) and pH of a soil cultivated with soybean and irrigated with swine wastewater in the 0, 25, 50 and 75% levels. The factorial scheme was constituted by the 20, 40 and 60 cm soil depths and four wastewater levels with five repetitions. The results showed that significant difference occurred only for P, K and CEC in the soil profile. However, in all parameters, the 60 cm soil depth showed that the concentrations levels are similar to before the application of treatments.