• Authors:
    • Cabezas, W. A. R. L.
    • Lange, A.
    • Trivelin, P. C. O.
  • Source: Revista Brasileira de Milho e Sorgo
  • Volume: 8
  • Issue: 1
  • Year: 2009
  • Summary: Strategies aiming to increase straw production by crops should be implemented in the Cerrado region in order to consolidate no-tillage cultivation. The objective of the present work was to evaluate the effect of time and splitting of supplementary nitrogen application to maize (in addition to the N-fertilization at seeding) on straw production and several yield components of black oat, a spontaneous native species. Treatments consisted of applying 70 kg ha -1 nitrogen in addition to maize fertilization at seeding, at distinct times: at black-oat seeding; 8 days before corn seeding; in covering in plants in the phases of 4-5 leaves and 6-7 leaves. At seeding, 42 kg N.ha -1 were applied in all plots. The nitrogen fertilization applied at oat seeding did not cause increase in out-of-season straw productivity. An increase in maize straw production was observed with nitrogen supply in addition to fertilization at seeding as well as the application closer to seeding resulted in an increased straw production when compared to fertilization at oat seeding.
  • Authors:
    • Fabian, E.
    • Vazquez, E.
    • Barbosa, F.
    • Bertol, I.
    • Luciano, R.
  • Source: REVISTA BRASILEIRA DE CIENCIA DO SOLO
  • Volume: 33
  • Issue: 3
  • Year: 2009
  • Summary: The sowing direction influences soil surface roughness, which, combined with rainfall and other variables, e.g., canopy cover, affects soil water erosion. Using a rotating-boom rainfall simulator, five tests of simulated rainfall were applied to black oat (Avena strigosa), and vetch (Vicia sativa), at a constant intensity of 64 mm h -1, between August and November 2006, to assess water and soil loss in the following treatment: mechanized seeding of oats in downslope rows; mechanized seeding of oats along contour lines; mechanized seeding of vetch in downslope rows, and mechanized seeding of vetch along contour lines. The experiment was conducted in two replications on an Inceptisol, with a mean slope of 0.119 m m -1. The canopy cover was greater in oat than vetch until rainfall test 2 and higher in vetch in the tests 3 and 4, with no variation due to the sowing direction of the crops and increasing from the beginning to the end of the growth period. The time until the water started to run off was longer in the treatments with seeding along contour lines than downslope, in both crops; the maximum runoff rate along the contour lines was lower and the time until maximum runoff rate longer. The sediment concentration in runoff decreased over the rainfall tests; it was lower in oat than vetch, and 52% lower in contour than downslope sowing. Soil loss decreased over the rainfall tests; these losses were 12% lower in oat and 56% lower in vetch contour than downslope sowing; the water loss had the same performance as soil loss, although with lower magnitudes. The accumulated soil losses increased with accumulated rain volume (VR) and rain erosivity (EI 30), between the first and fourth test, according to the equations: SL=0.859 (1-e -0.0059VR) (R 2=0.99) and SL=0.832 (1-e-0.0004EI 30) (R 2=0.99).
  • Authors:
    • Camara, F.
    • Mogor, A.
  • Source: Bioscience Journal
  • Volume: 25
  • Issue: 3
  • Year: 2009
  • Summary: A study was conducted to evaluate the effect of soil covering with black oat straw or black plastic on the phosphorus and potassium content as well as biomass production of three cultivars of lettuce in organic system. There were five handling systems for soil covering: without cover, covered with black plastic, covered with laying oats, covered with harvested oats, and covered with oats straw in natural form. Butter head lettuce showed the highest phosphorus content. Soil covering with oat straw promoted higher potassium accumulation and lettuce production in the second year, while soil covering with black plastic promoted lettuce production in first year.
  • Authors:
    • Camara, F.
    • Mogor, A.
  • Source: ACTA SCIENTIARUM-AGRONOMY
  • Volume: 31
  • Issue: 4
  • Year: 2009
  • Summary: The goal of this research was to evaluate the effect of soil covering with black oat straw, as well as soil covered with black plastic, on the production of biomass and levels of Mn and Zn in lettuce produced in an organic system, over two consecutive years. Five treatments were used: soil without cover, covered with black plastic, covered with laying oats, covered with harvested oats, and covered with oat straw in natural form, for growing three cultivars of lettuce. A randomized blocks design was used in a split-plot system, with four replications. It was concluded that soil covered with oat straw promoted satisfactory lettuce production, as well as adequate Mn and Zn content in plants, equivalent to those found in studies conducted under different growing systems; the soil covered with black plastic promoted satisfactory production and higher Zn content after the first year, and lower Mn content after the second year.
  • Authors:
    • Vargas, L.
    • Nohatto, M.
    • Amarante, C.
    • Mafra, A.
    • Pelizza, T.
  • Source: REVISTA BRASILEIRA DE FRUTICULTURA
  • Volume: 31
  • Issue: 3
  • Year: 2009
  • Summary: Soil cover is one of the options for weed management in the orchard but this might affect fruit trees development. The objective of this work was to evaluate apple trees growth during the orchard establishment stage by using different materials and soil cover plants. The experimental apple orchard was planted in 2003, in Vacaria, RS, Southern of Brazil, with the cv. Galaxy managed under organic system. The experiment followed the randomized block design, with three replications. The treatments were applied in the tree rows, as follows: control (without weed management), manual weeding, black plastic film, black net, pinus sawdust, pinus needle mulch, Andropogon sp. mulch, annual ryegrass ( Lolium multiflorum), black oat ( Avena strigosa), black oat+common vetch ( Vicia sativa), black oat+fodder radish ( Raphanus sativus), annual ryegrass+white clover ( Trifolium repens)+spontaneous plant cover, weed mowing. The soil covered by weeds was monthly measured, during the spring/summer season, over the second and third years of the orchard establishment, and this was related to the apple trees growth. The treatments with manual weeding, black plastic film, pinus needle and Andropogon mulch maintained the soil cover by weeds below 20%. The apple tree height and diameter decreased with the increase of soil cover by weeds, reflecting weeds competition with apple trees.
  • Authors:
    • Rosenthal, M. D.
    • Pinho, C. F.
    • Machado, A.
    • Noldin, J. A.
    • Pinto, J. J. O.
    • Donida, A.
    • Galon, L.
    • Durigan ,M.
  • Source: PLANTA DANINHA
  • Volume: 27
  • Issue: Especial
  • Year: 2009
  • Summary: The objective of this study was to evaluate the residual soil activity of herbicide (imazethapyr+imazapic), labeled for the Clearfield (CL) system and using corn, cv. Biomatrix 2202, as a bioindicator. The study was carried out in a greenhouse, at the Universidade Federal de Pelotas, in southern Brazil. Rice, cv. IRGA 422 CL, was planted in boxes (60*40*20 cm). At the 3-4 leaf stage, the herbicide Only (imazethapyr+imazapic) was sprayed at 0; 25+75; 37.5+112.5 and 50+150 g ha -1. After harvesting the rice, boxes were kept without flooding for 45 days. Black oat (Avena strigosa) was planted to keep the soil covered during the winter. In the spring, oat was harvested and 360 or 540 days after herbicide application (DAA), the soil from the boxes was transferred to two sets of pots labeled as experiment 1 (main corn crop) and experiment 2 (minor corn crop), respectively. The soil for experiment 2 was kept drained during the time period between seeding the two studies (360 to 540 DAA). Corn was planted in both studies and harvested at the 4-5 leaf stages. The variables evaluated were shoot and root biomass, plant height and leaf area index (for experiment 2). The data from both studies were analyzed using ANOVA (
  • Authors:
    • Miquelluti, D. J.
    • Oliveira, O. L. P. de
    • Ferreira, E. Z.
    • Nohatto, M. A.
    • Mafra, A. L.
    • Rosa, J. D.
    • Cassol, P. C.
    • Medeiros, J. C.
  • Source: REVISTA BRASILEIRA DE CIENCIA DO SOLO
  • Volume: 33
  • Issue: 1
  • Year: 2009
  • Summary: This study was conducted to evaluate the effect of phytomass management forms of different cover crop species on soil chemical properties related to organic matter, nutrient availability, and on grapevine yields. The experiment was carried out in Embrapa Uva e Vinho, in Bento Goncalves, Rio Grande do Sul, in Southern Brazil, on a Haplic Cambisol, in a vineyard established in 1989, using White and Rose Niagara grape in a horizontal overhead trelling system. The treatments established in 2002 were three cover crops: spontaneous native species, black oat ( Avena nuda), and a mixture of white clover ( Trifolium repens) + red clover ( Trifolium pratense) + annual ryegrass ( Lolium multiflorum); and two management systems: desiccation by herbicide spraying and mechanical mowing, performed each autumn prior to cover crop resowing. The experiment had a completely randomized block design, with three replications. Soil acidity and nutrient contents were little influenced by the plant cover. In comparison with the mowed management, herbicide application increased exchangeable Ca and Mg, extracted P, and organic C levels in the soil. The grape yield in the seasons 2004 and 2006 was low in view to the cultivar potential, probably affect by climatic limitations, but was higher when black oat was used as plant cover instead of the mixture of plant covers.
  • Authors:
    • Cao, E.
    • Andrigueti, M.
    • Carvalho, P.
    • Anghinoni, I.
    • Costa, S.
    • Souza, E.
  • Source: REVISTA BRASILEIRA DE CIENCIA DO SOLO
  • Volume: 33
  • Issue: 6
  • Year: 2009
  • Summary: The potential for adopting crop-livestock systems in southern Brazil is high, especially in untilled soybean areas with cover crops in the winter season. The long-term use of this system at different grazing intensities will result in different carbon and nitrogen stocks in the soil due to the different plant and animal residues. This research was conducted to evaluate alterations in total carbon and nitrogen pools and in organic matter fractions in a soil under different grazing intensities under no-tillage. The experiment on a Rhodic Hapludult (Oxisol) was initiated in 2001, after soybean harvest. The treatments were different cattle grazing (black oat+ryegrass) pressures (10, 20 and 40 cm sward height) and an ungrazed treatment in the winter and soybean in the summer, in a randomized block design. Soil samples were taken at the beginning of the experiment (May, 2001), after three years (May, 2004) and after six years (May, 2007) to evaluate the content and stocks of organic carbon and nitrogen. Moderate grazing intensities (20 and 40 cm plant height) resulted in an increase of total carbon and nitrogen and in the organic matter particulate fraction, similarly to the ungrazed area. However, at the most intensive grazing pressure (10 cm plant height) there were losses in the stocks of these elements and reduction in soil organic matter quality.
  • Authors:
    • Ernani, P.
    • Zanatta, J.
    • Bayer, C.
    • Vieira, F.
  • Source: Australian Journal of Soil Research
  • Volume: 47
  • Issue: 7
  • Year: 2009
  • Summary: Nitrogen-fixing crops and N fertilisation increase soil acidification, but few studies have attempted to evaluate the capacity of soil organic matter to alleviate the Al toxicity in acid no-tilled soils. This study was carried out in a 21-year-old experiment aiming to evaluate the effect of crop systems [fallow/maize ( Zea mays L.), F/M; oat ( Avena strigosa Schreb)/maize, O/M; oat+vetch ( Vigna sativa L.)/maize, O+V/M; lablab ( Dolichos lablab)+maize, L+M; and pigeon pea ( Cajanus cajan L. Millsp.)+maize, P+M] and mineral N fertilisation (0 and 149 kg/ha.year) on chemical attributes and Al speciation in the 0-0.05 and 0.05-0.10 m layers of a no-tilled Paleudult of Southern Brazil. The original soil pH (5.8) decreased in all crop systems, declining 0.37-1.52 units in 21 years without re-liming. This decrease was larger in subsoil layers and, in general, was exacerbated by legume-based crop systems and by N fertilisation. The drop in soil pH increased Al content in solid phase (range 0.07-1.85 cmol c/kg) and in soil solution (range 0.01-0.06 mmol/L), and decreased base saturation on cation exchange capacity (range 12.5-61.2%). However, the Al 3+ activity in the soil solution (1.03*10 -7-9.3*10 -8) was kept below threshold values of toxicity to maize roots, primarily due to the formation of organometallic complexes at low pH, which was estimated as up to 90% of the total Al in solution, but also due to the increased ionic strength in this no-till soil (0.0026-0.0104). Our results highlight that, although legume cover crops and N fertilisation can accelerate soil acidification, Al toxicity is offset by increased organic matter in no-till subtropical soils.
  • Authors:
    • Lal, R.
    • Blanco-Canqui, H.
  • Source: Soil Science Society of America Journal
  • Volume: 73
  • Issue: 2
  • Year: 2009
  • Summary: Franzluebbers (2009) is right about the need for a more intensive soil sampling, "repeated sampling with time,"and "stratified sampling" as well as for the use of multiple fields and collection of larger number of pseudoreplicates to overcome the high field variability in soil organic carbon (SOC) pools within each Major Land Resource Area (MLRA). The selected fields were representative of each MLRA in terms of soil type, slope, and management, but it is correct that a single soil would not capture all the variability in soil and management for the whole MLRA. This study was not intended to relate the data from the single soil to the whole MLRA but rather to emphasize the differences in SOC sequestration rates among the three management systems within each soil.