• Authors:
    • Carvalho, P. C. de F.
    • Cassol, L. C.
    • Anghinoni, I.
    • Flores, J. P. C.
    • Leite, J. G. dal B.
    • Fraga, T. I.
  • Source: REVISTA BRASILEIRA DE CIENCIA DO SOLO
  • Volume: 31
  • Issue: 4
  • Year: 2007
  • Summary: The integration of farming and cattle production activities in no-tillage system areas with winter cover crops can be an income supplement for summer grain farmers. However, many of them are afraid of adopting this integration system because of possible negative effects of animal treading on soil attributes, mainly of those related to soil compaction. This study was conducted: (1) to determine the alterations in the soil physical attributes promoted by animal treading; and (2) to verify if the alterations in soil attributes due to animal treading affect soyabean establishment and grain yield. The experiment was carried out with a Rhodic Hapludox (Oxisol), under black oat [ Avena nuda] + ryegrass [ Lolium] pasture grazed at different heights (10, 20, 30 and 40 cm) and an ungrazed area. After one cycle of animal treading, there were no significant modifications in soil bulk density, porosity and compressibility at different grazing heights. However, soil density and compressibility were higher and the porosity lower in the grazed plots. The soyabean population and grain yield were not affected by modifications in the soil physical attributes.
  • Authors:
    • Souza, R. A.
    • Crispino, C. C.
    • Franchini, J. C.
    • Torres, E.
    • Hungria, M.
  • Source: Soil & Tillage Research
  • Volume: 92
  • Issue: 1/2
  • Year: 2007
  • Summary: The objective of this work was to identify soil parameters potentially useful to monitor soil quality under different soil management and crop rotation systems. Microbiological and chemical parameters were evaluated in a field experiment in the State of Parana, southern Brazil, in response to soil management [no-tillage (NT) and conventional tillage (CT)] and crop rotation [including grain (soybean, S; maize, M; wheat, W) and legume (lupin, L.) and non-legume (oat, O) covers] systems. Three crop rotation systems were evaluated: (1) (O/M/O/S/W/S/L/M/O/S), (2) (O/S/L/M/O/S/W/S/L/M), and (3) (O/S/W/S/L/M/O/M/W/M), and soil parameters were monitored after the fifth year. Before ploughing, CO 2-emission rates were similar in NT and CT soils, but plough increased it by an average of 57%. Carbon dioxide emission was 13% higher with lupin residues than with wheat straw; decomposition rates were rapid with both soil management systems. Amounts of microbial biomass carbon and nitrogen (MB-C and MB-N, respectively) were 80 and 104% higher in NT than in CT, respectively; however, in general these parameters were not affected by crop rotation. Efficiency of the microbial community was significantly higher in NT: metabolic quotient ( qCO 2) was 55% lower than in CT. Soluble C and N levels were 37 and 24% greater in NT than in CT, respectively, with no effects of crop rotation. Furthermore, ratios of soluble C and N contents to MB-C and MB-N were consistently lower in NT, indicating higher immobilization of C and N per unit of MB. The decrease in qCO 2 and the increase in MB-C under NT allowed enhancements in soil C stocks, such that in the 0-40 cm profile, a gain of 2500 kg of C ha -1 was observed in relation to CT. Carbon stocks also varied with crop rotation, with net changes at 0-40 cm of 726, 1167 and -394 kg C ha -1 year, in rotations 1, 2 and 3, respectively. Similar results were obtained for the N stocks, with 410 kg N ha -1 gained in NT, while crop rotations 1, 2 and 3 accumulated 71, 137 and 37 kg of N ha -1 year -1, respectively. On average, microbial biomass corresponded to 2.4 and 1.7% of the total soil C, and 5.2 and 3.2% of the N in NT and CT systems, respectively. Soil management was the main factor affecting soil C and N levels, but enhancement also resulted from the ratios of legumes and non-legumes in the rotations. The results emphasize the importance of microorganisms as reservoirs of C and N in tropical soils. Furthermore, the parameters associated with microbiological activity were more responsive to soil management and crop rotation effects than were total stocks of C and N, demonstrating their usefulness as indicators of soil quality in the tropics.
  • Authors:
    • Pereira, J.
    • Prior, M.
    • Uribe-Opazo, M.
    • Nobrega, L.
    • Lopes, R.
  • Source: Acta Scientiarum Agronomy
  • Volume: 29
  • Issue: Suplemento Espec
  • Year: 2007
  • Summary: This study evaluated alterations in the physical properties water content, soil density and porosity in areas under no tillage and tillage systems in the cultures of soybean and maize in three agricultural years. The experiment was carried out at the Experimental Nucleus of Agricultural Engineering of Unioeste (Cascavel, state of Parana). Soybean culture occurred in the first two years and in the third year maize, as summer crop, black oats and forage turnip as winter cover crops. During these three years the study observed reduction of water content and soil density and increase of porosity. The variations as regards the physical properties of the soil showed direct proportional relation between water content and soil density and was in inverse proportion for soil porosity. The soil presented improvements on its physical conditions for the porosity increase and density reduction with the black oats and forage turnip crops and maize. The soybean/maize management in rotation with black oats and forage turnip showed more adequate in the improvement of the physical conditions of the soil as compared with the management systems, since neither of the systems had a major impact in the improvements of the physical properties evaluated throughout this whole period.
  • Authors:
    • Lucca e Braccini, A.
    • Pinheiro Neto, R.
    • Lopes, R.
    • Souza, E.
  • Source: Acta Scientiarum Agronomy
  • Volume: 29
  • Issue: 4
  • Year: 2007
  • Summary: This study evaluated the performance of the soybean under the influence of vegetal covering and soil management in Red Latosol dystrofic. Oats, turnip, hairy vetch, pea, millet and lupine were used. The study evaluated height and density of plants, height of insertion in string beans, number of string beans, productivity, a thousand grain mass, water contend, bulk density and soil resistance to penetration. The no-tillage system had greater height of insertion of string beans, amount of string beans, height of plants, water contend and soil bulk density. Greater values of soil resistance to penetration were verified in the tillage, though higher productivity was observed. The coverings and the soil tillage systems influenced the productivity of soybean plants. The vegetal coverings promoted improvement of the ground with reduction of the compactation in some layers of the soil. The oats/millet association is a viable option of soil covering predecessor of soybean. The no-tillage practice showed to be the adequate management technique for the type of soil studied.
  • Authors:
    • Rodrigues, E.
    • Marchetti, M.
    • Goncalves, M.
    • Souza, L.
    • Ontocelli, R.
    • Lourente, E.
  • Source: Acta Scientiarum Agronomy
  • Volume: 29
  • Issue: 1
  • Year: 2007
  • Summary: Some plants for mulching have the capacity to increase the availability of nutrients in the soil - nitrogen in particular - for crop succession, thus producing positive effects on the interaction between mineral fertilizer and green manure. As a result, there is a greater possibility to obtain higher incomes than by using each one separately. The objective of this study was to evaluate the effect of antecedent crops, levels and sources of nitrogen on yield compounds and foliar nitrogen content of maize by means of no-tillage system. These were constituted by crops preceding maize, i.e., black oat, wheat, pasture turnip, hairy vetch and one fallow treatment during winter. Subplots were established by four levels of nitrogen (0; 50; 100 and 200 kg ha -1 of N), which were applied as cover. Sub-subplots were represented by two sources of nitrogen (ammonium sulfate and urea). Results showed that antecedent crops had some influence upon yield, mass of 1000 grains and foliar nitrogen content of maize. The highest yield of maize was obtained after the winter rest, the pasture turnip and also in the absence of nitrogen fertilizer application as cover. Maximum yield of maize was also obtained when sowing was done after wheat and black oat, in nitrogen levels of 140 and 137 kg ha -1, respectively. The nitrogen sources utilized had some influence only upon the index of harvest, the number of grains per ear and the foliar nitrogen content.
  • Authors:
    • Coscione, A.
    • Quaggio, J.
    • Cantarella, H.
    • Moraes, M.
  • Source: REVISTA BRASILEIRA DE CIENCIA DO SOLO
  • Volume: 31
  • Issue: 4
  • Year: 2007
  • Summary: The efficiency of subsurface acidity alleviation by surface liming in the presence of crop residues is controversial and needs more information. The study aimed to quantify the contribution of cover crop residues, regarding their contents of low molar mass organic acids and soluble nutrients to the mobilization of reaction products of surface-applied lime in the soil profile. Two experiments were conducted under laboratory conditions using 30 cm high PVC cylinders filled with acid and clayey red latosol. Treatments consisted of sole application of lime to 80% soil base saturation (6.1 t ha -1) or lime in combination with radish ( Raphanus sativus) or black oat ( Avena strigosa) [ Avena nuda] crop residues (20 t ha -1), as well as the equivalent amounts of organic acids and inorganic salts present in the plant materials. The application of lime alone or in combination with plant material reduced soil acidity in the 0-8 cm surface layer only. The low recovery of organic acids added to the soils (≤7.2%) indicates that the acids were rapidly metabolized or adsorbed to the soil colloidal fraction, which explains the small effect on cation mobilization. A substantial part of the ion mobilization in the soil and leached solution after application of crop residues was probably due to the plant-own inorganic ion content due to the high water solubility: 65 to 71% for cations and 84% for anions. The greatest amount of aluminium displaced from the soil was due to the application of inorganic salt solutions. The presence of plant residues had little effect on the mobilization of the reaction products of surface-applied lime.
  • Authors:
    • Garcia, R.
    • Foloni, J.
    • Calonego, J.
    • Rosolem, C.
  • Source: PESQUISA AGROPECUARIA BRASILEIRA
  • Volume: 42
  • Issue: 8
  • Year: 2007
  • Summary: Potassium leaching from black oat ( Avena strigosa [ Avena nuda]) and pearl millet ( Pennisetum glaucum) straw as affected by simulated rainfall at different times after chemical desiccation was evaluated. Cover crops were grown in pots, in Botucatu, Sao Paulo, Brazil. Fifty days after emergence, the plants were sprayed with herbicide. The straw received simulated rains corresponding to 5 and 10 mm, considering a mulch of 8 t/ha, 3, 6, 9 and 15 days after desiccation. The amount of K leached from the plant residues increased after desiccation. Fifteen days after desiccation, a rainfall of 10 mm leached 11.1 kg/ha of K. A higher potential of black oat straw to leach K was observed with 10 mm of rain. The amount of K released by rains from black oat straw was greater than the pearl millet with 5 and 10 mm of rain, and this difference increased according to water loss from tissues.
  • Authors:
    • Mendez, M.
    • Vitti, M.
    • Costa, V.
    • Giacobbo, C.
    • Rufato, L.
    • Rossi, A.
    • Fachinello, J.
  • Source: Bragantia
  • Volume: 66
  • Issue: 3
  • Year: 2007
  • Summary: Field studies were conducted in Rio Grande do Sul, Brazil, to evaluate 5 different managements of black oat ( Avena nuda) crop cover. The treatments comprised: incorporation of black oat to soil; chemical management with herbicide; lodging; mowing at 5 cm; and control (uncovered soil). The sowing of the oat was accomplished by April of 2002 and the installation of the experiment by the end of August of the same year. The analysed variables were percentage of soil moisture at a depth of 15 cm, temperature of the soil at a depth of 5 cm, percentage of organic matter of the soil, soil resistance to the penetration and identification and degree of infestation by weeds. The data were submitted to analysis of variance through the F test and the averages compared by the Duncan Test. Maintenance of crop covering in orchards propitiated smaller temperature and larger soil moisture. The soil turn-over increased the diversity of weeds and the incorporation of black oat, after 60 days, had the same behaviour as the uncovered soil.
  • Authors:
    • Silva, P.
    • Ernani, P.
    • Sangoi, L.
  • Source: REVISTA BRASILEIRA DE CIENCIA DO SOLO
  • Volume: 31
  • Issue: 3
  • Year: 2007
  • Summary: No-tillage systems, associated with black oat as preceding cover crop, have been increasingly adopted. This has motivated anticipated maize nitrogen fertilizer application, transferring it from the side-dress system at the stage when plants have 5-6 expanded leaves to when the preceding cover crop is eliminated or to maize sowing. This study was conducted to evaluate the effects of soil tillage system and timing of N fertilizer application on maize grain yield and agronomic efficiency of N applied to a soil with high organic matter content. A three-year field experiment was conducted in Lages, state of Santa Catarina, Brazil, from 1999 onwards. Two soil tillage systems were tested in the main plots: conventional tillage (CT) and no-tillage (NT). Six N management systems were assessed in the split-plots: S1, control (without N application); S2, all N (100 kg ha -1) applied at oat desiccation; S3, all N applied at maize sowing; S4, all N side-dressed when maize had five expanded leaves (V5 growth stage); S5, 1/3 of N rate applied at maize sowing and 2/3 at V5; and S6, 2/3 of nitrogen rate applied at maize sowing and 1/3 at V5. Maize response to the time and form of splitting N was not affected by the soil tillage system. Grain yield ranged from 6.0 to 11.8 t ha -1. The anticipation of N application (S2 and S3) decreased grain yield in two of three years. In the rainiest early spring season (2000/2001) of the experiment, S4 promoted an yield advantage of 2.2 t ha -1 over S2 and S3. Application of total N rate before or at sowing decreased the number of kernels produced per ear in 2000/01 and 2001/02 and the number of ears produced per area in 2001/02, resulting in reduced grain yield. The agronomic efficiency of applied N (kg grain increase/kg of N applied) ranged from 13.9 to 38.8 and was always higher in the S4 than in the S2 and S3 N systems. Short-term N immobilization did not reduce grain yield when no N was applied before or at maize sowing in a soil with high organic matter content, regardless of the soil tillage system.
  • Authors:
    • Rambo, L.
    • Strieder, M.
    • Argenta, G.
    • Suhre, E.
    • Silva, P.
    • Silva, A.
  • Source: Ciencia Rural
  • Volume: 37
  • Issue: 4
  • Year: 2007
  • Summary: The black oats use ( Avena strigosa) as species of soil covering in the winter, cause immobilization of the nitrogen (N), that reduces the plant development and grain yield of maize cultivated in succession. Thus, the black oat intercropped systems with leguminous as common vetch ( Vicia sativa) and brassicas as oilseed radish ( Raphanus sativus) is aimed at increasing nitrogen (N) disponibility in the system and the permanence timing of its residues in the soil. Two experiments were carried out in the growth seasons of 2001/2002 and 2002/2003, in Rio Grande do Sul, Brazil. The first one was aimed at evaluating the effect of three winter species of soil covering, grown as a single culture and as intercropped crops on maize grain yield, with and without nitrogen side-dressed. The second one was aimed at determining the most adequate seed ratio of oilseed radish and black oat in intercropped systems, as soil covering crops in the winter preceding maize, under different nitrogen levels side-dressed. In Experiment I, treatments were composed by N application of 180 kg ha -1, a control without N side-dressed and seven winter soil covering systems. In the Experiment II, treatments consisted of two levels of N side-dressing application in maize, a control without N side-dressed, and of three seed ratio of oilseed radish and black oat, as single and as intercropped crops and a control without crop in the winter. In all intercropped systems, independently of seed ratio used, the oilseed radish was mostly responsible for the yield of dry mass of the systems. The intercropped systems of common vetch or oilseed radish with black oat minimize the negative effect of oat on maize grain yield cultivated in succession in systems with low N availability and, even with high N supply, maize grain yield also increases when grown after common vetch.