• Authors:
    • Nogueira, C. C. P.
    • Veloso, M. E. da C.
    • Freire Filho, F. R.
    • Cardoso, M. J.
    • Blanco, F. F.
    • Dias, N. da S.
  • Source: Pesquisa Agropecuária Brasileira
  • Volume: 46
  • Issue: 5
  • Year: 2011
  • Summary: The objective of this work was to evaluate the response of green maize ( Zea mays) intercropped with cowpea ( Vigna unguiculata) to irrigation depths and phosphorus doses. The experiments were carried out in 2008 and 2009 in a randomized block design, with 25 treatments and four replicates. Treatments consisted of five irrigation depths at 70, 110, 140, 180 and 220% of the crop evapotranspiration, and of five doses of P 2O 5: 0, 50, 100, 150 and 200% of the recommended P dose. Maize was sown at 0.80*0.40 m spacing, and cowpea was planted inside the lines among maize plants. There was no effect of P 2O 5 doses, but the response to irrigation depths was quadratic for maize and linear for cowpea. The maximum technical yield of green ears of maize with straw (10.76 Mg ha -1) and without straw (7.62 Mg ha -1) was obtained with 530 mm depth, intermediary to the 180 and 220% of the crop evapotranspiration. The highest cowpea green grain (3.40 Mg ha -1) was obtained with the highest water depth, of 644 mm.
  • Authors:
    • Encide-Olibone,A. P.
    • Olibone,D.
    • Rosolem,C. A.
  • Source: Soil Use and Management
  • Volume: 26
  • Issue: 4
  • Year: 2010
  • Summary: Crop rotation and the maintenance of plant residues over the soil can increase soil water storage capacity. Root access to water and nutrients depends on soil physical characteristics that may be expressed in the Least Limiting Water Range (LLWR) concept. In this work, the effects of crop rotation and chiselling on the soil LLWR to a depth of 0.1 m and crop yields under no-till were studied on a tropical Alfisol in Sao Paulo state, Brazil, for 3 yr. Soybean and corn were grown in the summer in rotation with pearl millet (Pennisetum glaucum, Linneu, cv. ADR 300), grain sorghum (Sorghum bicolor, L., Moench), congo grass (Brachiaria ruziziensis, Germain et Evrard) and castor bean (Ricinus comunis, Linneu) during fall/winter and spring, under no-till or chiselling. The LLWR was determined right after the desiccation of the cover crops and before soybean planting. Soil physico-hydraulic conditions were improved in the uppermost soil layers by crop rotations under zero tillage, without initial chiselling, from the second year and on, resulting in soil quality similar to that obtained with chiselling. In seasons without severe water shortage, crop yields were not limited by soil compaction, however, in a drier season, the rotation with congo grass alone or intercropped with castor resulted in the greatest cover crop dry matter yield. Soybean yields did not respond to modifications in the LLWR.
  • Authors:
    • Mielniczuk, J.
    • Vezzani, F. M.
  • Source: Proceedings of the 19th World Congress of Soil Science: Soil solutions for a changing world
  • Year: 2010
  • Summary: Soil use for agricultural production may increase soil structure quality as long as conservation management practices are adopted. The aggregates and single particles distribution into diameter classes (9.51-4.76, 4.76-2.00, 2.00-0.25, 0.25-0.053, 0.25 mm) also were increased from 22.8% to 53.5% and the C stock reached 17.9 Mg/ha building a complex soil structure with the capacity to increase soil quality.
  • Authors:
    • Inomoto, M. M.
    • Machado, A. C. Z.
    • Borges, D. C.
  • Source: Tropical Plant Pathology
  • Volume: 35
  • Issue: 3
  • Year: 2010
  • Summary: Black oat ( Avena strigosa), white oat ( A. sativa) and Algerian oat ( A. byzantina) are extensively cultivated in the south of Brazil for grain, forage, hay and silage production, or as cover crop in no-tillage and crop-pasture integration systems. In both systems, the genotypes of oat used as cover crop must be nonhosts or poor hosts of damaging nematodes for summer cash crops. Taking into account the relevance of Pratylenchus brachyurus as a pathogen for many cash crops in Brazil, two experiments were carried out in a glasshouse in order to evaluate the host suitability of selected oat cultivars to this nematode. The initial population inoculated (Pi) were 92 specimens/plot in experiment 1, and 270 in experiment 2. At the end of experimental periods (86 days after inoculation in experiment 1 and 67 days in experiment 2), the final population (Pf) of P. brachyurus was estimated and the reproductive factor (RF=Pf/Pi) was calculated. The results demonstrated that black oat (RF=0.04-1.03) is more valuable than Algerian oat (RF=2.63-2.88) or white oat (RF=1.37-1.93) for the management of P. brachyurus.
  • Authors:
    • Oliveira, O. L. P. de
    • Melo, G. W. B. de
    • Botton, M.
    • Onzi, I.
  • Source: ACTA SCIENTIARUM-AGRONOMY
  • Volume: 32
  • Issue: 4
  • Year: 2010
  • Summary: The use of cover crops is an important strategy to reduce erosion and improve chemical and physical soil properties. In this work, we evaluate the effect of cover crops to reduce Brazilian ground pearl Eurhizococcus brasiliensis (Hemiptera: Margarodidae) infestation in vineyards. In the first experiment, glyphosate was sprayed each three months to avoid cover crops. This treatment was compared with naturally occurring vegetation during the year and the use of Avena sativa in the winter. In a second experiment, Stizolobium aterrimum was cultivated during the summer compared with naturally occurring vegetation. Brazilian ground pearl population was higher in glyphosate sprayed areas than where cover crops were maintained during the year. No differences in inssect infestation were observed between naturally occurring vegetation and A. sativa during the winter. Scale infestation where S. aterrimum was cultivated during the summer was similar to naturally occurring vegetation. S. aterrimum is registered for the first time as a host of E. brasiliensis.
  • Authors:
    • Conte, O.
    • Levien, R.
    • Trein, C.
    • Cepik, C.
  • Source: REVISTA BRASILEIRA DE ENGENHARIA AGRICOLA E AMBIENTAL
  • Volume: 14
  • Issue: 5
  • Year: 2010
  • Summary: No tillage implies keeping the soil surface covered with crops or crop residues, which might influence planter performance. Using fixed shanks as furrow openers to place fertiliser is an alternative to minimize compaction, as it mobilizes the soil in the sowing line. The aim of this research was to evaluate the effect of different amounts of winter cover crop residues evenly distributed on the soil, the effect of the shanks working depth and quantity of planter lines on power demand, cross sectional furrow area and total volume of soil mobilized in the lines and corresponding wheel slippage in distrophic red Argisol. During winter, black oats and black oats plus turnip were used as cover crops before maize and beans, respectively. Increasing the working depth showed an increase in power demand, as measured directly at the shanks (three lines for maize and five for beans). There was also an effect of residue, increasing power demand on the shanks, but only measurable with the planter operating with three lines in maize sowing. Soil mobilization in the sowing lines was influenced by the amount of residues, the working depths of shank and the quantity of planter lines. Wheel slippage was higher with larger amounts of soil cover residues and when power demand was higher.
  • Authors:
    • Vieira, F. C. B.
    • Flores, J. P. C.
    • Anghinoni, I.
    • Souza, E. D.
    • Costa, S. E. V. G. A.
    • Martins, A. P.
    • Ferreira, E. V. O.
  • Source: Soil & Tillage Research
  • Volume: 109
  • Issue: 1
  • Year: 2010
  • Summary: The distribution of phosphorus in the soil profile as a function of soil tillage, fertilizer management system and cultivation time is strongly related to root distribution. As the dynamics of this process are not well understood, long-term experiments are useful to clarify the cumulative effect through time. The study evaluated an 18-year-old experiment carried out on Rhodic Paleudult soil, located in Rio Grande do Sul state - Brazil, with cover crops (black oat and vetch) in the winter and corn in the summer. In the 0- to 20-cm layer, the amounts of clay, silt and sand were 22, 14, and 64 g kg -1, respectively. This layer had a mean slope of 3%. The mean local annual rainfall is 1440 mm. The climate is subtropical with a warm humid summer (Cfa), according to the Koeppen classification. The treatments consisted of three soil managements (conventional tillage, no tillage and strip tillage) and three application modes (broadcast, row and strip) for triple superphosphate and potassium chloride fertilizers. Data for phosphorus and root distribution in the soil from the 1989/90, 1999/00 and 2006/07 growing seasons were used. Phosphorus stratification occurred through time, irrespective of soil and fertilizer management, mainly in the 0- to 5-cm layer. The tillage and fertilization systems promoted significant differences in the Pi and Pt fractions up to a depth of 20 cm. For the Po fraction, significant differences were found only in the 0- to 5- and 15- to 20-cm layers. Inorganic phosphorus accumulated in the fertilized zone (0-10 cm), with higher intensity in the no-tillage system under row fertilization with values around 150 mg dm -3. Root distribution presented a strong positive relationship with phosphorus distribution, exhibiting redistribution in the soil profile through time. This redistribution was accompanied by increases in organic phosphorus and total organic carbon content. Corn grain yield was not affected by long-term tillage systems.
  • Authors:
    • Conte, O.
    • Trein, C. R.
    • Levien, R.
    • Debiasi, H.
    • Kamimura, K. M.
  • Source: PESQUISA AGROPECUARIA BRASILEIRA
  • Volume: 45
  • Issue: 6
  • Year: 2010
  • Summary: The objective of this work was to evaluate the effect of soil winter covers and soil mechanical loosening on soybean and corn yield, in no-tillage system. Two experiments were carried out in Rio Grande do Sul state, Brazil, in a compacted Argissolo Vermelho (Haplic Acrisol), in the 2005/2006 and 2006/2007 crop seasons. The first experiment was carried out in a complete block design, with a split plot arrangement. The treatments were two theoretical working depths of a driller chisel-type furrow opener (0.06 and 0.12 m, split plot), and three soil winter covers (main plot): fallow, black oat ( Avena strigosa), and black oat+common vetch ( Vicia sativa). In 2006, the soil cover black oat+common vetch was replaced by oilseed radish ( Raphanus sativus). In the second experiment, in a complete block design, the soil was chiseled and treatments consisted of black oat or oilseed radish as winter cover crops. Cover crops reduced soil superficial (0-0,06 m) compaction compared to fallow and, in the 2005/2006-crop season, under low water availability, provided higher soybean and corn yields. In the 2006/2007-crop season, when water availability was higher, the same did not happen. Increasing working depths of the chisel-type furrow opener did not affect soybean or corn yields. Soil chiseling reduced soybean and corn yields in comparison to the continuous no-tillage system.
  • Authors:
    • Delatorre, C.
    • Federizzi, L.
    • Locatelli, A.
    • Martinelli, J.
    • Graichen, F.
    • Kulcheski, F.
  • Source: Euphytica
  • Volume: 175
  • Issue: 3
  • Year: 2010
  • Summary: Crown rust, which is caused by Puccinia coronata f. sp. avenae, P. Syd. & Syd., is the most destructive disease of cultivated oats ( Avena sativa L.) throughout the world. Resistance to the disease that is based on a single gene is often short-lived because of the extremely great genetic diversity of P. coronata, which suggests that there is a need to develop oat cultivars with several resistance genes. This study aimed to identify amplified fragment length polymorphism AFLP markers that are linked to the major resistance gene, Pc68, and to amplify the F 6 genetic map from Pc68/5*Starter * UFRGS8. Seventy-eight markers with normal segregation were discovered and distributed in 12 linkage groups. The map covered 409.4 cM of the Avena sativa genome. Two AFLP markers were linked in repulsion to Pc68: U8PM22 and U8PM25, which flank the gene at 18.60 and 18.83 centiMorgans (cM), respectively. The marker U8PM25 is located in the linkage group 4_12 in the Kanota * Ogle reference oat population. These markers should be useful for transferring Pc68 to genotypes with good agronomic characteristics and for pyramiding crown rust resistance genes.
  • Authors:
    • Rocha, D.
    • Cano, M.
    • Patino, H.
    • Medeiros, F.
    • Gonzalez, F.
  • Source: Ciencia Rural
  • Volume: 40
  • Issue: 1
  • Year: 2010
  • Summary: The impact of energy supplementation on the performance and carcass characteristics of 24 Aberdeen-Angus * Charolais steers grazing an annual ryegrass ( Lolium multiflorum) and oat ( Avena strigosa [ Avena nuda]) pasture managed in order to avoid constrains to animal performance was evaluated. Treatments were levels of supplementation of 0, 0.4, 0.8 and 1.2% BW with a corn and mineral based supplement. Animals were slaughtered after reaching 4.5 mm of fat cover in the rump (P8) evaluated ultrasonography. No differences were observed in fat deposition, measured in live animals with ultrasound at the end of performance period, and in liveweight gain, which showed average values of 3.9 mm and 1.54 kg/day, respectively. Blood serum levels of urea were linearly decreased and cholesterol linearly increased by energy supplementation, with no differences in the serum levels of glucose and triglycerides. Energy supplementation linearly increased the killing-out proportion and carcass weight gain, but no differences were observed on the rib eye area, slaughter weight and hot carcass weight, which averaged 67.85 cm 2, 438.95 kg and 227.75 kg, respectively. Increasing the levels of supplementation resulted in higher killing-out proportion and higher carcass daily gains, without changes in performance and carcass parameters evaluated.