841. Effects of a killed-cover crop mulching system on sweetpotato production, soil pests, and insect predators in South Carolina.

• Authors:
  • Harrison, H.
  • Jackson, D.
• Source: Journal of Economic Entomology
• Volume: 101
• Issue: 6
• Year: 2008
• Summary: Sweetpotatoes, Ipomoea batatas (L.) Lam. (Convolvulaceae), are typically grown on bare soil where weeds and erosion can be serious problems. Conservation tillage systems using cover crop residues as mulch can help reduce these problems, but little is known about how conservation tillage affects yield and quality of sweetpotato or how these systems impact populations of beneficial and pest insects. Therefore, field experiments were conducted at the U.S. Vegetable Laboratory, Charleston, SC, in 2002-2004 to evaluate production of sweetpotatoes in conventional tillage versus a conservation tillage system by using an oat ( Avena sativa L.) (Poaceae)-crimson clover ( Trifolium incarnatum L.) (Fabaceae) killed-cover crop (KCC) mulch. The four main treatments were (1) conventional tillage, hand-weeded; (2) KCC, hand-weeded; (3) conventional tillage, weedy; and (4) KCC, weedy. Each main plot was divided into three subplots, whose treatments were sweetpotato genotypes: 'Ruddy', which is resistant to soil insect pests; and 'SC1149-19' and 'Beauregard', which are susceptible to soil insect pests. For both the KCC and conventional tillage systems, sweetpotato yields were higher in plots that received hand weeding than in weedy plots. Orthogonal contrasts revealed a significant effect of tillage treatment (conventional tillage versus KCC) on yield in two of the 3 yr. Ruddy remained resistant to injury by soil insect pests in both cropping systems; and it consistently had significantly higher percentages of clean roots and less damage by wireworm- Diabrotica-Systena complex, sweetpotato flea beetles, grubs, and sweetpotato weevils than the two susceptible genotypes. In general, injury to sweetpotato roots by soil insect pests was not significantly higher in the KCC plots than in the conventionally tilled plots. Also, more fire ants, rove beetles, and carabid beetle were captured by pitfall traps in the KCC plots than in the conventional tillage plots during at least 1 yr of the study. This study suggests that a sweetpotatoes can be successfully grown under a killed-cover crop production system.

842. Efficiency of mechanical and biological chiseling in the improvement of physical attributes of a heavy clay oxisol and the increment of soybean yield.; Eficiencia da escarificacao mecanica e biologica na melhoria dos atributos fisicos de um latossolo muito argiloso e no incremento do rendimento de soja.

• Authors:
  • Bragagnolo, J.
  • Girardello, V.
  • Lanzanova, M.
  • Schneider, S.
  • Amado, T.
  • Nicoloso, R.
• Source: REVISTA BRASILEIRA DE CIENCIA DO SOLO
• Volume: 32
• Issue: 4
• Year: 2008
• Summary: This study aimed to evaluate the efficiency of a mechanical (chisel plough) and biological (forage radish) soil decompaction method or the combination of both to improve the physical properties of a very clayey texture Oxisol and to increase soyabean grain yield under no-tillage. The treatments were: black oat on no-till (NT-O), consortium of forage radish and black oat on no-till (NT-R+O), black oat on chiselled soil (CH-O) and consortium of forage radish and black oat on chiselled soil (CH-R+O). The following properties were evaluated: soil bulk density, macroporosity, microporosity and total porosity in the layers 0-0.05, 0.05-0.10, 0.10-0.15 and 0.15-0.20 m, soil penetration resistance, soil moisture and soil water infiltration at soyabean flowering. The winter cover biomass production and soyabean yield were also measured. The treatments did not affect the soil bulk density significantly at any of the soil depths. However, the treatments NT-R+O and CH-R+O doubled the mean soil macroporosity values in the 0-0.20 m layer, with more pronounced effects in the upper soil layers. The treatments NT-R+O and CH-R+O reduced soil penetration resistance compared to NT+O, while treatment CH-O had intermediate results. The treatments NTR+O and CH-R+O increased the accumulated infiltrated water by 44.6 as compared to treatments NT-O and CH-O. The highest soyabean yields were observed in the treatment CH-R+O (3.73 tonnes/ha), which did not differ significantly from treatment NT-R+O (3.49 tonnes/ha). The effect of winter mechanical chiseling was temporary and nine months later no soil physical improvements were observed, apart from the increase of total porosity and macroporosity in the 0-0.05 m layer. Biological chiselling increased soil macroporosity, reduced soil penetration resistance and improved soil water infiltration. Mechanical chiselling was only efficient to improve the soil physical conditions when associated with biological chiselling, which prevented soil reconsolidation.

843. Seeds quality and soybean productivity under non-tillage system and cover crops with black oat, forage turnip and vetch.

• Authors:
  • Coelho, S.
  • Rosa, D.
  • Mauli, M.
  • Nobrega, L.
  • Piccolo, G.
• Source: Central theme, technology for all: sharing the knowledge for development. Proceedings of the International Conference of Agricultural Engineering, XXXVII Brazilian Congress of Agricultural Engineering, International Livestock Environment Symposium - ILES V
• Year: 2008
• Summary: It was registered the allelopathic interference of remains of black oat (BO) in a consortium with BO, forage turnip and vetch (CO) in relation to seeds quality and soybean productivity, in interval of one, ten, twenty and thirty days between the covering desiccation with Glyphosate 480 (3 L ha -1) and the cultivar BRS 232 sowing (IDS). The coverings were prepared with plots of 5*2.5 m with 1 m of border, which were desiccated according to the IDS. So, there were four treatments and one control treatment for each covering, randomized with five replications. The soybean was sown with 0.45 m among rows, thirteen lines and 14 seeds by linear meter. The productivity was determined according to water content adjusted to 13%; germination percentage; mass of 100 seeds (m-100); water content and vigor (accelerated aging test). The experimental design was completely randomized, subdivided in parcels and averages were compared by Scott and Knott test at 5% of significance. The cropped soybean under BO presented the best answer for mass of 100 seeds, but when it was cropped under CO, it had the best vigor. Productivity did not differ between BO and CO. The IDS affected m-100 and productivity. IDS, at the first day, increased m-100, but did not reduce productivity. So, it does not recommend the soybean crop near the covering desiccation.

844. Seedlings emergence, plants heights and yield of soybean seeded under cover crops with black oat, forage turnip and vetch.

• Authors:
  • Rosa, D. M.
  • Mauli, M. M.
  • Nobrega, L. H. P.
  • Piccolo, G.
  • Smanhotto, A.
• Source: Central theme, technology for all: sharing the knowledge for development
• Year: 2008
• Summary: It was analyzed a possible allelopathic action of black oat ( Avena strigosa Schreb) (BO) in a consortium (CO) with BO, forage turnip ( Raphanus sativus L.) (FT) and vetch ( Vicia sativa L.) (V) in relation to seedling emergency (SE), emergency speed (ES), seedling emergency speed (SES) plants heights and soybean productivity, in interval between covering desiccation with Glyphosate 480 (3 L ha -1) and the cultivar BRS 232 sowing (IDS). Plots of 5*2.5 m were randomly prepared with 1 m of border, four treatments of BO and CO and two control treatments, with five replications of 0.15 among rows. At bloom term, the plots were desiccated in an IDS, of one, ten, twenty and thirty days. The soybean was sown in November 2006, with 0.45 m among rows, thirteen sowing lines and 14 seeds by linear m -1. The harvest was manual and productivity was adjusted to 13% of water content. The experimental design was completely randomized, subdivided in plots. The data were submitted to normality, while averages were compared by Scott and Knott test at 5% of significance. There was a possible effect of BO and CO on SES, with higher SES to CO. The coverings did not influence on the other parameters however, IDS interfered in all of them. Thus, it is recommended CO use with IDS from ten days.

845. Incidence of weeds species and soybean productivy under vegetal covering crops.

• Authors:
  • Souza Filho, A. P. da S.
  • Nobrega, L. H. P.
  • Piccolo, G.
  • Fortes, A. M. T.
  • Uribe-Opazo, M.
• Source: Central theme, technology for all: sharing the knowledge for development
• Year: 2008
• Summary: It was analyzed the possible allelopathic action of vegetal remains of black oat ( Avena strigosa Schreb) (BO) and a consortium (CO) of BO with forage turnip ( Raphanus sativus L.) and vetch ( Vicia sativa L.) in relation to the incidence of weed plants on soybean culture; in intervals (IDS) between covering desiccation with Glyphosate 480 (3 L ha -1) and the cultivar BRS 232 sowing; 5*2.5 m parcels with 1 m of border; four treatments of BO and CO and two control treatments, with five randomized replications, in August, 2006, with 0.15 m among rows. At bloom term, the plots were desiccated in an IDS, of one, ten, twenty and thirty days. The soybean was sown in November 2006, with 0.45 m among rows, thirteen sowing lines and 14 seeds by linear m -1. The incidence of weed plants was evaluated with a 0.5*0.5 m metal frame. The plants were counted and classified by narrow leaf (NL) and large leaf (LL). The soybean harvest was manual and its productivity was adjusted to 13% of water content. The experimental design was completely randomized, in split plot. The data were submitted to normality, while averages were compared by Scott and Knott test at 5% of significance. There was a possible suppressor allelopathic effect of BO and CO coverings on weed plants. The interval between desiccation and sowing interfered on weed population.

846. Performance of seed distribution mechanisms under different speeds and soil covering conditions.; Desempenho de mecanismos dosadores de sementes em diferentes velocidades e condicoes de cobertura do solo.

• Authors:
  • Scapim, C. A.
  • Lucca e Braccini, A. de
  • Pinheiro Neto, R.
  • Bortolotto, V. C.
  • Pinheiro, A. C.
• Source: Acta Scientiarum - Agronomy
• Volume: 30
• Issue: Suplemento Espec
• Year: 2008
• Summary: The objective of this work was to evaluate the performance of two seeders offered commercially for no-tillage. The assays were conducted at the Cazarotto Farm, located in the Iguatemi District, municipal district of Maringa, Parana State, in a HAPLOTOX Soil. Two experiments were set up: the first using a seeder with a horizontal plate distribution mechanism, and the second using a seeder with pneumatic-type mechanism. A split-plot design was used, with four replications. The main treatments were: soil covering conditions (spontaneous vegetation, desiccated black oat, and desiccated+rolled black oat); and the secondary treatments were the forward speeds (horizontal plate: 4.74, 5.41, 6.47 and 7.24 km h -1; and pneumatic: 5.56, 8.04 and 10.21 km h -1). With the increase in speed, the plant population and the percentage of acceptable spacings were reduced, and the recommended plant population was not reached by either seeder. The pneumatic mechanism obtained better results than the horizontal plate. The yield was larger where smaller populations were obtained, influenced by the water deficit.

847. Growth of Pinus elliottii and Eucalyptus tereticornis associated with cover plants, in degraded soils by arenization.; Desenvolvimento do Pinus elliottii e do Eucalyptus tereticornis consorciado com plantas de cobertura, em solos degradados por arenizacao.

• Authors:
  • Eltz, F.
  • Rovedder, A.
• Source: Ciencia Rural
• Volume: 38
• Issue: 1
• Year: 2008
• Summary: This study investigated the growth of Pinus elliottii and Eucalyptus tereticornis from Rio Grande do Sul, Brazil, and tested their capacity for reducing the arenization process. The treatments consisted of planting two species on: (i) arenization-degraded soil (DS); (ii) native grassland (C); (iii) native grassfield associated with cover crops (C+PC); and (iv) degraded soil associated with cover crops (DS+PC). Black oat ( Avena nuda) and Lupinus albescens were used as cover crops. The survival rate, height, basal diameter and productivity factor of tree species were obtained 30 days, 6 months and 12 months after planting. In relation to initial survival, only pine showed significant differences, with lower percentage in the treatment C+PC. Eucalyptus benefited from the consortium with cover crops, while pine presented higher sensibility to interspecific competition.

848. Agronomic and economic performance of maize irrigated in succession to winter cover crops and/or to species for grain production.; Desempenho agronomico e economico do milho irrigado em sucessao a especies invernais de cobertura de solo e/ou para producao de graos.

• Authors:
  • Jandrey, D.
  • Strieder, M.
  • Minetto, T.
  • Silva, P.
  • Silva, A.
  • Endrigo, P.
• Source: Ciencia Rural
• Volume: 38
• Issue: 3
• Year: 2008
• Summary: The growing of winter crop species results in benefits on soil characteristics, and can present economic advantages. Thus, it is important to introduce winter species that, besides straw, produce grains to increase the performance and the sustainability of agricultural activity. The objective of this research was to evaluate, in three growing seasons, the agronomic and economic performance of maize crop grown in succession to five winter cover crops and/or for grain production, cultivated under two rates of side dressing N fertilization. The experiment was carried out in the growing seasons of 2003/04, 2004/05 and 2005/06, in the state of Rio Grande do Sul, Brazil. In the three years, the treatments consisted of irrigated maize crop grown in succession to five winter cover crops species and to a control without cover crop. The maize cost production in succession to common vetch is lower than in succession to black oat and to wild radish. Comparing the winter cover crops for grain production, the gross income was higher when wheat was grown in relation to oat. The economic advantages of the use of wild radish and common vetch as previous crops to irrigated maize in relation to the poaceae species are only evident under conditions of low N availability in the soil.

849. Productivity of irrigated maize in succession to winter crops for straw and grain production.; Produtividade do milho irrigado em sucessao a especies invernais para producao de palha e graos.

• Authors:
  • Jandrey, D.
  • Strieder, M.
  • Piana, A.
  • Sangoi, L.
  • Silva, P.
  • Silva, A.
  • Endrigo, P.
• Source: PESQUISA AGROPECUARIA BRASILEIRA
• Volume: 43
• Issue: 8
• Year: 2008
• Summary: The objective of this work was to evaluate the productivity of irrigated maize, grown using several rates of nitrogen sidedress, in succession to different winter crops. The experiment was carried out in Eldorado do Sul, RS, Southern Brazil, during the 2003/2004, 2004/2005 and 2005/2006 growing seasons. Maize was sown in succession to five winter crops: black oat, common vetch, wild radish (straw production), white oat and wheat (grain and straw production), and to a control treatment, where the spontaneous vegetation was controlled by successive desiccant application. Maize grain yield was higher than 8 Mg ha -1 and was not affected by the specie of preceding winter crop, when nitrogen sidedress was applied. Maize grain yield was higher, when it succeeded wild radish and in the treatment without N in side-dressing. White oat and wheat added more than 3 Mg ha -1 of straw and produced more than 1.5 Mg ha -1 of grain. With supplementary irrigation and side-dress nitrogen application, it is possible to obtain high grain yield, when corn is cultivated as a sequential crop, independently of winter cover species.

850. Mechanisms of coulter of straw of direct planting seeder with different levels of applied vertical loads.; Mecanismos de corte de palha de uma semeadora-adubadora de plantio direto com diferentes niveis de cargas verticais aplicadas.

• Authors:
  • Benez, S.
  • Silva, P.
• Source: Energia na Agricultura
• Volume: 23
• Issue: 1
• Year: 2008
• Summary: This work had as objective evaluate the penetration depth of cut disks (flat, corrugated and wavy) of seeder in different vegetable coverings (corn, sorghum, black oats, triticale and grass) and applied vertical loads (750, 1500, 2250 and 3000 N). The work was developed at University of Agronomic Sciences - UNESP of Botucatu in a soil classified like NITOSSOLO VERMELHO distroferrico. The experimental design used was in blocks at random with factorial outline (3 coulter disks and 4 vertical loads) and 4 repetitions. The results showed that for all vegetable covering, as larger is the vertical load applied adult as larger is the penetration depth of the coulter disks. The wavy disk cut obtained the smallest values of penetration depth in relation to the others. This happened due to smaller cut pressure in the straw. The largest values of penetration depth of the cut disks were obtained for the covering with straw of nabica following by the triticale, black oats, corn and sorghum. The seeder should be regulated with minimum load of seed and fertilizer so that happen the cash cuts of the straw during the sowing process.