• 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:
    • 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:
    • Mimikou, M.
    • Panagopoulos, I.
    • Kapetanaki, M.
  • Source: Journal of Soils and Sediments
  • Volume: 7
  • Issue: 4
  • Year: 2007
  • Summary: This study investigated the behaviour of two groups of widespread and different textured soil types, on nutrient (N, P) losses under cold climate conditions. The investigation was conducted in the Norwegian Vansj-Hoblv catchment through the application of a physical model named Soil and Water Assessment Tool (SWAT), taking into consideration the additional aspect of freezing soils during winter, which distinguishes Scandinavian from other European soils. SWAT is a physical river-basin model that was developed for the USDA Agricultural Research Service, by the Blackland Research Center in Texas. In the current modelling approach the catchment was divided into 43 Hydrologic Response Units (HRUs) which consist of different combinations of the existed land cover and soil types. Nutrient losses arising from these HRUs were estimated for the period 1990-2001 through the simultaneous simulation of water and sediment processes that are closely linked to the nutrient processes. The model took into account soil temperature to quantify water and nutrient transport to deeper layers, considering negligible downward movement when the soil temperature was under 0°C. It also simulated the aboveground development of the snowpack and the snowmelt processes on a daily basis. The six different soil types were aggregated in two groups according to their similarity in texture and other physical properties, one group of fine-textured soils and a group of coarse soils. The results were evaluated for different crop cultivations (barley, oats and wheat) of the aforementioned soils. Finally, the model was calibrated and validated by comparing predicted results with measured data. Fine-textured soils caused significant runoff, sediment and nutrient yields to the river system while coarser soils were characterized by high water drainage and nitrates leaching. The first soil group caused a mean of 517 mm of runoff in annual basis, 200 mm higher than this arising from coarse soils. Moreover, 3 tonnes of sediments per hectare, 24.6 kg N/ha and 0.54 kg P/ha were lost annually to surface water from fine soils while the average respective losses originating from coarse soils were only 1.3 tonnes of sediments/ha, 13.6 kg N/ha and 0.17 kg P/ha. The sensitivity ranking of the soil types to nutrient losses was silty-clay-loam > silty-loam > clay > loamy > sandy-loam > sandy. An average of 277 mm of water was percolated annually under the bottom of the soil profile in coarse soils causing the additional leaching of 5.6 kg N-NO 3/ha whereas the losses originating from fine-textured soils were 153 mm and 2.5 kg/ha, respectively. According to their sensitivity in nitrates leaching, the six soil types were ranked in the following order: sandy > loamy > sandy-loam > silty-loam > silty-clay-loam > clay. The results showed that even though under cold climate conditions, with monthly periods of average air-temperatures below zero, the overall amounts of annual TN and TP losses to surface waters as well as nitrates leaching to groundwater were considerable. The results demonstrate the need of considering the soil differentiation in Scandinavian countries similarly to the rest of Europe in order to apply mitigation measures against nutrient losses to surface and groundwater.
  • Authors:
    • Balkcom, K. S.
    • Gamble, B. E.
    • Patterson, M. G.
    • Reeves, D. W.
    • Price, A. J.
    • Arriaga, F. J.
    • Monks, C. D.
  • Source: Peanut Science
  • Volume: 34
  • Issue: 1
  • Year: 2007
  • Summary: Information is needed on the role of cover crops as a weed control alternative due to the increase in adoption of conservation-tillage in peanut production. Field experiments were conducted from autumn 1994 through autumn 1997 in Alabama to evaluate three winter cereal cover crops in a high-residue conservation-tillage peanut production system. Black oat ( Avena strigosa Schreb.), rye ( Secale cereale L.), and wheat ( Triticum aestivum L.) were evaluated for their weed-suppressive characteristics compared to a winter fallow system. Three herbicide systems were utilized: no herbicide, preemergence (PRE) herbicides followed by (fb) postemergence (POST) herbicides, and PRE fb sequential POST herbicides. The PRE fb POST herbicide input system consisted of pendimethalin at 1.12 kg ai/ha fb an additional early POST application of paraquat at 0.14 kg ai/ha plus bentazon at 0.56 kg ai/ha. The PRE fb sequential POST herbicide input system contained the aforementioned herbicides fb 2,4-DB at 0.22 kg ai/ha plus chlorimuron at 0.14 kg ai/ha applied late POST. No cover crop was effective in controlling weeds without a herbicide program. However, when black oat or rye was utilized with PRE fb POST herbicides, weed control was similar to the high input system in two out of three years. Yield increased in 14 of 27 comparisons following conservation-tilled peanut using the Brazilian cover crop management system, compared to a winter fallow system. Yields never decreased following a winter cover crop compared to winter fallow. The winter fallow, high herbicide input system yielded between 7 and 26% less peanut compared to the highest yielding system that included a winter cover crop. The Brazilian system using black oat or rye cover crop has potential to increase peanut productivity and reduce herbicide inputs for peanuts grown in the Southeast.
  • 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.
  • Authors:
    • Souza, L.
    • Silva, D.
  • Source: Revista Brasileira de Milho e Sorgo
  • Volume: 6
  • Issue: 2
  • Year: 2007
  • Summary: Brazil has been producing maize in almost all regions, although the costs of production increased in the last years. New techniques which provide economy without yield loss can motivate producers, as maize is an important culture used at crop rotation system. Green manure may reduce maize production costs, maily to the incorporation of nitrogen. Data from an experiment were used for these comparisons; treatments were conducted in Mato Grosso do Sul, Brazil in three precedent maize cultures (black oat, oilseed radish and hairy vetch) and six nitrogen fertilizers levels (zero, 50, 100, 150, 200 and 250 kg/ha). Maize after black oat showed damage when N 25 kg/ha was used, while increasing levels increased yield up to 150 kg/ha, wherein the maximum yield was 1233 kg/ha. Maize after oilseed radish showed under zero rate a yield of 1500 kg/ha, but MEE occurs at N 40 kg/ha. Maize after hairy vetch showed no response to N, so MEE occurs at zero N, where yield was 2100 kg/ha. Maize antecessor cultures that release more nitrogen could provide higher yield to the system with lower use of fertilizers.
  • Authors:
    • Santen, E. van
    • Price, A.
    • Shaw, J. N.
    • Sullivan, D. G.
  • Source: Agronomy Journal
  • Volume: 99
  • Issue: 6
  • Year: 2007
  • Summary: Conservation tillage is a commonly adopted best management practice for reducing runoff and erosion, and increasing infiltration. Yet current methodologies in place to monitor conservation tillage adoption are largely inappropriate for regional or national assessments. A major goal of this study was to evaluate the spectral response properties of four alternative winter cover crops using remotely derived crop residue cover indices. Experimental plots were located in east-central Alabama on a coarse-loamy siliceous, subactive, thermic Plinthic Paleudult. The experiment was a randomized complete block design having four replications of each of the following treatments: one fallow conventional tillage treatment and four no-tillage treatments with black oat ( Avena strigosa Schreb.), crimson clover ( Trifolium incarnatum L.), turnip ( Brassica rapa L. subsp.rapa), or rye ( Secale cereale L.) cover crops. Remotely sensed data were acquired three times using a 14 d sampling interval beginning near planting and using a handheld multispectral radiometer (485-1650 nm) in 2005 and 2006. Three crop residue cover indices using combinations of middle-infrared and visible spectra were compared and evaluated. Rye, clover, and black oat were spectrally similar, having an overall spectral response ranging from 8 to 45% (440-1650 nm). Increasing soil water content between remotely sensed data acquisitions was evidenced by as much as a 24% decline in middle-infrared reflectance. Despite this variability, a normalized difference ratio of middle-infrared (1650 nm) and blue (445 nm) spectra (Crop Residue Cover Index) provided the most consistent differentiation between tillage systems, varying within 8% of benchmark conditions (low soil water and low canopy cover). Considering the impact that conservation tillage may have on soil and water resources, rapid, watershed scale assessments of conservation tillage adoption may facilitate natural resource inventories, carbon sequestration estimates, and improved agricultural water management regimes.