741. Crop residue effect on crop performance, soil N 2O and CO 2 emissions in alley cropping systems in subtropical China.

• Authors:
  • Zheng, M.
  • Wang, T.
  • Li, Z.
  • Cai, C.
  • Guo, Z.
• Source: Agroforestry Systems
• Volume: 76
• Issue: 1
• Year: 2009
• Summary: Land management practices that simultaneously improve soil properties are crucial to high crop production and minimize detrimental impact on the environment. The effects of crop residues on crop performance, the fluxes of soil N 2O and CO 2 under wheat-maize (WM) and/or faba bean-maize (FM) rotations in Amorpha fruticosa (A) and Vetiveria zizanioides (V) intercropping systems on a loamy clay soil, in subtropical China, were examined. Crop performance, soil N 2O and CO 2 as well as some potential factors such as soil water content, soil carbon, soil nitrogen, microbial biomass and N mineralization were recorded during 2006 maize crop cultivation. Soil N 2O and CO 2 fluxes are determined using a closed-based chamber. Maize yield was greater after faba bean than after wheat may be due to differences in supply of N from residues. The presence of hedgerow significantly improved maize grain yields. N 2O emissions from soils with maize were considerably greater after faba bean (345 g N 2O-N ha -1) than after wheat (289 g N 2O-N ha -1). However, the cumulated N 2O emissions did not differ significantly between WM and FM. The difference in N 2O emissions between WM and FM was mostly due to the amounts of crop residues. Hedgerow alley cropping tended to emit more N 2O than WM and FM, in particular A. fruticosa intercropping systems. Over the entire 118 days of measurement, the N 2O fluxes represented 534 g N 2O-N ha -1 (AWM) and 512 g N 2O-N ha -1 (AFM) under A. fruticosa species, 403 g N 2O-N ha -1 (VWM) and 423 g N 2O-N ha -1 (VFM) under Vetiver grass. A significantly higher CO 2 emission was observed in AFM (5335 kg CO 2-C ha -1) from June to October, whereas no significant difference was observed among WM (3480 kg CO 2-C ha -1), FM (3302 kg CO 2-C ha -1), AWM (3877 kg CO 2-C ha -1), VWM (3124 kg CO 2-C ha -1) and VFM (3309 kg CO 2-C ha -1), indicating the importance of A. fruticosa along with faba bean residue on CO 2 fluxes. As a result, crop residues and land conversion from agricultural to agroforestry can, in turn, influence microbial biomass, N mineralization, soil C and N content, which can further alter the magnitude of crop growth, soil N 2O and CO 2 emissions in the present environmental conditions.

742. Parameters of soil-machine in function of the amount of cover residues and different fertilizer deposition depths in direct drilling.; Parametros solo-maquina em funcao de doses de residuos vegetais e profundidades de deposicao de adubo em semeadura direta.

• Authors:
  • Debiasi, H.
  • Trein, C.
  • Levien, R.
  • Kamimura, K.
  • Conte, O.
• Source: ENGENHARIA AGRICOLA
• Volume: 29
• Issue: 3
• Year: 2009
• Summary: The continuous and inadequate machine traffic on soils under direct drilling has been changing the soil physical and mechanical properties, influencing therefore crop productivity. The experiment was carried out at the Agricultural Research Station of the Universidade Federal do Rio Grande do Sul (Eldorado do Sul, RS, Brazil) on Typic Paleudlt. The main aim of the work was to measure coulter draft requirements and physical attributes under black oats ( Avena strigosa Schieb) and common vetch (CV) ( Vicia sativa L.) partially decomposed. The experimental design was carried out in randomized blocks, with split-split-plots and three repetitions. The main treatments were plots with different amount of residues of the winter crop (0, 1,3; 2,6; 3,2; 3,8 and 5,1 Mg ha -1), sub-plots were two working depth of the driller chisel-type furrow opener, and two traffic conditions (combine and tractor wheel traffic). The physical characteristics of the soil were influenced by the traffic tracks. The whole tractor-drill was influenced by the depths of fertilizer shanks and traffic of traffic tracks and combine.

743. Winter cover crops in no-tillage system whitout herbicides: effects on weed biomass and tomato yield.; Plantas de cobertura de inverno em sistema de plantio direto de hortalicas sem herbicidas: efeitos sobre plantas espontaneas e na producao de tomate.

• Authors:
  • Lovato, P.
  • Lana, M.
  • Fayad, J.
  • Comin, J.
  • Kieling, A.
• Source: Ciencia Rural
• Volume: 39
• Issue: 7
• Year: 2009
• Summary: To eliminate herbicide use in no-tillage tomato production, an experiment was carried out to evaluate the best combination of winter cover crops for weed control and tomato production at the Ituporanga Experimental Station in Santa Catarina, Brazil. Oat ( Avena strigosa [ Avena nuda]), vetch ( Vicia villosa) and fodder radish ( Raphanus sativus) were grown in monoculture and in mixes. The tomato cv. Marcia-EPAGRI was stake-trained and grown under fertigation. The highest values in above-ground dry biomass were obtained by oat+vetch and oat monoculture, followed by vetch+radish, oat+radish, and oat+vetch+radish. Treatments with oats had the best performances in controlling resident vegetation, while vetch was associated with the worst performances. There were no significant differences between the treatments for total yield and marketable fruit production.

744. Soil covering, biomass production, and Mn and Zn content of lettuce in organic system.; Cobertura do solo, producao de biomassa e teores de Mn e Zn de alface no sistema organico.

• 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.

745. Soil coverage and apple tree growth on the establishment of an orchard under organic production system.; Coberturas do solo e crescimento da maciera na implantacao de um pomar em sistema organico de producao.

• 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.

746. Corn ( Zea mays) as bioindicator of the residual activity of (imazethapyr+imazapic).; Milho ( Zea mays) como especie bioindicadora da atividade residual de (imazethapyr+imazapic).

• 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 (

747. Comparison of mechanical and chemical winter cereal cover crop termination systems and cotton yield in conservation agriculture.

• Authors:
  • Komecki, T. S.
  • Balkcom, K. S.
  • Raper, R. L.
  • Arriaga, F. J.
  • Price, A. J.
  • Reeves, D. W.
• Source: Journal of Cotton Science
• Volume: 13
• Issue: 4
• Year: 2009
• Summary: An integral component of conservation agriculture systems in cotton ( Gossypium hirsutum L.) is the use of a high-residue winter cover crop; however, terminating cover crops is an additional expense and planting into high-residue can be a challenge. An experiment was conducted using black oat ( Avena strigosa Schreb.), rye ( Secale cereale L.), and wheat ( Triticum aestivum L.) cover crops established in early November at three locations. In mid-April each year all winter cover crops were flattened with a straight-blade mechanical roller-crimper alone or followed by three rates of glyphosate (0.84, 0.42, 0.21 kg ae/ha). Additionally, glyphosate alone at each rate and a non-treated check were included to complete the factorial treatment arrangement. Cotton was then planted 3 weeks after treatments were administered following in-row sub-soiling at E.V. Smith and direct seeding at Tennessee Valley and Robertsdale. Results showed that rolling followed by reduced glyphosate rates as low as 0.42 kg ae/ha can effectively and reliably terminate mature cereal winter cover crops; thus maintaining cotton population and protecting growth. Additionally, reduced glyphosate rates applied as low as 0.84 kg ae/ha alone can effectively terminate immature cereal covers while conserving soil moisture. Rolling mature winter cereal cover crops will likely conserve more soil moisture compared to standing covers; however, rolling immature cereal cover crops provides no benefit. In 2005 at E.V. Smith and at Tennessee Valley in 2006, increasing glyphosate rate increased cotton yield likely due to less mature cereal covers at time of treatment application. However, the inclusion of glyphosate did not increase cotton yield for any other comparison.

748. Soil chemical properties and grapevine yield affected by cover crop management in Serra Gaucha, Southern Brazil.; Atributos quimicos do solo e produtividade de videiras alterados pelo manejo de coberturas verdes na Serra Gaucha.

• 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.

749. Soil organic carbon and nitrogen stocks in an untilled crop-livestock integration system under different grazing intensities.; Estoques de carbono organico e de nitrogenio no solo em sistema de integracao lavoura-pecuaria em plantio direto, submetido a intensidades de pastejo.

• 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.

750. Organic matter kept Al toxicity low in a subtropical no-tillage soil under long-term (21-year) legume-based crop systems and N fertilisation.

• 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.